aeroplanes and dirigibles of war-第32节
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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 velocityabout 2;500 feet
per secondand 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。
Attempts have been and still are being made to adapt an explosive
projectile to this gun; but so far the measure of success
achieved has not proved very promising。 There are immense
difficulties connected with the design of an explosive shell of
this class; charged with a high explosive; especially in
connection with the timing。 So far as dependence upon percussive
detonation is concerned there is practically no difficulty。
Should such a missile strike; say; the motor of an aeroplane; or
even the hull of the craft itself; the latter would be
practically destroyed。 But all things considered; it is
concluded that more successful results are likely to be achieved
by the armour…piercing bullet striking the mechanism than by an
explosive projectile。
The Krupp company fully reahsed the difficulties pertaining to
the projectile problem in attacks upon aerial craft。 So far as
dirigibles are concerned shrapnel is practically useless;
inasmuch as even should the bag be riddled by the flying
fragments; little effective damage would be wroughtthe craft
would be ab