British Airships: Past, Present and Future

Part 2 out of 3

nose and meet at a point 2 1/4 inches in front of the nose. An
aluminium conical cap is fitted over the canes and a fabric nose
cap over the whole.

Two ballonets are provided, one forward and one aft, the capacity
of each being 6,375 cubic feet. The supply of air for filling
these is taken from the propeller draught by a slanting aluminium
tube to the underside of the envelope, where it meets a
longitudinal fabric hose which connects the two ballonet air
inlets. Non-return fabric valves known as crab-pots are fitted
in this fabric hose on either side of their junction with the air
scoop. Two automatic air valves are fitted to the underside of
the envelope, one for each ballonet. The air pressure tends to
open the valve instead of keeping it shut and to counteract this
the spring of the valve is inside the envelope. The springs are
set to open at a pressure of 25 to 28 mm.

Two gas valves are also fitted, one on the top of the envelope,
the other at the bottom. The bottom gas valve spring is set to
open at 30 to 35 mm. pressure, the top valve is hand controlled
only.

These valves are all very similar in design. They consist of two
wooden rings, between which the envelope is gripped, and which
are secured to each other by studs and butterfly nuts. The valve
disc, or moving portion of the valve, is made of aluminium and
takes a seating on a thin india rubber ring stretched between a
metal rod bent into a circle of smaller diameter than the valve
opening and the wooden ring of the valve. When it passes over
the wooden ring it is in contact with the envelope fabric and
makes the junction gastight. The disc is held against the rubber
by a compressed spring.

The valve cords are led to the pilot's seat through eyes attached
to the envelope.

The system of rigging or car suspension is simplicity itself and
is tangential to the envelope. On either side there are six main
suspensions of 25 cwt. stranded steel cable known as "C"
suspensions. Each "C" cable branches into two halves known as
the "B" bridles, which in turn are supported at each end by the
bridles known as "A." The ends of the "A" bridles are attached
to the envelope by means of Eta patches. These consist of a
metal D-shaped fitting round which the rigging is spliced and
through which a number of webbing bands are passed which
are spread out fanwise and solutioned to the envelope. It will
thus be seen that the total load on each main suspension is
proportionally taken up by each of the four "A" bridles, and that
the whole weight of the car is equally distributed over the
greater part of the length of the envelope. Four handling guys
for manoeuvering the ship on the ground are provided under the
bow and under the stem. A group of four Eta patches are placed
close together, which form the point of attachment for two guys
in each case. The forward of these groups of Eta patches forms
the anchoring point. The bridle, consisting of 25 cwt. steel
cable, is attached here and connected to the forepart of the
skids of the car. The junction of this bridle with the two
cables from the skids forms the mooring point and there the main
trail rope is attached. This is 120 feet long and composed of
2-inch manilla. This is attached, properly coiled, to the side
of the car and is dropped by a release gear. It is so designed
that when the airship is held in a wind by the trail rope the
strain is evenly divided between the envelope and the car. The
grapnel carried is fitted to a short length of rope. The other
end of the rope has an eye, and is fitted to slide down the main
trail rope and catch on a knot at the end.

For steering and stabilizing purposes the S.S. airship was
originally designed with four fins and rudders, which were to be
set exactly radial to the envelope. In some cases the two lower
fins and rudders were abandoned, and a single vertical fin and
rudder fitted centrally under the envelope were substituted. The
three planes are identical in size and measure 16 feet by 8 feet
6 inches, having a gross stabilizing area of 402 1/2 square feet.

They are composed of spruce and aluminium and steel tubing braced
with wire and covered by linen doped and varnished when in
position.

The original rudders measured 3 feet by 8 feet 6 inches. In the
case, however, of the single plane being fitted, 4-feet rudders
are invariably employed. Two kingposts of steel tube are fitted
to each plane and braced with wire to stiffen the whole
structure.

The planes are attached to the envelope by means of skids and
stay wires. The skids, composed of spruce, are fastened to the
envelope by eight lacing patches.

The car, it will be remembered, is a B.E. 2C fuselage stripped of
its wings, rudders and elevators, with certain other fittings
added to render it suitable for airship work. The undercarriage
is formed of two ash skids, each supported by three struts. The
aeroplane landing wheels, axle and suspensions are abandoned.

In the forward end of the fuselage was installed a 75 horse-power
air cooled Renault engine driving a single four-bladed tractor
propeller through a reduction gear of 2 to 1. The engine is of
the 8-cylinder V type, weighing 438 lb. with a bore of 96 mm. and
a stroke of 120 mm. The Claudel-Hobson type of carburettor is
employed with this engine. The type of magneto used is the Bosch
D.V.4, there being one magneto for each line of cylinders. In
the older French Renaults the Bosch H.L.8 is used, one magneto
supplying the current to all the plugs. Petrol is carried in
three tanks, a gravity and intermediate tank as fitted to the
original aeroplane, and a bottom tank placed underneath the front
seat of the car. The petrol is forced by air pressure from the
two lower tanks into the gravity tank and is obtained by a hand
pump fitted outside the car alongside the pilot's seat. The oil
tank is fitted inside the car in front of the observer.

The observer's seat is fitted abaft the engine and the pilot's
seat is aft of the observer. The observer, who is also the
wireless operator, has the wireless apparatus fitted about his
seat. This consists of a receiver and transmitter fitted inside
the car, which derives power from accumulator batteries. The
aerial reel is fitted outside the car. During patrols signals
can be sent and received up to and between 50 and 60 miles.

The pilot is responsible for the steering and the running of the
engine, and the controls utilized are the fittings supplied with
the aeroplane. Steering is operated by the feet and elevating by
a vertical wheel mounted in a fore and aft direction across the
seat. The control wires are led aft inside the fairing of the
fuselage to the extreme end, whence they pass to the elevators
and rudders.

The instrument board is mounted in front of the pilot. The
instruments comprise a watch, an air-speed indicator graduated in
knots, an aneroid reading to 10,000 feet, an Elliott revolution
counter, a Clift inclinometer reading up to 20 degrees depression
or elevation, a map case with celluloid front.

There are in addition an oil pressure gauge, a petrol pressure
gauge, a glass petrol level and two concentric glass pressure
gauges for gas pressure.

The steering compass is mounted on a small wooden pedestal on the
floor between the pilot's legs.

The water-ballast tank is situated immediately behind the pilot's
seat and contains 14 gallons of water weighing 140 lbs. The
armament consists of a Lewis gun and bombs. The bombs are
carried in frames suspended about the centre of the
undercarriage. The bomb sight is fitted near the bomb releasing
gear outside the car on the starboard side adjacent to the
pilot's seat. The Lewis gun, although not always carried on the
early S.S. airships, was mounted on a post alongside the pilot's
seat.

S.S. MAURICE FARMAN

For this type of S.S. the cars were built by Messrs. Airships
Ltd. In general appearance they resemble the Maurice Farman
aeroplane and were of the pusher type; 60,000 and in later cases
70,000 cubic feet envelopes were rigged to these ships, which
proved to be slightly slower than the B.E. 2C type, but this was
compensated for owing to the increased comfort provided for the
crew, the cars being more roomy and suitable for airship work in
every way.

The system of rigging to all intents and purposes is the same in
all types of S.S. ships, the suspensions being adjusted to suit
the different makes of car.

In these ships the pilot sits in front, and behind him is the
wireless telegraphy operator; in several cases a third seat was
fitted to accommodate a passenger or engineer; dual rudder and
elevator controls are provided for the pilot and observer.

The engine is mounted aft, driving a four-bladed pusher
propeller, with the petrol tanks situated in front feeding the
carburettors by gravity. The engines used are Rolls Royce
Renaults, although in one instance a 75 horse-power Rolls Royce
Hawk engine was fitted, which assisted in making an exceedingly
useful ship.

S.S. ARMSTRONG WHITWORTH

The car designed by Messrs. Armstrong Whitworth is of the tractor
type and is in all ways generally similar to the B.E. 2C. The
single-skid landing chassis with buffers is the outstanding
difference. These cars had to be rigged to 70,000 cubic feet
envelopes otherwise the margin of lift was decidedly small. A
water-cooled 100 horse-power Green engine propelled the ship, and
a new feature was the disposition of petrol, which was carried in
two aluminium tanks slung from the envelope and fed through
flexible pipes to a two-way cock and thence to the carburettors.
These tanks, which were supported in a fabric sling, showed a
saving in weight of 100 lb. compared with those fitted in the
B.E. 2C.

For over two years these three types of S.S. ships performed a
great part of our airship patrol and gave most excellent results.

Owing to the constant patrol which was maintained whenever
weather conditions were suitable, the hostile submarine hardly
dared to show her periscope in the waters which were under
observation. In addition to this, practically the whole of the
airship personnel now filling the higher positions, such as
Captains of Rigids and North Seas, graduated as pilots in this
type of airship. From these they passed to the Coastal and
onwards to the larger vessels.

As far as is known the height record for a British airship is
still held by an S.S.B.E. 2C, one of these ships reaching the
altitude of 10,300 feet in the summer of 1916.

The Maurice Farman previously mentioned as being fitted with the
Hawk engine, carried out a patrol one day of 18 hours 20 minutes.
In the summer of 1916 one of the Armstrong ships was rigged to an
envelope doped black and sent over to France. While there she
carried out certain operations at night which were attended with
success, proving that under certain circumstances the airship can
be of value in operating with the military forces over land.

S.S.P.

In 1916 the design was commenced for an S.S. ship which should
have a more comfortable car and be not merely an adaptation of
an aeroplane body. These cars, which were of rectangular shape
with a blunt nose, were fitted with a single landing skid aft,
and contained seats for three persons.

The engine, a 100 horse-power water-cooled Green, was mounted on
bearers aft and drove a four-bladed pusher propeller. The
petrol was carried in aluminium tanks attached by fabric slings
to the axis of the envelope.

Six of these ships were completed in the spring of 1917 and were
quite satisfactory, but owing to the success achieved by the
experimental S.S. Zero it was decided to make this the standard
type of S.S. ship, and with the completion of the sixth the
programme of the S.S.P's was brought to a close.

These ships enjoyed more than, perhaps, was a fair share of
misfortune, one was wrecked on proceeding to its patrol station
and was found to be beyond repair, and another was lost in a
snowstorm in the far north. The remainder, fitted at a later
date with 75 horse-power Rolls Royce engines, proved to be a most
valuable asset to our fleet of small airships.

S.S. ZERO

The original S.S. Zero was built at a south-coast station by Air
Service labour, and to the design of three officers stationed
there. The design of the car shows a radical departure from
anything that had been previously attempted, and as a model an
ordinary boat was taken. In shape it is as nearly streamline as
is practicable, having a keel and ribs of wood with curved
longitudinal members, the strut ends being housed in steel
sockets. The whole frame is braced with piano wire set
diagonally between the struts. The car is floored from end to
end, and the sides are enclosed with 8-ply wood covered with
fabric.

Accommodation is provided for a wireless telegraphy operator, who
is also a gunner, his compartment being situated forward,
amidships is the pilot and abaft this seat is a compartment for
the engineer.

The engine selected was the 75 horse-power water-cooled Rolls
Royce, it being considered to be the most efficient for the
purpose. The engine is mounted upon bearers above the level of
the top of the car, and drives a four-bladed pusher propeller.

The car is suspended from an envelope of 70,000 cubic feet
capacity, and the system of rigging is similar to that in use on
all S.S. ships. The petrol is carried in aluminium tanks slung
on the axis of the envelope, identically with the system in use
on the S.S.P's. The usual elevator planes are adopted with a
single long rudder plane.

The speed of the Zero is about 45 miles per hour and the ship has
a theoretical endurance of seventeen hours; but this has been
largely exceeded in practice.

The original ship proved an immediate success, and a large number
was shortly afterwards ordered.

As time went on the stations expanded and sub-stations were
added, while the Zero airship was turned out as fast as it could
be built, until upwards of seventy had been commissioned. The
work these ships were capable of exceeded the most sanguine
expectations. Owing to their greater stability in flight and
longer hours of endurance, they flew in weather never previously
attempted by the earlier ships. With experience gained it was
shown that a large fleet of airships of comparatively small
capacity is of far more value for an anti-submarine campaign than
a lesser fleet of ships of infinitely greater capacity. The
average length of patrol was eight hours, but some wonderful
duration flights were accomplished in the summer of 1918, as the
following figures will show. The record is held by S.S.Z. 39,
with 50 hours 55 minutes; another is 30 hours 20 minutes; while
three more vary from 25 1/2 hours to 26 1/4. Although small, the
Zero airship has been one of the successes of the war, and we can
claim proudly that she is entirely a British product.

S.S. TWIN

During the year 1917, designs were submitted for a twin-engined
S.S. airship, the idea being to render the small type of airship
less liable to loss from engine failure. The first design proved
to be a failure, but the second was considered more promising,
and several were built. Its capacity is 100,000 cubic feet, with
a length of 164 feet 6 inches, and the greatest diameter 32 feet.

The car is built to carry five, with the engines disposed on
gantries on the port and starboard side, driving pusher
propellers. This type, although in the experimental stage, is
being persevered with, and the intention is that it will
gradually supplant the other S.S. classes. It is calculated that
it will equal if not surpass the C Star ship in endurance,
besides being easier to handle and certainly cheaper to build.

"COASTAL" AND "C STAR" AIRSHIPS

The urgent need for a non-rigid airship to carry out
anti-submarine patrol having been satisfied for the time with the
production of the S.S. B.E. 2C type, the airship designers of the
Royal Naval Air Service turned their attention to the production
of an airship which would have greater lift and speed than the
S.S. type, and, consequently, an augmented radius of action,
together with a higher degree of reliability. As the name
"Coastal" or "Coast Patrol" implies, this ship was intended to
carry out extended sea patrols.

To obtain these main requirements the capacity of the envelope
for this type was fixed at 170,000 cubic feet, as compared with
the 60,000 cubic feet and, later, the 70,000 cubic feet envelopes
adopted for the S.S. ships. Greater speed was aimed at by
fitting two engines of 150 horse-power each, and it was hoped
that the chances of loss owing to engine failure would be
considerably minimized.

The Astra-Torres type of envelope, with its system of internal
rigging, was selected for this class of airship; in the original
ship the envelope us d was that manufactured by the French
Astra-Torres Company, and to which it had been intended to rig a
small enclosed car. The ship in question was to be known as No.
10. This plan was, however, departed from, and the car was
subsequently rigged to the envelope of the Eta, and a special car
was designed and constructed for the original Coastal. Coastal
airship No. 1 was commissioned towards the end of 1915 and was
retained solely for experimental and training purposes.
Approximately thirty of these airships were constructed during
the year 1916, and were allocated to the various stations for
patrol duties.

The work carried out by these ships during the two and a half
years in which they were in commission, is worthy of the highest
commendation. Before the advent of later and more reliable
ships, the bulk of anti-submarine patrol on the east coast and
south-west coast of England was maintained by the Coastal. On
the east coast, with the prevailing westerly and south-westerly
winds, these airships had many long and arduous voyages on their
return from patrol, and in the bitterness of winter their
difficulties were increased ten-fold. To the whole-hearted
efforts of Coastal pilots and crews is due, to a great extent,
the recognition which somewhat tardily was granted to the Airship
Service.

The envelope of the Coastal airship has been shown to be of
170,000 cubic feet capacity. It is trilobe in section to employ
the Astra-Torres system of internal and external rigging. The
great feature of this principle is that it enables the car to be
slung much closer to the envelope than would be possible with the
tangential system on an envelope of this size. As a natural
consequence there is far less head resistance, owing to the much
shorter rigging, between the envelope and the car.

The shape of the envelope is not all that could have been
desired, for it is by no means a true streamline, but has the
same cross section for the greater part of its length, which
tapers at either end to a point which is slightly more
accentuated aft. Owing to the shape, these ships, in the early
days until experience had been gained, were extremely difficult
to handle, both on the landing ground and also in the air. They
were extremely unstable both in a vertical and horizontal plane,
and were slow in answering to their rudders and elevators.

The envelope is composed of rubber-proofed fabric doped to hold
the gas and resist the effects of weather. Four ballonets are
situated in the envelope, two in each of the lower lobes, air
being conveyed to them by means of a fabric air duct, which is
parallel to the longitudinal centre line of the envelope, with
transverse ducts connecting each pair of ballonets. In earlier
types of the Coastal, the air scoop supplying air to the air duct
was fitted in the slip stream of the forward engine, but later
this was fitted aft of the after engine.

Six valves in all are used, four air valves, one fitted to each
ballonet, and two gas valves. These are situated well aft, one
to each of the lower lobes, and are fitted on either side of the
rudder plane. A top valve is dispensed with because in practice
when an Astra-Torres envelope loses shape, the tendency is for
the tail to be pulled upwards by the rigging, with the result
that the two gas valves always remain operative.

Crabpots and non-return valves are employed in a similar manner
to S.S. airships.

The Astra-Torres system of internal rigging must now be described
in some detail. The envelope is made up of three longitudinal
lobes, one above and two below, which when viewed end on gives it
a trefoil appearance. The internal rigging is attached to the
ridges formed on either side of the upper lobe, where it meets
the two side lobes. From here it forms a V, when viewed cross
sectionally, converging at he ridge formed by the two lobes on
the underside of the envelope which is known as the lower ridge.

To the whole length of the top ridges are attached the internal
rigging girdles and also the lacing girdles to which are secured
the top and side curtains. These curtains are composed of
ordinary unproofed fabric and their object is to make the
envelope keep its trilobe shape. They do not, however, divide
the ship into separate gas compartments. The rigging girdle
consists of a number of fabric scallops through which run strands
of Italian hemp. These strands, of which there are a large
number, are led towards the bottom ridge, where they are drawn
together and secured to a rigging sector. To these sectors the
main external rigging cables are attached. The diagram shows
better than any description this rigging system.

Ten main suspensions are incorporated in the Coastal envelope, of
which three take the handling guys, the remaining seven support
the weight of the car.

The horizontal fins with the elevator flaps, and the vertical fin
with the rudder flap, are fixed to the ridges of the envelope.

The car was evolved in the first instance by cutting away the
tail portion of two Avro seaplane fuselages and joining the
forward portions end on, the resulting car, therefore, had
engines at either end with seating accommodation for four. The
landing chassis were altered, single skids being substituted for
the wider landing chassis employed in the seaplane. The car
consists of four longerons with struts vertical and cross, and
stiffened with vertical and cross bracing wires. The sides are
covered with fabric and the flooring and fairing on the top of
the car are composed of three-ply wood. In the later cars five
seats were provided to enable a second officer to be carried.

The engines are mounted on bearers at each end of the car, and
the petrol and oil tanks were originally placed adjoining the
engines in the car. At a later date various methods of carrying
the petrol tanks were adopted, in some cases they were slung from
the envelope and in others mounted on bearers above the engines.

Wireless telegraphy is fitted as is the case with all airships.
In the Coastal a gun is mounted on the top of the envelope, which
is reached by a climbing shaft passing through the envelope,
another mounting being provided on the car itself.

Bombs are also carried on frames attached to the car. Sunbeam
engines originally supplied the motive power, but at a later date
a 220 horse-power Renault was fitted aft and a 100 horse-power,
Berliet forward. With the greater engine power the ship's
capabilities were considerably increased.

Exceedingly long flights were achieved by this type of ship, and
those exceeding ten hours are far too numerous to mention. The
moot noteworthy of all gave a total of 24 1/4 hours, which, at
the time, had only once been surpassed by any British airship.

Towards the end of 1917, these ships, having been in commission
for over two years, were in many cases in need of a complete
refit. Several were put in order, but it was decided that this
policy should not be continued, and that as each ship was no
longer fit for flying it should be replaced by the more modern
Coastal known as the C Star.

The record of one of these ships so deleted is surely worthy of
special mention. She was in commission for 2 years 75 days, and
averaged for each day of this period 3 hours 6 minutes flying.
During this time she covered upwards of 66,000 miles. From this
it will be seen that she did not pass her life by any means in
idleness.

"C STAR" AIRSHIP

After considerable experience had been gained with the Coastal,
it became obvious that a ship was required of greater
capabilities to maintain the long hours of escort duty and also
anti-submarine patrols. To meet these requirements it was felt
that a ship could be constructed, not departing to any extent
from the Coastal, with which many pilots were now quite familiar,
but which would show appreciable improvement over its
predecessor.

The design which was ultimately adopted was known as the C Star,
and provided an envelope of 210,000 cubic feet, which secured an
extra ton and a quarter in lifting capacity. This envelope,
although of the Astra-Torres type, was of streamline form, and in
that respect was a great advance on the early shape as used in
the Coastal. It is to all intents and purposes the same envelope
as is used on the North Sea ships, but on a smaller scale. An
entirely new type of fabric was employed for this purpose. The
same model of car was employed, but was made more comfortable,
the canvas covering for the sides being replaced by three-ply
wood. In all other details the car remained entirely the same.
The standard power units were a 100 horse-power Berliet forward
and a Fiat of 260 horse-power aft. The petrol tanks in this
design were carried inside the envelope, which was quite a new
departure.

These airships may be considered to have been successful, though
not perhaps to the extent which was expected by their most ardent
admirers. With the advent of the S.S. Twin it was resolved not
to embark on a large constructional progaramme, and when the
numbers reached double figures they were no longer proceeded
with. Notwithstanding this the ships which were commissioned
carried out most valuable work, and, like their prototypes, many
fine flights were recorded to their credit. Thirty-four and a
half hours was the record flight for this type of ship, and
another but little inferior was thirty hours ten minutes. These
flights speak well for the endurance of the crews, as it must be
borne in mind that no sleeping accommodation is possible in so
small a car.

The Coastal airship played no small part in the defeat of the
submarine, but its task was onerous and the enemy and the
elements unfortunately exacted a heavy toll. A German wireless
message received in this country testified to the valiant manner
in which one of these ships met with destruction.

THE "NORTH SEA" AIRSHIP

The North Sea or N.S. airship was originally designed to act as a
substitute for the Rigid, which, in 1916, was still a long way
from being available for work of practical utility. From
experience gained at this time with airships of the Coastal type
it was thought possible to construct a large Non-Rigid capable of
carrying out flights of twenty-four hours' duration, with a speed
of 55 to 60 knots, with sufficient accommodation for a double
crew.

The main requirements fall under four headings:

1. Capability to carry out flights of considerable duration.

2. Great reliability.

3. The necessary lift to carry an ample supply of fuel.

4. Adequate arrangements to accommodate the crew in comfort.

If these could be fulfilled the authorities were satisfied that
ships possessing these qualifications would be of value to the
Fleet and would prove efficient substitutes until rigid airships
were available. The North Sea, as may be gathered from its name,
was intended to operate on the east coasts of these islands.

The first ship, when completed and put through her trials, was
voted a success, and the others building were rapidly pushed on
with. When several were finished and experience had been gained,
after long flights had been carried out, the North Sea airship
suffered a partial eclipse and people were inclined to reconsider
their favourable opinion. Thus it was that for many months the
North Sea airship was decidedly unpopular, and it was quite a
common matter to hear her described as a complete failure. The
main cause of the prejudice was the unsatisfactory design of the
propelling machinery, which it will be see,, later was modified
altogether, and coupled with other improvements turned a ship of
doubtful value into one that can only be commended.

The envelope is of 360,000 cubic feet capacity, and is designed
on the Astra-Torres principle for the same reasons as held good
in the cases of the Coastal and C Star. All the improvements
which had been suggested by the ships of that class were
incorporated in the new design, which was of streamline shape
throughout, and looked at in elevation resembled in shape
that of the S.S. airship. Six ballonets are fitted, of which the
total capacity is 128,000 cubic feet, equivalent to 35.5 per cent
of the total volume. They are fitted with crabpots and
non-return valves in the usual manner.

The rigging is of the Astra-Torres system, and in no way differs
from that explained in the previous chapter. Nine fans of the
internal rigging support the main suspensions of the car, while
similar fans both fore and aft provide attachment for the
handling guys. Auxiliary fans on the same principle support the
petrol tanks and ballast bag.

Four gas and six air valves in all are fitted, all of which are
automatic.

Two ripping panels are embodied in the top lobe of the envelope.

The N.S. ship carries four fins, to three of which are attached
the elevator and rudder flaps. The fourth, the top fin, is
merely for stabilizing purposes, the other three being identical
in design, and are fitted with the ordinary system of wiring and
kingposts to prevent warping.

The petrol was originally carried in aluminium tanks disposed
above the top ridges of the envelope, but this system was
abandoned owing to the aluminium supply pipes becoming fractured
as the envelope changed shape at different pressures. They were
then placed inside the envelope, and this rearrangement has given
every satisfaction.

To the envelope of the N.S. is rigged a long covered-in car. The
framework of this is built up of light steel tubes, the
rectangular transverse frames of which are connected by
longitudinal tubes, the whole structure being braced by diagonal
wires. The car, which tapers towards the stern, has a length of
85 feet, with a height of 6 feet. The forward portion is covered
with duralumin sheeting, and the remainder with fabric laced to
the framework. Windows and portholes afford the crew both light
and space to see all that is required. In the forward portion of
the car are disposed all the controls and navigating instruments,
together with engine-telegraphs and voice pipes. Aft is the
wireless telegraphy cabin and sleeping accommodation for the
crew.

A complete electrical installation is carried of two dynamos and
batteries for lights, signalling lamps, telephones, etc. The
engines are mounted in a power unit structure separate from the
car and reached by a wooden gangway supported by wire cables.
This structure consists of two V-shaped frameworks connected by a
central frame and by an under-structure to which floats are
attached. The mechanics' compartment is built upon the central
frame, and the engine controls are operated from this cabin.

In the original power units two 250 horse-power Rolls Royce
engines were fitted, driving propellers on independent shafts
through an elaborate system of transmission. This proved to be a
great source of weakness, as continual trouble was experienced
with this method, and a fracture sooner or later occurred at the
universal joint nearest to the propeller. When the modified form
of ship was built the whole system of transmission was changed,
and the propellers were fitted directly on to the engine
crankshafts.

At a later date 240 horse-power Fiat engines were installed, and
the engineers' cabin was modified and an auxiliary blower was
fitted to supply air to the ballonets for use if the engines are
not running.

In the N.S. ship as modified the car has been raised to the same
level as the engineers' cabin, and all excrescences on the
envelope were placed inside. This, added to the improvement
effected by the abolition of the transmission shafts, increased
the reliability and speed of the ship, and also caused a
reduction in weight.

The leading dimensions of the ship are as follows: length, 262
feet; width, 56 feet 9 inches; height, 69 feet 3 inches. The
gross lift is 24,300 lb.; the disposable lift, without crew,
petrol, oil, and ballast, 8,500 lb. The normal crew carried when
on patrol is ten, which includes officers.

As in the case of the Coastal, a gun is mounted on the top of the
envelope, which is approached by a similar climbing shaft, and
guns and bombs are carried on the car.

These ships have become notorious for breaking all flying records
for non-rigid airships. Even the first ship of the class,
despite the unsatisfactory power units, so long ago as in the
summer of 1917 completed a flight of 49 hours 22 minutes, which
at the time was the record flight of any British airship. Since
that date numerous flights of quite unprecedented duration have
been achieved, one of 61 1/2 hours being particularly noteworthy,
and those of upwards of 30 hours have become quite commonplace.

Since the Armistice one of these ships completed the unparalleled
total of 101 hours, which at that date was the world's record
flight, and afforded considerable evidence as to the utility of
the non-rigid type for overseas patrol, and even opens up the
possibility of employing ships of similar or slightly greater
dimensions for commercial purposes.

N.S. 6 appeared several times over London in the summer months of
1918, and one could not help being struck by the ease with which
she was steered and her power to remain almost stationary over
such a small area as Trafalgar Square for a quite considerable
period.

The flights referred to above were not in any way stunt
performances to pile up a handsome aggregate of hours, but were
the ordinary flying routine of the station to which the ships
were attached, and most of the hours were spent in escorting
convoys and hunting for submarines. In addition to these duties,
manoeuvres were carried out on occasions with the Fleet or units
thereof.

From the foregoing observations it must be manifest that this
type of ship, in its present modified state, is a signal success,
and is probably the best large non-rigid airship that has been
produced in any country.

For the purposes of comparison it will be interesting to tabulate
the performances of the standard types of non-rigid airships.
The leading dimensions are also included in this summary:

Type S.S. Zero S.S. Twin Coastal North
Star Sea
Length 143' 0" 165' 0" 218' 0" 262' 0"
Overall width 32' 0" 35' 6" 49' 3" 56' 9"
Overall height 46' 0" 49' 0" 57' 6" 69' 3"
Hydrogen capacity
(cubic feet) 70,000 100,000 210,000 360,000
Gross lift (lb.) 4,900 7,000 14,500 24,300
Disposable
lift (lb.) 1,850 2,200 4,850 8,500
Crew 3 4 5 10
Lift available
for fuel and
freight (lb.) 1,370 1,540 4,050 6,900
Petrol consumption
at full speed
(lb. per hour) 3.6 7.2 18.4 29.8
Gals. per hour 0.36 0.72 2.05 3

CHAPTER VII
NAVAL AIRSHIPS.--THE RIGIDS
RIGID AIRSHIP No. 1

The responsibility for the development the Rigid airship having
been allotted to the Navy, with this object in view, in the years
1908 and 1909 a design was prepared by Messrs. Vickers Ltd., in
conjunction with certain naval officers, for a purely
experimental airship which should be as cheap as possible. The
ship was to be known as Naval Airship No. 1, and though popularly
called the Mayfly, this title was in no way official. In design
the following main objects were aimed at:

1. The airship was to be capable of carrying out the duties of an
aerial scout.

2. She was to be able to maintain a speed of 40 knots for
twenty-four hours, if possible.

3. She was to be so designed that mooring to a mast on the water
was to be feasible, to enable her to be independent of her
shed except for docking purposes, as in the case with surface
vessels.

4. She was to be fitted with wireless telegraphy.

5. Arrangements were to be made for the accommodation of the crew
in reasonable comfort.

6. She was to be capable of ascending to a height of not less
than 1,500 feet.

These conditions rendered it necessary that the airship should be
of greater dimensions than any built at the time, together with
larger horse-power, etc.

These stipulations having been settled by the Admiralty, the
Admiralty officials, in conjunction with Messrs. Vickers Ltd.,
determined the size, shape, and materials for the airship
required. The length of the ship was fixed at approximately 500
feet, with a diameter of 48 feet. Various shapes were
considered, and the one adopted was that recommended by an
American professor named Zahm. In this shape, a great proportion
of the longitudinal huff framework is parallel sided with curved
bow and stern portions, the radius of these curved portions
being, in the case of the bow, twice the diameter of the hull,
and in the case of the stern nine times the same diameter.
Experiments proved that the resistance of a ship of this shape
was only two-fifths of the resistance of a ship of the same
dimensions, having the 1 1/2 calibre bow and stern of the
Zeppelin airships at that time constructed.

A considerable difference of opinion existed as to the material
to be chosen for the construction of the hull. Bamboo, wood,
aluminium, or one of its alloys, were all considered. The first
was rejected as unreliable. The second would have been much
stronger than aluminium, and was urged by Messrs. Vickers. The
Admiralty, however, considered that there was a certainty of
better alloys being produced, and as the ship was regarded as an
experiment and its value would be largely negatived if later
ships were constructed of a totally different material, aluminium
or an alloy was selected. The various alloys then in existence
showed little advantage over the pure metal, so pure aluminium
was specified and ordered. This metal was expected to have a
strength of ten tons per square inch, but that which arrived was
found to be very unreliable, and many sections had, on test, only
half the strength required. The aluminium wire intended for the
mesh wiring of the framework was also found to be extremely
brittle. A section of the framework was, however, erected, and
also one of wood, as a test for providing comparisons. In the
tests, the wooden sections proved, beyond all comparison, the
better, but the Admiralty persisted in their decision to adopt
the metal.

Towards the end of 1909 a new aluminium alloy was discovered,
known as duralumin. Tests were made which proved that this new
metal possessed a strength of twenty-five tons per square inch,
which was over twice as strong as the nominal strength of
aluminium, and in practice was really five times stronger. The
specific gravity of the new metal varied from 2.75 to 2.86, as
opposed to the 2.56 of aluminium. As the weights were not much
different it was possible to double the strength of the ship and
save one ton in weight. Duralumin was therefore at once adopted.

The hull structure was composed of twelve longitudinal duralumin
girders which ran fore and aft the length of the ship and
followed the external shape. The girders were secured to a steel
nose-piece at the bow and a pointed stern-piece aft. These
girders, built of duralumin sections, were additionally braced
wherever the greatest weights occurred. To support these girders
in a thwartship direction a series of transverse frames were
placed at 12 feet 6 inches centres throughout the length of the
ship, and formed, when viewed cross-sectionally, a universal
polygon of twelve sides. For bracing purposes mesh wiring
stiffened each bay longitudinally, so formed by the junction of
the running girder and the transverse frames, while the
transverse frames between the gasbags were stiffened with radial
wiring which formed structure similar to a wheel with its
spokes. The frames where the gondolas occurred were strengthened
to take the addition weight, while the longitudinals were also
stiffened at the bow and stern.

Communication was provided between the gondolas by means of an
external keel which was suspended from extra keel longitudinals.
In this design the keel was provided for accommodation purposes
only, and in no way increased the structural stability of the
ship as in No. 9 and later ships. This keel, triangular in
section,widened out amidships to form a space for a cabin and the
wireless compartment. The fins and rudders, which were adopted,
were based entirely on submarine experience, and the Zeppelin
method was ignored. The fins were fitted at the stern of the
ship only, and comprised port and starboard horizontal fins,
which followed approximately the shape of the hull, and an upper
and lower vertical fin. Attached to these fins were box rudders
and elevators, instead of the balanced rudders first proposed.
Auxiliary rudders were also fitted in case of a breakdown of the
main steering gear abaft the after gondola. Elevators and
rudders were controlled from the forward gondola and the
auxiliary rudders from the after gondola.

The gasbags were seventeen in number and were twelve-sided in
section, giving approximately a volume of 663,000 cubic feet
when completely full. Continental fabric, as in use on the
Zeppelin airships, was adopted, although the original intention
was to use gold-beater's skin,, but this was abandoned owing to
shortage of material. These bags were fitted with the Parseval
type of valve, which is situated at the top, contrary to the
current Zeppelin practice, which had automatic valves at the
bottom of the bags, and hand-operated valves on the top of a few
bags for control purposes. Nets were laced to the framework to
prevent the bags bulging through the girders.

The whole exterior of the hull was fitted with an outer cover;
Zeppelin at this time used a plain light rubber-proofed fabric,
but this was not considered suitable for a ship which was
required to be moored in the open, as in wet weather the material
would get saturated and water-logged. Various experiments were
carried out with cotton, silk and ramie, and, as a result, silk
treated with Ioco was finally selected. This cover was laced
with cords to the girder work, and cover-strips rendered the
whole impervious to wet. Fire-proofed fabric was fitted in wake
of the gondolas for safety from the heat of the engines.

Two gondolas, each comprising a control compartment and
engine-room, were suspended from the main framework of the hull.
They were shaped to afford the least resistance possible to the
air, and were made of Honduras mahogany, three-ply where the
ballast tanks occurred, and two-ply elsewhere. The plies were
sewn together with copper wire. The gondolas were designed to
have sufficient strength to withstand the strain of alighting on
the water. They were suspended from the hull by wooden struts
streamline in shape, and fitted with internal steel-wire ropes;
additional wire suspensions were also fitted to distribute the
load over a greater length of the ship. The engines were
carried in the gondolas on four hollow wooden struts, also fitted
internally with wire. The wires were intended to support the
gondolas in the event of the struts being broken in making a
heavy landing.

Two engines were mounted, one in each gondola, the type used
being the 8-cylinder vertical water-cooled Wolseley developing a
horse-power of 160. The forward engine drove two wing propellers
through the medium of bevel gearing, while the after engine drove
a single large propeller aft through 4 gear box to reduce the
propeller revolutions to half that of the engine. The estimated
speed of the ship was calculated to be 42 miles per hour, petrol
was carried in tanks, fitted in the keel, and the water ballast
tanks were placed close to the keel and connected together by
means of a pipe.

No. 1 was completed in May, 1911. She had been built at Barrow in
a shed erected on the edge of Cavendish Dock. Arrangements were
made that she should be towed out of the shed to test her
efficiency at a mooring post which had been prepared in the
middle of the dock. She was launched on May 22nd in a flat calm
and was warped out of the shed and hauled to the post where she
was secured without incident. The ship rode at the mooring post
in a steady wind, which at one time increased to 36 miles per
hour, until the afternoon of May 25th, and sustained no damage
whatever. Various engine trials were carried out, but no
attempt was made to fly, as owing to various reasons the ship was
short of lift. Valuable information was, however, gained in
handling the ship, and much was learnt of her behaviour at the
mast. More trouble was experienced in getting her back into the
shed, but she was eventually housed without sustaining any damage
of importance.

Owing to the lack of disposable lift, the bags were deflated and
various modifications were carried out to lighten the ship, of
which the principal were the removal of the keel and cabin
entirely, and the removal of the water-trimming services. Other
minor alterations were made which gave the ship, on completion, a
disposable lift of 3.21 tons. The transverse frames between the
gasbags were strengthened, and a number of broken wires were
replaced.

On September 22nd the ship was again completed, and on the 24th
she was again to be taken out and tested at the mooring post.
Unfortunately, while being hauled across the dock, the framework
of the ship collapsed, and she was got back into the shed the
same day.

Examination showed that it was hopeless to attempt to reconstruct
her, and she was broken up at a later date. The failure of this
ship was a most regrettable incident, and increased the prejudice
against the rigid airship to such an extent that for some time
the Navy refused to entertain any idea of attempting a second
experiment.

RIGID AIRSHIP No. 9

Rigid Airship No. 1 having met with such a calamitous end, the
authorities became rather dubious as to the wisdom of continuing
such costly experiments. Most unfortunately, as the future
showed and as was the opinion of many at the time, rigid
construction in the following year 1912 was ordered to be
discontinued. This decision coincided with the disbanding of the
Naval Air Service, and for a time rigid airships in this country
were consigned to the limbo of forgetfulness. After the Naval
Air Service had been reconstituted, the success which attended
the Zeppelin airships in Germany could no longer be overlooked,
and it was decided to make another attempt to build a rigid
airship in conformity with existing Zeppelin construction. The
first proposals were put forward in 1913, and, finally, after
eleven months delay, the contract was signed. This airship, it
has been seen, was designated No. 9.

No. 9 experienced numerous vicissitudes, during the process of
design and later when construction was in progress. The contract
having been signed in March, 1914, work on the ship was suspended
in the following February, and was not recommenced until July of
the same year. From that date onwards construction was carried
forward; but so many alterations were made that it was fully
eighteen months before the ship was completed and finally
accepted by the Admiralty.

The ship as designed was intended "to be generally in conformity
with existing Zeppelin construction," with the following main
requirements stipulated for in the specification:

1. She was to attain a speed of at least 45 miles per hour at the
full power of the engines.

2. A minimum disposable lift of five tons was to be available for
movable weights.

3. She was to be capable of rising to a height of 2,000 feet
during flight.

The design of this ship was prepared by Messrs. Vickers, Ltd.,
and as it was considered likely that owing to inexperience the
ship would probably be roughly handled and that heavy landings
might be made, it was considered that the keel structure and also
the cars should be made very strong in case of accidents
occurring. This, while materially increasing the strength of the
ship, added to its weight, and coupled with the fact that
modifications were made in the design, rendered the lift somewhat
disappointing. The hull structure was of the "Zahm" shape as in
No. 1, a considerable portion being parallel sided, while in
transverse section it formed a 17-sided polygon. In length it was
526 feet with a maximum diameter of 53 feet. The hull framework
was composed of triangular duralumin girders, both in the
longitudinal and transverse frames, while the bracing was carried
out by means of high tensile steel wires and duralumin tubes.
Attached to the hull was a V-shaped keel composed of tubes with
suitable wire bracings, and in it a greater part of the strength
of the structure lay. It was designed to withstand the vertical
forces and bending moments which resulted from the lift given by
the gasbags and the weights of the car and the cabin. The keel
also provided the walking way from end to end of the ship, and
amidships was widened out to form a cabin and wireless
compartment.

The wiring of the transverse frames was radial and performed
similar functions to the spokes of a bicycle wheel. These wires
could be tightened up at the centre at a steel ring through which
they were threaded and secured by nuts.

In addition to the radial wires were the lift wires) which were
led to the two points on the transverse frames which were
attached to the keel; on the inflation of the gasbags, the bags
themselves pressed upon the longitudinal girders on the top of
the ship, which pressure was transferred to the transverse frames
and thence by means of the several lift wires to the keel. In
this way all the stresses set up by the gas were brought finally
to the keel in which we have already said lay the main strength
of the ship.

The hull was divided by the transverse frames into seventeen
compartments each containing a single gasbag. The bags were
composed of rubber-proofed fabric lined with gold-beater's skin
to reduce permeability, and when completely full gave a total
volume of 890,000 cubic feet. Two types of valve were fitted to
each bag, one the Parseval type of valve with the pressure cone
as fitted in No. 1, the other automatic but also controlled by
hand.

To distribute the pressure evenly throughout the upper
longitudinal frames, and also to prevent the gasbags bulging
between the girders, nets were fitted throughout the whole
structure of the hull.

The whole exterior of the ship was fitted with an outer cover, to
protect the gasbags and hull framework from weather and to render
the outer surface of the ship symmetrical and reduce "skin
friction" and resistance to the air to a minimum. To enable
this cover to be easily removed it was made in two sections, a
port and starboard side for each gasbag. The covers were laced
to the hull framework and the connections were covered over with
sealing strips to render the whole weathertight.

The system of fins for stabilizing purposes on No. 9 were two--
vertical and horizontal. The vertical fin was composed of two
parts, one above and the other below the centre line of the ship.

They were constructed of a framework of duralumin girders,
covered over with fabric. The fins were attached on one edge to
the hull structure and wire braced from the other edge to various
positions on the hull. The horizontal fins were of similar design
and attached in a like manner to the hull. Triplane rudders and
biplane elevators of the box type were fitted in accordance with
the German practice of the time. Auxiliary biplane rudders were
fitted originally abaft the after car, but during the first two
trial flights they proved so very unsatisfactory that it was
decided to remove them.

Two cars or gondolas were provided to act as navigating
compartments and a housing for the engines, and in design were
calculated to offer the least amount of head resistance to the
wind. The cars were composed of duralumin girders, which formed
a flooring, a main girder running the full length of the car with
a series of transverse girders spaced in accordance with the main
loads. From each of these transverse girders vertical standards
with a connecting piece on top were taken and the whole exterior
was covered with duralumin plating. The cars were suspended in
the following manner. Two steel tubes fitting into a junction
piece at each end were bolted to brackets at the floor level at
each end of the transverse girders. They met at an apex above
the roof level and were connected to the tubing of the keel. In
addition, to distribute the weight and prevent the cars from
rocking, steel wire suspensions were led to certain fixed points
in the hull.

Each car was divided into two parts by a bulkhead, the forward
portion being the control compartment in which were disposed
all instruments, valve and ballast controls, and all the steering
and elevating arrangements. Engine-room telegraphs, voice pipes
and telephones were fitted up for communication from one part
of the ship to the other. The keel could be reached by a ladder
from each car, thus providing with the climbing shaft through the
hull access to all parts of the ship.

The original engine equipment of No. 9 was composed of four
Wolseley-Maybach engines of 180 horse-power each, two being
installed in the forward car and two in the after car. As the
ship was deficient in lift after the initial flight trials had
been carried out, it was decided to remove the two engines from
the after car and replace them with a single engine of 250
horse-power; secondly, to remove the swivelling propeller gear
from the after car and substitute one directly-driven propeller
astern of the car. This as anticipated reduced the weight very
considerably and in no way lessened the speed of the ship.

The forward engines drove two four-bladed swivelling propellers
through gear boxes and transmission shafts, the whole system
being somewhat complicated, and was opposed to the Zeppelin
practice at the time which employed fixed propellers.

The after engine drove a large two-bladed propeller direct off
the main shaft.

The petrol and water ballast were carried in tanks situated in
the keel and the oil was carried in tanks beneath the floors of
the cars.

The wireless cabin was situated as before mentioned in a cabin in
the keel of the ship, and the plant comprised a main transmitter,
an auxiliary transmitter and receiver and the necessary aerial
for radiating and receiving.

No. 9 was inflated in the closing days of 1916, and the disposal
lift was found to be 2.1 tons under the specification conditions,
namely, barometer 29.5 inches and temperature 55 degrees
Fahrenheit. The contract requirements had been dropped to 3.1
tons, which showed that the ship was short by one ton of the lift
demanded. The flight trials were, however, carried out, which
showed that the ship had a speed of about 42 1/2 miles per hour.

The alterations previously mentioned were afterwards made, the
bags of the ship were changed and another lift and trim trial was
held in March, 1917, when it was found that these had had the
satisfactory result of increasing the disposable lift to 3.8 tons
or .7 ton above the contract requirements, and with the bags 100
per cent full gave a total disposable lift of 5.1 tons.

Additional trials were then carried out, which showed that the
speed of the ship had not been impaired.

For reference purposes the performances of the ship are tabulated
below.

Speed:
Full 45 miles per hour
Normal = 2/3 38 " " "
Cruising = 1/3 32 " " "

Endurance:
Full 18 hours = 800 miles
Normal 26 " = 1,000 "
Cruising 50 " = 1,600 "

No. 9 having finished her trials was accepted by the Admiralty
in Mar. 1917, and left Barrow, where she had,been built, for a
patrol station.

In many ways she was an excellent ship, for it must be remembered
that when completed she was some years out-of-date judged by
Zeppelin standards. Apart from the patrol and convoy work which
she accomplished, she proved simply invaluable for the training
of officers and men selected to be the crews of future rigid
airships. Many of these received their initial training in her,
and there were few officers or men in the airship service who
were not filled with regret when orders were issued that she was
to be broken up. The general feeling was that she should have
been preserved as a lasting exhibition of the infancy of the
airship service, but unfortunately rigid airships occupy so much
space that there is no museum in the country which could have
accommodated her. So she passed, and, except for minor trophies,
remains merely a recollection.

RIGID AIRSHIP No. 23 CLASS

After the decision had been made in 1915 that work on No. 9
should be restarted, the Admiralty determined that a programme of
rigid airships should be embarked upon, and design was commenced.

Several ships of the same class were, ordered, and the type was
to be known as the 23 class. Progress on these ships, although
slow, was more rapid than had been the case with No. 9, and
by the end of 1917 three were completed and a fourth was rapidly
approaching that state.

The specification, always ambitious, laid down the following main
stipulations.

(1) The ship is to attain a speed of at least 55 miles per hour
for the main power of the engines.

(2) A minimum of 8 tons is to be available for disposable weights
when full.

(3) The ship must be capable of rising at an average rate of not
less than 1,000 feet per minute, through a height of 3,000
feet starting from nearly sea level.

As will be seen later this class of ship, although marking a
certain advance on No. 9 both as regards workmanship and design,
proved on the whole somewhat disappointing, and it became more
evident every day that we had allowed the Germans to obtain such
a start in the race of airship construction as we could ill
afford to concede.

We may here state that all of the ships of this class which had
been ordered were not completed, the later numbers being modified
into what was known as the 23 X class; four in all of the 23
class were built, of which two--Nos. 23 and 26--were built by
Messrs. Vickers, Ltd., at Barrow, No. 24 by Messrs. Wm. Beardmore
and Co., at Glasgow, and No. 25 by Messrs. Armstrong, Whitworth
and Co., at Selby, Yorkshire.

In many respects the closest similarity of design exists between
No. 9 and No. 23, especially in the hull, but it will be of
interest to mention the salient differences between the two
ships.

The length of the hull, which in No. 9 was 520 feet, was
increased in No. 23 to 535 feet, and the number of gasbags from
seventeen to eighteen. This gave a total volume of 997,500 cubic
feet compared with 890,000 cubic feet in No. 9, with a disposable
lift under specification conditions of 5.7 tons as opposed to 3.8
tons.

The longitudinal shape of No. 23 is a modified form of "Zahm"
shape, the radius of the bow portion being twice the diameter of
the parallel portion, while the stern radius is three times the
same diameter.

In design the hull framework is almost a repetition of No. 9,
particularly in the parallel portion, the same longitudinal and
transverse frames dividing the hull into compartments, with tubes
completely encircling the section between each main transverse
frame. The system of wiring the hull is precisely the same in
both the ships, and nets are employed in the same way.

The triangular section of keel is adhered to, but its functions
in No. 23 are somewhat different. In No. 9 it was intended to be
sufficiently strong to support all the main vertical bending
moments and shearing forces, but in No. 23 it was primarily
intended to support the distributed weights of water ballast,
petrol tanks, etc., between the main transverse frames. Unlike
No. 9, the keel is attached to the main transverse frames only.
The cabin and wireless cabin are disposed in the keel in the same
manner, and it also furnishes a walking way for the total length
of the ship.

The stabilizing fins, both vertical and horizontal, are similar
to those attached to No. 9, but the system of rudders and
elevators is totally different. In place of the box rudders and
elevators in No. 9, single balanced rudders and elevators are
attached to the fins; they have their bearing on the outboard
side on the external girders of the fins, which are extended for
the purpose. The elevators and rudders are composed of a
duralumin framework, stiffened by a kingpost on either side with
bracing wires.

The bags, eighteen in number, are made of rubber-proofed fabric
lined with gold-beater's skin. It is interesting to note that
the number of skins used for the bags of a ship of this class is
approximately 350,000. The system of valves is entirely
different from that in No. 9. The Parseval type of valve with the
pressure cone at the bottom of the bag is omitted, and in the
place of the two top valves in the former ship are a side valve
of the Zeppelin type entirely automatic and a top valve entirely
hand controlled. The side valve is set to blow off at a pressure
of from 3 to 5 millimetres. The outer cover was fitted in the
same manner as in No. 9. Two cars or gondolas, one forward, the
other aft, each carry one engine provided with swivelling
propellers and gears. They are enclosed with sides and a
fireproof roof, and are divided into two compartments, one the
navigating compartment, the other the engine room. The cars are
in all respects very similar to those of No. 9, and are suspended
from the hull in a similar manner. The remaining two engines are
carried in a small streamline car situated amidships, which has
just sufficient room in it for the mechanics to attend to them.
Originally this car was open at the top, but it was found that
the engineers suffered from exposure, and it was afterwards
roofed in.

The engine arrangements in this ship were totally different to
those of No. 9, four 250 horse-power Rolls Royce engines being
installed in the following order. Single engines are fitted in
both the forward and after cars, each driving two swivelling
four-bladed propellers. In the centre car two similar engines
are placed transversely, which drive single fixed propellers
mounted on steel tube outriggers through suitable gearing.

The engines are the standard 12 cylinder V-type Rolls Royce which
will develop over 300 brake horse-power at full throttle opening.

The engine is water cooled, and in the case of those in the
forward and after cars the original system consisted of an
internal radiator supplied by an auxiliary water tank carried in
the keel. It was found on the flight trials that the cooling was
insufficient, and external radiators were fitted, the internal
radiator and fan being removed. In the case of the centre car no
alteration was necessary, as external radiators were fitted in
the first instance.

The engines are supported by two steel tubes held by four
brackets bolted to the crank case, these being carried by twelve
duralumin tubes bolted to the bearers and transverse frames of
the car respectively. The drive from the engine is transmitted
through a universal joint to a short longitudinal shaft, running
on ball bearings. This shaft gears into two transverse shafts,
which drive the propellers through the medium of a gear box to
the propeller shafts, making five shafts in all.

The engines in the centre car being placed transversely the
transmission is more direct, the engines driving the propellers
through two gear wheels only. The propeller gear box is
supported by steel tube outriggers attached by brackets to the
framework of the car. The petrol is carried in a series of tanks
situated beneath the keel walking way, and are interconnected so
that any tank either forward or aft can supply any engine, by
this means affording assistance for the trimming of the ship.

Four-bladed propellers are used throughout the ship.

Water ballast is carried in fabric bags also situated beneath the
keel walking way, and a certain amount is also carried beneath
the floor of the car.

Engine-room telegraphs, swivelling propeller telegraphs, speaking
tubes and telephones, with a lighting set for the illumination of
the cars and keel, were all fitted in accordance with the
practice standard in all rigid airships.

The lift and trim trials taken before the initial flight trials
showed that the ship possessed a disposable lift under standard
conditions of 5.7 tons. The original disposable lift demanded
by the specification was 3 tons but this was reduced by 2 tons
owing to the machinery weights being 2 tons in excess of the
estimate. Since then these weights had been increased by another
half-ton, making a total of 2 1/2 tons over the original
estimate. It was evident that with so small a margin of lift
these ships would never be of real use, and it was decided to
remove various weights to increase the lift and to substitute a
wing car of a similar type to those manufactured for the R 33
class for the heavy after car at present in use.

R 23 carried out her trials without the alteration to the car,
which was effected at a later date, and the same procedure was
adopted with R 24 and R 25. In the case of R 26, however, she
had not reached the same stage of completion as the other two
ships, and the alterations proposed for them were embodied in her
during construction. The gasbags were of lighter composition,
all cabin furniture was omitted and the wing car was fitted in
place of the original after car. This wing car is of streamline
shape with a rounded bow and tapered stern. The lower portion is
plated with duralumin sheets and the upper part is covered with
canvas attached to light wooden battens to give the necessary
shape. This effected a very considerable reduction in weight.
The original 250 horse-power Rolls Royce engine was installed,
now driving a single large two-bladed propeller astern. A test
having been taken, it was found that the disposable lift under
standard conditions was 6.28 tons. It was therefore decided that
all the ships of the class should be modified to this design when
circumstances permitted. Speed trials were carried out under
various conditions of running, when it was found that the ship
possessed a speed of 54 1/4 miles per hour with the engines
running full out.

To summarize the performances of these ships as we did in the
case of No. 9, we find:

Speed:
Full 54 miles per hour
Normal =2/3 48 " " "
Cruising =1/3 33 " " "

Endurance:
Full 18 hours = 1,000 miles
Normal 26 " = 1,250 "
Cruising 50 " = 1,900 "

The production of the rigid airship during the war was always
surrounded with a cloak of impenetrable mystery. Few people,
except those employed on their construction or who happened to
live in the immediate vicinity of where they were built, even
knew of their existence, and such ignorance prevailed concerning
airships of every description that the man in the street hailed a
small non-rigid as "the British Zeppelin" or admired the
appearance of R 23 as "the Silver Queen." The authorities no
doubt knew their own business in fostering this ignorance,
although for many reasons it was unfortunate that public interest
was not stimulated to a greater degree. In the summer months of
1918, however, they relented to a certain extent, and R 23 and
one of her sister ships were permitted to make several flights
over London to the intense delight of thousands of its
inhabitants, and a certain amount of descriptive matter appeared
in the Press.

From that time onwards these large airships have completely
captured the popular imagination, and many absurd rumours and
exaggerations have been circulated regarding their capabilities.
It has been gravely stated that these airships could accomplish
the circuit of the globe and perform other feats of the
imagination. It must be confessed that their merits do not
warrant these extravagant assertions. The fact remains, however,
that R 23 and her sister ship R 26 have each carried out patrols
of upwards of 40 hours duration and that, similarly to No. 9,
they have proved of the greatest value for training airship crews
and providing experience and data for the building programme of
the future. At the present time highly interesting experiments
are being carried out with them to determine the most efficient
system of mooring in the open, which will be discussed at some
length in the chapter dealing with the airship of the future.

RIGID AIRSHIP 23 X CLASS

During the early days of building the airships of the 23 class,
further information was obtained relating to rigid airship
construction in Germany, which caused our designers to modify
their views. It was considered a wrong policy to continue the
production of a fleet of ships the design of which was becoming
obsolete, and accordingly within ten months of placing the order
for this class a decision was reached that the last four ships
were to be altered to a modified design known as the 23 X class.
As was the case with the ships of the preceding class when
nearing completion, they were realized to be out of date, and
special efforts being required to complete the ships of the 33
class and to release building space for additional larger ships,
the construction of the second pair was abandoned.

The main modification in design was the abolition of the external
keel, and in this the later Zeppelin principles were adopted.
This secured a very considerable reduction in structural weight
with a corresponding large expansion of the effective
capabilities of the ship.

It has been seen that the purpose of the keel in No. 9 was to
provide a structure sufficiently strong to support all the main
vertical bending moments and shearing forces, and that in No. 23
this principle was somewhat different, in that the keel in this
ship was primarily intended to support the distributed weights of
petrol, water, ballast, etc., between the transverse frames.

In this later design, namely, the 23 X class, it was considered
that the weights could be concentrated and suspended from the
radial wiring of the transverse frames and that the keel,
incorporated in the design of the former ships, could be
dispensed with.

For all practical purposes, apart from the absence of the keel,
the 23 X class of airship may be regarded as a slightly varied
model of the 23 class. The main dimensions are nearly the same,
and the general arrangement of the ship is but little changed.
The loss of space owing to the introduction of the internal
corridor is compensated by a modification of the shape of the
bow, which was redesigned with a deeper curve. The hull
structure was also strengthened by utilizing a stronger type of
girder wherever the greatest weights occur. In these
strengthened transverse frames the girders, while still remaining
of the triangular section, familiar in the other ships, are
placed the opposite way round, that is, with the apex pointing
outwards.

The walking way is situated at the base of the hull passing
through the gas chambers, which are specially shaped for the
purpose. The corridor is formed of a light construction of
hollow wooden struts and duralumin arches covered with netting.

In all other leading features the design of the 23 class is
adhered to; the gasbags are the same, except for the alteration
due to the internal corridor, and the system of valves and the
various controls are all highly similar.

The arrangement of gondolas and the fitting of engines in all
ways corresponds to the original arrangement of R 23, with the
exception that they were suspended closer to the hull owing to
the absence of the external keel. The substitution of the wing
car of the 33 class for the original after gondola, carried out
in the modifications undergone by the ships of the 23 class, was
not adopted in these ships, as the wireless compartment installed
in the keel in the former was fitted in the after gondola in the
latter.

The disposable lift of these ships under standard conditions is 7
1/2 tons, which shows considerable improvement on the ships of
the former classes.

Summarizing as before, the performances appear as under--

Speed:
Full 56 1/2 miles per hour
Normal 53 " " "
Cruising 45 " " "

Endurance:
Normal 19 hours = 1,015 miles
Cruising 23 1/2 " = 1,050 "

The two ships of this class, which were commissioned, must be
regarded within certain limits as most satisfactory, and are the
most successful of those that appeared and were employed during
the war. Escort of convoys and extended anti-submarine patrols
were carried out, and certain valuable experiments will be
attempted now that peace has arrived.

In spite of the grave misgivings of many critics, the structure
without the keel has proved amply strong, and no mishap attended
this radical departure on the part of the designers.

RIGID AIRSHIP No. 31 CLASS

The airship known as R 81 was a complete deviation from any rigid
airship previously built in this country. In this case the
experiment was tried of constructing it in wood in accordance
with the practice adopted by the Schutte-Lanz Company in Germany.

It must be frankly acknowledged that this experiment resulted in
failure. The ship when completed showed great improvement both in
shape, speed and lifting capacity over any airship commissioned
in this country, and as a whole the workmanship exhibited in her
construction was exquisite. Unfortunately, under the conditions
to which it was subjected, the hull structure did not prove
durable, and to those conditions the failure is attributed.
Under different circumstances it may be hoped that the second
ship, when completed, will prove more fortunate.

In length R 31 was 615 feet, with a diameter of 66 feet, and the
capacity was 1 1/2 million cubic feet.

In shape the hull was similar to the later types of Zeppelin,
having a rounded bow and a long, tapering stern. The longitudinal
and transverse frames were composed of girders built up of
three-ply wood, the whole structure being braced in the usual
manner with wire bracings. It had been found in practice with
rigid airships that, if for any reason one gasbag becomes much
less inflated than those adjacent to it, there is considerable
pressure having the effect of forcing the radial wires of the
transverse frames towards the empty bag. The tension resulting
in these wires may produce very serious compressive strain in the
members of the transverse frames, and to counteract this action
an axial wire is led along the axis of the ship and secured to
the centre point of the radial wiring. This method, now current
practice in rigid airship construction, was introduced for the
first time in this ship.

As will be seen from the photograph, the control and navigating
compartment of the ship is contained in the hull, the cars in
each case being merely small engine rooms. These small cars were
beautifully made of wood of a shape to afford the least
resistance to the air, and in number were five, each housing a
single 250 horse-power Rolls Royce engine driving a single fixed
propeller. Here we see another decided departure from our
previous methods of rigid airship construction, in that for the
first time swivelling propellers were abandoned. R 31 when
completed carried out her trials, and it was evident that she was
much faster than previous ships. The trials were on the whole
satisfactory and, except for a few minor accidents to the hull
framework and fins, nothing untoward occurred.

At a later date the whole ship was through fortuitous
circumstances exposed to certain disadvantageous conditions which
rendered her incapable of further use.

R 33 CLASS

September 24th, 1916, is one of the most important days in the
history of rigid airship design in this country; on this date the
German Zeppelin airship L 33 was damaged by gunfire over London,
and being hit in the after gasbags attempted to return to
Germany. Owing to lack of buoyancy she was forced to land at
Little Wigborough, in Essex, where the crew, having set fire to
the ship, gave themselves up. Although practically the entire
fabric of the ship was destroyed, the hull structure most
fortunately remained to all intents and purposes intact, and was
of inestimable value to the design staff of the Admiralty, who
measured up the whole ship and made working drawings of every
part available.

During this year other German rigid airships had been brought
down, namely L 15, which was destroyed at the mouth of the Thames
in April, but which was of an old type, and from which little
useful information was obtained; and also the Army airship L.Z.
85, which was destroyed at Salonica in the month of May. A
Schutte-Lanz airship was also brought down at Cuffley, on
September 2nd, and afforded certain valuable details.

All these ships were, however, becoming out of date; but L 33 was
of the latest design, familiarly called the super-Zeppelin, and
had only been completed about six weeks before she encountered
disaster.

In view of the fact that the rigid airships building in this
country at this date, with the exception of the wooden
Schutte-Lanz ships were all based on pre-war designs of Zeppelin
airships, it can be readily understood that this latest capture
revolutionized all previous ideas, and to a greater extent than
might be imagined, owing to the immense advance, both in design
and construction, which had taken place in Germany since 1914.

All possible information having been obtained, both from the
wreck of the airship itself and from interrogation of the
captured crew, approval was obtained, in November of the same
year, for two ships of the L 33 design to be built; and in
January, 1917, this number was increased to five.

It was intended originally that these ships should be an exact
facsimile of L 33; but owing to the length of time occupied in
construction later information was obtained before they were
completed, both from ships of a more modern design, which were
subsequently brought down, and also from other sources. Acting
on this information, various improvements were embodied in R 33
and R 34, which were in a more advanced state; but in the case of
the three other ships the size was increased, and the ships, when
completed, will bear resemblance to a later type altogether.

As a comment on the slowness of construction before mentioned,
the fact that while we in this country were building two ships on
two slips, Germany had constructed no fewer than thirty on four
slips, certainly affords considerable food for reflection.

The two airships of this class having only just reached a state
of completion, a detailed description cannot be given without
making public much information which must necessarily remain
secret for the present. Various descriptions have, however, been
given in the daily and weekly Press, but it is not intended in
the present edition of this book to attempt to elaborate on
anything which has not been already revealed through these
channels.

It is regrettable that so much that would be of the utmost
interest has to be omitted; but the particulars which follow will
at any rate give sonic idea of the magnitude of the ship and show
that it marks a decided departure from previous experiments and a
great advance on any airship before constructed in Great Britain.

It is also a matter for regret that these two ships were not
completed before the termination of hostilities, as their
capabilities would appear to be sufficient to warrant the
expectations which have been based on their practical utility as
scouting agents for the Grand Fleet.

In all its main features the hull structure of R 33 and R 34
follows the design of the wrecked German Zeppelin airship L 33.
The hull follows more nearly a true streamline shape than in the
previous ships constructed of duralumin, in which a great
proportion of the total length was parallel-sided. The Germans
adopted this new shape from the Schutte-Lanz design and have not
departed from this practice. This consists of a short parallel
body with a long rounded bow and a long tapering stem culminating
in a point. The overall length of the ship is 643 feet with a
diameter of 79 feet and an extreme height of 92 feet.

The type of girders in this class has been much altered from
those in previous ships. The hull is fitted with an internal
triangular keel throughout practically the entire length. This
forms the main corridor of the ship, and is fitted with a footway
down the centre for its entire length. It contains water ballast
and petrol tanks, bomb stowage and crew accommodation and the
various control wires, petrol pipes and electric leads are
carried along the lower part.

Throughout this internal corridor runs a bridge girder, from
which the petrol and water ballast tanks are supported. These
tanks are so arranged that they can be dropped clear of the ship.

Amidships is the cabin space with sufficient room for a crew of
twenty-five. Hammocks can be slung from the bridge girder before
mentioned.

In accordance with the latest Zeppelin practice, monoplane
rudders and elevators are fitted to the horizontal and vertical
fins.

The ship is supported in the air by nineteen gasbags which give a
total capacity of approximately two million cubic feet of gas.
The gross lift works out at approximately 59 1/2 tons, of which
the total fixed weight is 33 tons, giving a disposable lift of 26
1/2 tons.

The arrangement of cars is as follows: At the forward end the
control car is slung, which contains all navigating instruments
and the various controls. Adjoining this is the wireless cabin,
which is also fitted for wireless telephony. Immediately aft of
this is the forward power car containing one engine, which gives
the appearance that the whole is one large car.

Amidships are two wing cars each containing a single engine.
These are small and just accommodate the engine with sufficient
room for mechanics to attend to them. Further aft is another
larger car which contains an auxiliary control position and two
engines

It will thus be seen that five engines are installed in the ship;
these are all of the same type and horse-power, namely, 250
horse-power Sunbeam. R 33 was constructed by Messrs. Armstrong
Whitworth Ltd., while her sister ship R 34 was built by Messrs.
Beardmore on the Clyde.

In the spring of 1918, R 33 and R 34 carried out several flight
trials, and though various difficulties were encountered both
with the engines and also with the elevator and rudder controls,
it was evident that, with these defects remedied, each of these
ships would prove to be singularly reliable.

On one of these trials made by R 34, exceedingly bad weather was
encountered, and the airship passed through several blinding
snowstorms; nevertheless the proposed flight of some seventeen
hours was completed, and though at times progress was practically
nil owing to the extreme force of the wind, the station was
reached in safety and the ship landed without any contretemps.
This trial run having been accomplished in weather such as would
never have been chosen in the earlier days of rigid trial
flights, those connected with the airship felt that their
confidence in the vessel's capabilities was by no means
exaggerated.

The lift of the ship warranted a greater supply of petrol being
carried than there was accommodation for, and the engines by now
had been "tuned up" to a high standard of efficiency.
Accordingly it was considered that the ship possessed the
necessary qualifications for a transatlantic flight. It was,
moreover, the opinion of the leading officers of the airship
service that such an enterprise would be of inestimable value to
the airship itself, as demonstrating its utility in the future
for commercial purposes.

Efforts were made to obtain permission for the flight to be
attempted, and although at first the naval authorities were
disinclined to risk such a valuable ship on what appeared to be
an adventure of doubtful outcome, eventually all opposition was
overcome and it was agreed that for the purposes of this voyage
the ship was to be taken over by the Air Ministry from the
Admiralty.

Work was started immediately to fit out the ship for a journey of
this description. Extra petrol tanks were disposed in the hull
structure to enable a greater supply of fuel to be carried, a new
and improved type of outer cover was fitted, and by May 29th, R
34 was completed to the satisfaction of the Admiralty and was
accepted. On the evening of the same day she left for her
station, East Fortune, on the Firth of Forth. This short passage
from the Clyde to the Forth was not devoid of incident, as soon
after leaving the ground a low-lying fog enveloped the whole
country and it was found impossible to land with any degree of
safety. It having been resolved not to land until the fog
lifted, the airship cruised about the north-east coast of England
and even came as far south as York. Returning to Scotland, she
found the fog had cleared, and was landed safely, having been in
the air for 21 hours.

The original intention was that the Atlantic flight should be
made at the beginning of June, but the apparent unwillingness of
the Germans to sign the Peace Treaty caused the Admiralty to
retain the ship for a time and commission her on a war footing.
During this period she went for an extended cruise over Denmark,
along the north coast of Germany and over the Baltic. This
flight was accomplished in 56 hours, during which extremely bad
weather conditions were experienced at times. On its conclusion
captain and crew of the ship expressed their opinion that the
crossing of the Atlantic was with ordinary luck a moral
certainty. Peace having been signed, the ship was overhauled
once more and made ready for the flight, and the day selected
some three weeks before was July 2nd.

A selected party of air-service ratings, together with two
officers, were sent over to America to make all the necessary
arrangements, and the American authorities afforded every
conceivable facility to render the flight successful.

As there is no shed in America capable of housing a big rigid,
there was no alternative but to moor her out in the open,
replenish supplies of gas and fuel and make the return journey as
quickly as possible.

On July 2nd, at 2.38 a.m. (British summer time), R 34 left the
ground at East Fortune, carrying a total number of 30 persons.
The route followed was a somewhat northerly one, the north coast
of Ireland being skirted and a more or less direct course was
kept to Newfoundland. From thence the south-east coast of Nova
Scotia was followed and the mainland was picked up near Cape Cod.

From Cape Cod the airship proceeded to Mineola, the landing place
on Long Island. All went well until Newfoundland was reached.
Over this island fog was encountered, and later electrical storms
became a disturbing element when over Nova Scotia and the Bay of
Fundy. The course had to be altered to avoid these storms, and
owing to this the petrol began to run short. No anxiety was
occasioned until on Saturday, July 5th, a wireless signal was
sent at 3.59 p.m. asking for assistance, and destroyers were
dispatched immediately to the scene. Later messages were
received indicating that the position was very acute, as head
winds were being encountered and petrol was running short. The
airship, however, struggled on, and though at one time the
possibility of landing at Montauk, at the northern end of Long
Island, was considered, she managed after a night of considerable
anxiety to reach Mineola and land there in safety on July 6th at
9.55 a.m. (British summer time). The total duration of the
outward voyage was 108 hours 12 minutes, and during this time
some 3,136 sea miles were covered. R 34 remained at Mineola
until midnight of July 9th according to American time. During
the four days in which she was moored out variable weather was
experienced, and in a gale of wind the mooring point was torn
out, but fortunately,another trail rope was dropped and made
fast,and the airship did not break away.

It was intended that the return should be delayed until daylight,
in order that spectators in New York should obtain a good view of
the airship, but an approaching storm was reported and the
preparations were advanced for her immediate departure. During
the last half-hour great difficulty was experienced in holding
the ship while gassing was completed.

At 5.57 a.m. (British summer time) R 34 set out on her return
voyage, steering for New York, to fly over the city before
heading out into the Atlantic. She was picked up by the
searchlights and was distinctly visible to an enormous concourse
of spectators. During the early part of the flight a strong
following wind was of great assistance, and for a short period an
air speed of 83 miles per hour was attained. On the morning of
July 11th the foremost of the two engines in the after car broke
down and was found to be beyond repair. The remainder of the
voyage was accomplished without further incident. On July 12th
at noon, a signal was sent telling R 34 to proceed to the airship
station at Pulham in Norfolk as the weather was unfavourable for
landing in Scotland. On the same day at 8.25 p.m., land was
first sighted and the coast line was crossed near Clifden, county
Galway, at 9 p.m. On the following morning, July 13th, at 7.57
a.m. (British summer time), the long voyage was completed and R
34 was safely housed in the shed, having been in the air 75 hours
3 minutes.

Thus a most remarkable undertaking was brought to a successful
conclusion. The weather experienced was by no means abnormally
good. This was not an opportunity waited for for weeks and then
hurriedly snatched, but on the preordained date the flight was
commenced. The airship enthusiast had always declared that the
crossing of the Atlantic presented no insuperable difficulty, and
when the moment arrived the sceptics found that he was correct.
We may therefore assume that this flight is a very important
landmark in the history of aerial transport, and has demonstrated
that the airship is to be the medium for long-distance travel.
We may rest assured that such flights, although creating
universal wonder to-day, will of a surety be accepted as everyday
occurrences before the world is many years older.

CHAPTER VIII
THE WORK OF THE AIRSHIP IN THE WORLD WAR

The outbreak of war found us, as we have seen, practically
without airships of any military value. For this unfortunate
circumstance there were many contributory causes. The
development of aeronautics generally in this country was behind
that of the Continent, and the airship had suffered to a greater
extent than either the seaplane or the aeroplane. Our attitude
in fact towards the air had not altered so very greatly from that
of the man who remarked, on reading in his paper that some
pioneer of aviation had met with destruction, "If we had been
meant to fly, God would have given us wings." Absurd as this
sounds nowadays, it was the opinion of most people in this
country, with the exception of a few enthusiasts, until only a
few years before we were plunged into war.

The year 1909 saw the vindication of the enthusiasts, for in this
summer Bleriot crossed the Channel in an aeroplane, and the
first passenger-carrying Zeppelin airship was completed. Those
who had previously scoffed came to the conclusion that flying was
not only possible but an accomplished fact, and the next two
years with their great aerial cross-country circuits revealed the
vast potentialities of aircraft in assisting in military
operations. We, therefore, began to study aeronautics as the
science of the future, and aircraft as an adjunct to the sea and
land forces of the empire.

The airship, unfortunately, suffered for many reasons from the
lack of encouragement afforded generally to the development of
aeronautics. The airship undoubtedly is expensive, and one
airship of size costs more to build than many aeroplanes. In
addition, everything connected with the airship is a source of
considerable outlay. The shed to house an airship is a most
costly undertaking, and takes time and an expenditure of material
to erect, and bears no comparison with the cheap hangar which can
be run up in a moment to accommodate the aeroplane. The gas to
lift the airship is by no means a cheap commodity. If it is to
be made on the station where the airship is based, it
necessitates the provision of an expensive and elaborate plant.
If, on the other hand, it is to be manufactured at a factory, the
question of transport comes in, which is a further source of
expense with costly hydrogen tubes for its conveyance.

Another drawback is the large tract of ground required for an
aerodrome, and the big airship needs a large number of
highly-trained personnel to handle it.

A further point always, raised when the policy of developing the
airship was mooted is its vulnerability. It cannot be denied
that it presents a large target to artillery or to the aeroplane
attacking it, and owing to the highly inflammable nature of
hydrogen when mixed with air there can be no escape if the gas
containers are pierced by incendiary bullets or shells.

Another contributing factor to the slow development of the
airship was the lack of private enterprise. Rivalry existed
between private firms for aeroplane contracts which consequently
produced improvements in design; airships could not be produced
in this way owing to the high initial cost, and if the resulting
ships ended in failure, as many were bound to do, there would be
no return for a large outlay of capital. The only way by which
private firms could be encouraged to embark on airship building
was by subsidies from the Government, and at this time the
prevalent idea of the doubtful value of the airship was too
strong for money to be voted for this purpose.

To strengthen this argument no demand had either been made from
those in command of the Fleet or from commanders of our Armies
for airships to act as auxiliaries to our forces.

The disasters experienced by all early airships and most
particularly by the Zeppelins were always seized upon by those
who desired to convince the country what unstable craft they
were, and however safe in the air they might be were always
liable to be wrecked when landing in anything but fine weather.
Those who might have sunk their money in airship building
thereupon patted themselves upon the back and rejoiced that they
had been so far-seeing as to avoid being engaged upon such a
profitless industry.

Finally, all in authority were agreed to adopt the policy of
letting other countries buy their experience and to profit from
it at a later date. Had the war been postponed for another
twenty years all might have been well, and we should have reaped
the benefit, but most calamitously for ourselves it arrived when
we were utterly unprepared, and having, as we repeat, only three
airships of any military value.

With these three ships, Astra-Torres (No. 3), Parseval (No. 4)
and Beta, the Navy did all that was possible. At the very
outbreak of war scouting trips were made out into the North Sea
beyond the mouth of the Thames by the Astra and Parseval, and
both these ships patrolled the Channel during the passage of the
Expeditionary Force.

The Astra was also employed off the Belgian coast to assist the
naval landing party at Ostend, and together with the Parseval
assisted in patrolling the Channel during the first winter of the
war.

The Beta was also sent over to Dunkirk to assist in spotting for
artillery fire and locating German batteries on the Belgian
coast. Our airships were also employed for aerial inspection of
London and other large towns by night to examine the effects of
lighting restrictions and obtain information for our
anti-aircraft batteries.

With the single exception of the S.S. ship, which carried out
certain manoeuvres in France in the summer of 1916, our airships
were confined to operations over the sea; but if we had possessed
ships of greater reliability in the early days of the war, it is
conceivable that they would have been of value for certain
purposes to the Army. The Germans employed their Zeppelins at
the bombardment of Antwerp, Warsaw, Nancy and Libau, and their
raids on England are too well remembered to need description.
The French also used airships for the observation of troops
mobilizing and for the destruction of railway depots. The
Italians relied entirely at the beginning of the war on airships,
constructed to fly at great heights, for the bombing of Austrian
troops and territory, and met with a considerable measure of
success.

When it was decided, early in 1915, to develop the airship for
anti-submarine work difficulties which appeared almost
insuperable were encountered at first. To begin with, there were
practically no firms in the country capable of airship
production. The construction of envelopes was a great problem;
as rubber-proofed fabric had been found by experiment to yield
the best results for the holding of gas, various waterproofing
firms were invited to make envelopes, and by whole-hearted
efforts and untiring industry they at last provided very
excellent samples. Fins, rudder planes, and cars were also
entrusted to firms which had had no previous experience of this
class of work, and it is rather curious to reflect that envelopes
were produced by the makers of mackintoshes and that cars and
planes were constructed by a shop-window furnisher. This was a
sure sign that all classes of the community were pulling together
for the good of the common cause.

Among other difficulties was the shortage of hydrogen tubes,
plants, and the silicol for making gas.

Sufficient sheds and aerodromes were also lacking, and the
airships themselves were completed more quickly than the sheds
which were to house them.

The lack of airship personnel to meet the expansion of the
service presented a further obstacle. To overcome this the
system of direct entry into the R.N.A.S. was instituted, which
enabled pilots to be enrolled from civil life in addition to the
midshipmen who were drafted from the Fleet. The majority of the
ratings were recruited from civil life and given instruction in
rigging and aero-engines as quickly as possible, while technical
officers were nearly all civilians and granted commissions in the
R.N.V.R.

A tremendous drawback was the absence of rigid airships and the
lack of duralumin with which to construct them.

Few men were also experienced in airship work at this time, and
there was no central airship training establishment as was
afterwards instituted. Pilots were instructed as occasion

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