British Airships: Past, Present and Future

Part 1 out of 3

This etext was created by Dianne Bean, Chino Valley, Arizona.

British Airships: Past, Present and Future
by George Whale (Late Major, R.A.F.)










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

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

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.


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

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

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.


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

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


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

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


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

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

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.


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

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

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

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


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

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

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

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.


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.


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


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.


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.


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.


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.


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.


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.


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.


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.


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

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.


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.


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.


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


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 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.


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.


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.


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


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.


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.


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

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

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

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.


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 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

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

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.


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

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

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


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