Aeroplanes and Dirigibles of War

F >> Frederick A. Talbot >> Aeroplanes and Dirigibles of War

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15

On the other hand, the artilleryman is favoured in certain
directions. The range of utility of the airship is severely
limited. If its avowed mission is reconnaissance and conclusive
information concerning the disposition of forces, artillery and
so forth is required, experience has proved that such work cannot
be carried out satisfactorily or with any degree of accuracy at a
height exceeding 5,000 feet, and a distance beyond six miles.
But even under these circumstances the climatic conditions must
be extremely favourable. If the elements are unpropitious the
airship must venture nearer to its objective. These data were
not difficult to collect, inasmuch as they were more or less
available from the results of military observations with captive
balloons, the conditions being somewhat similar. With the
ordinary captive balloon it has been found that, in clear
weather, a radius of about 3 3/4 miles at the maximum elevation
constitutes its range of reliable utility.

With the aeroplane, however, the conditions are very dissimilar.
In the first place the machine owing to its diminutive size as
compared with the airship, offers a small and inconspicuous
target. Then there is its high independent speed, which is far
beyond that of the airship. Furthermore its mobility is greater.
It can wheel, turn sharply to the right or to the left, and
pursue an irregular undulating flight in the horizontal plane,
which renders it well nigh impossible for a gunner to pick it up.
The machine moves at a higher relative speed than that at which
the gun can be trained. It is the rapid and devious variation
which so baffles the gunner, who unless he be highly skilled and
patient, is apt to commence to fire wildly after striving for a
few moments, and in vain, to pick up the range; he trusts to luck
or depends upon blind-shooting, which invariably results in a
waste of ammunition.

A gun, to be of tangible destructive efficiency when directed
against aircraft, especially those depending upon the gas-bag for
equilibrium, must be of special design. It must be capable of
firing at an angle only a few degrees less than the absolute
vertical, and in order to follow the rapid and involved movements
of its objective, must be so mobile that it can be trained
through a complete circle at any angle of inclination less than
its maximum. At the same time, if the weapon is being used in
field operations it must be mounted upon a carriage of adequate
mobility to enable it to follow the airship, and thereby keep
pace with the latter, so that the aerial craft may be sorely
harassed if not actually hit. The automobile is the obvious
vehicle for this duty, and it has accordingly been extensively
used in this service.

The automobile and the gun mounted thereon follow widely
different lines. Some vehicles are designed especially for this
duty, while others are improvisations, and be it noted, in
passing, that many of the latter have proved more serviceable
than the former. Still, the first-named is to be preferred,
inasmuch as necessarily it is designed to meet the all-round
requirements imposed, and consequently is better able to stand up
to the intended work, whereas the extemporised vehicle is only
serviceable under favourable conditions.

The Krupp Company has evolved many designs of anti-aircraft
motor-driven guns--"Archibalds" the British airmen term them with
emphatic levity. They are sturdily-built vehicles fitted with
heavy motors, developing from 40 to 50 horse-power, with the
chassis not widely dissimilar from that adopted for motor-omnibus
traffic. Consequently, they are not necessarily condemned to the
high-roads, but within certain limits are able to travel across
country, i.e., upon fields or other level expanses, where the
soil is not unduly soft.

But the very character of the problem rendered the evolution of
the vehicle a somewhat perplexing matter. There were many
factors which had to be taken into consideration, and it was
possible to meet the imposed requirements only within certain
limits. In the first place, the weight of the gun itself had to
be kept down. It was obviously useless to overload the chassis.
Again, the weight of the projectile and its velocity had to be
borne in mind. A high velocity was imperative. Accordingly, an
initial velocity varying from 2,200 to 2,700 feet per second,
according to the calibre of the gun, was determined.

Moreover, as mobility was an indispensable condition, the gun had
to be so mounted that it could be fired from the motor-car even
if the latter were travelling at high speed. This requirement
entailed another difficulty. The gun had to be mounted in such a
manner as to enable the gunner to train it easily and readily
through the complete circle and through its complete range of
vertical inclination. As the result of prolonged experiments it
was ascertained that the most suitable arrangement was a pedestal
mounting, either within a turret or upon an open deck. To meet
the weight of the gun, as well as the strains and stresses
incidental to firing, the chassis was strengthened, especially
over the rear axle near which the mounting is placed.

The heaviest gun of this type is the 10.5 centimetre (4 1/4-inch)
quick-firer, throwing a shell weighing nearly forty pounds, with
an initial velocity of 2,333 feet per second. This "Archibald"
is totally unprotected. The gun is mounted centrally upon the
carriage over the rear axle, and occupies the centre of the deck
between the driver's seat and that of the gun crew behind. The
whole of the deck is clear, thereby offering no obstruction to
the gunner in training the weapon, while the space may be widened
by dropping down the wings of the vehicle. At the rear is a seat
to accommodate the gun crew, beneath which the ammunition is
stowed. When travelling and out of action, the gun lies
horizontally, the muzzle pointing from the rear of the car.

To reduce the strains arising from firing, the arm is fitted with
what is known as the "differential recoil." Above the breach is
an air recuperator and a piston, while there is no hydraulic
brake such as is generally used. The compressor is kept under
compression while the car is travelling with the gun out of
action, so that the arm is available for instant firing. This is
a departure from the general practice in connection with such
weapons. When the gun is loaded the bolt which holds the
compressor back is withdrawn, either by the hand for manual
firing, or by the action of the automatic closing of the
breech when the arm is being used as a quick-firer. In firing
the gun is thrown forward under the pressure of the released air
which occurs at the moment of discharge. The energy of the
recoil brings the gun back and at the same time recharges the
compressed air reservoir.

The gun is so mounted upon its pedestal as to enable a maximum
vertical inclination of 75 degrees to be obtained. The mounting
system also enables the weapon to be trained in any desired
direction up to the foregoing maximum elevation throughout a
complete circle, and it can be handled with ease and celerity. A
smaller "Archibald" is the 7.5 centimetre (3-inch gun) throwing a
14.3 pound shell at an initial velocity of about 2,170 feet per
second.

The turret anti-aircraft gun carried upon a motor-car differs
from the foregoing very considerably. This is a protected arm.
The gun of 7.1 centimetres--approximately 2.75 inches--is mounted
in the same manner upon the car-deck and over the driving axle,
but is enclosed within a sheet steel turret, which is proof
against rifle and machine-gun fire. This turret resembles the
conning-tower of a battleship, and is sufficiently spacious to
house the whole of the gun crew, the internal diameter being
about seven feet. Access to the turret is obtained through a
rear door. This gun has a maximum elevation of about 75 degrees,
while its operation and mechanism are similar to those of the
unprotected weapon.

The vehicle itself is practically identical with the armoured
motor-car, which has played such an important part during the
present campaign, the driver being protected by a bullet-proof
steel screen similar in design to the ordinary glass wind-screen
fitted to touring automobiles. This is carried sufficiently high
to offer complete protection to his head when seated at the
wheel, while through a small orifice in this shield he is able to
obtain a clear view of the road. The engine and its vital parts
are also adequately protected. The ammunition is carried in a
cupboard-like recess forming part of the driver's seat, encased
in bullet-proof steel sheeting with flap-doors. This device
enables the shells to be withdrawn readily from the side of the
car and passed to the crew within the turret. The caisson is of
sufficient dimensions to receive 69 shells.

The Ehrhardt airship fighting ordnance is similarly adapted to
motor-car operations, one type being especially powerful. The
whole of the vehicle is encased in armour-plating impervious to
rifle and machine-gun fire. The driver is provided with a small
orifice through which he is able to obtain a clear uninterrupted
view of the road ahead, while the armouring over the tonneau is
carried to a sufficient height to allow head-room to the gun crew
when standing at the gun. All four wheels are of the disk type
and fashioned from heavy sheet steel. The motor develops 40-50
horse-power and, in one type, in order to mitigate the risk of
breakdown or disablement, all four wheels are driven. The gun, a
small quick-firer, is mounted on a pedestalin a projecting
conning-tower. The mounting is placed behind the driver's seat,
and is trained and operated from the tonneau. The maximum
elevation is 75 degrees, and like the gun carriage bearing the
tube guide it can be moved through a complete circle, being free
to rotate in the fixed pivot jack to enable this end to be
attained.

The foregoing may be said to represent the most powerful types of
mobile anti-aircraft weapons used by the Austro-German forces
to-day. Arms of similar design, roughly speaking, have also been
introduced into the French and Russian services. In addition
many semi-armoured weapons of this character are in operation,
some specially built for the work, while others have been
improvised. In the semi-armoured motor-car the carriage follows
the usual lines; it has an open top, the armouring comprising the
body of the tonneau and the diskwheels, which are made of light
bullet-proof steel. Here again the prevailing practice is to
mount the gun as nearly above the rear axle as possible, and
to work it from the tonneau. The maximum elevation is also 75
degrees, with training throughout the entire circle.

Another type comprises a very light machine gun of rifle calibre,
and this is intended for attachment to an ordinary motor car.
There is a pedestal mounting which can be set within the tonneau,
while the weapon is pivoted in an outrigger, the latter being
free to rotate in its pivot jack. This arrangement enables the
arm to cover a wide range,while it also admits of training
through an extensive angle of elevation.

The Allied forces improvised travelling anti-aircraft offences
by mounting the latest types of Vickers, Hotchkiss, and other
machine guns in armoured motor cars. Some of these have the
domed turret form, with the gun projecting through the roof,
while others are protected against hostile attack from the side
only, the carriage being panelled with bullet-proof steel
sheeting. While such weapons are useful, inasmuch as they can
maintain a hot fire ranging up to 750 shots per minute, they are
not to be compared with the "Archibalds," which are able to throw
heavy shrapnel and incendiary shells, and have a vertical range
of about 6,000 to 8,000 feet.

The improvised motor-gun has not proved a complete success,
except in those instances when the hostile aircraft has ventured
to approach somewhat closely to the ground. The more formidable
weapons cannot be mounted upon ordinary vehicles, inasmuch as the
increase in weight, which is appreciable, impairs the efficiency
of the vehicle, and at the same time enhances the possibility of
breakdown at a critical moment. For such arms a special and
substantial chassis is imperative, while the motive power and
gearing must be adapted to the circumstances.

Motor-mounted anti-aircraft weapons, however, have not proved an
unqualified success. The fact that the vehicles are condemned to
the high roads, or at least to comparatively smooth and level
ground, constitutes a severe handicap. Again, when travelling at
high speed, and this is essential when pursuing a fast aeroplane,
the accurate laying of the weapon is extremely difficult, owing
to the oscillation of the vehicle itself, especially if the road
surface is in a bad condition. The sighting arrangements are of
a wonderfully complete character, as described elsewhere, but the
irregular rolling movement arising from high speed is a
nullifying quantity. It is tolerably easy for the aircraft,
especially an aeroplane, to evade successful pursuit, either by
rising to an elevation beyond the range of the gun, or by
carrying out baffling evolutions such as irregular undulating
flight, wheeling, and climbing. According to the reports of the
British and French airmen the "Archibald" has failed to establish
the glowing reputation which was anticipated, for the simple
reason that, unless it has a clear straight road and can maintain
its high speed, it can easily be out-distanced by the fleet human
bird.

The motor-car suffers from another serious disability. It cannot
manoeuvre with sufficient celerity. For instance, if it is
necessary to turn round in a narrow lane, valuable time is lost
in the process, and this the airman turns to account. In hilly
country it is at a still greater disadvantage, the inclines,
gradients, and sinuosities of the roads restricting its
effectiveness very pronouncedly. It must also be remembered
that, relatively speaking, the "Archibald" offers a better target
to the airman than the aeroplane offers to the man behind the
anti-aircraft gun on the motor below. A few well-placed bombs
are sufficient to induce the pursuers to cease their activities.
Even if the missiles fail to strike the motor-car itself they can
wreak disaster in directly by rendering the road impassable or
dangerous to negotiate at high speed. On the whole therefore,
the "Archibald" is a greatly exaggerated weapon of offence
against aircraft, and, so far as is known, has failed to fulfil
expectations. In fact, the Germans have practically abandoned
the idea of using it in the manner of a pursuing arm; they work
the weapon as a fixture, depending upon the car merely as a means
of moving it from point to point. Thus, in reality, it has been
converted into a light field-piece, and may almost be included in
the category of fixed weapons for combating aerial operations.

CHAPTER XV
ANTI-AIRCRAFT GUNS. IMMOBILE WEAPONS

The immobile anti-aircraft gun, as distinct from that attached to
a travelling carriage such as a motor-car, may be subdivided into
two classes. The one is the fixed arm which cannot be moved
readily, mounted upon a permanent emplacement; the other is the
field-piece which, while fired from a stationary position, may be
moved from point to point upon a suitable carriage. The
distinction has its parallel in ordinary artillery, the
first-named weapon coinciding with the heavy siege gun, which is
built into and forms part and parcel of the defensive or
offensive scheme, while the second is analogous to the field
artillery, which may be wheeled from position to position.

In this phase of artillery the Germans led the way, for the
simple reason that they recognised the military value of aerial
navigation years in advance of their contemporaries. Again, in
this field the Krupp Organisation has played a prominent part.
It embarked upon actual construction of weapons while its rivals
in other countries were content to prepare their drawings, which
were filed against "The Day." But it must not be thought that
because the German manufacturers of armaments were ahead of
their contemporaries they dominated the situation. Far from it.
Their competitors in the market of destruction were every whit as
keen, as ingenious, and as enterprising. Kruppism saw a
commercial opportunity to profit from advertisement and seized
it: its rivals were content to work in secret upon paper, to keep
pace with the trend of thought, and to perfect their
organisations so as to be ready for the crisis when it developed.

The first Krupp anti-aircraft field-piece was a 6.5 centimetre (2
9/16 inch) arm. It possessed many interesting features, the most
salient of which was the design of the axle of the carriage. The
rigid axle for the two wheels was replaced by an axle made in two
sections, and joined together in the form of a universal
coupling, so that each wheel virtually possessed its own axle, or
rather half-axle. This was connected with the cradle of the gun
in such a manner that the wheels were laterally pivoted thereon.

The result is that each axle can be turned forward together with
its wheel, and thus the wheels have their rims brought into line
to form an arc of a circle, of which the rear end of the spade of
the gun carriage constitutes the centre. This acts as a pivot,
about which the gun can be turned, the pair of wheels forming the
runners for the achievement of this movement. The setting of the
weapon in the firing position or its reversion to the travelling
position can be easily and speedily effected merely by the
rotation of a handwheel and gearing.

With this gun a maximum elevation of 60 degrees is possible,
owing to the trunnions being carried well behind the breech in
combination with the system of long steady recoil. The balancing
spring which encloses the elevating screw is contained in a
protected box. The recoil brake, together with the spring
recuperator, follows the usual Krupp practice in connection with
ordinary field pieces, as does also the automatic breech-closing
and firing mechanism. In fact there is no pronounced deviation
from theprevailing Krupp system, and only such modifications as
are necessary to adapt the arm to its special duty. When the gun
is elevated to high angles the shell, after insertioin the
breech, is prevented from slipping out by means of a special
device, so that the proper and automatic closing of the breech is
not impaired in any way.

In such an arm as this, which is designed essentially for
high-angle firing, the sighting and training facilities require
to be carried out upon special lines, inasmuch as the objective
is necessarily at a considerable altitude above the horizon of
the gun. In other words, in firing at a high inclination,
distance between the gun and the target cannot be utilised
directly for the back sight. On the other hand, it is essential
that in proportion as the angle from the horizontal increases,
the back sight should be lowered progressively in a manner
corresponding to the distance.

To assist the range-finder in his task of sighting it is
necessary that he should be provided with firing tables set out
in a convenient form, which, in conjunction with the telemeter,
serve to facilitate training for each successive round. In this
way it is possible to pick up the range quickly and to keep the
objective in the line of fire until it either has been put hors
de combat, or has succeeded in retiring beyond the range of the
gun.

The sighting arrangements of these Krupp anti-aircraft guns are
carried out upon these lines. Beneath the barrel of the
back-sight is an observing glass with an eye-piece for the
artillerist, while above and behind the observing glass is
another eye-piece, to be used in conjunction with the
manipulation of the back-sight. The eye-piece of the observation
glass is so made that it can be turned through a vertical plane
in proportion as the angle of fire increases in relation to the
horizontal. The determination of the distance from the objective
and from the corresponding back-sight as well as the observation
of the altitude is carried out with the aid of the telemeter.
This again carries an observation glass fitted with an eye-piece
which can be turned in the vertical plane in the same manner as
that of the fore-sight. By means of this ingenious sighting
device it is possible to ascertain the range and angle of fire
very easily and speedily.

The weight of the special Krupp anti-aircraft field-piece,
exclusive of the protecting shield, is approximately identical
with that of the ordinary light artillery field-piece. It throws
a shell weighing 8.8 pounds with an initial velocity of about
2,066 feet per second.

Although the German armament manufacturers were among the first
to enter the field with an anti-aircraft gun of this character
they were speedily followed by the French, who devised a superior
weapon. In fact, the latter represented such a decisive advance
that the German artillerists did not hesitate to appropriate
their improvements in sundry essential details, and to
incorporate them with their own weapons. This applies especially
to the differential recoil system which is utilised in the small
anti-aircraft guns now mounted upon the roofs of high buildings
of cities throughout Germany for the express purpose of repelling
aerial attack.

The French system is admitted by the leading artillery
technicians of the world to be the finest which has ever been
designed, its remarkable success being due to the fact that it
takes advantage of the laws of Nature. In this system the gun is
drawn back upon its cradle preparatory to firing. In some
instances the barrel is compressed against a spring, but in the
more modern guns it is forced to rest against a cushion of
compressed air contained within a cylinder. When first bringing
the gun into action, the barrel is brought into the preliminary
position by manually compressing the air or spring by means of a
lever. Thereafter the gun works automatically. When the gun is
fired the barrel is released and it flies forward. At a critical
point in its forward travel the charge is fired and the
projectile speeds on its way. The kick or recoil serves to
arrest the forward movement of the barrel and finally drives it
back again against the strong spring or cushion of compressed air
within the cylinder to its normal position, when it is ready for
the introduction of the next shell.

The outstanding feature of this system is that the projectile is
given a higher initial velocity than is possible with the barrel
held rigid at the moment of discharge, because the shell is
already travelling at the moment of firing.

The fixed anti-aircraft guns such as are stationed upon eminences
and buildings are of the quick firing type, the object being to
hurl a steady, con tinuous stream of missiles upon the swiftly
moving aeroplane. Some of the weapons throw a one-pound shell
and are closely similar to the pom-pom which proved so effective
during the South African war. Machine guns also have been
extensively adopted for this duty by all the combatants, their
range of approximately 2,000 yards and rapidity of fire being
distinctly valuable when hostile aircraft descend to an altitude
which brings them within the range of the weapon.

The greatest difficulty in connection with this phase of
artillery, however, is not so much the evolution of a serviceable
and efficient type of gun, as the determination of the type of
projectile which is likely to be most effective. While shrapnel
is employed somewhat extensively it has not proved completely
satisfactory. It is difficult to set the timing fuse even after
the range has been found approximately, which in itself is no
easy matter when the aircraft is moving rapidly and irregularly,
but reliance is placed thereon in the hope that the machine may
happen to be within the cone of dispersion when the shell bursts,
and that one or more of the pieces of projectile and bullets may
chance to penetrate either the body of the airman or a vital part
of the mechanism.

It is this uncertainty which has led to a preference for a direct
missile such as the bullet discharged from a machine gun. A
stream of missiles, even of rifle calibre, maintained at the rate
of some 400 shots per minute is certain to be more effective,
provided range and aim are correct, than shrapnel. But the
ordinary rifle-bullet, unless the objective is within very close
range, is not likely to cause much harm, at least not to the
mechanism of the aerial vessel.

It is for this reason that greater attention is being devoted,
especially by the French artillerists, to the Chevalier
anti-aircraft gun, a weapon perfected by a Swiss technician
resident in Great Britain. It projects a formidable missile
which in fact is an armour-piercing bullet 1/2- to 3/4-inch in
diameter. It is designed for use with an automatic machinegun,
which the inventor has devised more or less upon the well-known
French system. The bullet has a high velocity--about 2,500 feet
per second--and a maximum range of 6,000 to 8,000 feet at the
maximum elevation. Should such a missile strike the motor or
other mechanism of the vessel it would wreak widespread havoc,
and probably cause the machine to come to earth. This arm has
been designed for the express purpose of disabling the aeroplane,
and not for the subjugation of the airman, which is a minor
consideration, inasmuch as he is condemned to a descent when his
craft receives a mortal wound.

Pages:
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15