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by George Whale
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British Airships: Past, Present and Future
by George Whale
December, 1996 [Etext #762]
Project Gutenberg Etext of British Airships, Past/Present/Future
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This etext was created by Dianne Bean, Chino Valley, Arizona.
British Airships: Past, Present and Future
by George Whale (Late Major, R.A.F.)
CHAPTER I
INTRODUCTION
CHAPTER II
EARLY AIRSHIPS AND THEIR DEVELOPMENT TO THE PRESENT DAY
CHAPTER III
BRITISH AIRSHIPS BUILT BY PRIVATE FIRMS
CHAPTER IV
BRITISH ARMY AIRSHIPS
CHAPTER V
EARLY DAYS OF THE NAVAL AIRSHIP SECTION--
PARSEVAL AIRSHIPS, ASTRA-TORRES TYPE, ETC.
CHAPTER VI
NAVAL AIRSHIPS: THE NON-RIGIDS--
S.S. TYPE
COASTAL AND C STAR AIRSHIPS
THE NORTH SEA AIRSHIP
CHAPTER VII
NAVAL AIRSHIPS: THE RIGIDS
RIGID AIRSHIP NO. 1
RIGID AIRSHIP NO. 9
RIGID AIRSHIP NO. 23 CLASS
RIGID AIRSHIP NO. 23 X CLASS
RIGID AIRSHIP NO. 31 CLASS
RIGID AIRSHIP NO. 33 CLASS
CHAPTER VIII
THE WORK OF THE AIRSHIP IN THE WORLD WAR
CHAPTER IX
THE FUTURE OF AIRSHIPS
CHAPTER I
INTRODUCTION
Lighter-than-air craft consist of three distinct types:
Airships, which are by far the most important, Free Balloons, and
Kite Balloons, which are attached to the ground or to a ship by a
cable. They derive their appellation from the fact that when
charged with hydrogen, or some other form of gas, they are
lighter than the air which they displace. Of these three types
the free balloon is by far the oldest and the simplest, but it is
entirely at the mercy of the wind and other elements, and cannot
be controlled for direction, but must drift whithersoever the
wind or air currents take it. On the other hand, the airship,
being provided with engines to propel it through the air, and
with rudders and elevators to control it for direction and
height, can be steered in whatever direction is desired, and
voyages can be made from one place to another--always provided
that the force of the wind is not sufficiently strong to overcome
the power of the engines. The airship is, therefore, nothing
else than a dirigible balloon, for the engines and other weights
connected with the structure are supported in the air by an
envelope or balloon, or a series of such chambers, according to
design, filled with hydrogen or gas of some other nature.
It is not proposed, in this book, to embark upon a lengthy and
highly technical dissertation on aerostatics, although it is an
intricate science which must be thoroughly grasped by anyone who
wishes to possess a full knowledge of airships and the various
problems which occur in their design. Certain technical
expressions and terms are, however, bound to occur, even in the
most rudimentary work on airships, and the main principles
underlying airship construction will be described as briefly and
as simply as is possible.
The term "lift" will appear many times in the following pages,
and it is necessary to understand what it really means. The
difference between the weight of air displaced and the weight of
gas in a balloon or airship is called the "gross lift." The
term "disposable," or "nett" lift, is obtained by deducting the
weight of the structure, cars, machinery and other fixed weights
from the gross lift. The resultant weight obtained by this
calculation determines the crew, ballast, fuel and other
necessities which can be carried by the balloon or airship.
The amount of air displaced by an airship can be accurately
weighed, and varies according to barometric pressure and the
temperature; but for the purposes of this example we may take it
that under normal conditions air weighs 75 lb. per 1,000 cubic
feet. Therefore, if a balloon of 1,000 cubic feet volume is
charged with air, this air contained will weigh 75 lb. It is
then manifest that a balloon filled with air would not lift,
because the air is not displaced with a lighter gas.
Hydrogen is the lightest gas known to science, and is used in
airships to displace the air and raise them from the ground.
Hydrogen weighs about one-fifteenth as much as air, and under
normal conditions 1,000 cubic feet weighs 5 lb. Pursuing our
analogy, if we fill our balloon of 1,000 cubic feet with hydrogen
we find the gross lift is as follows:
1,000 cubic feet of air weighs 75 lb.
1,000 cubic feet of hydrogen weighs 5 lb.
------
The balance is the gross lift of the balloon 70 lb.
It follows, then, that apart from the weight of the structure
itself the balloon is 70 lb. lighter than the air it displaces,
and provided that it weighs less than 70 lb. it will ascend into
the air.
As the balloon or airship ascends the density of the air
decreases as the height is increased. As an illustration of this
the barometer falls, as everyone knows, the higher it is taken,
and it is accurate to say that up to an elevation of 10,000 feet
it falls one inch for every 1,000 feet rise. It follows that as
the pressure of the air decreases, the volume of the gas
contained expands at a corresponding rate. It has been shown
that a balloon filled with 1,000 feet of hydrogen has a lift of
70 lb. under normal conditions, that is to say, at a barometric
pressure of 80 inches. Taking the barometric pressure at 2
inches lower, namely 28, we get the following figures:
1,000 cubic feet of air weighs 70 lb.
1,000 cubic feet of hydrogen weighs 4.67 "
--------
65.33 lb.
It is therefore seen that the very considerable loss of lift,
4.67 lb. per 1,000 cubic feet, takes place with the barometric
pressure 2 inches lower, from which it may be taken approximately
that 1/30 of the volume gross lift and weight is lost for every
1,000 feet rise. From this example it is obvious that the
greater the pressure of the atmosphere, as indicated by the
barometer, the greater will be the lift of the airship or
balloon.
Temperature is another factor which must be considered while
discussing lift. The volume of gas is affected by temperature,
as gases expand or contract about 1/500 part for every degree
Fahrenheit rise or fall in temperature.
In the case of the 1,000 cubic feet balloon, the air at 30 inches
barometric pressure and 60 degrees Fahrenheit weighs 75 lb., and
the hydrogen weighs 5 lb.
At the same pressure, but with the temperature increased to 90
degrees Fahrenheit, the air will be expanded and 1,000 cubic feet
of air will weigh only 70.9 lb., while 1,000 cubic feet of
hydrogen will weigh 4.7 lb.
The lift being the difference between the weight of the volume of
air and the weight of the hydrogen contained in the balloon, it
will be seen that with the temperature at 60 degrees Fahrenheit
the lift is 75 lb. - 5 lb. = 70 lb., while the temperature,
having risen to 90 degrees, the lift now becomes 70.9 lb. - 4.7
lb. = 66.2 lb.
Conversely, with a fall in the temperature the lift is increased.
We accordingly find from the foregoing observations that at the
start of a voyage the lift of an airship may be expected to be
greater when the temperature is colder, and the greater the
barometric pressure so will also the lift be greater. To put
this into other words, the most favourable conditions for the
lift of an airship are when the weather is cold and the barometer
is high.
It must be mentioned that the air and hydrogen are not subject in
the same way to changes of temperature. Important variations in
lift may occur when the temperature of the gas inside the
envelope becomes higher, owing to the action of the sun, than the
air which surrounds it. A difference of some 20 degrees
Fahrenheit may result between the gas and the air temperatures;
this renders it highly necessary that the pilot should by able to
tell at any moment the relative temperatures of gas and air, as
otherwise a false impression will be gained of the lifting
capacity of the airship.
The lift of an airship is also affected by flying through snow
and rain. A considerable amount of moisture can be taken up by
the fabric and suspensions of a large airship which, however, may
be largely neutralized by the waterproofing of the envelope.
Snow, as a rule, is brushed off the surface by the passage of the
ship through the air, though in the event of its freezing
suddenly, while in a melting state, a very considerable addition
of weight might be caused. There have been many instances of
airships flying through snow, and as far as is known no serious
difficulty has been encountered through the adhesion of this
substance. The humidity of the air may also cause slight
variations in lift, but for rough calculations it may be ignored,
as the difference in lift is not likely to amount to more than
0.3 lb. per 1,000 cubic feet of gas.
The purity of hydrogen has an important effect upon the lift of
an airship. One of the greatest difficulties to be contended
with is maintaining the hydrogen pure in the envelope or gasbags
for any length of time. Owing to diffusion gas escapes with
extraordinary rapidity, and if the fabric used is not absolutely
gastight the air finds its way in where the gas has escaped. The
maximum purity of gas in an airship never exceeds 98 per cent by
volume, and the following example shows how greatly lift can be
reduced:
Under mean atmospheric conditions, which are taken at a
temperature of 55 degrees Fahrenheit, and the barometer at 29.5
inches, the lift of 1,000 cubic feet of hydrogen at 98 per cent
purity is 69.6 lb. Under same conditions at 80 per cent purity
the lift of 1,000 cubic feet of hydrogen is 56.9 lb., a resultant
loss of 12.9 lb. per 1,000 cubic feet.
The whole of this statement on "lift" can now be condensed into
three absolute laws:
1. Lift is directly proportional to barometric pressure.
2. Lift is inversely proportional to absolute temperature.
3. Lift is directly proportional to purity.
AIRSHIP DESIGN
The design of airships has been developed under three distinct
types, the Rigid, the Semi-Rigid, and the Non-Rigid.
The rigid, of which the German Zeppelin is the leading example,
consists of a framework, or hull composed of aluminium, wood,
or other materials from which are suspended the cars, machinery
and other weights, and which of itself is sufficiently strong to
support its own weight. Enclosed within this structure are a
number of gas chambers or bags filled with hydrogen, which
provide the necessary buoyancy. The hull is completely encased
within a fabric outer cover to protect the hull framework and
bags from the effects of weather, and also to temper the rays of
the sun.
The semi-rigid, which has been exploited principally by the
Italians with their Forlanini airships, and in France by Lebaudy,
has an envelope, in some cases divided into separate
compartments, to which is attached close underneath a long girder
or keel. This supports the car and other weights and prevents
the whole ship from buckling in the event of losing gas. The
semi-rigid type has been practically undeveloped in this country.
The non-rigid, of which we may now claim to be the leading
builders, is of many varieties, and has been developed in several
countries. In Germany the chief production has been that of
Major von Parseval, and of which one ship was purchased by the
Navy shortly before the outbreak of war. In the earliest
examples of this type the car was slung a long way from the
envelope and was supported by wires from all parts. This
necessitated a lofty shed for its accommodation as the ship was
of great overall height; but this difficulty was overcome by the
employment of the elliptical and trajectory bands, and is
described in the chapter dealing with No. 4.
A second system is that of the Astra-Torres. This envelope is
trilobe in section, with internal rigging, which enables the car
to be slung very close up to the envelope. The inventor of these
envelopes was a Spaniard, Senor Torres Quevedo, who manufactured
them in conjunction with the Astra Company in Paris. This type
of envelope has been employed in this country in the Coastal, C
Star, and North Sea airships, and has been found on the whole to
give good results. It is questionable if an envelope of
streamline shape would not be easier to handle, both in the air
and on the landing ground, and at present there are partisans of
both types.
Thirdly, there is the streamline envelope with tangential
suspensions, which has been adopted for all classes of the S.S.
airship, and which has proved for its purpose in every way highly
satisfactory.
Of these three types the rigid has the inherent disadvantage of
not being able to be dismantled, if it should become compelled
to make a forced landing away from its base. Even if it were so
fortunate as to escape damage in the actual landing, there is the
practical certainty that it would be completely wrecked
immediately any increase occurred in the force of the wind. On
the other hand, for military purposes, it possesses the advantage
of having several gas compartments, and is in consequence less
susceptible to damage from shell fire and other causes.
Both the semi-rigid and the non-rigid have the very great
advantage of being easily deflated and packed up. In addition to
the valves, these ships have a ripping panel incorporated in the
envelope which can easily be torn away and allows the gas to
escape with considerable rapidity. Innumerable instances have
occurred of ships being compelled to land in out-of-the-way
places owing to engine failure or other reasons; they have been
ripped and deflated and brought back to the station without
incurring any but the most trifling damage.
Experience in the war has proved that for military purposes the
large rigid, capable of long hours of endurances and the small
non-rigid made thoroughly reliable, are the most valuable types
for future development. The larger non-rigids, with the possible
exception of the North Sea, do not appear to be likely to fulfil
any very useful function.
Airship design introduces so many problems which are not met with
in the ordinary theory of structures, that a whole volume could
easily be devoted to the subject, and even then much valuable
information would have to be omitted from lack of space. It is,
therefore, impossible, in only a section of a chapter, to do more
than indicate in the briefest manner a few salient features
concerning these problems. The suspension of weights from the
lightest possible gas compartment must be based on the ordinary
principles of calculating the distribution loads as in ships and
other structures. In the non-rigid, the envelope being made of
flexible fabric has, in itself, no rigidity whatsoever, and its
shape must be maintained by the internal pressure kept slightly
in excess of the pressure outside. Fabric is capable of
resisting tension, but is naturally not able to resist
compression. If the car was rigged beneath the centre of the
envelope with vertical suspensions it would tend to produce
compression in the underside of the envelope, owing to the load
not being fully distributed. This would cause, in practice, the
centre portion of the envelope to sag downwards, while the ends
would have a tendency to rise. The principle which has been found
to be most satisfactory is to fix the points of suspension
distributed over the greatest length of envelope possible
proportional to the lift of gas at each section thus formed.
From these points the wires are led to the car. If the car is
placed close to the envelope it will be seen that the suspensions
of necessity lie at a very flat angle and exert a serious
longitudinal compression. This must be resisted by a high
internal pressure, which demands a stouter fabric for the
envelope and, therefore, increased weight. It follows that the
tendency of the envelope to deform is decreased as the distance
of the car from the gas compartment is increased.
One method of overcoming this difficulty is found by using the
Astra-Torres design. As will be seen from the diagram of the
North Sea airship, the loads are excellently distributed by the
several fans of internal rigging, while external head resistance
is reduced to a minimum, as the car can be slung close underneath
the envelope. Moreover, the direct longitudinal compression due
to the rigging is applied to a point considerably above the axis
of the ship. In a large non-rigid many of these difficulties can
be overcome by distributing the weight into separate cars along
the envelope itself.
We have seen that as an airship rises the gas contained in the
envelope expands. If the envelope were hermetically sealed, the
higher the ship rose the greater would become the internal
pressure, until the envelope finally burst. To avoid this
difficulty in a balloon, a valve is provided through which the
gas can escape. In a balloon, therefore, which ascends from the
ground full, gas is lost throughout its upward journey, and when
it comes down again it is partially empty or flabby. This would
be an impossible situation in the case of the airship, for she
would become unmanageable, owing to the buckling of the envelope
and the sagging of the planes. Ballonets are therefore fitted to
prevent this happening.
Ballonets are internal balloons or air compartments fitted inside
the main envelope, and were originally filled with air by a
blower driven either by the main engines or an auxiliary motor.
These blowers were a continual source of trouble, and at the
present day it has been arranged to collect air from the
slip-stream of the propeller through a metal air scoop or
blower-pipe and discharge it into an air duct which distributes
it to the ballonets.
The following example will explain their functions:
An airship ascends from the ground full to 1,000 feet. The
ballonets are empty, and remain so throughout the ascent. By the
time the airship reaches 1,000 feet it will have lost 1/30th of
its volume of gas which will have escaped through the valves. If
the ship has a capacity of 300,000 cubic feet it will have lost
10,000 cubic feet of gas. The airship now commences to descend;
as it descends the gas within contracts and air is blown into the
ballonets. By the time the ground is reached 10,000 cubic feet
of air will have been blown into the ballonets and the airship
will have retained its shape and not be flabby.
On making a second ascent, as the airship rises the air must be
let out of the ballonet instead of gas from the envelope, and by
the time 1,000 feet is reached the ballonets will be empty. To
ensure that this is always done the ballonet valves are set to
open at less pressure than the gas valves.
It therefore follows in the example under consideration that it
will not be necessary to lose gas during flight, provided that an
ascent is not made over 1,000 feet.
Valves are provided to prevent the pressure in the envelope from
exceeding a certain determined maximum and are fitted both to
ballonets and the gaschamber. They are automatic in action, and,
as we have said, the gas valve is set to blow off at a pressure
in excess of that for the air valve.
In rigid airships ballonets are not provided for the gasbags, and
as a consequence a long flight results in a considerable
expenditure of gas. If great heights are required to be reached,
it is obvious that the wastage of gas would be enormous, and it
is understood that the Germans on starting for a raid on England,
where the highest altitudes were necessary, commenced the flight
with the gasbags only about 60 per cent full.
To stabilize the ship in flight, fins or planes are fitted to the
after end of the envelope or hull. Without the horizontal planes
the ship will continually pitch up and down, and without the
vertical planes it will be found impossible to keep the ship on a
straight course. The planes are composed of a framework covered
with fabric and are attached to the envelope by means of stay
wires fixed to suitable points, in the case of non-rigid ships
skids being employed to prevent the edge of the plane forcing its
way through the surface of the fabric. The rudder and elevator
flaps in modern practice are hinged to the after edges of the
planes.
The airship car contains all instruments and controls required
for navigating the ship and also provides a housing for the
engines. In the early days swivelling propellers were considered
a great adjunct, as with their upward and downward thrust they
proved of great value in landing. Nowadays, owing to greater
experience, landing does not possess the same difficulty as in
the past, and swivelling propellers have been abandoned except in
rigid airships, and even in the later types of these they have
been dispensed with.
Owing to the great range of an airship a thoroughly reliable
engine is a paramount necessity. The main requirements
are--firstly, that it must be capable of running for long periods
without a breakdown; secondly, that it must be so arranged that
minor repairs can be effected in the air; and thirdly, that
economy of oil and fuel is of far greater importance to an
airship than the initial weight of the engine itself.
HANDLING AND FLYING OF AIRSHIPS
The arrangements made for handling airships on the ground and
while landing, and also for moving them in the open, provide
scope for great ingenuity. An airship when about to land is
brought over the aerodrome and is "ballasted up" so that she
becomes considerably lighter than the air which she displaces.
The handling party needs considerable training, as in gusty
weather the safety of the ship depends to a great extent upon its
skill in handling her. The ship approaches the handling party
head to wind and the trail rope is dropped; it is taken by the
handling party and led through a block secured to the ground and
the ship is slowly hauled down. When near the ground the
handling party seize the guys which are attached to the ship at
suitable points, other detachments also support the car or cars,
as the case may be, and the ship can then be taken into the shed.
In the case of large airships the size of the handling party has
to be increased and mechanical traction is also at times
employed.
As long as the airship is kept head to wind, handling on the
ground presents little difficulty; on many occasions, however,
unless the shed is revolving, as is the case on certain stations
in Germany, the wind will be found to be blowing across the
entrance to the shed. The ship will then have to be turned, and
during this operation, unless great discretion is used, serious
trouble may be experienced.
Many experiments have been and are still being conducted to
determine the best method of mooring airships in the open. These
will be described and discussed at some length in the chapter
devoted to the airship of the future.
During flight certain details require attention, and carelessness
on the pilot's part, even on the calmest of days, may lead to
disaster. The valves and especially the gas valves should be
continually tested, as on occasions they have been known to jam,
and the loss of gas has not been discovered until the ship had
become unduly heavy.
Pressure should be kept as constant as possible. Most airships
work up to 30 millimetres as a maximum and 15 millimetres as a
minimum flying pressure. During a descent the pressure should be
watched continuously, as it may fall so low as to cause the nose
to blow in. This will right itself when the speed is reduced or
the pressure is raised, but there is always the danger of the
envelope becoming punctured by the bow stiffeners when this
occurs.
HOUSING ACCOMMODATION FOR AIRSHIPS, ETC.
During the early days of the war, when stations were being
equipped, the small type of airship was the only one we
possessed. The sheds to accommodate them were constructed of
wood both for cheapness and speed of construction and erection.
These early sheds were all of very similar design, and were
composed of trestles with some ordinary form of roof-truss. They
were covered externally with corrugated sheeting. The doors have
always been a source of difficulty, as they are compelled to open
for the full width of the shed and have to stand alone without
support. They are fitted with wheels which run on guide rails,
and are opened by means of winches and winding gear.
The later sheds built to accommodate the rigid airship are of
much greater dimensions, and are constructed of steel, but
otherwise are of much the same design.
The sheds are always constructed with sliding doors at either
end, to enable the ship to be taken out of the lee end according
to the direction of the wind.
It has been the practice in this country to erect windscreens in
order to break the force of the wind at the mouth of the shed.
These screens are covered with corrugated sheeting, but it is a
debatable point as to whether the comparative shelter found at
the actual opening of the shed is compensated for by the eddies
and air currents which are found between the screens themselves.
Experiments have been carried out to reduce these disturbances,
in some cases by removing alternate bays of the sheeting and in
other cases by substituting expanded metal for the original
corrugated sheets.
It must be acknowledged that where this has been done, the
airships have been found easier to handle.
At the outbreak of war, with the exception of a silicol plant at
Kingsnorth, now of obsolete type, and a small electrolytic plant
at Farnborough, there was no facility for the production of
hydrogen in this country for the airship service.
When the new stations were being equipped, small portable silicol
plants were supplied capable of a small output of hydrogen.
These were replaced at a later date by larger plants of a fixed
type, and a permanent gas plant, complete with gasholders and
high pressure storage tanks was erected at each station, the
capacity being 5,000 or 10,000 cubic feet per hour according to
the needs of the station.
With the development of the rigid building programme, and the
consequent large requirements of gas, it was necessary to
reconsider the whole hydrogen situation, and after preliminary
experimental work it was decided to adopt the water gas contact
process, and plants of this kind with a large capacity of
production were erected at most of the larger stations. At
others electrolytic plants were put down. Hydrogen was also
found to be the bye-product of certain industries, and
considerable supplies were obtained from commercial firms, the
hydrogen being compressed into steel cylinders and dispatched to
the various stations.
Before concluding this chapter, certain words must be written on
parachutes. A considerable controversy raged in the press and
elsewhere a few months before the cessation of hostilities on the
subject of equipping the aeroplane with parachutes as a
life-saving device. In the airship service this had been done
for two years. The best type of parachute available was
selected, and these were fitted according to circumstances in
each type of ship. The usual method is to insert the parachute,
properly folded for use, in a containing case which is fastened
either in the car or on the side of the envelope as is most
convenient. In a small ship the crew are all the time attached to
their parachutes and in the event of the ship catching fire have
only to jump overboard and possess an excellent chance of being
saved. In rigid airships where members of the crew have to move
from one end of the ship to the other, the harness is worn and
parachutes are disposed in the keel and cars as are lifebuoys in
seagoing vessels. Should an emergency arise, the nearest
parachute can be attached to the harness by means of a spring
hook, which is the work of a second, and a descent can be made.
It is worthy of note that there has never been a fatal accident
or any case of a parachute failing to open properly with a man
attached.
The material embodied in this chapter, brief and inadequate as it
is, should enable the process of the development of the airship
to be easily followed. Much has been omitted that ought by right
to have been included, but, on the other hand, intricate
calculations are apt to be tedious except to mathematicians, and
these have been avoided as far as possible in the following
pages.
CHAPTER II
EARLY AIRSHIPS AND THEIR DEVELOPMENT TO THE PRESENT DAY
The science of ballooning had reached quite an advanced stage by
the middle of the eighteenth century, but the construction of
an airship was at that time beyond the range of possibility.
Discussions had taken place at various times as to the
practicability of rendering a balloon navigable, but no attempts
had been made to put these points of argument to a practical
test.
Airship history may be said to date from January 24th, 1784. On
that day Brisson, a member of the Academy in Paris, read before
that Society a paper on airships and the methods to be utilized
in propelling them. He stated that the balloon, or envelope as
it is now called, must be cylindrical in shape with conical ends,
the ratio of diameter to length should be one to five or one to
six and that the smallest cross-sectional area should face the
wind. He proposed that the method of propulsion should be by
oars, although he appeared to be by no means sanguine if human
strength would be sufficient to move them. Finally, he referred
to the use of different currents of the atmosphere lying one
above the other.
This paper caused a great amount of interest to be taken in
aeronautics, with the result that various Frenchmen turned their
attention to airship design and production. To France must be
due the acknowledgment that she was the pioneer in airship
construction and to her belongs the chief credit for early
experiments.
At a later date Germany entered the lists and tackled the
problems presented with that thoroughness so characteristic of
the nation. It is just twenty-one years ago since Count
Zeppelin, regardless of public ridicule, commenced building his
rigid airships, and in that time such enormous strides were made
that Germany, at the outbreak of the war, was ahead of any other
country in building the large airship.
In 1908 Italy joined the pioneers, and as regards the semi-rigid
is in that type still pre-eminent. Great Britain, it is rather
sad to say, adopted the policy of "wait and see," and, with the
exception of a few small ships described in the two succeeding
chapters, had produced nothing worthy of mention before the
outbreak of the great European war. She then bestirred herself,
and we shall see later that she has produced the largest fleet of
airships built by any country and, while pre-eminent with the
non-rigid, is seriously challenging Germany for the right to say
that she has now built the finest rigid airship.
FRANCE
To revert to early history, in the same year in which Brisson
read his paper before the Academy, the Duke of Chartres gave the
order for an airship to the brothers Robert, who were mechanics
in Paris. This ship was shaped like a fish, on the supposition
that an airship would swim through the air like a fish through
water. The gas-chamber was provided with a double envelope, in
order that it might travel for a long distance without loss of
gas.
The airship was built in St. Cloud Park; in length it was 52 feet
with a diameter of 82 feet, and was ellipsoidal in shape with a
capacity of 30,000 cubic feet. Oars were provided to propel it
through the air, experiments having proved that with two oars of
six feet diameter a back pressure of 90 lb. was obtained and with
four oars 140 lb.
On July 6th in the same year the first ascent was made from St.
Cloud. The passengers were the Duke of Chartres, the two
brothers Robert and Colin-Hulin. No valves having been fitted,
there was no outlet for the expansion of gas and the envelope was
on the point of bursting, when the Duke of Chartres, with great
presence of mind, seized a pole and forced an opening through
both the envelopes. The ship descended in the Park of Meudon.
On September 19th the airship made a second ascent with the same
passengers as before, with the exception of the Duke. According
to the report of the brothers Robert, they succeeded in
completing an ellipse and then travelled further in the direction
of the wind without using the oars or steering arrangements.
They then deviated their course somewhat by the use of these
implements and landed at Bethune, about 180 miles distant from
Paris.
In those days it was considered possible that a balloon could be
rendered navigable by oars, wings, millwheels, etc., and it was
not until the last decades of the nineteenth century, when light
and powerful motors had been constructed, that the problem became
really practical of solution.
During the nineteenth century several airships were built in
France and innumerable experiments were carried out, but the
vessels produced were of little real value except in so far as
they stimulated their designers to make further efforts. Two of
these only will be mentioned, and that because the illustrations
show how totally different they were from the airship of to-day.
In 1834 the Compte de Lennox built an airship of 98,700 cubic
feet capacity. It was cylindrical in form with conical ends, and
is of interest because a small balloon or ballonet, 7,050 cubic
feet contents, was placed inside the larger one for an air
filling. A car 66 feet in length was rigged beneath the envelope
by means of ropes eighteen inches long. Above the car the
envelope was provided with a long air cushion in connection with
a valve. The intention was by compression of the air in the
cushion and the inner balloon, to alter the height of the
airship, in order to travel with the most favourable air
currents. The motive power was 20 oar propellers worked by men.
This airship proved to be too heavy on completion to lift its own
weight, and was destroyed by the onlookers.
The next airship, the Dupuy de Lome, is of interest because the
experiments were carried out at the cost of the State by the
French Government. This ship consisted of a spindle-shaped
balloon with a length of 112 feet, diameter of 48 1/2 feet and a
volume of 121,800 cubic feet. An inner air balloon of 6,000
cubic feet volume was contained in the envelope. The method of
suspension was by means of diagonal ropes with a net covering. A
rudder in the form of a triangular sail was fitted beneath the
envelope and at the after part of the ship. The motive power was
double-winged screws 29 feet 6 inches diameter, to be worked by
four to eight men.
On her trials the ship became practically a free balloon, an
independent velocity of about six miles per hour being achieved
and deviation from the direction of the wind of ten degrees.
At the close of the nineteenth century Santos-Dumont turned his
attention to airships. The experiments which he carried out
marked a new epoch and there arose the nucleus of the airship as
we know it to-day. Between the years 1898 and 1905 he had in all
built fourteen airships, and they were continually improved as
each succeeding one made its appearance. In the last one he
made a circular flight; starting from the aerodrome of the aero
club, he flew round the Eiffel Tower and back to the starting
point in thirty-one minutes on October 19th, 1902. For this feat
the Deutsch prize was awarded to him.
The envelopes he used were in design much nearer approach to a
streamline form than those previously adopted, but tapered to an
extremely fine point both at the both and stem. For rigging he
employed a long nacelle, in the centre of which was supported the
car, and unusually long suspensions distributed the weight
throughout practically the entire length of the envelope. To the
name of Santos-Dumont much credit is due. He may be regarded as
the originator of the airship for pleasure purposes, and by his
success did much to popularize them. He also was responsible to
a large extent for the development and expansion of the airship
industry in Paris.
At a little later date, in 1902 to be precise, the Lebaudy
brothers, in conjunction with Julliot, an engineer, and Surcoup,
an aeronaut, commenced building an airship of a new type. This
ship was a semirigid and was of a new shape, the envelope
resembling in external appearance a cigar. In length it was 178
feet with a diameter of 30 feet and the total capacity was 64,800
cubic feet. This envelope was attached to a rigid elliptical
keel-shaped girder made of steel tubes, which was about a third
of the length of the ship. The girder was covered with a
shirting and intended to prevent the ship pitching and rolling
while in flight. A horizontal rudder was attached to the under
side of this girder, while right aft a large vertical rudder was
fixed.
A small car was suspended by steel rods at a distance of 17 feet
9 inches from the girder, with a framework built up underneath to
absorb the shock on landing.
A 35 horse-power Daimler-Mercedes motor, weighing some 800 lb.
without cooling water and fuel, drove two twin-bladed propellers
on either side of the car.
In the year 1903 a number of experimental flights were made with
this ship and various details in the construction were
continually introduced. The longest flight was 2 hours 46
minutes. Towards the end of that year, while a voyage was being
made from Paris to Chalais Meudon, the airship came in contact
with a tree and the envelope was badly torn.
In the following year it was rebuilt, and the volume was slightly
increased with fixed and movable planes added to increase the
stability. After several trips had been made, the airship again
on landing came in contact with a tree and was burst.
The ship was rebuilt and after carrying out trials was purchased
by the French Army. The Lebaudy airship had at that time been a
distinct success, and in 1910 one was purchased for the British
Government by the readers of the Morning Post.
In the ten-ton Lebaudy the length of the keel framework was
greatly extended, and ran for very nearly the full length of the
envelope. The disadvantage of this ship was its slowness,
considering its size and power, and was due to the enormous
resistance offered by the framework and rigging.
Airships known as the "Clement-Bayard" were also built about this
time. They were manufactured by the Astra Company in conjunction
with Monsieur Clement, a motor engineer.
In later days vessels were built by the Astra Company of the
peculiar design introduced by Senor Torres. These ships, some of
which were of considerable size, were highly successful, and we
became purchasers at a later date of several.
The Zodiac Company also constructed a number of small ships which
were utilized during the war for anti-submarine patrol. It
cannot be said, however, that the French have fulfilled their
early promise as airship designers, the chief reason for this
being that the airship is peculiarly suitable for work at sea and
the French relied on us to maintain the commerce routes on the
high seas and concentrated their main efforts on defeating the
Germans in the field, in which as all the world acknowledges they
were singularly successful and hold us under an eternal
obligation.
GERMANY
The progress and development of the airship in Germany must now
be considered; it will be seen that, although the production of
satisfactory ships was in very few hands, considerable success
attended their efforts in the early days of the twentieth
century.
In 1812, Leppig built an airship at the cost of the State at
Woronzowo in Russia. This was of the shape of a fish with a
rigid framework beginning at the height of the longitudinal axis.
The lower keel-shaped part of the same formed the car. Two fans
were attached to the sides and a tail piece was provided behind
to act as a rudder. The ship was inflated, but structural damage
occurred during this operation and rendered it incapable of
flight.
In 1836, Georg Rebenstein, of Nurnburg, was considering the use
of the fall of inclined planes to obtain horizontal motion.
Nothing of importance was produced until a much later date. when
in 1885 M. Wolf constructed an envelope of 26,500 cubic feet. An
engine and propeller were fixed in a triangular framework in
front of the airship, supported by the steam pipe of a steam
engine fixed under the body of the envelope. The framework
lacked rigidity, and the envelope tore during inflation and the
airship failed to ascend.
In the following year Dr. Woelfert, of Berlin, produced a
cigar-shaped envelope, to which was attached rigidly a long
bamboo framework containing the car. An 8 horse-power benzine
Daimler motor drove a twin-bladed aluminium propeller, and
another propeller for vertical movement was provided beneath the
car. Four trial flights were attempted, but on each occasion the
motor gave unsatisfactory results, and Woelfert sought to improve
it with a benzine vaporizer of his own pattern. This improvement
was not a success, as during the last flight an explosion took
place and both Woelfert and an aeronaut named Knabe, who was
accompanying him, were killed.
In 1906, Major von Parseval experimented, in Berlin, with a
non-rigid type of airship. His first ship had a volume of 65,200
cubic feet, but owing to his system of suspensions, the car hung
27 feet 6 inches below the envelope. A Daimler engine was used,
driving a four-bladed propeller. Owing to the great overall
height of this ship, experiments were made to determine a system
of rigging, enabling the car to be slung closer to the envelope,
and in later types the elliptical rigging girdle was adopted.
His later ships were of large dimensions and proved very
satisfactory. About the same time Major Gross also built
airships for the German aeronautical battalion.
It is, however, the rigid airship that has made Germany famous,
and we must now glance at the evolution of these ships with which
we became so familiar during the war.
The first rigid airship bearing any resemblance to those of the
present day was designed by David Schwartz, and was built in St.
Petersburg in 1893. It was composed of aluminium plates riveted
to an aluminium framework. On inflation, the frame-work
collapsed and the ship was unusable.
In 1895 he designed a second rigid airship, which was built in
Berlin by Messrs. Weisspfennig and Watzesch. The hull framework
was composed of aluminium and was 155 feet long, elliptical in
cross section, giving a volume of 130,500 cubic feet. It was
pointed in front and rounded off aft. The car, also constructed
of the same material, was rigidly attached to the hull by a
lattice framework, and the whole hull structure was covered in
with aluminium sheeting. A 12 horse-power Daimler benzine motor
was installed in the car, driving through the medium of a belt
twin aluminium screw propellers; no rudders were supplied, the
steering being arranged by means of a steering screw placed
centrally to the ship above the top of the car. Inflation took
place at the end of 1897 by a method of pressing out air-filled
fabric cells which were previously introduced into the hull.
This operation took three and a half hours. On the day of the
first flight trials there was a fresh wind of about 17 miles per
hour. The airship ascended into the air, but, apparently, could
make little headway against the wind. During the trip the
driving-belt became disengaged from the propellers and the ship
drifted at the mercy of the wind, but sustained little damage on
landing. After being deflated, the hull began to break up under
the pressure of the wind and was completely destroyed by the
vandalism of the spectators.
In 1898 Graf F. von Zeppelin, inspired by the example of
Schwartz, and assisted by the engineers Kober and Kubler,
conceived the idea of constructing a rigid airship of
considerable dimensions. For this purpose a floating shed was
built on Lake Constance, near to Friedrichshafen. The hull was
built of aluminium lattice-work girders, and had the form of a
prism of twenty-four surfaces with arch-shaped ends. In length
it was 420 feet, with a diameter of 38 feet 6 inches, and its
capacity was 400,000 cubic feet. The longitudinal framework was
divided by a series of rings, called transverse frames, into
seventeen compartments containing fabric gasbags. The transverse
frames were fitted with steel wire bracings, both radial and
chord, and to strengthen the whole a triangular aluminium keel
of lattice work was used. A vertical and horizontal rudder were
fitted to the forward portion of the ship, and aft another
vertical rudder. The whole exterior of the ship was fitted with
a fabric outer cover.
Two aluminium cars, each about 20 feet long, were rigidly
attached to the framework of the hull. Each car was furnished
with a 16 horse-power Daimler engine, driving two four-bladed
screw propellers of aluminium sheeting. These propellers were
situated on the side of the hull at the centre of resistance.
The transmission was supplied by steel tubes with universal cross
joints through the medium of bevel gears. Reversible driving
arrangements were installed in the cars in order that the ship
could be driven backwards and forwards. Electric bells,
telegraphs, and speaking tubes were also fitted, and it can be
seen that for general arrangements this airship was a long way
ahead of any built at that date.
The first flight was made on July 2nd, 1900. The ship attained a
speed of 17 per hour, and the numerous technical details stood
the tests well. The stability was considered sufficient, and the
height of flight could be altered by the horizontal rudder. The
landing on the water was accomplished without difficulty, and
could be regarded as free from danger. The faults requiring
remedy were, firstly, the upper cross stays, which buckled in
flight owing to insufficient strength for the length of the hull;
secondly, the gasbags were not sufficiently gastight and,
thirdly, the power of the engines were not sufficient for such a
heavy ship.
This airship was broken up in 1902.
In 1905 the second ship of the series was completed. She was of
nearly the same size as the previous ship, but the workmanship
was much superior. Increased engine-power was also supplied, as
in this instance two 85 horse-power Mercedes engines were fitted.
This ship was destroyed by a storm while landing during the next
year.
The third ship, which was completed in 1906, was the first
Zeppelin airship acquired by the Government, and lasted for a
considerable time, being rebuilt twice, first in 1908 and again
in 1911. She was slightly larger than the previous two.
The building was continued, and up to the outbreak of war no
fewer than twenty-five had been completed. It is impossible, in
the space at our disposal, to trace the career of all of them.
Several came to an untimely end, but as the years went by each
succeeding ship proved more efficient, and the first ship which
was delivered to the Navy performed the notable flight of
thirty-one hours.
To revert, for a moment, once more to the earlier ships--the
fourth was wrecked and burned at Echterdingen in the same year in
which she was completed. The fifth, which was the second
military airship, was fitted with two 110 horse-power engines and
also came to a tragic end, being destroyed by wind at Weilberg in
1910, and the following ship was burnt at Baden in the same year.
The seventh ship was the first passenger airship of the series,
and was known as the Deutschland. By this time the capacity had
increased to 536,000 cubic feet, and she was propelled by three
120 horse-power engines. She also fell a victim to the wind, and
was wrecked in the Teutoberg Forest in 1910; and yet another was
destroyed in the following year at Dusseldorf.
The tenth ship to be completed was the passenger ship Schwaben;
her capacity was 636,500 cubic feet, and she had three 150
horse-power engines. This ship carried out her first flight in
June, 1911, and was followed four months later by the Victoria
Luise. The fourth passenger airship was known as the Hansa.
These three ships were all in commission at the outbreak of war.
The first naval airship, L 1, mentioned above, was larger than
any of these. The total length was 525 feet, diameter 50 feet,
and cubic contents 776,000 cubic feet. Her hull framework in
section formed a regular polygon of seventeen sides, and was
built up of triangular aluminium girders. The gasbags were
eighteen in number. This ship was fitted with three 170
horse-power Maybach engines, which were disposed as follows--one
in the forward car, driving two two-bladed propellers; two in the
after car, each driving a single four-bladed propeller. For
steering purposes she had six vertical and eight horizontal
planes. The total lift was 27 tons, with a disposable lift of 7
tons. Her speed was about 50 miles per hour, and she could carry
fuel for about 48 hours. Her normal crew consisted of fourteen
persons, including officers.
It will probably be remembered that the military Zeppelin Z III
was compelled to make a forced landing in France. This ship was
of similar construction to L 1, but of smaller volume, her
capacity being 620,000 cubic feet. A trial flight was being
carried out, and while above the clouds the crew lost their
bearings. Descending they saw some French troops and rose again
immediately. After flying for four hours they thought they must
be safely over the frontier and, running short of petrol, made a
landing--not knowing that they were still in France until too
late. The airship was taken over by the French authorities.
Until the year 1916 the Zeppelin may be considered to have passed
through three stages of design. Of the twenty-five ships
constructed before the war, twenty-four were of the first type
and one of the second. Each type possessed certain salient
features, which, for simplicity, will be set out in the form of a
tabulated statement, and may be useful for comparison when our
own rigid airships are reviewed.
Stage 1.
Long parallel portion of hull with bluff nose and tail.
External keel with walking way.
Box rudders and elevators.
Two cars.
Four wing propellers.
Stage 2.
Long parallel portion of hull with bluff nose, tail portion
finer than in Stage I
Internal keel walking way.
Box rudders and elevators.
Three cars, foremost for control only.
Four wing propellers.
Stage 3.
Shorter parallel portion of hull framework, bluff nose and
tapering tail.
Internal keel walking way.
Balanced monoplane rudders and elevators.
Three cars, foremost for control only.
Two foremost cars close together and connected by
a canvas joint to look like one car.
Four engines and four propellers. One engine in forward
car driving pusher propeller. Three engines in after
car driving two wing and one pusher propeller.
To the second stage belongs naval airship L 2, which was
destroyed by fire a month after completion in 1913. In 1916 a
fourth stage made its appearance, of which the first ship was L
30, completed in May, and to which the ill-fated L 33 belonged.
This type is known as the super-Zeppelin, and has been developed
through various stage until L 70, the latest product before the
armistice. In this stage the following are its main features:
Stage 4.
Short parallel portion of hull, long rounded bow and
long tapering stern. In all respects a good
streamline shape.
Internal keel walking way.
Balanced monoplane rudders and elevators.
Five cars. Two forward (combined as in Stage 3),
one aft, and two amidships abreast.
Six engines and six propellers. The after one of the
forecar and the sidecars each contain one engine
driving direct a pusher propeller. The after car
contains three engines, two of which drive two wing
propellers; the third, placed aft, drives direct a
pusher propeller.
In this stage the type of girders was greatly altered.
A company known as the Schutte-Lanz Company was also responsible
for the production of rigid airships. They introduced a design,
which was a distinct departure from Zeppelin or anyone else. The
hull framework was composed of wood, the girders being built up
of wooden sections. The shape of these ships was much more of a
true streamline than had been the Zeppelin practice, and it was
on this model that the shape of the super-Zeppelin was based.
These ships proved of use and took part in raids on this country,
but the Company was taken over by the Government and the
personnel was amalgamated with that engaged on Zeppelin
construction during the war.
ITALY
In 1908, Italy, stimulated by the progress made by other
continental nations, commenced experimental work. Three types
were considered for a commencement, the P type or Piccolo was the
first effort, then followed the M type, which signifies "medium
sized," and also the semirigid Forlanini.
In the Forlanini type the envelope is divided into several
compartments with an internal rigid keel and to-day these ships
are of considerable size, the most modem being over 600,000 cubic
feet capacity. During the war, Italian airships were developed
on entirely dissimilar lines to those in other countries. Both
we and our Allies, and to a great extent the Germans, employed
airships exclusively for naval operations; on the other hand, the
Italian ships were utilized for bombing raids in conjunction with
military evolutions.
For this reason height was of primary importance and speed was
quite a secondary consideration, owing to the low velocity of
prevailing winds in that country. Flights were never of long
duration compared with those carried out by our airships. Height
was always of the utmost importance, as the Italian ships were
used for bombing enemy towns and must evade hostile gunfire. For
this reason weight was saved in every possible manner, to
increase the height of the "ceiling."
In addition to the types already mentioned, three other varieties
have been constructed since the war--the Usuelli D.E. type and G
class. The G class was a rigid design which has not been
proceeded with, and, with this single exception, all are of a
semirigid type in which an essentially non-rigid envelope is
reinforced by a metal keel. In the Forlanini and Usuelli types
the keel is completely rigid and assists in maintaining the shape
of the envelopes, and in the Forlanini is enclosed within the
envelope. In the other types the keel is in reality a chain of
rigid links similar to that of a bicycle. The form of the
envelope is maintained by the internal pressure and not by the
keel, but the resistance of the latter to compression enables a
lower pressure to be maintained than would be possible in a
purely non-rigid ship.
The M type ship is of considerable size, the P smaller, while the
D.E. is a small ship comparable to our own S.S. design. The
review of these three countries brings the early history of
airships to a conclusion. Little of importance was done
elsewhere before the war, though Baldwin's airship is perhaps
worthy of mention. It was built in America in 1908 by Charles
Baldwin for the American Government. The capacity of the
envelope was 20,000 cubic feet, she carried a crew of two, and
her speed was 16 miles per hour. She carried out her trial
flight in August, 1908, and was accepted by the American military
authorities. During the war both the naval and military
authorities became greatly interested in airships, and purchased
several from the French and English. In addition to this a ship
in design closely resembling the S.S. was built in America, but
suffered from the same lack of experience which we did in the
early days of airship construction.
We must now see what had been happening in this country in those
fateful years before the bombshell of war exploded in our midst.
CHAPTER III
BRITISH AIRSHIPS BUILT BY PRIVATE FIRMS
It has been shown in the previous chapter that the development of
the airship had been practically neglected in England prior to
the twentieth century. Ballooning had been carried out both as a
form of sport and also by the showman as a Saturday afternoon's
sensational entertainment, with a parachute descent as the piece
de resistance. The experiments in adapting the balloon into the
dirigible had, however, been left to the pioneers on the
Continent.
PARTRIDGE'S AIRSHIP
It appears that in the nineteenth century only one airship was
constructed in this country, which proved to be capable of
ascending into the air and being propelled by its own machinery.
This airship made its appearance in the year 1848, and was built
to the designs of a man named Partridge. Very little information
is available concerning this ship. The envelope was cylindrical
in shape, tapering at each end, and was composed of a light rigid
framework covered with fabric. The envelope itself was covered
with a light wire net, from which the car was suspended. The
envelope contained a single ballonet for regulating the pressure
of the gas. Planes, which in design more nearly resembled sails,
were used for steering purposes. In the car, at the after end,
were fitted three propellers which were driven by compressed air.
Several trips of short duration were carried out in this airship,
but steering was never successfully accomplished owing to
difficulties encountered with the planes, and, except in weather
of the calmest description, she may be said to have been
practically uncontrollable.
HUGH BELL'S AIRSHIP
In the same year, 1848, Bell's airship was constructed. The
envelope of this ship was also cylindrical in shape, tapering at
each end to a point, the length of which was 56 feet and the
diameter 21 feet 4 inches. A keel composed of metal tubes was
attached to the underside of the envelope from which the car was
suspended. On either side of the car screw propellers were
fitted to be worked by hand. A rudder was attached behind the
car. It was arranged that trials should be carried out in the
Vauxhall Gardens in London, but these proved fruitless.
BARTON'S AIRSHIP
In the closing years of the nineteenth century appeared the
forerunners of airships as they are to-day, and interest was
aroused in this country by the performances of the ships designed
by Santos-Dumont and Count Zeppelin. From now onwards we find
various British firms turning their attention to the conquest of
the air.
In 1903 Dr. Barton commenced the construction of a large
non-rigid airship. The envelope was 176 feet long with a height
of 43 feet and a capacity of 235,000 cubic feet; it was
cylindrical in shape, tapering to a point at each end. Beneath
the whole length of the cylindrical portion was suspended a
bamboo framework which served as a car for the crew, and a
housing for the motors supplying the motive power of the ship.
This framework was suspended from the envelope by means of steel
cables. Installed in the car were two 50 horse-power Buchet
engines which were mounted at the forward and after ends of the
framework. The propellers in themselves were of singular design,
as they consisted of three pairs of blades mounted one behind the
other. The were situated on each side of the car, two forward
and two aft. The drive also include large friction clutches, and
each engine was under separate control.
To enable the ship to be trimmed horizontally, water tanks were
fitted at either end of the framework, the water being
transferred from one to the other as was found necessary.
A series of planes was mounted at intervals along the framework
to control the elevation of the ship.
This ship was completed in 1905 and was tried at the Alexandra
Palace in the July of that year. She, unfortunately, did not
come up to expectations, owing to the difficulty in controlling
her, and during the trial flight she drifted away and was
destroyed in landing.
WILLOWS No. 1
From the year 1905 until the outbreak of war Messrs. Willows &
Co. were engaged on the construction of airships of a small type,
and considerable success attended their efforts. Each succeeding
ship was an improvement on its predecessor, and flights were made
which, in their day, created a considerable amount of interest.
In 1905 their first ship was completed. This was a very small
non-rigid of only 12,500 cubic feet capacity. The envelope was
made of Japanese silk, cylindrical in shape, with rather blunt
conical ends. A long nacelle or framework, triangular in section
and built up of light steel tubes, was suspended beneath the
envelope by means of diagonally crossed suspensions.
A 7 horse-power Peugeot engine was fitted at the after end of the
nacelle which drove a 10-feet diameter propeller. In front were
a pair of swivelling tractor screws for steering the ship in the
vertical and horizontal plane. No elevators or rudders were
fixed to the ship.
WILLOWS No. 2
The second ship was practically a semi-rigid. The envelope was
over twice the capacity of the earlier ship, being of 29,000
cubic feet capacity. This envelope was attached to a keel of
bamboo and steel, from which was suspended by steel cables a
small car. At the after end of the keel was mounted a small
rudder for the horizontal steering. For steering in the vertical
plane two propellers were mounted on each side of the car,
swivelling to give an upward or downward thrust. A 30
horse-power J.A.P. engine was fitted in this case. Several
successful flights were carried out by this ship, of which the
most noteworthy was from Cardiff to London.
WILLOWS No. 3
No. 2, having been rebuilt and both enlarged and improved, became
known as No. 3. The capacity of the envelope, which was composed
of rubber and cotton, was increased to 32,000 cubic feet, and
contained two ballonets. The gross lift amounted to about half a
ton. As before, a 30 horse-power J.A.P. engine was installed,
driving the swivelling propellers. These propellers were
two-bladed with a diameter of 61 feet. The maximum speed was
supposed to be 25 miles per hour, but it is questionable if this
was ever attained.
This ship flew from London to Paris, and was the first
British-built airship to fly across the Channel.
WILLOWS No. 4
The fourth ship constructed by this firm was completed in 1912,
and was slightly smaller than the two preceding ships. The
capacity of the envelope in this instance was reduced to 24,000
cubic feet, but was a much better shape, having a diameter of 20
feet, which was gradually tapered towards the stern. A different
material was also used, varnished silk being tried as an
experiment. The envelope was attached to a keel on which was
mounted the engine, a 35 horse-power Anzani, driving two
swivelling four-bladed propellers. From the keel was suspended a
torpedo-shaped boat car in which a crew of two was accommodated.
Originally a vertical fin and rudder were mounted at the stern
end of the keel, but these were later replaced by fins on the
stern of the envelope.
This ship was purchased by the naval authorities, and after
purchase was more or less reconstructed, but carried out little
flying. At the outbreak of war she was lying deflated in the shed
at Farnborough. As will be seen later, this was the envelope
which was rigged to the original experimental S.S. airship in
the early days of 1915, and is for this reason, if for no other,
particularly interesting.
WILLOWS No. 5
This ship was of similar design, but of greater capacity. The
envelope, which was composed of rubber-proofed fabric, gave a
volume of 50,000 cubic feet, and contained two ballonets. A 60
horsepower engine drove two swivelling propellers at an estimated
speed of 38 miles per hour. She was constructed at Hendon, from
where she made several short trips.
MARSHALL FOX'S AIRSHIP
In the early days of the war an airship was constructed by Mr.
Marshall Fox which is worthy of mention, although it never flew.
It was claimed that this ship was a rigid airship, although from
its construction it could only be looked upon as a non-rigid
ship, having a wooden net-work around its envelope. The hull was
composed of wooden transverse frames forming a polygon of sixteen
sides, with radial wiring fitted to each transverse frame. The
longitudinal members were spiral in form and were built up of
three-ply lathes. A keel of similar construction ran along the
under side of the hull which carried the control position and
compartments for two Green engines, one of 40 horse-power, the
other of 80 horse-power, together with the petrol, bombs, etc.
In the hull were fitted fourteen gasbags giving a total capacity
of 100,000 cubic feet. The propeller drive was obtained by means
of a wire rope. The gross lift of the ship was 4,276 lb., and
the weight of the structure, complete with engines, exceeded
this.
It became apparent that the ship could never fly, and work was
suspended. She was afterwards used for carrying out certain
experiments and at a later date was broken up.
Apart from the various airships built under contract for the
Government there do not appear to be any other ships built by
private firms which were completed and actually flew. It is
impossible to view this lack of enterprise with any other
feelings than those of regret, and it was entirely due to this
want of foresight that Great Britain entered upon the World War
worse equipped, as regards airships, than the Central Empires or
any of the greater Allied Powers.
CHAPTER IV
BRITISH ARMY AIRSHIPS
The French and German military authorities began to consider
airships as an arm of the Service in the closing years of the
nineteenth century, and devoted both time and considerable sums
of money in the attempt to bring them to perfection. Their
appearance in the British Army was delayed for many years on
account of the expense that would be incurred in carrying out
experiments. In 1902, Colonel Templer, at that time head of the
Balloon Section, obtained the necessary sanction to commence
experiments, and two envelopes of gold-beaters skin of 50,000
cubic feet capacity were built. With their completion the funds
were exhausted, and nothing further done until 1907.
NULLI SECUNDUS I
In 1907 the first complete military airship in England was built,
which bore the grandiloquent title of Nulli Secundus. One of the
envelopes constructed by Colonel Templer was used: it was
cylindrical in shape with spherical ends. Suspended beneath the
envelope by means of a net and four broad silk bands was a
triangular steel framework or keel from which was slung a small
car. A 50 horsepower Antoinette engine was situated in the
forward part of the car which drove two metal-bladed propellers
by belts. At the after part of the keel were fitted a rudder and
small elevators, and two pairs of movable horizontal planes were
also fitted forward. It is remarkable that no stabilizing
surfaces whatsoever were mounted. The envelope was so
exceedingly strong that a high pressure of gas could be
sustained, and ballonets were considered unnecessary, but relief
valves were employed. The first flight took place in September
and was fairly successful. Several were made afterwards, and in
October she was flown over London and landed at the Crystal
Palace. The flight lasted 3 hours and 25 minutes, which
constituted at the time a world's record. Three days later,
owing to heavy winds, the ship had to be deflated and was taken
back to Farnborough.
NULLI SECUNDUS II
In 1908 the old ship was rebuilt with several modifications. The
envelope was increased in length and was united to the keel by
means of a covering of silk fabric in place of the net, four
suspension bands being again used. A large bow elevator was
mounted which made the ship rather unstable. A few flights were
accomplished, but the ship proved of little value and was broken
up.
BABY
This little airship made its first appearance in the spring of
1909. The envelope was fish-shaped and composed of gold-beater's
skin, with a volume of 21,000 cubic feet. One ballonet was
contained in the envelope which, at first, had three inflated
fins to act as stabilizers. These proved unsatisfactory as they
lacked rigidity, and were replaced after the first inflation by
the ordinary type. Two 8 horse-power 3-cylinder Berliet engines
were mounted in a long car driving a simple propeller, and at a
later date were substituted by a R.E.P. engine which proved most
unsatisfactory. During the autumn permission was obtained to
enlarge the envelope and fit a more powerful engine.
BETA
Beta was completed in May, 1910. The envelope was that of the
Baby enlarged, and now had a volume of 35,000 cubic feet. The
car was composed of a long frame, having a centre compartment for
the crew and engines, which was the standard practice at that
time for ships designed by the Astra Company. A 35 horse-power
Green engine drove two wooden two-bladed propellers by chains.
The ship was fitted with an unbalanced rudder, while the
elevators were in the front of the frame. This ship was
successful, and in June flew to London and back, and in September
took part in the Army manoeuvres, on one occasion being in the
air for 7 3/4 hours without landing, carrying a crew of three.
Trouble was experienced in the steering, the elevators being
situated too near the centre of the ship to be really efficient
and were altogether too small.
In 1912, Beta, having been employed regularly during the previous
year, was provided with a new car having a Clerget engine of 45
horse-power. In 1913 she was inflated for over three months and
made innumerable flights, on one occasion carrying H.R.H. the
Prince of Wales as passenger. She had at that time a maximum
speed of 35 miles per hour, and could carry fuel for about eight
hours with a crew of three.
GAMMA
In 1910 the Gamma was also completed. This was a much bigger
ship with an envelope of 75,000 cubic feet capacity, which,
though designed in England, had been built by the Astra Company
in Paris. The car, as in Beta, was carried in a long framework
suspended from the envelope. This portion of the ship was
manufactured in England, together with the machinery. This
consisted of an 80 horse-power Green engine driving swivelling
propellers, the gears and shafts of which were made by Rolls
Royce. The engine drove the propeller shafts direct, one from
each end of the crankshaft.
Originally the envelope was fitted with inflated streamline
stabilizers on either side, but at a later date these were
replaced by fixed stabilizing planes. At the same time the Green
engine was removed and two Iris engines of 45 horse-power were
installed, each driving a single propeller. There were two pairs
of elevators, each situated in the framework, one forward, the
other aft. In 1912, having been rigged to a new envelope of
101,000 cubic feet capacity, the ship took part in the autumn
manoeuvres, and considerable use was made of wireless telegraphy.
In a height reconnaissance the pilot lost his way, and running
out of petrol drifted all night, but was safely landed. When
returning to Farnborough the rudder controls were broken and the
ship was ripped. In this operation the framework was
considerably damaged. When repairs were being carried out the
elevators were removed from the car framework and attached to the
stabilizing fins in accordance with the method in use to-day.
CLEMENT-BAYARD
In 1910 it was arranged by a committee of Members of Parliament
that the Clement-Bayard firm should send over to England a large
airship on approval, with a view to its ultimate purchase by the
War Office, and a shed was erected at Wormwood Scrubs for its
accommodation. This ship arrived safely in October, but was very
slow and difficult to control. The envelope, moreover, was of
exceedingly poor quality and consumed so much gas that it was
decided to deflate it. She was taken to pieces and never rebuilt.
LEBAUDY
About the same time, interest having been aroused in this country
by the success of airships on the Continent, the readers of the
Morning Post subscribed a large sum to purchase an airship for
presentation to the Government. This was a large ship of 350,000
cubic feet capacity and was of semi-rigid design, a long
framework being suspended from the envelope which supported the
weight of the car. It had two engines of 150 horse-power which
developed a speed of about 32 miles per hour. The War Office
built a shed at Farnborough to house it, and in accordance with
dimensions given by the firm a clearance of 10 feet was allowed
between the top of the ship and the roof of the shed.
Inconceivable as it may sound, the overall height of the ship
was increased by practically 10 feet without the War Office
being informed. The ship flew over and was landed safely, but on
being taken into the shed the envelope caught on the roof
girders, owing to lack of headroom, and was ripped from end to
end. The Government agreed to increase the height of the shed
and the firm to rebuild the ship. This was completed in March,
1911, and the ship was inflated again. On carrying out a trial
flight, having made several circuits at 600 feet, she attempted
to land, but collided with a house and was completely wrecked.
This was the end of a most unfortunate ship, and her loss was not
regretted.
DELTA
Towards the end Of 1910 the design was commenced of the ship to
be known as the Delta, and in 1911 the work was put in hand. The
first envelope was made of waterproofed silk. This proved a
failure, as whenever the envelope was put up to pressure it
invariably burst. Experiments were continued, but no good
resulting, the idea was abandoned and a rubber-proofed fabric
envelope was constructed of 173,000 cubic feet volume. This ship
was inflated in 1912. The first idea was to make the ship a
semi-rigid by lacing two flat girders to the sides of the
envelope to take the weight of the car. This idea had to be
abandoned, as in practice, when the weight of the car was
applied, the girders buckled. The ship was then rigged as a
non-rigid. A novelty was introduced by attaching a rudder flap
to the top stabilizing fin, but as it worked somewhat stiffly it
was later on removed. This ship took part in the manoeuvres of
1912 and carried out several flights. She proved to be
exceedingly fast, being capable of a speed of 44 miles per hour.
In 1913 she was completely re-rigged and exhibited at the Aero
Show, but the re-designed rigging revealed various faults and it
was not until late in the year that she carried out her flight
trials. Two rather interesting experiments were made during
these flights. In one a parachute descent was successfully
accomplished; and in another the equivalent weight of a man was
picked up from the ground without assistance or landing the ship.
ETA
The Eta was somewhat smaller than the Delta, containing only
118,000 cubic feet of hydrogen, and was first inflated in 1913.
The envelope was composed of rubber-proofed fabric and a long
tapering car was suspended, this being in the nature of a
compromise between the short car of the, Delta and the long
framework gear of the Gamma. Her engines were two 80 horse-power
Canton-Unne, each driving one propeller by a chain. This ship
proved to be a good design and completed an eight-hour trial
flight in September. On her fourth trial she succeeded in towing
the disabled naval airship No. 2 a distance of fifteen miles.
Her speed was 42 miles per hour, and she could carry a crew of
five with fuel for ten hours.
On January 1st, 1914, the Army disbanded their Airship Section,
and the airships Beta, Gamma, Delta and Eta were handed over to
the Navy together with a number of officers and men.
CHAPTER V
EARLY DAYS OF THE NAVAL AIRSHIP SECTION--
PARSEVAL AIRSHIPS, ASTRA-TORRES TYPE, ETC.
The rapid development of the rigid airships in Germany began to
create a considerable amount of interest in official circles. It
was realized that those large airships in the future would be
invaluable to a fleet for scouting purposes. It was manifest
that our fleet, in the event of war, would be gravely handicapped
by the absence of such aerial scouts, and that Germany would hold
an enormous advantage if her fleet went to sea preceded by a
squadron of Zeppelin airships.
The Imperial Committee, therefore, decided that the development
of the rigid airship should be allotted to the Navy, and a design
for Rigid Airship No. 1 was prepared by Messrs. Vickers in
conjunction with certain naval officers in the early part of
1909.
As will be seen later this ship was completed in 1911, but broke
in two in September of that year and nothing more was done with
her. In February, 1912, the construction of rigid airships was
discontinued, and in March the Naval Airship section was
disbanded.
In September, 1912, the Naval Airship section was once more
reconstituted and was stationed at Farnborough. The first
requirements were airships, and owing to the fact that airship
construction was so behindhand in this country, in comparison
with the Continent, it was determined that purchases should be
made abroad until sufficient experience had been gained by
British firms to enable them to compete with any chance of
success against foreign rivals.
First a small non-rigid, built by Messrs. Willows, was bought by
the Navy to be used for the training of airship pilots. In
addition an Astra-Torres airship was ordered from France. This
was a ship of 229,450 cubic feet capacity and was driven by twin
Chenu engines of 210 horse-power each. She carried a crew of
six, and was equipped with wireless and machine guns. The car
could be moved fore and aft for trimming purposes, either by
power or by hand. This was, however, not satisfactory, and was
abandoned.
In April 1918, Messrs. Vickers were asked to forward proposals
for a rigid airship which afterwards became e known as No. 9.
Full details of the vicissitudes connected with this ship will be
given in the chapter devoted to Rigid Airships.
In July, approval was granted for the construction of six
non-rigid ships. Three of these were to be of the German design
of Major von Parseval and three of the Forlanini type, which was
a semi-rigid design manufactured in Italy. The order for the
Parsevals was placed with Messrs. Vickers and for the Forlaninis
with Messrs. Armstrong.
The Parseval airship was delivered to this country and became
known as No. 4; a second ship of the same type was also building
when war broke out; needless to say this ship was never
delivered. At a later date Messrs. Vickers, who had obtained the
patent rights of the Parseval envelope, completed the other two
ships of the order.
The Forlanini ship was completing in Italy on the declaration of
war and was taken over by the Italians; Messrs. Armstrong had not
commenced work on the other two. These ships, although allocated
numbers, never actually came into being.
PARSEVAL AIRSHIP No. 4
This airship deserves special consideration for two reasons;
firstly, on account of the active-service flying carried out by
it during the first three years of the war, and, secondly, for
its great value in training of the officers and men who later on
became the captains and crews of rigid airships.
The Parseval envelope is of streamline shape which tapers to a
point at the tail, and in this ship was of 300,000 cubic feet
capacity. The system of rigging being patented, can only be
described in very general terms. The suspensions carrying the
car are attached to a large elliptical rigging band which is
formed under the central portion of the envelope. To this
rigging band are attached the trajectory bands which pass up the
sides and over the top of the envelope, sloping away from the
centre at the bottom towards the nose and tail at the top. The
object of this is to distribute the load fore and aft over the
envelope. These bands, particularly at the after end of the
ship, follow a curved path, so that they become more nearly
vertical as they approach the upper surface of the envelope.
This has the effect of bringing the vertical load on the top of
the envelope; but a greater portion of the compressive force
comes on the lower half, where it helps to resist the bending
moment due to the unusually short suspensions. A single rudder
plane and the ordinary elevator planes were fitted to the
envelope. A roomy open car was provided for this ship, composed
of a duralumin framework and covered with duralumin sheeting.
Two 170 horse-power Maybach engines were mounted at the after end
of the car, which drove two metal-bladed reversible propellers.
These propellers were later replaced by standard four-bladed
wooden ones and a notable increase of speed was obtained.
Two officers and a crew of seven men were carried, together with
a wireless installation and armament.
This airship, together with No. 3, took part in the great naval
review at Spithead, shortly before the commencement of the war,
and in addition to the duties performed by her in the autumn of
1914, which are mentioned later, carried out long hours of patrol
duty from an east coast station in the summer of 1917. In all
respects she must be accounted a most valuable purchase.
PARSEVAL AIRSHIPS 5, 6 and 7
Parseval No. 5 was not delivered by Germany owing to the war, so
three envelopes and two cars were built by Messrs. Vickers on the
design of the original ship. These were delivered somewhat late
in the war, and on account of the production of the North Sea
airship with its greater speed were not persevered with. The
dimensions of the envelopes were somewhat increased, giving a
cubic capacity of 325,000 cubic feet. Twin Maybach engines
driving swivelling propellers were installed in the car, which
was completely covered in, but these ships were slow in
comparison with later designs, and were only used for the
instruction of officers and men destined for the crews of rigid
airships then building.
An experimental ship was made in 1917 which was known as Parseval
5; a car of a modified coastal pattern with two 240 horse-power
Renault engines was rigged to one of envelopes. During a speed
trial, this ship was calculated to have a ground speed of 50 to
53 miles per hour. The envelope, however, consumed an enormous
amount gas and for this reason the ship was deflated and struck
off the list of active ships.
This digression on Parseval airships has anticipated events
somewhat, and a return must now be made to earlier days.
Two more Astra-Torres were ordered from France, one known as No.
8, being a large ship of 4,00,000 cubic feet capacity. She was
fitted with two Chenu engines of 240 horse-power, driving
swivelling propellers. This ship was delivered towards the end
of the year 1914. The second Astra was of smaller capacity and
was delivered, but as will be seen later, was never rigged, the
envelope being used for the original coastal ship and the car
slung to the envelope of the ex-army airship Eta.
On January 1st, 1914, an important event took place: the Army
disbanded their airship service, and the military ships together
with certain officers and men were transferred to the Naval Air
Service.
Before proceeding further, it may be helpful to explain the
system by which the naval airships have been given numbers.
These craft are always known by the numbers which they bear, and
the public is completely mystified as to their significance
whenever they fly over London or any large town. It must be
admitted that the method is extremely confusing, but the table
which follows should help to elucidate the matter. The original
intention was to designate each airship owned by the Navy by a
successive number. The original airship, the rigid Mayfly, was
known as No. 1, the Willows airship No. 2, and so on. These
numbers were allocated regardless of type and as each airship was
ordered, consequently some of these ships, for example the
Forlaninis, never existed. That did not matter, however, and
these numbers were not utilized for ships which actually were
commissioned. On the transfer of the army airships, four of
these, the Beta, Gamma, Delta and Eta, were given their numbers
as they were taken over, together with two ships of the Epsilon
class which were ordered from Messrs. Rolls Royce, but never
completed. In this way it will be seen that numbers 1 to 22 are
accounted for.
In 1915 it was decided to build a large number of small ships for
anti-submarine patrol, which were called S.S.'s or Submarine
Scouts. It was felt that it would only make confusion worse
confounded if these ships bore the original system of successive
numbering and were mixed up with those of later classes which it
was known would be produced as soon as the designs were
completed. Each of these ships was accordingly numbered in its
own class, S.S., S.S.P., S.S. Zero, Coastal, C Star and North
Sea, from 1 onwards as they were completed.
In the case of the rigids, however, for some occult reason the
old system of numbering was persisted in. The letter R is
prefixed before the number to show that the ship is a rigid.
Hence we have No. 1 a rigid, the second rigid constructed is No.
9, or R 9, and the third becomes R 23. From this number onwards
all are rigids and are numbered in sequence as they are ordered,
with the exception of the last on the list, which is a ship in a
class of itself. This ship the authorities, in their wisdom,
have called R 80--why, nobody knows.
With this somewhat lengthy and tedious explanation the following
table may be understood:
No. Type. Remarks.
1. Rigid Wrecked, Sept. 24, 1911.
2. Willows Became S.S. 1.
3. Astra-Torres Deleted, May 1916.
4. Parseval Deleted, July, 1917.
5. Parseval Never delivered from Germany.
(Substitute ship built by Messrs. Vickers).
6. Parseval Built by Messrs. Vickers.
7. Parseval Built by Messrs. Vickers.
8. Astra-Torres Deleted, May, 1916.
9. Rigid Deleted, June, 1918.
10. Astra-Torres Envelope used for C 1.
11. Forlanini Never delivered owing to war.
12. Forlanini Never delivered owing to war.
13. Forlanini Never delivered owing to war.
14. Rigid Never built.
15. Rigid Never built.
16. Astra-Torres See No. 8.
17. Beta Transferred from Army.
Deleted, May, 1916.
18. Gamma Deleted, May, 1916.
19. Delta Deleted, May, 1916.
20. Eta Transferred from the Army.
Fitted with car from No. 10.
Deleted May, 1916.
21. Epsilon Construction cancelled May, 1916.
22. Epsilon Construction cancelled May, 1916.
23. Rigid 23 Class.
24. Rigid 23 Class.
25. Rigid 23 Class.
26. Rigid 23 Class.
27. Rigid 23x Class.
28. Rigid 23x Class. Never completed.
29. Rigid 23x Class.
30. Rigid 23x Class. Never completed.
31. Rigid 31 Class.
32. Rigid 31 Class, building.
33. Rigid 33 Class.
34. Rigid 33 Class.
35. Rigid Cancelled.
36. Rigid Building.
37. Rigid Building.
38. Rigid Building.
39. Rigid Building.
40. Rigid Building.
80. Rigid Building.
In August, 1914, Europe, which had been in a state of diplomatic
tension for several years, was plunged into the world war. The
naval airship service at the time was in possession of two
stations, Farnborough and Kingsnorth, the latter in a
half-finished condition. Seven airships were possessed, Nos. 2,
3 and 4, and the four ex-army ships--Beta, Gamma, Delta and
Eta--and of these only three, Nos. 3, 4 and the Beta, were in any
condition for flying. Notwithstanding this, the utmost use was
made of the ships which were available.
On the very first night of the war, Nos. 3 and 4 carried out a
reconnaissance flight over the southern portion of the North Sea,
and No. 4 came under the fire of territorial detachments at the
mouth of the Thames on her return to her station. These zealous
soldiers imagined that she was a German ship bent on observation
of the dockyard at Chatham.
No. 3 and No. 4 rendered most noteworthy service in escorting the
original Expeditionary Force across the Channel, and in addition
to this No. 4 carried out long patrols over the channel
throughout the following winter.
No. 17 (Beta) also saw active service, as she was based for a
short period early in 1915 at Dunkirk, and was employed in
spotting duties with the Belgian artillery near Ostend.
The Gamma and the Delta were both lying deflated at Farnborough
at the outbreak of the war, and in the case of the latter the car
was found to be beyond repair, and she was accordingly deleted.
The Gamma was inflated in January, 1915, and was used for mooring
experiments.
The Eta, having been inflated and deflated several times owing to
the poor quality of the envelope, attempted to fly to Dunkirk in
November, 1914. She encountered a snowstorm near Redhill and
was compelled to make a forced landing. In doing this she was so
badly damaged as to be incapable of repair, and at a later date
was deleted.
No. 8, which was delivered towards the end of 1914, was also
moored out in the open for a short time near Dunkirk, and carried
out patrol in the war zone of the Belgian coast.
So ends the story of the Naval Airship Service before the war.
With the submarine campaign ruthlessly waged by the Germans from
the spring of 1915 and onwards, came the airship's opportunity,
and the authorities grasped the fact that, with development, here
was the weapon to defeat the most dangerous enemy of the Empire.
The method of development and the success attending it the
following chapters will show.
CHAPTER VI
NAVAL AIRSHIPS.--THE NON-RIGIDS--
S.S. TYPE
The development of the British airships of to-day may be said to
date from February 28th, 1915. On that day approval was given
for the construction of the original S.S. airship.
At this time the Germans had embarked upon their submarine
campaign, realizing, with the failure of their great assaults on
the British troops in Flanders, that their main hope of victory
lay in starving Great Britain into surrender. There is no doubt
that the wholesale sinking of our merchant shipping was
sufficient to cause grave alarm, and the authorities were much
concerned to devise means of minimizing, even if they could not
completely eliminate the danger. One proposal which was adopted,
and which chiefly concerns the interests of this book, was the
establishment of airship stations round the coasts of Great
Britain. These stations were to be equipped with airships
capable of patrolling the main shipping routes, whose functions
were to search for submarines and mines and to escort shipping
through the danger zones in conjunction with surface craft.
Airship construction in this country at the time was, practically
speaking, non-existent. There was no time to be wasted in
carrying out long and expensive experiments, for the demand for
airships which could fulfil these requirements was terribly
urgent, and speed of construction was of primary importance. The
non-rigid design having been selected for simplicity in
construction, the expedient was tried of slinging the fuselage of
an ordinary B.E. 2C aeroplane, minus the wings, rudder and
elevators and one or two other minor fittings, beneath an
envelope with tangential suspensions, as considerable experience
had been gained already in a design of this type.
For this purpose the envelope of airship No. 2, which was lying
deflated in the shed at Farnborough, was rushed post haste to
Kingsnorth, inflated and rigged to the fuselage prepared for it.
The work was completed with such despatch that the airship
carried out her trial flight in less than a fortnight from
approval being granted to the scheme. The trials were in every
way most satisfactory, and a large number of ships of this design
was ordered immediately. At the same time two private firms were
invited to submit designs of their own to fulfil the Admiralty
requirements. One firm's design, S.S. 2, did not fulfil the
conditions laid down and was put out of commission; the other,
designed by Messrs. Armstrong, was sufficiently successful for
them to receive further orders. In addition to these a car was
designed by Messrs. Airships Ltd., which somewhat resembled a
Maurice Farman aeroplane body, and as it appeared to be suitable
for the purpose, a certain number of these was also ordered.
About this period the station at Farnborough was abandoned by the
Naval Airship Service to make room for the expansion of the
military aeroplane squadrons. The personnel and airships were
transferred to Kingsnorth, which became the airship headquarters.
The greatest energy was displayed in preparing the new stations,
which were selected as bases for the airships building for this
anti-submarine patrol. Small sheds, composed of wood, were
erected with almost incredible rapidity, additional personnel was
recruited, stores were collected, huts built for their
accommodation and that of the men, and by the end of the summer
the organization was so complete that operations were enabled to
commence.
The S.S., or submarine scout, airship proved itself a great
success. Beginning originally with a small programme the type
passed through various developments until, at the conclusion of
the war, no fewer than 150 ships of various kinds had been
constructed. The alterations which took place and the
improvements effected thereby will be considered at some length
in the following pages.
S.S.B.E. 2C
The envelope of the experimental ship S.S. 1 was only of 20,500
cubic feet capacity; for the active-service ships, envelopes of
similar shape of 60,000 cubic feet capacity were built. The
shape was streamline, that is to say, somewhat blunt at the nose
and tapering towards the tail, the total length being 143 feet 6
inches, with a maximum diameter of 27 feet 9 inches.
The gross lift of these ships with 98% pure gas at a temperature
of 60 degrees Fahrenheit and barometer 30 inches, is 4,180 lb.
The net lift available for crew, fuel, ballast, armament, etc.,
1,434 lb., and the disposable lift still remaining with crew of
two on board and full tanks, 659 lb.
The theoretical endurance at full speed as regards petrol
consumption is a little over 8 hours, but in practice it is
probable that the oil would run short before this time had been
reached. At cruising speed, running the engine at 1,250
revolutions, the consumption is at the rate of 3.6 gallons per
hour, which corresponds to an endurance of 16 1/2 hours.
With the engine running at 1,800 revolutions, a speed of 50.6
miles per hour has been reached by one of these ships, but
actually very few attained a greater speed than 40 miles per
hour.
The envelopes of S.S. airships are composed of rubber-proofed
fabric, two fabrics being used with rubber interposed between and
also on the inner or gas surface. To render them completely
gastight and as impervious to the action of the weather, sun,
etc., as possible, five coats of dope are applied externally, two
coats of Delta dope, two of aluminium dope and one of aluminium
varnish applied in that order.
One ripping panel is fitted, which is situated on the top of the
envelope towards the nose. It has a length of 14 feet 5 inches
and a breadth of about 8 inches. The actual fabric which has to
be torn away overlaps the edge of the opening on each side. This
overlap is sewn and taped on to the envelope and forms a seam as
strong and gastight as any other portion of the envelope. Stuck
on this fabric is a length of biased fabric 8 1/4 inches wide.
These two strips overlap the opening at the forward end by about
three feet. At this end the two strips are loose and have a
toggle inserted at the end to which the ripping cord is tied.
The ripping cord is operated from the car. It is led aft from
the ripping panel to a pulley fixed centrally over the centre of
the car, from the pulley the cord passes round the side of the
envelope and through a gland immediately below the pulley.
The nose of the envelope is stiffened to prevent it blowing in.
For this purpose 24 canes are fitted in fabric pockets around the
nose and meet at a point 2 1/4 inches in front of the nose. An
aluminium conical cap is fitted over the canes and a fabric nose
cap over the whole.
Two ballonets are provided, one forward and one aft, the capacity
of each being 6,375 cubic feet. The supply of air for filling
these is taken from the propeller draught by a slanting aluminium
tube to the underside of the envelope, where it meets a
longitudinal fabric hose which connects the two ballonet air
inlets. Non-return fabric valves known as crab-pots are fitted
in this fabric hose on either side of their junction with the air
scoop. Two automatic air valves are fitted to the underside of
the envelope, one for each ballonet. The air pressure tends to
open the valve instead of keeping it shut and to counteract this
the spring of the valve is inside the envelope. The springs are
set to open at a pressure of 25 to 28 mm.
Two gas valves are also fitted, one on the top of the envelope,
the other at the bottom. The bottom gas valve spring is set to
open at 30 to 35 mm. pressure, the top valve is hand controlled
only.
These valves are all very similar in design. They consist of two
wooden rings, between which the envelope is gripped, and which
are secured to each other by studs and butterfly nuts. The valve
disc, or moving portion of the valve, is made of aluminium and
takes a seating on a thin india rubber ring stretched between a
metal rod bent into a circle of smaller diameter than the valve
opening and the wooden ring of the valve. When it passes over
the wooden ring it is in contact with the envelope fabric and
makes the junction gastight. The disc is held against the rubber
by a compressed spring.
The valve cords are led to the pilot's seat through eyes attached
to the envelope.
The system of rigging or car suspension is simplicity itself and
is tangential to the envelope. On either side there are six main
suspensions of 25 cwt. stranded steel cable known as "C"
suspensions. Each "C" cable branches into two halves known as
the "B" bridles, which in turn are supported at each end by the
bridles known as "A." The ends of the "A" bridles are attached
to the envelope by means of Eta patches. These consist of a
metal D-shaped fitting round which the rigging is spliced and
through which a number of webbing bands are passed which
are spread out fanwise and solutioned to the envelope. It will
thus be seen that the total load on each main suspension is
proportionally taken up by each of the four "A" bridles, and that
the whole weight of the car is equally distributed over the
greater part of the length of the envelope. Four handling guys
for manoeuvering the ship on the ground are provided under the
bow and under the stem. A group of four Eta patches are placed
close together, which form the point of attachment for two guys
in each case. The forward of these groups of Eta patches forms
the anchoring point. The bridle, consisting of 25 cwt. steel
cable, is attached here and connected to the forepart of the
skids of the car. The junction of this bridle with the two
cables from the skids forms the mooring point and there the main
trail rope is attached. This is 120 feet long and composed of
2-inch manilla. This is attached, properly coiled, to the side
of the car and is dropped by a release gear. It is so designed
that when the airship is held in a wind by the trail rope the
strain is evenly divided between the envelope and the car. The
grapnel carried is fitted to a short length of rope. The other
end of the rope has an eye, and is fitted to slide down the main
trail rope and catch on a knot at the end.
For steering and stabilizing purposes the S.S. airship was
originally designed with four fins and rudders, which were to be
set exactly radial to the envelope. In some cases the two lower
fins and rudders were abandoned, and a single vertical fin and
rudder fitted centrally under the envelope were substituted. The
three planes are identical in size and measure 16 feet by 8 feet
6 inches, having a gross stabilizing area of 402 1/2 square feet.
They are composed of spruce and aluminium and steel tubing braced
with wire and covered by linen doped and varnished when in
position.
The original rudders measured 3 feet by 8 feet 6 inches. In the
case, however, of the single plane being fitted, 4-feet rudders
are invariably employed. Two kingposts of steel tube are fitted
to each plane and braced with wire to stiffen the whole
structure.
The planes are attached to the envelope by means of skids and
stay wires. The skids, composed of spruce, are fastened to the
envelope by eight lacing patches.
The car, it will be remembered, is a B.E. 2C fuselage stripped of
its wings, rudders and elevators, with certain other fittings
added to render it suitable for airship work. The undercarriage
is formed of two ash skids, each supported by three struts. The
aeroplane landing wheels, axle and suspensions are abandoned.
In the forward end of the fuselage was installed a 75 horse-power
air cooled Renault engine driving a single four-bladed tractor
propeller through a reduction gear of 2 to 1. The engine is of
the 8-cylinder V type, weighing 438 lb. with a bore of 96 mm. and
a stroke of 120 mm. The Claudel-Hobson type of carburettor is
employed with this engine. The type of magneto used is the Bosch
D.V.4, there being one magneto for each line of cylinders. In
the older French Renaults the Bosch H.L.8 is used, one magneto
supplying the current to all the plugs. Petrol is carried in
three tanks, a gravity and intermediate tank as fitted to the
original aeroplane, and a bottom tank placed underneath the front
seat of the car. The petrol is forced by air pressure from the
two lower tanks into the gravity tank and is obtained by a hand
pump fitted outside the car alongside the pilot's seat. The oil
tank is fitted inside the car in front of the observer.
The observer's seat is fitted abaft the engine and the pilot's
seat is aft of the observer. The observer, who is also the
wireless operator, has the wireless apparatus fitted about his
seat. This consists of a receiver and transmitter fitted inside
the car, which derives power from accumulator batteries. The
aerial reel is fitted outside the car. During patrols signals
can be sent and received up to and between 50 and 60 miles.
The pilot is responsible for the steering and the running of the
engine, and the controls utilized are the fittings supplied with
the aeroplane. Steering is operated by the feet and elevating by
a vertical wheel mounted in a fore and aft direction across the
seat. The control wires are led aft inside the fairing of the
fuselage to the extreme end, whence they pass to the elevators
and rudders.
The instrument board is mounted in front of the pilot. The
instruments comprise a watch, an air-speed indicator graduated in
knots, an aneroid reading to 10,000 feet, an Elliott revolution
counter, a Clift inclinometer reading up to 20 degrees depression
or elevation, a map case with celluloid front.
There are in addition an oil pressure gauge, a petrol pressure
gauge, a glass petrol level and two concentric glass pressure
gauges for gas pressure.
The steering compass is mounted on a small wooden pedestal on the
floor between the pilot's legs.
The water-ballast tank is situated immediately behind the pilot's
seat and contains 14 gallons of water weighing 140 lbs. The
armament consists of a Lewis gun and bombs. The bombs are
carried in frames suspended about the centre of the
undercarriage. The bomb sight is fitted near the bomb releasing
gear outside the car on the starboard side adjacent to the
pilot's seat. The Lewis gun, although not always carried on the
early S.S. airships, was mounted on a post alongside the pilot's
seat.
S.S. MAURICE FARMAN
For this type of S.S. the cars were built by Messrs. Airships
Ltd. In general appearance they resemble the Maurice Farman
aeroplane and were of the pusher type; 60,000 and in later cases
70,000 cubic feet envelopes were rigged to these ships, which
proved to be slightly slower than the B.E. 2C type, but this was
compensated for owing to the increased comfort provided for the
crew, the cars being more roomy and suitable for airship work in
every way.
The system of rigging to all intents and purposes is the same in
all types of S.S. ships, the suspensions being adjusted to suit
the different makes of car.
In these ships the pilot sits in front, and behind him is the
wireless telegraphy operator; in several cases a third seat was
fitted to accommodate a passenger or engineer; dual rudder and
elevator controls are provided for the pilot and observer.
The engine is mounted aft, driving a four-bladed pusher
propeller, with the petrol tanks situated in front feeding the
carburettors by gravity. The engines used are Rolls Royce
Renaults, although in one instance a 75 horse-power Rolls Royce
Hawk engine was fitted, which assisted in making an exceedingly
useful ship.
S.S. ARMSTRONG WHITWORTH
The car designed by Messrs. Armstrong Whitworth is of the tractor
type and is in all ways generally similar to the B.E. 2C. The
single-skid landing chassis with buffers is the outstanding
difference. These cars had to be rigged to 70,000 cubic feet
envelopes otherwise the margin of lift was decidedly small. A
water-cooled 100 horse-power Green engine propelled the ship, and
a new feature was the disposition of petrol, which was carried in
two aluminium tanks slung from the envelope and fed through
flexible pipes to a two-way cock and thence to the carburettors.
These tanks, which were supported in a fabric sling, showed a
saving in weight of 100 lb. compared with those fitted in the
B.E. 2C.
For over two years these three types of S.S. ships performed a
great part of our airship patrol and gave most excellent results.
Owing to the constant patrol which was maintained whenever
weather conditions were suitable, the hostile submarine hardly
dared to show her periscope in the waters which were under
observation. In addition to this, practically the whole of the
airship personnel now filling the higher positions, such as
Captains of Rigids and North Seas, graduated as pilots in this
type of airship. From these they passed to the Coastal and
onwards to the larger vessels.
As far as is known the height record for a British airship is
still held by an S.S.B.E. 2C, one of these ships reaching the
altitude of 10,300 feet in the summer of 1916.
The Maurice Farman previously mentioned as being fitted with the
Hawk engine, carried out a patrol one day of 18 hours 20 minutes.
In the summer of 1916 one of the Armstrong ships was rigged to an
envelope doped black and sent over to France. While there she
carried out certain operations at night which were attended with
success, proving that under certain circumstances the airship can
be of value in operating with the military forces over land.
S.S.P.
In 1916 the design was commenced for an S.S. ship which should
have a more comfortable car and be not merely an adaptation of
an aeroplane body. These cars, which were of rectangular shape
with a blunt nose, were fitted with a single landing skid aft,
and contained seats for three persons.
The engine, a 100 horse-power water-cooled Green, was mounted on
bearers aft and drove a four-bladed pusher propeller. The
petrol was carried in aluminium tanks attached by fabric slings
to the axis of the envelope.
Six of these ships were completed in the spring of 1917 and were
quite satisfactory, but owing to the success achieved by the
experimental S.S. Zero it was decided to make this the standard
type of S.S. ship, and with the completion of the sixth the
programme of the S.S.P's was brought to a close.
These ships enjoyed more than, perhaps, was a fair share of
misfortune, one was wrecked on proceeding to its patrol station
and was found to be beyond repair, and another was lost in a
snowstorm in the far north. The remainder, fitted at a later
date with 75 horse-power Rolls Royce engines, proved to be a most
valuable asset to our fleet of small airships.
S.S. ZERO
The original S.S. Zero was built at a south-coast station by Air
Service labour, and to the design of three officers stationed
there. The design of the car shows a radical departure from
anything that had been previously attempted, and as a model an
ordinary boat was taken. In shape it is as nearly streamline as
is practicable, having a keel and ribs of wood with curved
longitudinal members, the strut ends being housed in steel
sockets. The whole frame is braced with piano wire set
diagonally between the struts. The car is floored from end to
end, and the sides are enclosed with 8-ply wood covered with
fabric.
Accommodation is provided for a wireless telegraphy operator, who
is also a gunner, his compartment being situated forward,
amidships is the pilot and abaft this seat is a compartment for
the engineer.
The engine selected was the 75 horse-power water-cooled Rolls
Royce, it being considered to be the most efficient for the
purpose. The engine is mounted upon bearers above the level of
the top of the car, and drives a four-bladed pusher propeller.
The car is suspended from an envelope of 70,000 cubic feet
capacity, and the system of rigging is similar to that in use on
all S.S. ships. The petrol is carried in aluminium tanks slung
on the axis of the envelope, identically with the system in use
on the S.S.P's. The usual elevator planes are adopted with a
single long rudder plane.
The speed of the Zero is about 45 miles per hour and the ship has
a theoretical endurance of seventeen hours; but this has been
largely exceeded in practice.
The original ship proved an immediate success, and a large number
was shortly afterwards ordered.
As time went on the stations expanded and sub-stations were
added, while the Zero airship was turned out as fast as it could
be built, until upwards of seventy had been commissioned. The
work these ships were capable of exceeded the most sanguine
expectations. Owing to their greater stability in flight and
longer hours of endurance, they flew in weather never previously
attempted by the earlier ships. With experience gained it was
shown that a large fleet of airships of comparatively small
capacity is of far more value for an anti-submarine campaign than
a lesser fleet of ships of infinitely greater capacity. The
average length of patrol was eight hours, but some wonderful
duration flights were accomplished in the summer of 1918, as the
following figures will show. The record is held by S.S.Z. 39,
with 50 hours 55 minutes; another is 30 hours 20 minutes; while
three more vary from 25 1/2 hours to 26 1/4. Although small, the
Zero airship has been one of the successes of the war, and we can
claim proudly that she is entirely a British product.
S.S. TWIN
During the year 1917, designs were submitted for a twin-engined
S.S. airship, the idea being to render the small type of airship
less liable to loss from engine failure. The first design proved
to be a failure, but the second was considered more promising,
and several were built. Its capacity is 100,000 cubic feet, with
a length of 164 feet 6 inches, and the greatest diameter 32 feet.
The car is built to carry five, with the engines disposed on
gantries on the port and starboard side, driving pusher
propellers. This type, although in the experimental stage, is
being persevered with, and the intention is that it will
gradually supplant the other S.S. classes. It is calculated that
it will equal if not surpass the C Star ship in endurance,
besides being easier to handle and certainly cheaper to build.
"COASTAL" AND "C STAR" AIRSHIPS
The urgent need for a non-rigid airship to carry out
anti-submarine patrol having been satisfied for the time with the
production of the S.S. B.E. 2C type, the airship designers of the
Royal Naval Air Service turned their attention to the production
of an airship which would have greater lift and speed than the
S.S. type, and, consequently, an augmented radius of action,
together with a higher degree of reliability. As the name
"Coastal" or "Coast Patrol" implies, this ship was intended to
carry out extended sea patrols.
To obtain these main requirements the capacity of the envelope
for this type was fixed at 170,000 cubic feet, as compared with
the 60,000 cubic feet and, later, the 70,000 cubic feet envelopes
adopted for the S.S. ships. Greater speed was aimed at by
fitting two engines of 150 horse-power each, and it was hoped
that the chances of loss owing to engine failure would be
considerably minimized.
The Astra-Torres type of envelope, with its system of internal
rigging, was selected for this class of airship; in the original
ship the envelope us d was that manufactured by the French
Astra-Torres Company, and to which it had been intended to rig a
small enclosed car. The ship in question was to be known as No.
10. This plan was, however, departed from, and the car was
subsequently rigged to the envelope of the Eta, and a special car
was designed and constructed for the original Coastal. Coastal
airship No. 1 was commissioned towards the end of 1915 and was
retained solely for experimental and training purposes.
Approximately thirty of these airships were constructed during
the year 1916, and were allocated to the various stations for
patrol duties.
The work carried out by these ships during the two and a half
years in which they were in commission, is worthy of the highest
commendation. Before the advent of later and more reliable
ships, the bulk of anti-submarine patrol on the east coast and
south-west coast of England was maintained by the Coastal. On
the east coast, with the prevailing westerly and south-westerly
winds, these airships had many long and arduous voyages on their
return from patrol, and in the bitterness of winter their
difficulties were increased ten-fold. To the whole-hearted
efforts of Coastal pilots and crews is due, to a great extent,
the recognition which somewhat tardily was granted to the Airship
Service.
The envelope of the Coastal airship has been shown to be of
170,000 cubic feet capacity. It is trilobe in section to employ
the Astra-Torres system of internal and external rigging. The
great feature of this principle is that it enables the car to be
slung much closer to the envelope than would be possible with the
tangential system on an envelope of this size. As a natural
consequence there is far less head resistance, owing to the much
shorter rigging, between the envelope and the car.
The shape of the envelope is not all that could have been
desired, for it is by no means a true streamline, but has the
same cross section for the greater part of its length, which
tapers at either end to a point which is slightly more
accentuated aft. Owing to the shape, these ships, in the early
days until experience had been gained, were extremely difficult
to handle, both on the landing ground and also in the air. They
were extremely unstable both in a vertical and horizontal plane,
and were slow in answering to their rudders and elevators.
The envelope is composed of rubber-proofed fabric doped to hold
the gas and resist the effects of weather. Four ballonets are
situated in the envelope, two in each of the lower lobes, air
being conveyed to them by means of a fabric air duct, which is
parallel to the longitudinal centre line of the envelope, with
transverse ducts connecting each pair of ballonets. In earlier
types of the Coastal, the air scoop supplying air to the air duct
was fitted in the slip stream of the forward engine, but later
this was fitted aft of the after engine.
Six valves in all are used, four air valves, one fitted to each
ballonet, and two gas valves. These are situated well aft, one
to each of the lower lobes, and are fitted on either side of the
rudder plane. A top valve is dispensed with because in practice
when an Astra-Torres envelope loses shape, the tendency is for
the tail to be pulled upwards by the rigging, with the result
that the two gas valves always remain operative.
Crabpots and non-return valves are employed in a similar manner
to S.S. airships.
The Astra-Torres system of internal rigging must now be described
in some detail. The envelope is made up of three longitudinal
lobes, one above and two below, which when viewed end on gives it
a trefoil appearance. The internal rigging is attached to the
ridges formed on either side of the upper lobe, where it meets
the two side lobes. From here it forms a V, when viewed cross
sectionally, converging at he ridge formed by the two lobes on
the underside of the envelope which is known as the lower ridge.
To the whole length of the top ridges are attached the internal
rigging girdles and also the lacing girdles to which are secured
the top and side curtains. These curtains are composed of
ordinary unproofed fabric and their object is to make the
envelope keep its trilobe shape. They do not, however, divide
the ship into separate gas compartments. The rigging girdle
consists of a number of fabric scallops through which run strands
of Italian hemp. These strands, of which there are a large
number, are led towards the bottom ridge, where they are drawn
together and secured to a rigging sector. To these sectors the
main external rigging cables are attached. The diagram shows
better than any description this rigging system.
Ten main suspensions are incorporated in the Coastal envelope, of
which three take the handling guys, the remaining seven support
the weight of the car.
The horizontal fins with the elevator flaps, and the vertical fin
with the rudder flap, are fixed to the ridges of the envelope.
The car was evolved in the first instance by cutting away the
tail portion of two Avro seaplane fuselages and joining the
forward portions end on, the resulting car, therefore, had
engines at either end with seating accommodation for four. The
landing chassis were altered, single skids being substituted for
the wider landing chassis employed in the seaplane. The car
consists of four longerons with struts vertical and cross, and
stiffened with vertical and cross bracing wires. The sides are
covered with fabric and the flooring and fairing on the top of
the car are composed of three-ply wood. In the later cars five
seats were provided to enable a second officer to be carried.
The engines are mounted on bearers at each end of the car, and
the petrol and oil tanks were originally placed adjoining the
engines in the car. At a later date various methods of carrying
the petrol tanks were adopted, in some cases they were slung from
the envelope and in others mounted on bearers above the engines.
Wireless telegraphy is fitted as is the case with all airships.
In the Coastal a gun is mounted on the top of the envelope, which
is reached by a climbing shaft passing through the envelope,
another mounting being provided on the car itself.
Bombs are also carried on frames attached to the car. Sunbeam
engines originally supplied the motive power, but at a later date
a 220 horse-power Renault was fitted aft and a 100 horse-power,
Berliet forward. With the greater engine power the ship's
capabilities were considerably increased.
Exceedingly long flights were achieved by this type of ship, and
those exceeding ten hours are far too numerous to mention. The
moot noteworthy of all gave a total of 24 1/4 hours, which, at
the time, had only once been surpassed by any British airship.
Towards the end of 1917, these ships, having been in commission
for over two years, were in many cases in need of a complete
refit. Several were put in order, but it was decided that this
policy should not be continued, and that as each ship was no
longer fit for flying it should be replaced by the more modern
Coastal known as the C Star.
The record of one of these ships so deleted is surely worthy of
special mention. She was in commission for 2 years 75 days, and
averaged for each day of this period 3 hours 6 minutes flying.
During this time she covered upwards of 66,000 miles. From this
it will be seen that she did not pass her life by any means in
idleness.
"C STAR" AIRSHIP
After considerable experience had been gained with the Coastal,
it became obvious that a ship was required of greater
capabilities to maintain the long hours of escort duty and also
anti-submarine patrols. To meet these requirements it was felt
that a ship could be constructed, not departing to any extent
from the Coastal, with which many pilots were now quite familiar,
but which would show appreciable improvement over its
predecessor.
The design which was ultimately adopted was known as the C Star,
and provided an envelope of 210,000 cubic feet, which secured an
extra ton and a quarter in lifting capacity. This envelope,
although of the Astra-Torres type, was of streamline form, and in
that respect was a great advance on the early shape as used in
the Coastal. It is to all intents and purposes the same envelope
as is used on the North Sea ships, but on a smaller scale. An
entirely new type of fabric was employed for this purpose. The
same model of car was employed, but was made more comfortable,
the canvas covering for the sides being replaced by three-ply
wood. In all other details the car remained entirely the same.
The standard power units were a 100 horse-power Berliet forward
and a Fiat of 260 horse-power aft. The petrol tanks in this
design were carried inside the envelope, which was quite a new
departure.
These airships may be considered to have been successful, though
not perhaps to the extent which was expected by their most ardent
admirers. With the advent of the S.S. Twin it was resolved not
to embark on a large constructional progaramme, and when the
numbers reached double figures they were no longer proceeded
with. Notwithstanding this the ships which were commissioned
carried out most valuable work, and, like their prototypes, many
fine flights were recorded to their credit. Thirty-four and a
half hours was the record flight for this type of ship, and
another but little inferior was thirty hours ten minutes. These
flights speak well for the endurance of the crews, as it must be
borne in mind that no sleeping accommodation is possible in so
small a car.
The Coastal airship played no small part in the defeat of the
submarine, but its task was onerous and the enemy and the
elements unfortunately exacted a heavy toll. A German wireless
message received in this country testified to the valiant manner
in which one of these ships met with destruction.
THE "NORTH SEA" AIRSHIP
The North Sea or N.S. airship was originally designed to act as a
substitute for the Rigid, which, in 1916, was still a long way
from being available for work of practical utility. From
experience gained at this time with airships of the Coastal type
it was thought possible to construct a large Non-Rigid capable of
carrying out flights of twenty-four hours' duration, with a speed
of 55 to 60 knots, with sufficient accommodation for a double
crew.
The main requirements fall under four headings:
1. Capability to carry out flights of considerable duration.
2. Great reliability.
3. The necessary lift to carry an ample supply of fuel.
4. Adequate arrangements to accommodate the crew in comfort.
If these could be fulfilled the authorities were satisfied that
ships possessing these qualifications would be of value to the
Fleet and would prove efficient substitutes until rigid airships
were available. The North Sea, as may be gathered from its name,
was intended to operate on the east coasts of these islands.
The first ship, when completed and put through her trials, was
voted a success, and the others building were rapidly pushed on
with. When several were finished and experience had been gained,
after long flights had been carried out, the North Sea airship
suffered a partial eclipse and people were inclined to reconsider
their favourable opinion. Thus it was that for many months the
North Sea airship was decidedly unpopular, and it was quite a
common matter to hear her described as a complete failure. The
main cause of the prejudice was the unsatisfactory design of the
propelling machinery, which it will be see,, later was modified
altogether, and coupled with other improvements turned a ship of
doubtful value into one that can only be commended.
The envelope is of 360,000 cubic feet capacity, and is designed
on the Astra-Torres principle for the same reasons as held good
in the cases of the Coastal and C Star. All the improvements
which had been suggested by the ships of that class were
incorporated in the new design, which was of streamline shape
throughout, and looked at in elevation resembled in shape
that of the S.S. airship. Six ballonets are fitted, of which the
total capacity is 128,000 cubic feet, equivalent to 35.5 per cent
of the total volume. They are fitted with crabpots and
non-return valves in the usual manner.
The rigging is of the Astra-Torres system, and in no way differs
from that explained in the previous chapter. Nine fans of the
internal rigging support the main suspensions of the car, while
similar fans both fore and aft provide attachment for the
handling guys. Auxiliary fans on the same principle support the
petrol tanks and ballast bag.
Four gas and six air valves in all are fitted, all of which are
automatic.
Two ripping panels are embodied in the top lobe of the envelope.
The N.S. ship carries four fins, to three of which are attached
the elevator and rudder flaps. The fourth, the top fin, is
merely for stabilizing purposes, the other three being identical
in design, and are fitted with the ordinary system of wiring and
kingposts to prevent warping.
The petrol was originally carried in aluminium tanks disposed
above the top ridges of the envelope, but this system was
abandoned owing to the aluminium supply pipes becoming fractured
as the envelope changed shape at different pressures. They were
then placed inside the envelope, and this rearrangement has given
every satisfaction.
To the envelope of the N.S. is rigged a long covered-in car. The
framework of this is built up of light steel tubes, the
rectangular transverse frames of which are connected by
longitudinal tubes, the whole structure being braced by diagonal
wires. The car, which tapers towards the stern, has a length of
85 feet, with a height of 6 feet. The forward portion is covered
with duralumin sheeting, and the remainder with fabric laced to
the framework. Windows and portholes afford the crew both light
and space to see all that is required. In the forward portion of
the car are disposed all the controls and navigating instruments,
together with engine-telegraphs and voice pipes. Aft is the
wireless telegraphy cabin and sleeping accommodation for the
crew.
A complete electrical installation is carried of two dynamos and
batteries for lights, signalling lamps, telephones, etc. The
engines are mounted in a power unit structure separate from the
car and reached by a wooden gangway supported by wire cables.
This structure consists of two V-shaped frameworks connected by a
central frame and by an under-structure to which floats are
attached. The mechanics' compartment is built upon the central
frame, and the engine controls are operated from this cabin.
In the original power units two 250 horse-power Rolls Royce
engines were fitted, driving propellers on independent shafts
through an elaborate system of transmission. This proved to be a
great source of weakness, as continual trouble was experienced
with this method, and a fracture sooner or later occurred at the
universal joint nearest to the propeller. When the modified form
of ship was built the whole system of transmission was changed,
and the propellers were fitted directly on to the engine
crankshafts.
At a later date 240 horse-power Fiat engines were installed, and
the engineers' cabin was modified and an auxiliary blower was
fitted to supply air to the ballonets for use if the engines are
not running.
In the N.S. ship as modified the car has been raised to the same
level as the engineers' cabin, and all excrescences on the
envelope were placed inside. This, added to the improvement
effected by the abolition of the transmission shafts, increased
the reliability and speed of the ship, and also caused a
reduction in weight.
The leading dimensions of the ship are as follows: length, 262
feet; width, 56 feet 9 inches; height, 69 feet 3 inches. The
gross lift is 24,300 lb.; the disposable lift, without crew,
petrol, oil, and ballast, 8,500 lb. The normal crew carried when
on patrol is ten, which includes officers.
As in the case of the Coastal, a gun is mounted on the top of the
envelope, which is approached by a similar climbing shaft, and
guns and bombs are carried on the car.
These ships have become notorious for breaking all flying records
for non-rigid airships. Even the first ship of the class,
despite the unsatisfactory power units, so long ago as in the
summer of 1917 completed a flight of 49 hours 22 minutes, which
at the time was the record flight of any British airship. Since
that date numerous flights of quite unprecedented duration have
been achieved, one of 61 1/2 hours being particularly noteworthy,
and those of upwards of 30 hours have become quite commonplace.
Since the Armistice one of these ships completed the unparalleled
total of 101 hours, which at that date was the world's record
flight, and afforded considerable evidence as to the utility of
the non-rigid type for overseas patrol, and even opens up the
possibility of employing ships of similar or slightly greater
dimensions for commercial purposes.
N.S. 6 appeared several times over London in the summer months of
1918, and one could not help being struck by the ease with which
she was steered and her power to remain almost stationary over
such a small area as Trafalgar Square for a quite considerable
period.
The flights referred to above were not in any way stunt
performances to pile up a handsome aggregate of hours, but were
the ordinary flying routine of the station to which the ships
were attached, and most of the hours were spent in escorting
convoys and hunting for submarines. In addition to these duties,
manoeuvres were carried out on occasions with the Fleet or units
thereof.
From the foregoing observations it must be manifest that this
type of ship, in its present modified state, is a signal success,
and is probably the best large non-rigid airship that has been
produced in any country.
For the purposes of comparison it will be interesting to tabulate
the performances of the standard types of non-rigid airships.
The leading dimensions are also included in this summary:
Type S.S. Zero S.S. Twin Coastal North
Star Sea
Length 143' 0" 165' 0" 218' 0" 262' 0"
Overall width 32' 0" 35' 6" 49' 3" 56' 9"
Overall height 46' 0" 49' 0" 57' 6" 69' 3"
Hydrogen capacity
(cubic feet) 70,000 100,000 210,000 360,000
Gross lift (lb.) 4,900 7,000 14,500 24,300
Disposable
lift (lb.) 1,850 2,200 4,850 8,500
Crew 3 4 5 10
Lift available
for fuel and
freight (lb.) 1,370 1,540 4,050 6,900
Petrol consumption
at full speed
(lb. per hour) 3.6 7.2 18.4 29.8
Gals. per hour 0.36 0.72 2.05 3
CHAPTER VII
NAVAL AIRSHIPS.--THE RIGIDS
RIGID AIRSHIP No. 1
The responsibility for the development the Rigid airship having
been allotted to the Navy, with this object in view, in the years
1908 and 1909 a design was prepared by Messrs. Vickers Ltd., in
conjunction with certain naval officers, for a purely
experimental airship which should be as cheap as possible. The
ship was to be known as Naval Airship No. 1, and though popularly
called the Mayfly, this title was in no way official. In design
the following main objects were aimed at:
1. The airship was to be capable of carrying out the duties of an
aerial scout.
2. She was to be able to maintain a speed of 40 knots for
twenty-four hours, if possible.
3. She was to be so designed that mooring to a mast on the water
was to be feasible, to enable her to be independent of her
shed except for docking purposes, as in the case with surface
vessels.
4. She was to be fitted with wireless telegraphy.
5. Arrangements were to be made for the accommodation of the crew
in reasonable comfort.
6. She was to be capable of ascending to a height of not less
than 1,500 feet.
These conditions rendered it necessary that the airship should be
of greater dimensions than any built at the time, together with
larger horse-power, etc.
These stipulations having been settled by the Admiralty, the
Admiralty officials, in conjunction with Messrs. Vickers Ltd.,
determined the size, shape, and materials for the airship
required. The length of the ship was fixed at approximately 500
feet, with a diameter of 48 feet. Various shapes were
considered, and the one adopted was that recommended by an
American professor named Zahm. In this shape, a great proportion
of the longitudinal huff framework is parallel sided with curved
bow and stern portions, the radius of these curved portions
being, in the case of the bow, twice the diameter of the hull,
and in the case of the stern nine times the same diameter.
Experiments proved that the resistance of a ship of this shape
was only two-fifths of the resistance of a ship of the same
dimensions, having the 1 1/2 calibre bow and stern of the
Zeppelin airships at that time constructed.
A considerable difference of opinion existed as to the material
to be chosen for the construction of the hull. Bamboo, wood,
aluminium, or one of its alloys, were all considered. The first
was rejected as unreliable. The second would have been much
stronger than aluminium, and was urged by Messrs. Vickers. The
Admiralty, however, considered that there was a certainty of
better alloys being produced, and as the ship was regarded as an
experiment and its value would be largely negatived if later
ships were constructed of a totally different material, aluminium
or an alloy was selected. The various alloys then in existence
showed little advantage over the pure metal, so pure aluminium
was specified and ordered. This metal was expected to have a
strength of ten tons per square inch, but that which arrived was
found to be very unreliable, and many sections had, on test, only
half the strength required. The aluminium wire intended for the
mesh wiring of the framework was also found to be extremely
brittle. A section of the framework was, however, erected, and
also one of wood, as a test for providing comparisons. In the
tests, the wooden sections proved, beyond all comparison, the
better, but the Admiralty persisted in their decision to adopt
the metal.
Towards the end of 1909 a new aluminium alloy was discovered,
known as duralumin. Tests were made which proved that this new
metal possessed a strength of twenty-five tons per square inch,
which was over twice as strong as the nominal strength of
aluminium, and in practice was really five times stronger. The
specific gravity of the new metal varied from 2.75 to 2.86, as
opposed to the 2.56 of aluminium. As the weights were not much
different it was possible to double the strength of the ship and
save one ton in weight. Duralumin was therefore at once adopted.
The hull structure was composed of twelve longitudinal duralumin
girders which ran fore and aft the length of the ship and
followed the external shape. The girders were secured to a steel
nose-piece at the bow and a pointed stern-piece aft. These
girders, built of duralumin sections, were additionally braced
wherever the greatest weights occurred. To support these girders
in a thwartship direction a series of transverse frames were
placed at 12 feet 6 inches centres throughout the length of the
ship, and formed, when viewed cross-sectionally, a universal
polygon of twelve sides. For bracing purposes mesh wiring
stiffened each bay longitudinally, so formed by the junction of
the running girder and the transverse frames, while the
transverse frames between the gasbags were stiffened with radial
wiring which formed structure similar to a wheel with its
spokes. The frames where the gondolas occurred were strengthened
to take the addition weight, while the longitudinals were also
stiffened at the bow and stern.
Communication was provided between the gondolas by means of an
external keel which was suspended from extra keel longitudinals.
In this design the keel was provided for accommodation purposes
only, and in no way increased the structural stability of the
ship as in No. 9 and later ships. This keel, triangular in
section,widened out amidships to form a space for a cabin and the
wireless compartment. The fins and rudders, which were adopted,
were based entirely on submarine experience, and the Zeppelin
method was ignored. The fins were fitted at the stern of the
ship only, and comprised port and starboard horizontal fins,
which followed approximately the shape of the hull, and an upper
and lower vertical fin. Attached to these fins were box rudders
and elevators, instead of the balanced rudders first proposed.
Auxiliary rudders were also fitted in case of a breakdown of the
main steering gear abaft the after gondola. Elevators and
rudders were controlled from the forward gondola and the
auxiliary rudders from the after gondola.
The gasbags were seventeen in number and were twelve-sided in
section, giving approximately a volume of 663,000 cubic feet
when completely full. Continental fabric, as in use on the
Zeppelin airships, was adopted, although the original intention
was to use gold-beater's skin,, but this was abandoned owing to
shortage of material. These bags were fitted with the Parseval
type of valve, which is situated at the top, contrary to the
current Zeppelin practice, which had automatic valves at the
bottom of the bags, and hand-operated valves on the top of a few
bags for control purposes. Nets were laced to the framework to
prevent the bags bulging through the girders.
The whole exterior of the hull was fitted with an outer cover;
Zeppelin at this time used a plain light rubber-proofed fabric,
but this was not considered suitable for a ship which was
required to be moored in the open, as in wet weather the material
would get saturated and water-logged. Various experiments were
carried out with cotton, silk and ramie, and, as a result, silk
treated with Ioco was finally selected. This cover was laced
with cords to the girder work, and cover-strips rendered the
whole impervious to wet. Fire-proofed fabric was fitted in wake
of the gondolas for safety from the heat of the engines.
Two gondolas, each comprising a control compartment and
engine-room, were suspended from the main framework of the hull.
They were shaped to afford the least resistance possible to the
air, and were made of Honduras mahogany, three-ply where the
ballast tanks occurred, and two-ply elsewhere. The plies were
sewn together with copper wire. The gondolas were designed to
have sufficient strength to withstand the strain of alighting on
the water. They were suspended from the hull by wooden struts
streamline in shape, and fitted with internal steel-wire ropes;
additional wire suspensions were also fitted to distribute the
load over a greater length of the ship. The engines were
carried in the gondolas on four hollow wooden struts, also fitted
internally with wire. The wires were intended to support the
gondolas in the event of the struts being broken in making a
heavy landing.
Two engines were mounted, one in each gondola, the type used
being the 8-cylinder vertical water-cooled Wolseley developing a
horse-power of 160. The forward engine drove two wing propellers
through the medium of bevel gearing, while the after engine drove
a single large propeller aft through 4 gear box to reduce the
propeller revolutions to half that of the engine. The estimated
speed of the ship was calculated to be 42 miles per hour, petrol
was carried in tanks, fitted in the keel, and the water ballast
tanks were placed close to the keel and connected together by
means of a pipe.
No. 1 was completed in May, 1911. She had been built at Barrow in
a shed erected on the edge of Cavendish Dock. Arrangements were
made that she should be towed out of the shed to test her
efficiency at a mooring post which had been prepared in the
middle of the dock. She was launched on May 22nd in a flat calm
and was warped out of the shed and hauled to the post where she
was secured without incident. The ship rode at the mooring post
in a steady wind, which at one time increased to 36 miles per
hour, until the afternoon of May 25th, and sustained no damage
whatever. Various engine trials were carried out, but no
attempt was made to fly, as owing to various reasons the ship was
short of lift. Valuable information was, however, gained in
handling the ship, and much was learnt of her behaviour at the
mast. More trouble was experienced in getting her back into the
shed, but she was eventually housed without sustaining any damage
of importance.
Owing to the lack of disposable lift, the bags were deflated and
various modifications were carried out to lighten the ship, of
which the principal were the removal of the keel and cabin
entirely, and the removal of the water-trimming services. Other
minor alterations were made which gave the ship, on completion, a
disposable lift of 3.21 tons. The transverse frames between the
gasbags were strengthened, and a number of broken wires were
replaced.
On September 22nd the ship was again completed, and on the 24th
she was again to be taken out and tested at the mooring post.
Unfortunately, while being hauled across the dock, the framework
of the ship collapsed, and she was got back into the shed the
same day.
Examination showed that it was hopeless to attempt to reconstruct
her, and she was broken up at a later date. The failure of this
ship was a most regrettable incident, and increased the prejudice
against the rigid airship to such an extent that for some time
the Navy refused to entertain any idea of attempting a second
experiment.
RIGID AIRSHIP No. 9
Rigid Airship No. 1 having met with such a calamitous end, the
authorities became rather dubious as to the wisdom of continuing
such costly experiments. Most unfortunately, as the future
showed and as was the opinion of many at the time, rigid
construction in the following year 1912 was ordered to be
discontinued. This decision coincided with the disbanding of the
Naval Air Service, and for a time rigid airships in this country
were consigned to the limbo of forgetfulness. After the Naval
Air Service had been reconstituted, the success which attended
the Zeppelin airships in Germany could no longer be overlooked,
and it was decided to make another attempt to build a rigid
airship in conformity with existing Zeppelin construction. The
first proposals were put forward in 1913, and, finally, after
eleven months delay, the contract was signed. This airship, it
has been seen, was designated No. 9.
No. 9 experienced numerous vicissitudes, during the process of
design and later when construction was in progress. The contract
having been signed in March, 1914, work on the ship was suspended
in the following February, and was not recommenced until July of
the same year. From that date onwards construction was carried
forward; but so many alterations were made that it was fully
eighteen months before the ship was completed and finally
accepted by the Admiralty.
The ship as designed was intended "to be generally in conformity
with existing Zeppelin construction," with the following main
requirements stipulated for in the specification:
1. She was to attain a speed of at least 45 miles per hour at the
full power of the engines.
2. A minimum disposable lift of five tons was to be available for
movable weights.
3. She was to be capable of rising to a height of 2,000 feet
during flight.
The design of this ship was prepared by Messrs. Vickers, Ltd.,
and as it was considered likely that owing to inexperience the
ship would probably be roughly handled and that heavy landings
might be made, it was considered that the keel structure and also
the cars should be made very strong in case of accidents
occurring. This, while materially increasing the strength of the
ship, added to its weight, and coupled with the fact that
modifications were made in the design, rendered the lift somewhat
disappointing. The hull structure was of the "Zahm" shape as in
No. 1, a considerable portion being parallel sided, while in
transverse section it formed a 17-sided polygon. In length it was
526 feet with a maximum diameter of 53 feet. The hull framework
was composed of triangular duralumin girders, both in the
longitudinal and transverse frames, while the bracing was carried
out by means of high tensile steel wires and duralumin tubes.
Attached to the hull was a V-shaped keel composed of tubes with
suitable wire bracings, and in it a greater part of the strength
of the structure lay. It was designed to withstand the vertical
forces and bending moments which resulted from the lift given by
the gasbags and the weights of the car and the cabin. The keel
also provided the walking way from end to end of the ship, and
amidships was widened out to form a cabin and wireless
compartment.
The wiring of the transverse frames was radial and performed
similar functions to the spokes of a bicycle wheel. These wires
could be tightened up at the centre at a steel ring through which
they were threaded and secured by nuts.
In addition to the radial wires were the lift wires) which were
led to the two points on the transverse frames which were
attached to the keel; on the inflation of the gasbags, the bags
themselves pressed upon the longitudinal girders on the top of
the ship, which pressure was transferred to the transverse frames
and thence by means of the several lift wires to the keel. In
this way all the stresses set up by the gas were brought finally
to the keel in which we have already said lay the main strength
of the ship.
The hull was divided by the transverse frames into seventeen
compartments each containing a single gasbag. The bags were
composed of rubber-proofed fabric lined with gold-beater's skin
to reduce permeability, and when completely full gave a total
volume of 890,000 cubic feet. Two types of valve were fitted to
each bag, one the Parseval type of valve with the pressure cone
as fitted in No. 1, the other automatic but also controlled by
hand.
To distribute the pressure evenly throughout the upper
longitudinal frames, and also to prevent the gasbags bulging
between the girders, nets were fitted throughout the whole
structure of the hull.
The whole exterior of the ship was fitted with an outer cover, to
protect the gasbags and hull framework from weather and to render
the outer surface of the ship symmetrical and reduce "skin
friction" and resistance to the air to a minimum. To enable
this cover to be easily removed it was made in two sections, a
port and starboard side for each gasbag. The covers were laced
to the hull framework and the connections were covered over with
sealing strips to render the whole weathertight.
The system of fins for stabilizing purposes on No. 9 were two--
vertical and horizontal. The vertical fin was composed of two
parts, one above and the other below the centre line of the ship.
They were constructed of a framework of duralumin girders,
covered over with fabric. The fins were attached on one edge to
the hull structure and wire braced from the other edge to various
positions on the hull. The horizontal fins were of similar design
and attached in a like manner to the hull. Triplane rudders and
biplane elevators of the box type were fitted in accordance with
the German practice of the time. Auxiliary biplane rudders were
fitted originally abaft the after car, but during the first two
trial flights they proved so very unsatisfactory that it was
decided to remove them.
Two cars or gondolas were provided to act as navigating
compartments and a housing for the engines, and in design were
calculated to offer the least amount of head resistance to the
wind. The cars were composed of duralumin girders, which formed
a flooring, a main girder running the full length of the car with
a series of transverse girders spaced in accordance with the main
loads. From each of these transverse girders vertical standards
with a connecting piece on top were taken and the whole exterior
was covered with duralumin plating. The cars were suspended in
the following manner. Two steel tubes fitting into a junction
piece at each end were bolted to brackets at the floor level at
each end of the transverse girders. They met at an apex above
the roof level and were connected to the tubing of the keel. In
addition, to distribute the weight and prevent the cars from
rocking, steel wire suspensions were led to certain fixed points
in the hull.
Each car was divided into two parts by a bulkhead, the forward
portion being the control compartment in which were disposed
all instruments, valve and ballast controls, and all the steering
and elevating arrangements. Engine-room telegraphs, voice pipes
and telephones were fitted up for communication from one part
of the ship to the other. The keel could be reached by a ladder
from each car, thus providing with the climbing shaft through the
hull access to all parts of the ship.
The original engine equipment of No. 9 was composed of four
Wolseley-Maybach engines of 180 horse-power each, two being
installed in the forward car and two in the after car. As the
ship was deficient in lift after the initial flight trials had
been carried out, it was decided to remove the two engines from
the after car and replace them with a single engine of 250
horse-power; secondly, to remove the swivelling propeller gear
from the after car and substitute one directly-driven propeller
astern of the car. This as anticipated reduced the weight very
considerably and in no way lessened the speed of the ship.
The forward engines drove two four-bladed swivelling propellers
through gear boxes and transmission shafts, the whole system
being somewhat complicated, and was opposed to the Zeppelin
practice at the time which employed fixed propellers.
The after engine drove a large two-bladed propeller direct off
the main shaft.
The petrol and water ballast were carried in tanks situated in
the keel and the oil was carried in tanks beneath the floors of
the cars.
The wireless cabin was situated as before mentioned in a cabin in
the keel of the ship, and the plant comprised a main transmitter,
an auxiliary transmitter and receiver and the necessary aerial
for radiating and receiving.
No. 9 was inflated in the closing days of 1916, and the disposal
lift was found to be 2.1 tons under the specification conditions,
namely, barometer 29.5 inches and temperature 55 degrees
Fahrenheit. The contract requirements had been dropped to 3.1
tons, which showed that the ship was short by one ton of the lift
demanded. The flight trials were, however, carried out, which
showed that the ship had a speed of about 42 1/2 miles per hour.
The alterations previously mentioned were afterwards made, the
bags of the ship were changed and another lift and trim trial was
held in March, 1917, when it was found that these had had the
satisfactory result of increasing the disposable lift to 3.8 tons
or .7 ton above the contract requirements, and with the bags 100
per cent full gave a total disposable lift of 5.1 tons.
Additional trials were then carried out, which showed that the
speed of the ship had not been impaired.
For reference purposes the performances of the ship are tabulated
below.
Speed:
Full 45 miles per hour
Normal = 2/3 38 " " "
Cruising = 1/3 32 " " "
Endurance:
Full 18 hours = 800 miles
Normal 26 " = 1,000 "
Cruising 50 " = 1,600 "
No. 9 having finished her trials was accepted by the Admiralty
in Mar. 1917, and left Barrow, where she had,been built, for a
patrol station.
In many ways she was an excellent ship, for it must be remembered
that when completed she was some years out-of-date judged by
Zeppelin standards. Apart from the patrol and convoy work which
she accomplished, she proved simply invaluable for the training
of officers and men selected to be the crews of future rigid
airships. Many of these received their initial training in her,
and there were few officers or men in the airship service who
were not filled with regret when orders were issued that she was
to be broken up. The general feeling was that she should have
been preserved as a lasting exhibition of the infancy of the
airship service, but unfortunately rigid airships occupy so much
space that there is no museum in the country which could have
accommodated her. So she passed, and, except for minor trophies,
remains merely a recollection.
RIGID AIRSHIP No. 23 CLASS
After the decision had been made in 1915 that work on No. 9
should be restarted, the Admiralty determined that a programme of
rigid airships should be embarked upon, and design was commenced.
Several ships of the same class were, ordered, and the type was
to be known as the 23 class. Progress on these ships, although
slow, was more rapid than had been the case with No. 9, and
by the end of 1917 three were completed and a fourth was rapidly
approaching that state.
The specification, always ambitious, laid down the following main
stipulations.
(1) The ship is to attain a speed of at least 55 miles per hour
for the main power of the engines.
(2) A minimum of 8 tons is to be available for disposable weights
when full.
(3) The ship must be capable of rising at an average rate of not
less than 1,000 feet per minute, through a height of 3,000
feet starting from nearly sea level.
As will be seen later this class of ship, although marking a
certain advance on No. 9 both as regards workmanship and design,
proved on the whole somewhat disappointing, and it became more
evident every day that we had allowed the Germans to obtain such
a start in the race of airship construction as we could ill
afford to concede.
We may here state that all of the ships of this class which had
been ordered were not completed, the later numbers being modified
into what was known as the 23 X class; four in all of the 23
class were built, of which two--Nos. 23 and 26--were built by
Messrs. Vickers, Ltd., at Barrow, No. 24 by Messrs. Wm. Beardmore
and Co., at Glasgow, and No. 25 by Messrs. Armstrong, Whitworth
and Co., at Selby, Yorkshire.
In many respects the closest similarity of design exists between
No. 9 and No. 23, especially in the hull, but it will be of
interest to mention the salient differences between the two
ships.
The length of the hull, which in No. 9 was 520 feet, was
increased in No. 23 to 535 feet, and the number of gasbags from
seventeen to eighteen. This gave a total volume of 997,500 cubic
feet compared with 890,000 cubic feet in No. 9, with a disposable
lift under specification conditions of 5.7 tons as opposed to 3.8
tons.
The longitudinal shape of No. 23 is a modified form of "Zahm"
shape, the radius of the bow portion being twice the diameter of
the parallel portion, while the stern radius is three times the
same diameter.
In design the hull framework is almost a repetition of No. 9,
particularly in the parallel portion, the same longitudinal and
transverse frames dividing the hull into compartments, with tubes
completely encircling the section between each main transverse
frame. The system of wiring the hull is precisely the same in
both the ships, and nets are employed in the same way.
The triangular section of keel is adhered to, but its functions
in No. 23 are somewhat different. In No. 9 it was intended to be
sufficiently strong to support all the main vertical bending
moments and shearing forces, but in No. 23 it was primarily
intended to support the distributed weights of water ballast,
petrol tanks, etc., between the main transverse frames. Unlike
No. 9, the keel is attached to the main transverse frames only.
The cabin and wireless cabin are disposed in the keel in the same
manner, and it also furnishes a walking way for the total length
of the ship.
The stabilizing fins, both vertical and horizontal, are similar
to those attached to No. 9, but the system of rudders and
elevators is totally different. In place of the box rudders and
elevators in No. 9, single balanced rudders and elevators are
attached to the fins; they have their bearing on the outboard
side on the external girders of the fins, which are extended for
the purpose. The elevators and rudders are composed of a
duralumin framework, stiffened by a kingpost on either side with
bracing wires.
The bags, eighteen in number, are made of rubber-proofed fabric
lined with gold-beater's skin. It is interesting to note that
the number of skins used for the bags of a ship of this class is
approximately 350,000. The system of valves is entirely
different from that in No. 9. The Parseval type of valve with the
pressure cone at the bottom of the bag is omitted, and in the
place of the two top valves in the former ship are a side valve
of the Zeppelin type entirely automatic and a top valve entirely
hand controlled. The side valve is set to blow off at a pressure
of from 3 to 5 millimetres. The outer cover was fitted in the
same manner as in No. 9. Two cars or gondolas, one forward, the
other aft, each carry one engine provided with swivelling
propellers and gears. They are enclosed with sides and a
fireproof roof, and are divided into two compartments, one the
navigating compartment, the other the engine room. The cars are
in all respects very similar to those of No. 9, and are suspended
from the hull in a similar manner. The remaining two engines are
carried in a small streamline car situated amidships, which has
just sufficient room in it for the mechanics to attend to them.
Originally this car was open at the top, but it was found that
the engineers suffered from exposure, and it was afterwards
roofed in.
The engine arrangements in this ship were totally different to
those of No. 9, four 250 horse-power Rolls Royce engines being
installed in the following order. Single engines are fitted in
both the forward and after cars, each driving two swivelling
four-bladed propellers. In the centre car two similar engines
are placed transversely, which drive single fixed propellers
mounted on steel tube outriggers through suitable gearing.
The engines are the standard 12 cylinder V-type Rolls Royce which
will develop over 300 brake horse-power at full throttle opening.
The engine is water cooled, and in the case of those in the
forward and after cars the original system consisted of an
internal radiator supplied by an auxiliary water tank carried in
the keel. It was found on the flight trials that the cooling was
insufficient, and external radiators were fitted, the internal
radiator and fan being removed. In the case of the centre car no
alteration was necessary, as external radiators were fitted in
the first instance.
The engines are supported by two steel tubes held by four
brackets bolted to the crank case, these being carried by twelve
duralumin tubes bolted to the bearers and transverse frames of
the car respectively. The drive from the engine is transmitted
through a universal joint to a short longitudinal shaft, running
on ball bearings. This shaft gears into two transverse shafts,
which drive the propellers through the medium of a gear box to
the propeller shafts, making five shafts in all.
The engines in the centre car being placed transversely the
transmission is more direct, the engines driving the propellers
through two gear wheels only. The propeller gear box is
supported by steel tube outriggers attached by brackets to the
framework of the car. The petrol is carried in a series of tanks
situated beneath the keel walking way, and are interconnected so
that any tank either forward or aft can supply any engine, by
this means affording assistance for the trimming of the ship.
Four-bladed propellers are used throughout the ship.
Water ballast is carried in fabric bags also situated beneath the
keel walking way, and a certain amount is also carried beneath
the floor of the car.
Engine-room telegraphs, swivelling propeller telegraphs, speaking
tubes and telephones, with a lighting set for the illumination of
the cars and keel, were all fitted in accordance with the
practice standard in all rigid airships.
The lift and trim trials taken before the initial flight trials
showed that the ship possessed a disposable lift under standard
conditions of 5.7 tons. The original disposable lift demanded
by the specification was 3 tons but this was reduced by 2 tons
owing to the machinery weights being 2 tons in excess of the
estimate. Since then these weights had been increased by another
half-ton, making a total of 2 1/2 tons over the original
estimate. It was evident that with so small a margin of lift
these ships would never be of real use, and it was decided to
remove various weights to increase the lift and to substitute a
wing car of a similar type to those manufactured for the R 33
class for the heavy after car at present in use.
R 23 carried out her trials without the alteration to the car,
which was effected at a later date, and the same procedure was
adopted with R 24 and R 25. In the case of R 26, however, she
had not reached the same stage of completion as the other two
ships, and the alterations proposed for them were embodied in her
during construction. The gasbags were of lighter composition,
all cabin furniture was omitted and the wing car was fitted in
place of the original after car. This wing car is of streamline
shape with a rounded bow and tapered stern. The lower portion is
plated with duralumin sheets and the upper part is covered with
canvas attached to light wooden battens to give the necessary
shape. This effected a very considerable reduction in weight.
The original 250 horse-power Rolls Royce engine was installed,
now driving a single large two-bladed propeller astern. A test
having been taken, it was found that the disposable lift under
standard conditions was 6.28 tons. It was therefore decided that
all the ships of the class should be modified to this design when
circumstances permitted. Speed trials were carried out under
various conditions of running, when it was found that the ship
possessed a speed of 54 1/4 miles per hour with the engines
running full out.
To summarize the performances of these ships as we did in the
case of No. 9, we find:
Speed:
Full 54 miles per hour
Normal =2/3 48 " " "
Cruising =1/3 33 " " "
Endurance:
Full 18 hours = 1,000 miles
Normal 26 " = 1,250 "
Cruising 50 " = 1,900 "
The production of the rigid airship during the war was always
surrounded with a cloak of impenetrable mystery. Few people,
except those employed on their construction or who happened to
live in the immediate vicinity of where they were built, even
knew of their existence, and such ignorance prevailed concerning
airships of every description that the man in the street hailed a
small non-rigid as "the British Zeppelin" or admired the
appearance of R 23 as "the Silver Queen." The authorities no
doubt knew their own business in fostering this ignorance,
although for many reasons it was unfortunate that public interest
was not stimulated to a greater degree. In the summer months of
1918, however, they relented to a certain extent, and R 23 and
one of her sister ships were permitted to make several flights
over London to the intense delight of thousands of its
inhabitants, and a certain amount of descriptive matter appeared
in the Press.
From that time onwards these large airships have completely
captured the popular imagination, and many absurd rumours and
exaggerations have been circulated regarding their capabilities.
It has been gravely stated that these airships could accomplish
the circuit of the globe and perform other feats of the
imagination. It must be confessed that their merits do not
warrant these extravagant assertions. The fact remains, however,
that R 23 and her sister ship R 26 have each carried out patrols
of upwards of 40 hours duration and that, similarly to No. 9,
they have proved of the greatest value for training airship crews
and providing experience and data for the building programme of
the future. At the present time highly interesting experiments
are being carried out with them to determine the most efficient
system of mooring in the open, which will be discussed at some
length in the chapter dealing with the airship of the future.
RIGID AIRSHIP 23 X CLASS
During the early days of building the airships of the 23 class,
further information was obtained relating to rigid airship
construction in Germany, which caused our designers to modify
their views. It was considered a wrong policy to continue the
production of a fleet of ships the design of which was becoming
obsolete, and accordingly within ten months of placing the order
for this class a decision was reached that the last four ships
were to be altered to a modified design known as the 23 X class.
As was the case with the ships of the preceding class when
nearing completion, they were realized to be out of date, and
special efforts being required to complete the ships of the 33
class and to release building space for additional larger ships,
the construction of the second pair was abandoned.
The main modification in design was the abolition of the external
keel, and in this the later Zeppelin principles were adopted.
This secured a very considerable reduction in structural weight
with a corresponding large expansion of the effective
capabilities of the ship.
It has been seen that the purpose of the keel in No. 9 was to
provide a structure sufficiently strong to support all the main
vertical bending moments and shearing forces, and that in No. 23
this principle was somewhat different, in that the keel in this
ship was primarily intended to support the distributed weights of
petrol, water, ballast, etc., between the transverse frames.
In this later design, namely, the 23 X class, it was considered
that the weights could be concentrated and suspended from the
radial wiring of the transverse frames and that the keel,
incorporated in the design of the former ships, could be
dispensed with.
For all practical purposes, apart from the absence of the keel,
the 23 X class of airship may be regarded as a slightly varied
model of the 23 class. The main dimensions are nearly the same,
and the general arrangement of the ship is but little changed.
The loss of space owing to the introduction of the internal
corridor is compensated by a modification of the shape of the
bow, which was redesigned with a deeper curve. The hull
structure was also strengthened by utilizing a stronger type of
girder wherever the greatest weights occur. In these
strengthened transverse frames the girders, while still remaining
of the triangular section, familiar in the other ships, are
placed the opposite way round, that is, with the apex pointing
outwards.
The walking way is situated at the base of the hull passing
through the gas chambers, which are specially shaped for the
purpose. The corridor is formed of a light construction of
hollow wooden struts and duralumin arches covered with netting.
In all other leading features the design of the 23 class is
adhered to; the gasbags are the same, except for the alteration
due to the internal corridor, and the system of valves and the
various controls are all highly similar.
The arrangement of gondolas and the fitting of engines in all
ways corresponds to the original arrangement of R 23, with the
exception that they were suspended closer to the hull owing to
the absence of the external keel. The substitution of the wing
car of the 33 class for the original after gondola, carried out
in the modifications undergone by the ships of the 23 class, was
not adopted in these ships, as the wireless compartment installed
in the keel in the former was fitted in the after gondola in the
latter.
The disposable lift of these ships under standard conditions is 7
1/2 tons, which shows considerable improvement on the ships of
the former classes.
Summarizing as before, the performances appear as under--
Speed:
Full 56 1/2 miles per hour
Normal 53 " " "
Cruising 45 " " "
Endurance:
Normal 19 hours = 1,015 miles
Cruising 23 1/2 " = 1,050 "
The two ships of this class, which were commissioned, must be
regarded within certain limits as most satisfactory, and are the
most successful of those that appeared and were employed during
the war. Escort of convoys and extended anti-submarine patrols
were carried out, and certain valuable experiments will be
attempted now that peace has arrived.
In spite of the grave misgivings of many critics, the structure
without the keel has proved amply strong, and no mishap attended
this radical departure on the part of the designers.
RIGID AIRSHIP No. 31 CLASS
The airship known as R 81 was a complete deviation from any rigid
airship previously built in this country. In this case the
experiment was tried of constructing it in wood in accordance
with the practice adopted by the Schutte-Lanz Company in Germany.
It must be frankly acknowledged that this experiment resulted in
failure. The ship when completed showed great improvement both in
shape, speed and lifting capacity over any airship commissioned
in this country, and as a whole the workmanship exhibited in her
construction was exquisite. Unfortunately, under the conditions
to which it was subjected, the hull structure did not prove
durable, and to those conditions the failure is attributed.
Under different circumstances it may be hoped that the second
ship, when completed, will prove more fortunate.
In length R 31 was 615 feet, with a diameter of 66 feet, and the
capacity was 1 1/2 million cubic feet.
In shape the hull was similar to the later types of Zeppelin,
having a rounded bow and a long, tapering stern. The longitudinal
and transverse frames were composed of girders built up of
three-ply wood, the whole structure being braced in the usual
manner with wire bracings. It had been found in practice with
rigid airships that, if for any reason one gasbag becomes much
less inflated than those adjacent to it, there is considerable
pressure having the effect of forcing the radial wires of the
transverse frames towards the empty bag. The tension resulting
in these wires may produce very serious compressive strain in the
members of the transverse frames, and to counteract this action
an axial wire is led along the axis of the ship and secured to
the centre point of the radial wiring. This method, now current
practice in rigid airship construction, was introduced for the
first time in this ship.
As will be seen from the photograph, the control and navigating
compartment of the ship is contained in the hull, the cars in
each case being merely small engine rooms. These small cars were
beautifully made of wood of a shape to afford the least
resistance to the air, and in number were five, each housing a
single 250 horse-power Rolls Royce engine driving a single fixed
propeller. Here we see another decided departure from our
previous methods of rigid airship construction, in that for the
first time swivelling propellers were abandoned. R 31 when
completed carried out her trials, and it was evident that she was
much faster than previous ships. The trials were on the whole
satisfactory and, except for a few minor accidents to the hull
framework and fins, nothing untoward occurred.
At a later date the whole ship was through fortuitous
circumstances exposed to certain disadvantageous conditions which
rendered her incapable of further use.
R 33 CLASS
September 24th, 1916, is one of the most important days in the
history of rigid airship design in this country; on this date the
German Zeppelin airship L 33 was damaged by gunfire over London,
and being hit in the after gasbags attempted to return to
Germany. Owing to lack of buoyancy she was forced to land at
Little Wigborough, in Essex, where the crew, having set fire to
the ship, gave themselves up. Although practically the entire
fabric of the ship was destroyed, the hull structure most
fortunately remained to all intents and purposes intact, and was
of inestimable value to the design staff of the Admiralty, who
measured up the whole ship and made working drawings of every
part available.
During this year other German rigid airships had been brought
down, namely L 15, which was destroyed at the mouth of the Thames
in April, but which was of an old type, and from which little
useful information was obtained; and also the Army airship L.Z.
85, which was destroyed at Salonica in the month of May. A
Schutte-Lanz airship was also brought down at Cuffley, on
September 2nd, and afforded certain valuable details.
All these ships were, however, becoming out of date; but L 33 was
of the latest design, familiarly called the super-Zeppelin, and
had only been completed about six weeks before she encountered
disaster.
In view of the fact that the rigid airships building in this
country at this date, with the exception of the wooden
Schutte-Lanz ships were all based on pre-war designs of Zeppelin
airships, it can be readily understood that this latest capture
revolutionized all previous ideas, and to a greater extent than
might be imagined, owing to the immense advance, both in design
and construction, which had taken place in Germany since 1914.
All possible information having been obtained, both from the
wreck of the airship itself and from interrogation of the
captured crew, approval was obtained, in November of the same
year, for two ships of the L 33 design to be built; and in
January, 1917, this number was increased to five.
It was intended originally that these ships should be an exact
facsimile of L 33; but owing to the length of time occupied in
construction later information was obtained before they were
completed, both from ships of a more modern design, which were
subsequently brought down, and also from other sources. Acting
on this information, various improvements were embodied in R 33
and R 34, which were in a more advanced state; but in the case of
the three other ships the size was increased, and the ships, when
completed, will bear resemblance to a later type altogether.
As a comment on the slowness of construction before mentioned,
the fact that while we in this country were building two ships on
two slips, Germany had constructed no fewer than thirty on four
slips, certainly affords considerable food for reflection.
The two airships of this class having only just reached a state
of completion, a detailed description cannot be given without
making public much information which must necessarily remain
secret for the present. Various descriptions have, however, been
given in the daily and weekly Press, but it is not intended in
the present edition of this book to attempt to elaborate on
anything which has not been already revealed through these
channels.
It is regrettable that so much that would be of the utmost
interest has to be omitted; but the particulars which follow will
at any rate give sonic idea of the magnitude of the ship and show
that it marks a decided departure from previous experiments and a
great advance on any airship before constructed in Great Britain.
It is also a matter for regret that these two ships were not
completed before the termination of hostilities, as their
capabilities would appear to be sufficient to warrant the
expectations which have been based on their practical utility as
scouting agents for the Grand Fleet.
In all its main features the hull structure of R 33 and R 34
follows the design of the wrecked German Zeppelin airship L 33.
The hull follows more nearly a true streamline shape than in the
previous ships constructed of duralumin, in which a great
proportion of the total length was parallel-sided. The Germans
adopted this new shape from the Schutte-Lanz design and have not
departed from this practice. This consists of a short parallel
body with a long rounded bow and a long tapering stem culminating
in a point. The overall length of the ship is 643 feet with a
diameter of 79 feet and an extreme height of 92 feet.
The type of girders in this class has been much altered from
those in previous ships. The hull is fitted with an internal
triangular keel throughout practically the entire length. This
forms the main corridor of the ship, and is fitted with a footway
down the centre for its entire length. It contains water ballast
and petrol tanks, bomb stowage and crew accommodation and the
various control wires, petrol pipes and electric leads are
carried along the lower part.
Throughout this internal corridor runs a bridge girder, from
which the petrol and water ballast tanks are supported. These
tanks are so arranged that they can be dropped clear of the ship.
Amidships is the cabin space with sufficient room for a crew of
twenty-five. Hammocks can be slung from the bridge girder before
mentioned.
In accordance with the latest Zeppelin practice, monoplane
rudders and elevators are fitted to the horizontal and vertical
fins.
The ship is supported in the air by nineteen gasbags which give a
total capacity of approximately two million cubic feet of gas.
The gross lift works out at approximately 59 1/2 tons, of which
the total fixed weight is 33 tons, giving a disposable lift of 26
1/2 tons.
The arrangement of cars is as follows: At the forward end the
control car is slung, which contains all navigating instruments
and the various controls. Adjoining this is the wireless cabin,
which is also fitted for wireless telephony. Immediately aft of
this is the forward power car containing one engine, which gives
the appearance that the whole is one large car.
Amidships are two wing cars each containing a single engine.
These are small and just accommodate the engine with sufficient
room for mechanics to attend to them. Further aft is another
larger car which contains an auxiliary control position and two
engines
It will thus be seen that five engines are installed in the ship;
these are all of the same type and horse-power, namely, 250
horse-power Sunbeam. R 33 was constructed by Messrs. Armstrong
Whitworth Ltd., while her sister ship R 34 was built by Messrs.
Beardmore on the Clyde.
In the spring of 1918, R 33 and R 34 carried out several flight
trials, and though various difficulties were encountered both
with the engines and also with the elevator and rudder controls,
it was evident that, with these defects remedied, each of these
ships would prove to be singularly reliable.
On one of these trials made by R 34, exceedingly bad weather was
encountered, and the airship passed through several blinding
snowstorms; nevertheless the proposed flight of some seventeen
hours was completed, and though at times progress was practically
nil owing to the extreme force of the wind, the station was
reached in safety and the ship landed without any contretemps.
This trial run having been accomplished in weather such as would
never have been chosen in the earlier days of rigid trial
flights, those connected with the airship felt that their
confidence in the vessel's capabilities was by no means
exaggerated.
The lift of the ship warranted a greater supply of petrol being
carried than there was accommodation for, and the engines by now
had been "tuned up" to a high standard of efficiency.
Accordingly it was considered that the ship possessed the
necessary qualifications for a transatlantic flight. It was,
moreover, the opinion of the leading officers of the airship
service that such an enterprise would be of inestimable value to
the airship itself, as demonstrating its utility in the future
for commercial purposes.
Efforts were made to obtain permission for the flight to be
attempted, and although at first the naval authorities were
disinclined to risk such a valuable ship on what appeared to be
an adventure of doubtful outcome, eventually all opposition was
overcome and it was agreed that for the purposes of this voyage
the ship was to be taken over by the Air Ministry from the
Admiralty.
Work was started immediately to fit out the ship for a journey of
this description. Extra petrol tanks were disposed in the hull
structure to enable a greater supply of fuel to be carried, a new
and improved type of outer cover was fitted, and by May 29th, R
34 was completed to the satisfaction of the Admiralty and was
accepted. On the evening of the same day she left for her
station, East Fortune, on the Firth of Forth. This short passage
from the Clyde to the Forth was not devoid of incident, as soon
after leaving the ground a low-lying fog enveloped the whole
country and it was found impossible to land with any degree of
safety. It having been resolved not to land until the fog
lifted, the airship cruised about the north-east coast of England
and even came as far south as York. Returning to Scotland, she
found the fog had cleared, and was landed safely, having been in
the air for 21 hours.
The original intention was that the Atlantic flight should be
made at the beginning of June, but the apparent unwillingness of
the Germans to sign the Peace Treaty caused the Admiralty to
retain the ship for a time and commission her on a war footing.
During this period she went for an extended cruise over Denmark,
along the north coast of Germany and over the Baltic. This
flight was accomplished in 56 hours, during which extremely bad
weather conditions were experienced at times. On its conclusion
captain and crew of the ship expressed their opinion that the
crossing of the Atlantic was with ordinary luck a moral
certainty. Peace having been signed, the ship was overhauled
once more and made ready for the flight, and the day selected
some three weeks before was July 2nd.
A selected party of air-service ratings, together with two
officers, were sent over to America to make all the necessary
arrangements, and the American authorities afforded every
conceivable facility to render the flight successful.
As there is no shed in America capable of housing a big rigid,
there was no alternative but to moor her out in the open,
replenish supplies of gas and fuel and make the return journey as
quickly as possible.
On July 2nd, at 2.38 a.m. (British summer time), R 34 left the
ground at East Fortune, carrying a total number of 30 persons.
The route followed was a somewhat northerly one, the north coast
of Ireland being skirted and a more or less direct course was
kept to Newfoundland. From thence the south-east coast of Nova
Scotia was followed and the mainland was picked up near Cape Cod.
From Cape Cod the airship proceeded to Mineola, the landing place
on Long Island. All went well until Newfoundland was reached.
Over this island fog was encountered, and later electrical storms
became a disturbing element when over Nova Scotia and the Bay of
Fundy. The course had to be altered to avoid these storms, and
owing to this the petrol began to run short. No anxiety was
occasioned until on Saturday, July 5th, a wireless signal was
sent at 3.59 p.m. asking for assistance, and destroyers were
dispatched immediately to the scene. Later messages were
received indicating that the position was very acute, as head
winds were being encountered and petrol was running short. The
airship, however, struggled on, and though at one time the
possibility of landing at Montauk, at the northern end of Long
Island, was considered, she managed after a night of considerable
anxiety to reach Mineola and land there in safety on July 6th at
9.55 a.m. (British summer time). The total duration of the
outward voyage was 108 hours 12 minutes, and during this time
some 3,136 sea miles were covered. R 34 remained at Mineola
until midnight of July 9th according to American time. During
the four days in which she was moored out variable weather was
experienced, and in a gale of wind the mooring point was torn
out, but fortunately,another trail rope was dropped and made
fast,and the airship did not break away.
It was intended that the return should be delayed until daylight,
in order that spectators in New York should obtain a good view of
the airship, but an approaching storm was reported and the
preparations were advanced for her immediate departure. During
the last half-hour great difficulty was experienced in holding
the ship while gassing was completed.
At 5.57 a.m. (British summer time) R 34 set out on her return
voyage, steering for New York, to fly over the city before
heading out into the Atlantic. She was picked up by the
searchlights and was distinctly visible to an enormous concourse
of spectators. During the early part of the flight a strong
following wind was of great assistance, and for a short period an
air speed of 83 miles per hour was attained. On the morning of
July 11th the foremost of the two engines in the after car broke
down and was found to be beyond repair. The remainder of the
voyage was accomplished without further incident. On July 12th
at noon, a signal was sent telling R 34 to proceed to the airship
station at Pulham in Norfolk as the weather was unfavourable for
landing in Scotland. On the same day at 8.25 p.m., land was
first sighted and the coast line was crossed near Clifden, county
Galway, at 9 p.m. On the following morning, July 13th, at 7.57
a.m. (British summer time), the long voyage was completed and R
34 was safely housed in the shed, having been in the air 75 hours
3 minutes.
Thus a most remarkable undertaking was brought to a successful
conclusion. The weather experienced was by no means abnormally
good. This was not an opportunity waited for for weeks and then
hurriedly snatched, but on the preordained date the flight was
commenced. The airship enthusiast had always declared that the
crossing of the Atlantic presented no insuperable difficulty, and
when the moment arrived the sceptics found that he was correct.
We may therefore assume that this flight is a very important
landmark in the history of aerial transport, and has demonstrated
that the airship is to be the medium for long-distance travel.
We may rest assured that such flights, although creating
universal wonder to-day, will of a surety be accepted as everyday
occurrences before the world is many years older.
CHAPTER VIII
THE WORK OF THE AIRSHIP IN THE WORLD WAR
The outbreak of war found us, as we have seen, practically
without airships of any military value. For this unfortunate
circumstance there were many contributory causes. The
development of aeronautics generally in this country was behind
that of the Continent, and the airship had suffered to a greater
extent than either the seaplane or the aeroplane. Our attitude
in fact towards the air had not altered so very greatly from that
of the man who remarked, on reading in his paper that some
pioneer of aviation had met with destruction, "If we had been
meant to fly, God would have given us wings." Absurd as this
sounds nowadays, it was the opinion of most people in this
country, with the exception of a few enthusiasts, until only a
few years before we were plunged into war.
The year 1909 saw the vindication of the enthusiasts, for in this
summer Bleriot crossed the Channel in an aeroplane, and the
first passenger-carrying Zeppelin airship was completed. Those
who had previously scoffed came to the conclusion that flying was
not only possible but an accomplished fact, and the next two
years with their great aerial cross-country circuits revealed the
vast potentialities of aircraft in assisting in military
operations. We, therefore, began to study aeronautics as the
science of the future, and aircraft as an adjunct to the sea and
land forces of the empire.
The airship, unfortunately, suffered for many reasons from the
lack of encouragement afforded generally to the development of
aeronautics. The airship undoubtedly is expensive, and one
airship of size costs more to build than many aeroplanes. In
addition, everything connected with the airship is a source of
considerable outlay. The shed to house an airship is a most
costly undertaking, and takes time and an expenditure of material
to erect, and bears no comparison with the cheap hangar which can
be run up in a moment to accommodate the aeroplane. The gas to
lift the airship is by no means a cheap commodity. If it is to
be made on the station where the airship is based, it
necessitates the provision of an expensive and elaborate plant.
If, on the other hand, it is to be manufactured at a factory, the
question of transport comes in, which is a further source of
expense with costly hydrogen tubes for its conveyance.
Another drawback is the large tract of ground required for an
aerodrome, and the big airship needs a large number of
highly-trained personnel to handle it.
A further point always, raised when the policy of developing the
airship was mooted is its vulnerability. It cannot be denied
that it presents a large target to artillery or to the aeroplane
attacking it, and owing to the highly inflammable nature of
hydrogen when mixed with air there can be no escape if the gas
containers are pierced by incendiary bullets or shells.
Another contributing factor to the slow development of the
airship was the lack of private enterprise. Rivalry existed
between private firms for aeroplane contracts which consequently
produced improvements in design; airships could not be produced
in this way owing to the high initial cost, and if the resulting
ships ended in failure, as many were bound to do, there would be
no return for a large outlay of capital. The only way by which
private firms could be encouraged to embark on airship building
was by subsidies from the Government, and at this time the
prevalent idea of the doubtful value of the airship was too
strong for money to be voted for this purpose.
To strengthen this argument no demand had either been made from
those in command of the Fleet or from commanders of our Armies
for airships to act as auxiliaries to our forces.
The disasters experienced by all early airships and most
particularly by the Zeppelins were always seized upon by those
who desired to convince the country what unstable craft they
were, and however safe in the air they might be were always
liable to be wrecked when landing in anything but fine weather.
Those who might have sunk their money in airship building
thereupon patted themselves upon the back and rejoiced that they
had been so far-seeing as to avoid being engaged upon such a
profitless industry.
Finally, all in authority were agreed to adopt the policy of
letting other countries buy their experience and to profit from
it at a later date. Had the war been postponed for another
twenty years all might have been well, and we should have reaped
the benefit, but most calamitously for ourselves it arrived when
we were utterly unprepared, and having, as we repeat, only three
airships of any military value.
With these three ships, Astra-Torres (No. 3), Parseval (No. 4)
and Beta, the Navy did all that was possible. At the very
outbreak of war scouting trips were made out into the North Sea
beyond the mouth of the Thames by the Astra and Parseval, and
both these ships patrolled the Channel during the passage of the
Expeditionary Force.
The Astra was also employed off the Belgian coast to assist the
naval landing party at Ostend, and together with the Parseval
assisted in patrolling the Channel during the first winter of the
war.
The Beta was also sent over to Dunkirk to assist in spotting for
artillery fire and locating German batteries on the Belgian
coast. Our airships were also employed for aerial inspection of
London and other large towns by night to examine the effects of
lighting restrictions and obtain information for our
anti-aircraft batteries.
With the single exception of the S.S. ship, which carried out
certain manoeuvres in France in the summer of 1916, our airships
were confined to operations over the sea; but if we had possessed
ships of greater reliability in the early days of the war, it is
conceivable that they would have been of value for certain
purposes to the Army. The Germans employed their Zeppelins at
the bombardment of Antwerp, Warsaw, Nancy and Libau, and their
raids on England are too well remembered to need description.
The French also used airships for the observation of troops
mobilizing and for the destruction of railway depots. The
Italians relied entirely at the beginning of the war on airships,
constructed to fly at great heights, for the bombing of Austrian
troops and territory, and met with a considerable measure of
success.
When it was decided, early in 1915, to develop the airship for
anti-submarine work difficulties which appeared almost
insuperable were encountered at first. To begin with, there were
practically no firms in the country capable of airship
production. The construction of envelopes was a great problem;
as rubber-proofed fabric had been found by experiment to yield
the best results for the holding of gas, various waterproofing
firms were invited to make envelopes, and by whole-hearted
efforts and untiring industry they at last provided very
excellent samples. Fins, rudder planes, and cars were also
entrusted to firms which had had no previous experience of this
class of work, and it is rather curious to reflect that envelopes
were produced by the makers of mackintoshes and that cars and
planes were constructed by a shop-window furnisher. This was a
sure sign that all classes of the community were pulling together
for the good of the common cause.
Among other difficulties was the shortage of hydrogen tubes,
plants, and the silicol for making gas.
Sufficient sheds and aerodromes were also lacking, and the
airships themselves were completed more quickly than the sheds
which were to house them.
The lack of airship personnel to meet the expansion of the
service presented a further obstacle. To overcome this the
system of direct entry into the R.N.A.S. was instituted, which
enabled pilots to be enrolled from civil life in addition to the
midshipmen who were drafted from the Fleet. The majority of the
ratings were recruited from civil life and given instruction in
rigging and aero-engines as quickly as possible, while technical
officers were nearly all civilians and granted commissions in the
R.N.V.R.
A tremendous drawback was the absence of rigid airships and the
lack of duralumin with which to construct them.
Few men were also experienced in airship work at this time, and
there was no central airship training establishment as was
afterwards instituted. Pilots were instructed as occasion
permitted at the various patrol stations, having passed a balloon
course and undergone a rudimentary training at various places.
To conclude, the greatest of all difficulties was the shortage of
money voted for airship development, and this was a disadvantage
under which airships laboured even until the conclusion of
hostilities.
We have seen previously how the other difficulties were
surmounted and how our airships were evolved, type by type, and
the measure of success which attended them. It is interesting to
recall that five years ago we only possessed three ships capable
of flying, and that during the war we built upwards of two
hundred, of which no fewer than 103 were actually in commission
on the date of the signing of the Armistice.
The work carried out by our airships during the war falls under
three main headings:
1. Operations with the fleet or with various units.
2. Anti-submarine patrol and searching for mines.
3. Escort of shipping and examination duties.
With regard to the first heading it is only permissible at
present to say very little; certain manoeuvres were carried out
in connection with the fleet, but the slow development of our
rigid airships prohibited anything on a large scale being
attempted. The Germans, on the other hand, made the fullest use
of their Zeppelins for scouting purposes with the high seas
fleet. Responsible people were guilty of a grave mistake when
speaking in public in denouncing the Zeppelin as a useless
monster every time one was destroyed in a raid on this country.
The main function of the Zeppelin airship was to act as an aerial
scout, and it carried out these duties with the utmost efficiency
during the war. It is acknowledged that the German fleet owed
its escape after the Battle of Jutland to the information
received from their airships, while again the Zeppelin was
instrumental in effecting the escape of the flotilla which
bombarded Scarborough in 1916.
Very probably, also, the large airship was responsible for the
success which attended the U boats during their attack on the
cruisers Nottingham and Falmouth, and also at the Hogue disaster.
Various experiments were carried out in towing airships by
cruisers, in refuelling while in tow and changing crews, all of
which would have borne good fruit had the war lasted longer.
An exceedingly interesting experiment was carried out during the
closing stages of the war by an airship of the S.S. Zero type.
At this period the German submarines were gradually extending
their operations at a greater distance from our coasts, and the
authorities became concerned at the prospect that the small type
of airship would not possess sufficient endurance to carry out
patrol over these increased distances. The possibility was
considered of carrying a small airship on board a ship which
should carry out patrol and return to the ship for refuelling
purposes, to replenish gas, and change her crew. To test the
feasibility of this idea S.S. Z 57 carried out landing
experiments on the deck of H.M.S. Furious, which had been adapted
as an aeroplane carrier. S.S. Z 57 came over the deck and
dropped her trail rope, which was passed through a block secured
to the deck, and was hauled down without difficulty. These
experiments were continued while the ship was under weigh and
were highly successful. No great difficulty was encountered in
making fast the trail rope, and the airship proved quite easy to
handle. The car was also lowered into the hangar below the upper
deck, the envelope only remaining on the upper level, and
everything worked smoothly. If the war had continued there is no
doubt that some attempt would have been made to test the
practical efficiency of the problem.
Anti-submarine patrol was the chief work of the airship during
the war, and, like everything else, underwent most striking
changes. Submarine hunting probably had more clever brains
concentrated upon it than anything else in the war, and the part
allotted to the airship in conjunction with the hunting flotillas
of surface craft was carefully thought out.
In the case of a suspected submarine in a certain spot, all
surface and air craft were concentrated by means of wireless
signals at the appointed rendezvous. It is in operations of this
kind that the airship is so superior to the seaplane or
aeroplane, as she can hover over a fixed point for an indefinite
period with engines shut off. If the submarine was located from
the air, signals were given and depth charges dropped in the
position pointed out. Incidents of this kind were of frequent
occurrence, and in them the value of the airship was fully
recognized.
The most monotonous and arduous of the airship's duties was the
routine patrol. The ship would leave her shed before dawn and
be at the appointed place many miles away from land. She then
would carry out patrol, closely scanning the sea all round, and
investigating any suspicious object. For hours this might last
with nothing seen, and then in the gathering darkness the ship
would make her way home often against a rising wind, and in the
winter through hail and snow. Bombs were always carried, and on
many occasions direct hits were observed on enemy submarines. A
sharp look-out was always kept for mines, and many were
destroyed, either by gunfire from the airship herself or through
the agency of patrol boats in the vicinity. This was the chief
work of the S.S. ships, and was brought to a high pitch of
perfection by the S.S. Zero. These ships proved so handy that
they could circle round an object without ever losing sight of
it, and yet could be taken in and out of sheds in weather too bad
to handle bigger ships.
The hunting of the submarine has been likened to big-game
hunting, and certainly no one ever set out to destroy a bigger
quarry. It needs the same amount of patience and the same
vigilance. Days may pass without the opportunity, and that will
only be a fleeting one: the psychological moment must be seized
and it will not brook a moment's delay. The eye must be trained
to pick up the minutest detail, and must be capable of doing this
for hour after hour. For those on submarine patrol in a small
ship there is not one second's rest. As is well known, the
submarine campaign reached its climax in April, 1917. In that
month British and Allied shipping sustained its greatest losses.
The value of the airship in combating this menace was now fully
recognized, and with the big building programme of Zero airships
approved, the housing accommodation again reached an acute stage.
Shortage of steel and timber for shed building, and the lack of
labour to erect these materials had they been available, rendered
other methods necessary. It was resolved to try the experiment
of mooring airships in clearings cut into belts of trees or small
woods.
A suitable site was selected and the trees were felled by service
labour. The ships were then taken into the gaps thus formed and
were moored by steel wires to the adjacent trees. Screens of
brushwood were then built up between the trees, and the whole
scheme proved so successful that even in winter, when the trees
were stripped of their foliage, airships rode out gales of over
60 miles per hour. The personnel were housed either in tents or
billeted in cottages or houses in the neighbourhood, and gas was
supplied in tubes as in the earlier days of the stations before
the gas plants had been erected.
This method having succeeded beyond the most sanguine
expectations, every station had one or more of these sub-stations
based on it, the airships allocated to them making a periodical
visit to the parent station for overhaul as required.
Engineering repairs were effected by workshop lorries, provided
that extensive work was not required.
In this way a large fleet of small airships was maintained around
our coasts, leaving the bigger types of ships on the parent
stations, and the operations were enabled to be considerably
extended. Of course, certain ships were wrecked when gales of
unprecedented violence sprung up; but the output of envelopes,
planes and cars was by this time so good that a ship could be
replaced at a few hours' notice, and the cost compared with
building of additional sheds was so small as to be negligible.
From the month of April, 1917, the convoy system was introduced,
by which all ships on entering the danger zones were collected at
an appointed rendezvous and escorted by destroyers and
patrolboats. The airship was singularly suitable to assist in
these duties. Owing to her power of reducing her speed to
whatever was required, she could keep her station ahead or abeam
of the convoy as was necessary, and from her altitude was able to
exercise an outlook for a far greater distance than was possible
from the bridge of a destroyer. She could also sweep the surface
ahead of the approaching convoy, and warn it by wireless or by
flash-lamp of the presence of submarines or mines. By these
timely warnings many vessels were saved. Owing to the position
of the stations it was possible for a convoy to be met by
airships west of the Scilly Isles and escorted by the airships of
the succeeding stations right up the Channel. In a similar
manner, the main shipping routes on the east coast and also in
the Irish Sea were under constant observation. The mail steamers
between England and Ireland and transports between England and
France were always escorted whenever flying conditions were
possible. For escort duties involving long hours of flying, the
Coastal and C Star types were peculiarly suitable, and at a later
date the North Sea, which could accompany a convoy for the length
of Scotland. Airships have often proved of value in summoning
help to torpedoed vessels, and on occasions survivors in open
boats have been rescued through the agency of patrolling
airships. Examination duties are reckoned among the many
obligations of the airship. Suspicious-looking vessels were
always carefully scrutinized, and if unable to give a
satisfactory answer to signals made, were reported to vessels of
the auxiliary patrol for closer examination. Isolated fishing
vessels always were kept under close observation, for one of the
many ruses of the submarine was to adopt the disguise of a
harmless fishing boat with masts and sails.
The large transports, conveying American troops who passed
through England on their way to France, were always provided with
escorting airships whenever possible, and their officers have
extolled their merits in most laudatory terms.
Our rigid airships also contributed their share in convoy work,
although their appearance as active units was delayed owing to
slowness in construction.
A disturbing feature to the advocate of the large airship, has
been the destruction of raiding Zeppelins by heavier-than-air
machines, and the Jeremiahs have not lost this opportunity of
declaring that for war purposes the huge rigid is now useless and
will always be at the complete mercy of the fast scouting
aeroplane. There is never any obstacle in this world that cannot
be surmounted by some means or other. On the one hand there is
helium, a non-inflammable gas which would render airships almost
immune to such attacks. On the other hand, one opinion of
thought is that the rigid airship in the future will proceed to
sea escorted by a squadron of scouting aeroplanes for its
defence, in the same way that the capital ship is escorted at sea
by destroyers and torpedo boats. This latter idea has been even
further developed by those who look into the future, and have
conceived the possibility of a gigantic airship carrying its own
aeroplanes for its protection.
To test the possibility of this innovation, a small aeroplane was
attached to one of our rigid airships beneath the keel.
Attachments were made to the top of the wings and were carried to
the main framework of the hull. The release gear was tested on
the ground to preclude the possibility of any accident, and on
the day appointed the airship was got ready for flight. While
the airship was flying, the pilot of the aeroplane was in his
position with his engine just ticking over. The bows of the
airship were then inclined upwards and the release gear was put
into operation. The pilot afterwards said that he had no notion
that anything had been done until he noticed that the airship was
some considerable height above him. The machine made a circuit of
the aerodrome and landed in perfect safety, while no trouble was
experienced in any way in the airship. Whether this satisfactory
experiment will have any practical outcome the future alone can
say, but this achievement would have been considered,beyond all
the possibilities of attainment only a few years ago.
Since the Armistice several notable endurance flights were
accomplished by ships of the North Sea class, several voyages
being made to the coast of Norway, and quite recently a trip was
carried out all round the North Sea.
The weather has ceased to be the deterrent of the early days.
Many will no doubt remember seeing the North Sea airship over
London on a day of squalls and snow showers, and R 34 encountered
heavy snow storms on the occasion of one of her flight trials,
which goes to prove that the airship is scarcely the fair-weather
aircraft as maintained by her opponents.
Throughout the war our airships flew for approximately 89,000
hours and covered a distance of upwards of two and a quarter
million miles. The Germans attempted to win the war by the
wholesale sinking of our merchant shipping, bringing supplies and
food to these islands, and by torpedoing our transports and
ships carrying guns and munitions of war. They were, perhaps,
nearer to success than we thought at the time, but we were saved
by the defeat of the submarine. In the victory won over the
underseas craft the airship certainly played a prominent part and
we, who never suffered the pinch of hunger, should gratefully
remember those who never lost heart, but in spite of all
difficulties and discouragement, designed, built, maintained and
flew our fleet of airships.
CHAPTER IX
THE FUTURE OF AIRSHIPS
With the signing of the Armistice on November 11th, 1918, the
airship's work in the war was practically completed and peace
reigned on the stations which for so many months had been centres
of feverish activity. The enemy submarines were withdrawn from
our shipping routes and merchant ships could traverse the sea in
safety except for the occasional danger of drifting mines. "What
is to be the future of the airship?" is the question which is
agitating the minds of innumerable people at the present moment.
During the war we have built the largest fleet of airships in the
world, in non-rigids we have reached a stage in design which is
unsurpassed by any country, and in rigid airships we are second
only to the Germans, who have declared that, with the signing of
the peace terms, their aircraft industry will be destroyed. Such
is our position at the present moment, a position almost
incredible if we look back to the closing days of the year 1914.
Are we now to allow ourselves to drift gradually back to our old
policy of supineness and negligence as existed before the war?
Surely such a thought is inconceivable; as we have organized our
airship production for the purposes of war, so shall we have to
redouble our efforts for its development in peace, if we intend
to maintain our supremacy in the air.
Unless all war is from henceforth to cease, a most improbable
supposition when the violence of human nature is considered,
aircraft will be in the future almost the most important arm.
Owing to its speed, there will not be that period of waiting for
the concentration and marching of the armies of the past, but the
nation resolved on war will be able to strike its blow, and that
a very powerful and terrible one, within a few hours of the
rupture of negotiations. Every nation to be prepared to counter
such a blow must be possessed of adequate resources, and unless
the enormous expense is incurred of maintaining in peace a huge
establishment of aircraft and personnel, other methods must be
adopted of possessing both of these available for war while
employed in peace for other purposes.
From the war two new methods of transportation have emerged--the
aeroplane and the airship. To the business man neither of these
is at the present juncture likely to commend itself on the basis
of cost per ton mile. When, however, it is considered that the
aeroplane is faster than the express train and the airship's
speed is double that of the fastest merchant ship, it will be
appreciated that for certain commercial purposes both these
mediums for transport have their possibilities. The future may
prove that in the time to come both the airship and the aeroplane
will become self-supporting, but for the present, if assisted by
the Government, a fair return may be given for the capital laid
out, and a large fleet of aircraft together with the necessary
personnel will always be available for military purposes should
the emergency arise. The present war has shown that the merchant
service provided a valuable addition both of highly-trained
personnel and of vessels readily adapted for war purposes, and it
appears that a similar organization can be effected to reinforce
our aerial navies in future times of danger.
In discussions relative to the commercial possibilities of
aircraft, a heated controversy always rages between advocates of
the airship and those of the heavier-than-air machine, but into
this it is not proposed to plunge the reader of this volume. The
aeroplane is eminently adapted for certain purposes, and the
greatest bigot in favour of the airship can hardly dispute the
claims of this machine to remain predominant for short-distance
travel, where high speed is essential and the load to be carried
is light. For long distance voyages over the oceans or broken or
unpopulated country, where large loads are to be carried, the
airship should be found to be the more suitable.
The demand for airships for commercial purposes falls under three
main headings, which will be considered in some detail. It will
be shown to what extent the present types will fill this demand,
and how they can be developed in the future to render the
proposed undertakings successful.
1. Pleasure.
2. A quick and safe means of transport for passengers.
3. A quick commercial service for delivering goods of reasonable
weight from one country to another.
1. Pleasure.--In the past, men have kept mechanically-driven
means of transport such as yachts, motor cars, and motor boats
for their amusement, and to a limited extent have taken
recreation in the air by means of balloons. For short cruises
about this country and round the coast a small airship, somewhat
similar to the S.S. Zero, would be an ideal craft. In cost it
would be considerably less than a small yacht, and as it would
only be required in the summer months, it would be inflated and
moored out in the open in a park or grounds and the expense of
providing a shed need not be incurred. For longer distances, a
ship of 150,000 cubic feet capacity, with a covered-in car and
driven by two engines, would have an endurance of 25 hours at a
cruising speed of 45 miles per hour. With such a ship voyages
could easily be made from the south coast to the Riviera or
Spain, and mooring out would still be possible under the lee of a
small wood or to a buoy on the water.
Possibilities also exist for an enterprising firm to start a
series of short pleasure trips at various fashionable seaside
resorts, and until the novelty had worn off the demand for such
excursions will probably be far in excess of the supply.
2. Passenger transport.--In the re-organization of the world
after this devastating war the business man's time will be of
even more value than it was before. This country is largely
bound up with the United States of America in business interests
which necessitate continual visits between the two countries.
The time occupied by steamer in completing this journey is at
present about five days. If this time can be cut down to two and
a half days, no doubt a large number of passengers will be only
too anxious to avail themselves of this means of travel,
providing that it will be accomplished in reasonable safety and
comfort. The requirements for this purpose are an aerial liner
capable of carrying a hundred passengers with a certain quantity
of luggage and sufficient provisions for a voyage which may be
extended over the specified time owing to weather conditions.
The transatlantic service if successful could then be extended
until regular passenger routes are established encircling the
globe.
3. Quick commercial service for certain types of goods.--
Certain mails and parcels are largely enhanced in value by the
rapidity of transport, and here, as in the passenger service
outlined above, the airship offers undoubted facilities. As we
have said before, it is mainly over long distances that the
airship will score, and for long distances on the amount carried
the success of the enterprise will be secured. For this purpose
the rigid airship will be essential. There are certain instances
in which the non-rigid may possibly be profitably utilized, and
one such is suggested by a mail service between this country and
Scandinavia. A service is feasible between Newcastle and Norway
by airships of a capacity of the S.S. Twin type. These ships
would carry 700 lb. of mails each trip at about 4d. per ounce,
which would reduce the time of delivering letters from about two
and a half to three days to twenty-four hours.
A commercial airship company is regarded in this country as a new
and highly hazardous undertaking, and it seems to be somewhat
overlooked that it is not quite the novel idea so many people
imagine. Before the war, in the years 1910 to 1914, the Deutsche
Luftfahrt Actien Gesellschaft successfully ran a commercial
Zeppelin service in which four airships were used, namely,
Schwaben, Victoria Luise, Hansa and Sachsan. During this period
over 17,000 passengers were carried a total distance of over
100,000 miles without incurring a single fatal accident.
Numerous English people made trips in these airships, including
Viscount Jellicoe, but the success of the company has apparently
been forgotten.
We have endeavoured to show that the non-rigid airship has
potentialities even for commercial purposes, but there is no
doubt whatever that the future of the airship in the commercial
world rests entirely with the rigid type, and the airships of
this type moreover must be of infinitely greater capacity than
those at present in existence, if a return is to be expected for
the capital invested in them. General Sykes stated, in the paper
which he read before the London Chamber of Commerce, "that for
commercial purposes the airship is eminently adapted for
long-distance journeys involving non-stop flights. It has this
inherent advantage over the aeroplane, that while there appears
to be a limit to the range of the aeroplane as at present
constructed, there is practically no limit whatever to that of
the airship, as this can be overcome by merely increasing the
size. It thus appears that for such journeys as crossing the
Atlantic, or crossing the Pacific from the west coast of America
to Australia or Japan, the airship will be peculiarly suitable."
He also remarked that, "it having been conceded that the scope of
the airship is long-distance travel, the only type which need be
considered for this purpose is the rigid. The rigid airship is
still in an embryonic state, but sufficient has already been
accomplished in this country, and more particularly in Germany,
to show that with increased capacity there is no reason why,
within a few years' time, airships should not be built capable of
completing the circuit of the globe and of conveying sufficient
passengers and merchandise to render such an undertaking a paying
proposition."
The report of the Civil Aerial Transport Committee also states
that, "airships are the most suitable aircraft for the carrying
of passengers where safety, comfort and reliability are
essential."
When we consider the rapid development of the rigid airship since
1914, it should not be insuperable to construct an airship with
the capabilities suggested by General Sykes. In 1914, the
average endurance of the Zeppelin at cruising speed was under one
day and the maximum full speed about 50 miles per hour. In 1918,
the German L 70, which is of 2,195,000 cubic feet capacity, the
endurance at 45 miles per hour has risen to 7.4 days and the
maximum full speed to 77 miles per hour. The "ceiling" has
correspondingly increased from 6,000 feet to 23,000 feet.
The British R 38 class, at present building, with a capacity of
approximately 2 3/4 million cubic feet has an estimated endurance
at 45 miles per hour of 211 hours or 8.8 days, which is 34 hours
greater than the German L 70 class. It is evident that for a
ship of this calibre the crossing of the Atlantic will possess no
difficulty, and as an instance of what has already been
accomplished in the way of a long-distance flight the exploit of
a Zeppelin airship based in Bulgaria during the war is
sufficiently remarkable. This airship in the autumn of 1917 left
the station at Jamboli to carry twelve tons of ammunition for the
relief of a force operating in German East Africa. Having
crossed the Mediterranean, she proceeded up the course of the
Nile until she had reached the upper waters of this river.
Information was then received by wireless of the surrender of the
force, and that its commander, Von Lettow, was a fugitive in the
bush. She thereupon set out for home and reached her station in
safety, having been in the air 96 hours, or four days, without
landing.
It is therefore patent that in R 33 and R 34 we possess two
airships which can cross to America to-morrow as far as actual
distance is concerned, but various other conditions are necessary
before such voyages can be undertaken with any prospects of
commercial success.
The distance between England and America must be roughly taken as
3,000 miles. It is not reasonable for airship stations to be
situated either in the inaccessible extreme west of Ireland or
among the prevailing fogs of Newfoundland.
Weather conditions must also be taken into account; head winds
may prevail, rendering the forward speed of the ship to be small
even with the engines running full out. In calculations it is
considered that the following assumptions should be made:
1. At least 75 per cent additional petrol to be carried as would
be necessary for the passage in calm air, should unfavourable
weather conditions be met. This amount could be reduced to 50
per cent in future airships with a speed of upwards of 80
miles per hour.
2. About a quarter of the total discharge able lift of the ship
should be in the form of merchandise or passengers to render
the project a reasonable commercial proposition.
We will consider the commercial loads that can be carried by the
German airship L 70 and our airships R 33 and R 38 under the
conditions given above. Two speeds will be taken for the
purposes of this comparison: normal full speed, or about 60 miles
per hour, and cruising speed of 45 miles per hour.
L 70.--At 60 miles per hour a distance of 3,000 miles will be
accomplished in 50 hours.
Fuel consumption about
13 tons + 9.75 tons (additional for safety) = 22.75 tons.
Available lift for fuel and freight = 27.8 tons.
Fuel carried = 22.75 "
------------
Balance for freight = 5 " about.
-----------
At 45 miles per hour, distance will be
accomplished in 66.6 hours.
Fuel consumption about
10 tons + 7.5 tons additional = 17.5 tons.
Available lift = 27.8 tons
Fuel carried = 17.5 "
------------
Balance for freight = 10 " about.
------------
R. 33.--At 60 miles per hour.
Fuel consumption
14.25 tons + 10.68 tons additional = 24.93 tons.
Lift available for fuel and freight = 21.5 tons.
Fuel carried = 24.93 "
------------
Minus balance = 3. 43 "
------------
At 45 miles per hour.
Fuel consumption
9.66 tons + 7.23 tons (17 tons approx.)
Lift available for fuel and freight = 21.5 tons.
Fuel carried = 17 "
------------
Balance for freight = 4.5 "
------------
R. 38.-Estimated only. At 60 miles per hour.
Fuel consumption
20 tons + 15 tons additional = 35 tons.
Lift available for fuel and freight = 42 tons.
Fuel carried = 35 "
------------
Balance for freight = 7 "
------------
At 45 miles per hour.
Fuel consumption 12 tons + 9 tons additional = 21 tons.
Lift available for fuel and freight = 42 "
Fuel carried = 21 "
------------
Balance for freight = 21 "
------------
It will thus be seen that at the faster speed small commercial
loads can be carried by L 70 and R 38 and not at all in the case
of R 33, that is assuming, of course, that the extra fuel is
carried, of which 75 per cent of the total does not appear at all
excessive in view of the weather continually experienced over the
Atlantic.
At the cruising speed the loads naturally increase but still, in
L 70, and more particularly in R 33, they are too small to be
considered commercially. In R 38, however, the load that can be
carried at cruising speed is sufficient to become a commercial
proposition.
From this short statement it is evident that, by a comparatively
small increase in volume, the lifting capacity of an airship is
enormously increased, and it is in this subject that the airship
possesses such undoubted advantage over the aeroplane. In the
heavier-than-air machine there is no automatic improvement in
efficiency resulting from greater dimensions. In the airship,
however, this automatic improvement takes place in a very marked
degree; for example, an airship of 10,000,000 cubic feet capacity
has five times the lift of the present 2,000,000 cubic feet
capacity rigid, but the length of the former is only 1.7 times
greater, and therefore the weight of the structure only five
times greater (1.7); that is, the weight of the structure is
directly proportional to the total lift. Having seen that the
total lift varies as the cube of the linear dimensions while air
resistance, B.H.P.--other things being equal--vary as the square
of the linear dimensions,it follows that the ratio "weight of
machinery/total lift" decreases automatically.
In comparing the different methods of transport for efficiency,
the resistance or thrust required is compared as a percentage of
the total weight. The result obtained is known as the
"co-efficient of tractive resistance." Experiments have shown
that as the size of the airship increases, the co-efficient of
tractive resistance decreases to a marked extent; with a
proportionate increase in horse-power it is proportionally more
economical for a 10,000,000 cubic feet capacity rigid to fly at
80 miles per hour than for a 2,000,000 cubic feet capacity to fly
at 60 miles per hour.
As the ratio "weight structure/total lift" is in airships fairly
constant, it follows that the ratio "disposable lift/total lift"
increases with the dimensions.
It is therefore obvious that increased benefits are obtained by
building airships of a larger size, and that the bigger the ship
the greater will be its efficiency, providing, of course, that it
is kept within such limits that it can be handled on the ground
and manoeuvred in the air.
The proportion of the useful lift in a large rigid, that is the
lift available for fuel, crew, passengers, and merchandise, is
well over 50 per cent when compared with the gross lift. When the
accompanying table is studied it will be seen that with airships
of large capacity the available lift will be such that
considerable weights of merchandise or passengers can be carried.
Capacity in Gross Lift Length Diameter
cubic feet in tons in feet in feet
2,000,000 60.7 643 79
3,000,000 91.1 736 90.4
4,000,000 121.4 810 99.5
5,000,000 151.8 872 107.2
6,000,000 182.2 927 113.9
7,000,000 212.5 976 119.9
8,000,000 242.8 1,021 125.5
9,000,000 273.3 1,061 130.4
10,000,000 303.6 1,100 135.1
In airships of their present capacity, in order to obtain the
greatest amount of lift possible, lightness of construction has
been of paramount importance. With this object in view duralumin
has been used, and complicated girders built up to obtain
strength without increase of weight. In a large ship with a
considerable gain in lift, steel will probably be employed with a
simpler form of girder work. In that way cheapness of
construction will be effected together with increased rapidity of
output, and in addition the strength of the whole structure
should be increased.
The rigid airship of 10,000,000 cubic feet capacity will have a
disposable lift of over 200 tons available for fuel, crew,
passengers, and merchandise in such proportions as are desired.
The endurance of such a ship at a cruising speed of 45 miles per
hour will be in the neighbourhood of three weeks, with a maximum
speed of 70 to 80 miles per hour, and a "ceiling" of some 30,000
feet can be reached. This will give a range of over 20,000
miles, or very nearly a complete circuit of the globe.
For commercial purposes the possibilities of such a craft are
enormous, and the uses to which it could be put are manifestly of
great importance. Urgent mails and passengers could be
transported from England to America in under half the time at
present taken by the steamship routes, and any city in the world
could be reached from London in a fortnight.
In the event of war in the future, which may be waged with a
nation situated at a greater distance from this country than was
Germany, aircraft Of long endurance will be necessary both for
scouting in conjunction with our fleets and convoy duties. The
British Empire is widely scattered, and large tracts of ocean lie
between the various colonies, all of which will require
protection for the safe-guarding of our merchant shipping. The
provision of a force of these large airships will greatly add to
the security of our out-lying dominions.
We have now reached a point where it is incumbent on us to face
certain difficulties which beset the airship of large dimensions,
and which are always magnified by its detractors. Firstly, there
is the expense of sheds in which to house it; secondly, the large
number of trained personnel to assist in landing and handling it
when on the ground; thirdly, the risks attendant on the weather--
for the airship is still considered the general public as a
fair-weather craft; and fourthly, though this is principally in
connection with its efficiency for military purposes, its
vulnerability. We will deal with the four difficulties
enumerated under these headings seriatim, and endeavour to show
to what extent they may be surmounted if not entirely removed.
The solution of the first two problems may be summed up in two
words: "mooring out"; on the success of this it is considered
that the whole future of airships for commercial purposes rests.
It will be essential that in every country which the airship
visits on its voyages, one large central station is established
for housing and repairs. The position of such a station is
dependent on good weather conditions and the best railway
facilities possible. In all respects this station will be
comparable to a dry dock for surface vessels. The airship will
be taken into the shed for overhaul of hull structure, renewing
of gasbags or outer cover, and in short to undergo a periodical
refit. The cost of a shed capable of housing two rigid airships,
even at the present time, should not greatly exceed L500,000.
This sum, though considerable, is but a small item compared with
the cost of constructing docks to accommodate the Atlantic liner,
and when once completed the cost of maintenance is small when
weighed against the amount annually expended in dredging and
making good the wear and tear of a dock.
Apart from these occasional visits to a shed, the airship, in the
ordinary way at the end of a voyage, will pick up its moorings as
does the big steamer, and land its passengers and cargo, at the
same time replenishing its supplies of fuel, gas, provisions,
etc., while minor repairs to the machinery can be carried out as
she rides in the air.
A completely satisfactory solution of the mooring problem for the
rigid airship has yet to reach its consummation. We saw in the
previous chapter how, in the case of small non-rigids, they were
sheltered in berths cut into woods or belts of trees, but for the
rigid airship something more secure and less at the mercy of the
elements is required.
At the present moment three systems of mooring are in an
experimental stage: one, known as "the single-wire system," is
now practically acknowledged to fall short of perfection; the
second, "the three-wire system," and the third, "mooring to a
mast," both have their champions, but it is probable that the
last will be the one finally chosen, and when thoroughly tried
out with its imperfections eliminated will satisfy the most
exacting critics.
The single-wire system is at the same time the simplest and most
obvious method which suggests itself, and means that the ship is
secured by a wire cable attached to a suitable point in the ship
and led to some fixed point on the ground. It has been found
that an airship secured in this way requires constant attention,
and that steering is always necessary to render her steady in the
air. Considerable improvement is obtained if a dragging weight
is added to the wire, as it tends to check to a considerable
extent lateral motion of the bow of the ship.
The three-wire system is an adaptation and an improvement on the
one previously mentioned. In this case the mooring point of the
ship is attached to three long wire cables, which, when raised in
the air, form a pyramid to the head of which the ship is
attached. These wires are led to bollards which form in plan an
equilateral triangle. The lift of the ship raises these wires
off the ground, and if the ship is trimmed up by the bows she
will be found to resist the action of the wind. A rigid airship
moored out by this method remained in the open for a considerable
time and rendered the future of this experiment most hopeful. It
was resolved to continue these experiments by adding a subsidiary
system of wires with running blocks, the whole wiring to form a
polygon revolving round a fixed centre. The disadvantages of
this method appear to be rather serious. It seems that great
difficulty will always be found in picking up these moorings in a
high wind, and though this also applies to the method with the
mast, the initial obstacles do not appear to be so great. A
powerful engine driving a winch will be necessary to raise these
heavy wires from the ground, although of course the lift of the
airship will assist in this. Secondly, the lowering of
passengers and cargo will not be easy as the ship will not be
rigidly secured. This, however, can probably be managed when
experiments have reached a further stage, and at present the
system may be said to present distinct possibilities.
The third system, that of mooring to a mast, possesses several
features peculiar to itself, and not embraced by the other two,
which should secure it prolonged investigations. The system is
by no means new and has been tried from time to time for several
years, but since the question of mooring in the open has been so
ventilated and is now considered of such vital importance, these
experiments have been continued, and in less spasmodic fashion
than in the past. In a trial with a small non-rigid airship some
months ago a signal success was achieved. The ship remained
attached to a mast in open country with no protection whatsoever
for six weeks in two of the worst months of the year. During
this period two men only were required to look after the ship,
which experienced gales in which the force of the wind rose to 52
miles per hour, and not the slightest damage was sustained.
Two or three methods of attaching the airship to the mast have
been proposed, but the one which appears to be most practical
is to attach the extreme bow point of the ship to some form of
cap, in which the nose of the ship will fit, and will revolve
round the top of the mast in accordance with the direction of the
wind.
For large airships, employed as passenger and commerce carriers,
we can imagine the mast advanced a stage further, and transformed
into a tower with a revolving head. Incorporated in this tower
will be a lift for passengers and luggage, pipes also will be
led to the summit through which both gas and water can be pumped
into the ship. With the airship rigidly held at the head of such
a structure all the difficulties of changing crews, embarking and
disembarking passengers, shipping and discharging cargo and also
refuelling, vanish at once. Assuming the mooring problem solved
with success, and we feel correct in this assumption, the first
two of our difficulties automatically disappear. Sheds will only
be necessary as repair depots and will not be extensively
required, all intermediate stopping places being provided with
masts and necessary arrangements for taking in gas, etc. At
these intermediate stations the number of men employed will be
comparatively speaking few. At the depots or repair stations the
number must, of course, be considerably increased, but the
provision of an enormous handling party will not be necessary. At
present large numbers of men are only required to take a large
airship in or out of a shed when the wind is blowing in a
direction across the shed; when these conditions prevail the
airship will, unless compelled by accident or other unforeseen
circumstances, remain moored out in the open until the direction
of the wind has changed.
Mechanical traction will also help effectually in handling
airships on the ground, and the difficulty of taking them in and
out of sheds has always been unduly magnified. The provision of
track rails and travellers to which the guys of the ship can be
attached, as is the practice in Germany, will tend to eliminate
the source of trouble.
We must now consider the effect that weather will have on the big
airship. In the past it has been a great handicap owing to the
short hours of endurance, with the resulting probability of the
ship having to land before the wind dropped and being wrecked in
consequence. Bad weather will not endanger the big airship in
flight, and its endurance will be such that, should it encounter
bad weather, it will be able to wait for a lull to land.
Meteorological forecasts have now reached a high state of
efficiency, and it should be possible for ample warnings to be
received of depressions to be met with during a voyage, and these
will be avoided by the airship flying round them. In the
northern hemisphere, depressions generally travel from west to
east and invariably rotate in a counter-clockwise direction with
the wind on the south side blowing from the west and on the north
side blowing from the east. Going west, the airship would fly to
the north of a depression to take advantage of the wind
circulating round the edge, and going east the southern course
would be taken.
Lastly, the vulnerability of the airship must be taken into
account. Hydrogen is, as everyone knows, most highly inflammable
when mixed with air. The public still feels uncomfortable
misgivings at the close proximity of an immense volume of gas to
a number of running engines. It may be said that the danger of
disaster due to the gas catching fire is for peace flying to all
intents and purposes negligible. At the risk of being thought
hackneyed we must point out a fact which has appeared in every
discussion of the kind, namely, that British airships flew during
the war some 21 million miles, and there is only one case of an
airship catching fire in the air. This was during a trial flight
in a purely experimental ship, and the cause which was afterwards
discovered has been completely eliminated.
For airships employed for military purposes this danger, due to
the use of incendiary bullets, rockets and various other
munitions evolved for their destruction, still exists.
Owing to its ceiling, rate of climb and speed, which we take to
be from 70 to 80 miles per hour in the airship of the future, the
airship may be regarded as comparatively safe against attack from
the ordinary type of seaplane. The chief danger to be
apprehended is attack from small scouting seaplanes, possessing
great speed and the power to climb to a great height, or from
aeroplanes launched from the decks of ships. If, however, the
airship is fitted to carry several small scout aeroplanes of high
efficiency in the manner described in the previous chapter, it
will probably be able to defend itself sufficiently to enable it
to climb to a great height and thus make good its escape.
The airship, moreover, will be more or less immune from such
dangers if the non-inflamable gas, known as "C" gas, becomes
sufficiently cheap to be used for inflating airships. In the
past the expense of this gas has rendered its use absolutely
prohibitive, but it is believed that it can be produced in
the United States for such a figure as will make it compare
favourably with hydrogen.
The navigation of an airship during these long voyages proposed
will present no difficulty whatever. The airship, as opposed to
the aeroplane, is reasonably steady in the air and the ordinary
naval instruments can be used. In addition, "directional"
wireless telegraphy will prove of immense assistance. The method
at present in use is to call up simultaneously two land stations
which, knowing their own distance apart, and reading the
direction of the call, plot a triangle on a chart which fixes the
position of the airship. This position is then transmitted by
wireless to the airship. In the future the airship itself will
carry its own directional apparatus, with which it will be able
to judge the direction of a call received from a single land
station and plot its own position on a chart.
We have so far confined our attention to the utilization of
airships for transport of passengers, mails and goods, but there
appear to be other fields of activity which can be exploited in
times of peace. The photographic work carried out by aeroplanes
during the war on the western front and in Syria and Mesopotamia
has shown the value of aerial photography for map making and
preliminary surveys of virgin country. Photography of broken
country and vast tracks of forest can be much more easily
undertaken from an airship than an aeroplane, on account of its
power to hover for prolonged periods over any given area and its
greater powers of endurance. For exploring the unmapped regions
of the Amazon or the upper reaches of the Chinese rivers the
airship offers unbounded facilities. Another scope suggested by
the above is searching for pearl-oyster beds, sunken treasure,
and assisting in salvage operations. Owing to the clearness of
the water in tropical regions, objects can be located at a great
depth when viewed from the air, and it is imagined that an
airship will be of great assistance in searching for likely
places. Sponges and coral are also obtained by diving, and here
the airship's co-operation will be of value. Small ships such as
the S.S. Zero would be ideal craft for these and similar
operations.
The mine patrol, as maintained by airships during the war,
encourages the opinion that a systematic search for icebergs in
the northern Atlantic might be carried out by airships during
certain months of the year. As is well known, icebergs are a
source of great danger to shipping in these waters during the
late spring and summer; if the situation becomes bad the main
shipping routes are altered and a southerly course is taken which
adds considerably to the length of the voyage. The proposal put
forward is that during these months as continuous a patrol as
possible should be carried out over these waters. The airship
employed could be based in Newfoundland and the method of working
would be very similar to anti-submarine patrol. Fixes could be
obtained from D.F. stations and warnings issued by wireless
telegraphy. Ice is chiefly found within five hundred miles of
the coast of Newfoundland, so that this work would come within
the scope of the N.S. airship. The knowledge that reliable
information concerning the presence of ice will always be to hand
would prove of inestimable value to the captains of Atlantic
liners, and would also relieve the shipping companies and the
public of great anxiety.
There are possibly many other uses to which airships can be put
such as the policing of wide stretches of desert country as in
Arabia and the Soudan. The merits of all of these will doubtless
be considered in due course and there for the present we must
leave them.
Finally, a few words must be written regarding the means to be
adopted in introducing the airship into the realms of commerce.
As we said at the beginning of the chapter it is not likely that
the formation of a company to exploit airships only will at the
present moment appeal to business men. Airships are very costly
and are still in their infancy, which means that the premiums
demanded for their insurance must of necessity be enormous. One
suggestion is to place a reasonable scheme before the great
shipping companies in case they will care to find the necessary
capital and form subsidiary companies.
Another suggestion is that the Government should make
arrangements to subsidize commercial airships. The subsidy might
take the form of insuring them. If the burden of insurance is
taken off their shoulders, it is considered feasible to promote
companies which will give an adequate return for capital
invested. The Government could also give a financial guarantee
if mails are carried, in the same manner as is done by shipping
companies.
In return for this the Government could at the outbreak of
hostilities commandeer all or any of the airships for war
purposes and so save the number to be kept in commission.
By this means the Government will have a large number of
highly-trained and efficient personnel to call upon when the
emergency arises, in the same way as the fleet can call upon the
R.N.R. This system appears to be the best in every respect, and
it cannot be denied that in the long run it would be the most
economical for the country.
The airship has now arrived at the parting of the ways, and at
this point we must leave it. The flying in war has been
concluded, the flying in peace has not yet commenced. It seems a
far cry to the dark days of 1914, when we only possessed two
airships of utility, the one manufactured in France, the other in
Germany, while to-day we have built the mighty airship which can
fly to America and back. We are now at the dawn of a new period
of reconstruction and progress, and during this period many
wonderful things will happen. Not the least of these will be the
development of the airship.
[End Project Gutenberg Etext British Airships: Past, Present, and
Future]