I. Conflicting opinions as to an aeroplane’s vulnerability—Experiments
which have been carried out.
So far, the military aeroplane has been described as a reconnoitring or
dispatch-bearing craft, carrying out its important work, in time of war,
without any interference save that brought about by adverse weather
conditions.
But there is an aspect of the case, so far as actual service conditions
are concerned, which will—according to many vehement critics of the
aeroplane—nullify the utility of an air-scout, and make expenditure upon
fleets of machines largely a waste of money.
They affirm, in a word, that well-directed artillery-fire will prove so
deadly that no aeroplane will be able to live through it, and that any
reconnoitring machine, which ventures over an enemy’s position, will be
destroyed with the greatest ease.
On the other hand, there is an equally definite statement by staunch
advocates of military flying. They declare, emphatically, that
artillery-fire, when directed against aeroplanes, will prove a
negligible quantity. No point, indeed, arouses more controversy than the
problem of the vulnerability of the aeroplane to artillery or
rifle-fire.
The question is a moot one, and it is bound to remain so until the
coming of a war in which aeroplanes are employed in fair numbers; but
nothing could be more ill-advised than a policy which stints aeroplane
development, because it is _believed_ they will be destroyed by
gun-fire.
As a matter of fact, tests which have been made up to the present time
are in favour, not of the gunner, but of the aeroplane. This fact is,
however, frequently ignored by the artillery experts. They adhere to
their view, and the airmen to theirs. "Aeroplanes will be swept away
when they come into the danger zone," declare the champions of
artillery. "Nothing of the sort will happen," retort the advocates of
the aeroplane.
It is probable that an unbiased reader will prefer to take a view rather
midway between these two, and be willing to grant that, while some
aeroplanes are likely to be "winged" by skilful gunners, the greater
proportion of them will, on account of their height and speed, escape
being hit.
Since the aeroplane has demonstrated its unquestionable value as a
reconnoitring craft, special guns have been made in order to combat it.
These have long range, and are designed to fire vertically into the air.
Many tests have, also, been made with kites and balloons, to reveal the
ease, or otherwise, of striking an aeroplane in flight.
As regards these experiments, the opinion among experts is again
divided. Artillerymen do not hesitate to say that they prove their
case—which is, of course, that the aeroplane is a vulnerable target.
Aeroplane enthusiasts combat such suggestions; and so the controversy
goes on.
One fact stands suggestively revealed; wise countries, despite
assertions that artillery will blow aeroplanes to pieces, are buying
more and more machines, instead of curtailing their orders.
France and Germany, for instance, which have carried out more tests than
any other countries in regard to the vulnerability of aircraft, are
determined to increase their fleets of aeroplanes.
This, surely, should tell its own story. It is unusually impressive, as
a matter of fact, seeing that artillery experts, both in France and
Germany, have been ready to declare that well-directed gun-fire will rob
aeroplane scouting of its significance. But those who control
constructive policy, both in France and Germany, have judged
impartially; and, as a result, they have bought more aeroplanes.
The difficulty, in carrying out tests of gun-fire, as directed against
aeroplanes, is to obtain artificial conditions which shall, even
roughly, approximate to those which would prevail in actual war. So far,
it has been clear that, in all tests which have been carried out,
conditions have been in favour of the gunner. But, even so, the results
obtained have been inconclusive—to say the least of it.
Let us take, for purpose of illustration, one of the experiments
conducted in France. In this a large box-kite was employed. It was
allowed to ascend, in a strong wind, until it flew at a height, in
regard to its size, which represented, approximately, the target which
would be represented by a scouting aeroplane.
Then it was towed past a battery of artillery. Twelve shots were fired
at it; and, out of the dozen, one hit was recorded. This was not a good
result, from the gunner’s point of view. In this test, too, conditions
favoured the men at the guns.
To begin with, they expected their target, and knew from which direction
it would appear. In the second place, the target was, in comparison with
an aeroplane, moving much more slowly than the flying machine would have
done; and, in the third place, the kite was towed in a
perfectly-straight line, and was not pursuing an erratic course, as an
aeroplane would certainly do—in the efforts of the pilot to escape being
hit—were it under fire. And yet, even with these points in their favour,
the gunners achieved but one hit in a dozen shots.
It is possible to cite another instance, in this connection—that of a
series of tests carried out, in American waters, from a warship. Here,
again, the target was a box-kite, and it was flown above the vessel at
an altitude of about 800 feet. Ten blue-jackets were then formed up upon
the deck; and they fired three volleys at this representation of an
aeroplane. The bullets, in the first two volleys, all went wide of the
mark. In the third, however, the box-kite was hit.
Here, again, although conditions favoured the riflemen, they failed to
obtain satisfactory results. During the three volleys, the box-kite was
flown at an unvarying height. This was a point very greatly in their
favour.
In actual warfare, had they been firing at an aeroplane, the machine
would, probably, have been travelling at a speed of sixty miles an hour
or more; and it would, therefore, have presented a different range, at
each volley fired.
Another experiment, carried out from an American battleship, is also of
interest. In this case, a plunging kite was sent up to a specified
height, and 160 rounds were fired at it with rifles. Although the kite
swung about a good deal, it did not vary its altitude. In connection
with this test—in which picked shots were employed—40 hits, out of the
160 rounds, were recorded.
As a result of the tests recorded above, and of others less interesting,
the Secretary of the United States Navy was led to make the
pronouncement that no aeroplane could, with any degree of safety,
approach nearer than 1000 yards of a position protected by rifle-fire.
As opposed to this view, the opinion of experts at the Hythe School of
Musketry is that it would be more or less a waste of ammunition to
attempt to "wing," with rifle-fire, an aeroplane 3000 feet high. In the
practical work of the aeroplane in Tripoli, machines flying less than
2000 feet high were not damaged by rifle-fire.
The point to bear in mind, in this connection, is that an aeroplane
flying 3000 feet high, and at a speed greater than that of an express
train, would, inevitably, prove a very difficult target. The airman
would appear suddenly, and quickly go out of view again; and he would
alter his height, and course, so that a perplexed gunner—needing to fire
quickly, or not at all—would find the range constantly varying.
[Illustration: MILITARY AIRMAN’S REPORT.
Photo, M. Branger.
After descending from a reconnoitring flight on a Blériot monoplane, in
the French manœuvres, the pilot seen above is imparting details of what
he has observed to another officer.]
Quite recently, a famous military expert has pronounced the opinion that
high-angle gun-fire would have no great potentiality against fast-flying
aeroplanes.
Amplifying some tests first carried out in France, have come a series of
more recent experiments, in which the conditions imposed have been more
disadvantageous to the gunners. The result has been a striking testimony
to the invulnerability of the aeroplane. For example, kites have been
towed by motor-cars at a speed actually representing the flight of fast
monoplanes. Gunners, when firing under such fairly realistic conditions,
have failed to secure anything like a satisfactory percentage of hits.
Tests on a somewhat similar scale have, also, been carried out in
Germany; and, here again, the artillery has not distinguished itself. In
Germany, also, small balloons have been used as targets. These have been
set free, and have been permitted to ascend to a certain height, before
being fired at. In connection with these experiments, a fairly-large
percentage of hits was recorded. This was due, no doubt, to the fact
that there was no erratic movement to be allowed for—the balloons moving
on an easily determined line.
These target tests, as can be seen, represent conditions which are quite
artificial. It is possible to take, for the sake of comparison, the
practice indulged in by gunners at coast defences. Targets are towed at
specified distances out to sea, and then the gunners pound away at them.
Such practice is good, of course. It accustoms the men to the handling
of their guns; and it certainly improves their marksmanship.
But now contrast this target practice with a sudden attack, in war-time,
by hostile torpedo craft.
Here will be no mechanically-moving target, at which to take a leisurely
aim. Instead, there will be the rush and tear of war. Marksmanship,
under such conditions, is a very different thing to quietly-conducted
practice firing. And a similar argument—only with greater force—applies
to shooting at aeroplanes in war-time.
Among distinguished students of this problem of gun-fire and the
aeroplane is Colonel J. E. Capper, who was, for seven years, in charge
of the aeronautical work of the British Government. His view is that
artillery, however well-trained, would have very great difficulty in
firing accurately at a fast-flying machine.
An instance which Colonel Capper gives is this: if the range of a gun is
5000 yards, an aeroplane, moving across it at a speed of fifty miles an
hour, would be in range for less than 3 1/2 minutes. During this period
of 3 1/2 minutes, the gun would need to travel across an angle of 60
degrees, altering its range down to 4330 yards in the first 1 3/4
minutes, and increasing it again to 5000 yards in the next 1 3/4
minutes.
To do this would be an extremely difficult task, even if the aeroplane,
while flying past, made itself the easiest possible target; that is to
say, if it flew steadily at one level, all the time, and moved directly
across in front of the guns. But an airman would, naturally, seek to
make himself as difficult a target as possible. He would, therefore,
constantly alter his altitude by movements of his elevating plane; and
he would, in addition, steer erratically from side to side.
How confusing this would be for the gunner may easily be imagined. Apart
from the speed of the aeroplane, which would, as shown, only permit him
a brief opportunity of firing at it, he would be faced with the fact
that range, elevation, and direction of the elusive target would
constantly be altering. In addition, he would probably be called upon to
make allowance for a wind, when aiming at the machine.
Apropos the rapidity with which a modern-type machine will come into the
range of a gun, and disappear again, an incident in some minor manœuvres
held in France is of interest. On this occasion, a special gun, designed
to shoot at aircraft, and mounted upon a motor-car, was taken out with
the troops. Suddenly, an aeroplane appeared in sight. It was flying
straight towards the troops, which were on the march. The special gun
was called for; but, before it could be brought into action, and trained
upon the aeroplane, the latter had gone completely out of range. This
illustration shows what an unsatisfactory and elusive target an
aeroplane is bound to be.
II. Shrapnel shell—Question of hitting a vital part of the
aeroplane—Difficulty of identifying friend or foe.
It is generally agreed, among artillery experts, that shrapnel shell
should form a suitable projectile to be fired against an aeroplane. The
shrapnel is, indeed, a particularly-deadly missile. This shell consists
of a metal case, containing a sufficient amount of explosive to burst
it, when the fuse explodes the charge. This fuse can, of course, be set
so that the shell explodes at any given distance from the gun which
fires it.
Inside the metal case, or shell, is a charge of bullets. When the shell
bursts, these bullets fly out from it, ready to spread destruction over
an appreciable area. Should a shell burst in close proximity to an
aeroplane, for instance, the scattering charge would, it is anticipated,
break struts and stays, and possibly hit the pilot, or some vital part
of his machine.
But, granting the deadly nature of a well-aimed shrapnel shell, there
are several points to be considered, before we can imagine it bringing
an aeroplane to the ground. In the first place, there is the question of
the timing of the fuse. This must be done, of course, with absolute
accuracy; and the gunner must aim his weapon at a point in front of the
aeroplane, as it flies across his view. This represents a matter for
nice calculation, being determined by the speed of the aeroplane aimed
at, the speed of the shell, and the distance of the aircraft from the
gun.
Thus, when he is firing at a sixty-mile-an-hour monoplane, passing
swiftly through the air, several thousand feet away, a gunner must
obtain his range without delay, set his fuse accurately, and aim his gun
with the greatest care. And, all the time, his target will be moving as
fast as an express train, and perhaps making erratic twists and turns in
the air.
It is not surprising, in view of such circumstances, that one of the
greatest of military experts has declared that an aeroplane, flying at
sixty miles an hour, and at an altitude of from 3000 to 4000 feet, will
present an exceptionally-difficult mark, even to the most skilled of
gunners, equipped with special weapons.
It does not follow, even should a shrapnel shell be exploded
successfully in the vicinity of an aeroplane, that the machine will be
brought to the ground. There is still the question as to striking a
vital part of the aircraft. It should be remembered that the greater
portion of the target which a machine exposes to gun-fire is represented
by its planes; and these could be pierced by many bullets before their
efficiency was affected.
Thus, a number of bullets from a shrapnel shell might strike an
aeroplane without producing any result. What would be necessary, would
be to hit the airman, or place a shot in some vital part of his machine.
Damage to a working part of the engine would, for example, bring the
machine down. So would injury to radiator, petrol tank, or propeller. A
bullet might, also, break an important stay—or cut a controlling wire.
In such a case, the machine might fall, and be wrecked.
The point to be made, which is of importance, is this: it does not
follow that, even if an aeroplane were hit, it would be brought to the
ground. Many bullets from a shrapnel shell might, as has been shown,
strike a machine in flight, without having any effect upon it at all.
This is certainly a factor in favour of the aeroplane.
A fact to be considered, also, when the problem of aeroplanes and
gun-fire is under review, is the distance at which aircraft are visible
from the ground. In ordinary weather, and under normal conditions, it is
generally estimated that a reconnoitring aeroplane should be sighted
when it is about three miles away.
But, even in clear atmospheric conditions, the aircraft is an elusive
object to locate. Even when one is expected to appear, from a certain
direction, and all eyes are fixed upon the sky, awaiting its advent, it
is frequently almost at its destination before anyone locates it.
More difficult, as can be imagined, is the task of sighting an aeroplane
when it is not known from what point of the compass it is likely to
appear. And yet this, of course, will be the position of the gunner in
war-time. A hostile aircraft may loom up from anywhere—even from over
his own troops. It will be possible for a reconnoitring machine to
ascend to a great height, and conceal itself in low-lying clouds. From
these it will be able to descend swiftly, effect a rapid reconnaissance,
and then "climb" again until lost to sight.
In such circumstances, the artilleryman will need to be phenomenally
handy with his gun if he is to note the approach of so cunning a scout,
and "wing" him before he has slipped out of range.
A point which has been referred to before—but which artillery experts
are prone to ignore—is the skill a military pilot will be able to
exercise, in avoiding fire from below. In many cases, during a
reconnaissance, the observer should be able to obtain all the
information he seeks without once coming within range of the enemy’s
guns.
Naturally, the aeroplanist will never fly intentionally over artillery,
or court infantry-fire. Long-distance observations will often be
possible, giving the gunner no chance of using a shell; or, if it is
necessary to come fairly close to troops, for a detailed piece of
reconnaissance, the airman will swoop down, and as speedily get clear
again.
When he knows he is likely to be within range of any of the enemy’s
guns, he will pursue an erratic course. Therefore, the gunner, when he
does obtain a chance of firing at a machine, will find his target
darting about in disconcerting fashion.
A point arises as to establishing the identity of an aircraft, when it
is sighted during time of war. Machines will fly flags, indicating their
nationality, but these flags are not likely to be seen at any great
distance. Therefore, if an artilleryman detects an aeroplane,
approaching at an appreciable altitude, it will frequently be impossible
for him to determine whether it is friend or foe.
That it is, obviously, a machine of a particular type, or make, will not
help the artilleryman, because aeroplanes of all forms of construction
will be employed, in connection with the various armies. The fact that
it may be flying over from behind him, as though it had risen from his
own lines, will prove nothing, as a hostile scout might have made a wide
detour, and so approached the enemy from the rear.
This difficulty as to identifying friend or foe is likely to prove a
real one in time of war, particularly when a large number of machines
are in the air; and, exactly how it will be met, is not easy to see.
Having reviewed the position, so far as the aeroplane and gun-fire are
concerned, it is possible to form more or less definite conclusions
concerning the subject. In the first place, one point is clear: extreme
views are unwise in regard to such a problem as this. What tests so far
carried out have proved, if they have proved anything, is that there are
two points of view.
Artillery experts, who declare that every reconnoitring aeroplane will
be blown to pieces before it can carry out its work, are obviously
wrong; so, too, is the enthusiast who affirms that guns will be
altogether useless when directed against airmen.
What it is possible to deduce, from the generally-inconclusive
experiments recorded, is that the balance of testimony—so far as it can
be estimated—is in favour of the aeroplane. As a matter of fact, the
reasonable view to take is that, when a squadron of aeroplanes
deliberately sets forth to reconnoitre an enemy’s position, a certain
percentage of machines will be hit by gun-fire, and brought to the
ground.
Exactly what that percentage will be is a moot point; experience alone
can tell. But the tests already described suggest, very plainly, that
the percentage should be low.
The skill of the pilot in avoiding fire will be an important factor in
the question—as already mentioned. An over-daring airman may quickly
find himself in danger; a careful, cautious man may do all the work
required of him without giving hostile artillery a chance to get in a
shot.
Level-headed officers, who have practical experience in military flying,
do not anticipate, for a moment, that the aeroplanes which ascend in
time of war will escape scot-free.
"Casualties there are bound to be." The words are those of an expert of
international repute. "Risks will be taken knowingly, according to the
value of the information which is required. War is not a kid-glove
affair. Large squadrons of aeroplanes will be used; and, apart
altogether from the question of the loss of life, the destruction of a
small proportion of machines will not affect the utility of a corps. The
position, in a nutshell, is this: the news that an aeroplane can obtain
is so vitally important that the risk of men, and machines, will be
considered amply justified."
This much appears certain. No artillery-fire, however skilfully
directed, is likely to nullify the effects of aeroplane reconnoitring.
Machines will be hit; lives will be lost. But the value of the
aeroplane’s work will lie in the number of machines employed. If fifty
are sent out upon a reconnoitring flight, and if some of them fall
victims to the enemy’s gun-fire, a sufficient number will return to
impart, to a Commander-in-Chief, the information he seeks to obtain.
The only sensible policy, for any nation, is to do what France and
Germany are doing. Both these countries are developing war aeroplanes;
and they are also building, and experimenting with, special guns for the
destruction of aircraft. While you cannot destroy an enemy’s air-fleet,
the obvious policy is to cripple it as much as possible; and,
recognising that no gun-fire can altogether prevent the aeroplane from
doing its work, the equally obvious thing to do is to obtain an
efficient fleet of machines, as well as batteries of guns.
THIRTEENTH SECTION DESTRUCTIVE POTENTIALITIES OF WEIGHT-CARRYING
AEROPLANES