THE WAR IN THE AIR
We Americans are a peace-loving people, which is the very reason why we
went into the war. We had to help down the power that was disturbing
the peace of the world. We do not believe in conquests--at least of the
type that Germany tried to force--and yet there are certain conquests
that we do indulge in once in a while.
Eleven years before Germany undertook to conquer Europe two young
Americans made the greatest conquest that the world has ever seen. The
Wright brothers sailed up into the heavens and gained the mastery of
the air. They offered their conquest to the United States; but while
we accepted their offering with enthusiasm at first, we did not know
what to do with the new realm after we got it. There seemed to be no
particular use in flying. It was just a bit too risky to be pleasant
sport, and about all we could see in it was an exhibition for the
circus or the county fair.
Not so in Europe, however. Flying meant something over there--there
where the frontiers have ever bristled with big guns and strong
fortifications, and where huge military forces have slept on their
arms, never knowing what dreadful war the morning would bring forth.
The war-lovers hailed the airplane as a new instrument with which to
terrorize their neighbors; the peace-lovers saw in it another menace to
their homes; it gave them a new frontier to defend. And so the military
powers of Europe took up the airplane seriously and earnestly and
developed it.
At first military authorities had rated the airplane chiefly as a
flying scout. Some bomb-dropping experiments had been made with it,
but it proved very difficult to land the bombs near the target, and,
besides, machines of those days were not built to carry very heavy
loads, so that it did not seem especially profitable to attack the
enemy from the skies. As for actual battles up among the clouds, they
were dreamed of only by the writers of fiction. But wild dreams became
stern realities in the mighty struggle between the great powers of the
world.
EYES IN THE SKY
As a scouting-machine the airplane did prove to be far superior to
mounted patrols which used to perform scout-work. In fact, it changed
completely the character of modern warfare. From his position high up
in the heavens the flying scout had an unobstructed view of the country
for miles and he could see just what the enemy was doing. He could see
whether large forces of men were collecting for an attack. He could
watch the course of supply-trains, and judge of their size. He could
locate the artillery of the enemy and come back with information which
in former times a scout posted in a tall tree or even in a captive
balloon could not begin to acquire. Surprise attacks were impossible,
with eyes in the sky. The aviator could help his own batteries by
signaling to them where to send their shell, and when the firing began
he would spot the shots as they landed and signal back to the battery
how to correct its aim so as to drop the shell squarely on the target.
The French sprang a surprise on the Germans by actually attacking the
infantry from the sky. The idea of attack from overhead was so novel
that armies did not realize the danger of exposing themselves behind
the battle-front. Long convoys of trucks and masses of infantry moved
freely over the roads behind the lines and they were taken by surprise
when the French began dropping steel darts upon them. These were about
the size of a pencil, with pointed end and fluted tail, so that they
would travel through the air like an arrow. The darts were dropped by
the hundred wherever the airmen saw a large group of the enemy, and
they struck with sufficient velocity to pierce a man from head to foot.
But steel darts were not used very long. The enemy took to cover and
then the only way to attack him was to drop explosives which would blow
up his shelter.
At the outset, air scouts were more afraid of the enemy on the ground
than in the sky. The Germans had anti-aircraft guns that were fired
with accuracy and accounted for many Allied planes. In those days,
airplanes flew at comparatively low altitudes and they were well
within the reach of the enemy's guns. But it was not long before the
airplanes began to fight one another. Each side was very much annoyed
by the flying scouts of its opponents and after a number of pistol
duels in the sky the French began to arm their planes with machine-guns.
Two months after the war started the first airplane was sent crashing
to earth after a battle in the sky. The fight took place five thousand
feet above the earth, between a French and a German machine. The
German pilot was killed and the plane fell behind the French lines,
carrying with it a Prussian nobleman who died before he could be pulled
out of the wreckage. The war had been carried into the skies. But if
scouts were to fight one another, they could not pay much attention
to scouting and spotting and it began to be realized that there were
four distinct classes of work for the airplane to do--scouting,
artillery-spotting, battling, and bombing. Each called for special
training and its own type of machine. As air fighting grew more
specialized these classes were further subdivided, but we need not go
into such refinements.
AIR SCOUTS AND THEIR DANGERS
The scouting-airplane usually carried two men, one to drive the machine
and the other to make observations. The observer had to carry a camera,
to take photographs of what lay below, and he was usually equipped
with a wireless outfit, with which he could send important information
back to his own base. The camera was sometimes fitted with a stock
like that of a gun, so that it could be aimed from the shoulder. Some
small cameras were shaped so that they could be held in the hand like
a pistol and aimed over the side of the fuselage, or body, of the
airplane; but the best work was done with large cameras fitted with
telescopic lenses, or "telephoto" lenses, as they are called. Some of
these were built into the airplane, with the lens opening down through
the bottom of the fuselage.
[Illustration: (C) Underwood & Underwood
A Handley-Page Bombing Plane with One of its Wings Folded Back]
The scouting-airplane carried a machine-gun, not for attack, but for
defense. It had to be a quick climber and a good dodger, so that it
could escape from an attacking plane. Usually it did not have to go
very far into the enemy country, and it was provided with a large
wing-spread, so that if anything happened to the engine, it could
_volplane_, or glide back, to its own lines. As the scouting-planes
were large, they offered a big target to anti-aircraft guns, and so
the work of the air scout was to swoop down upon the enemy, when,
of course, the machine would be traveling at high velocity, because
it would have all the speed of falling added to that which its own
propeller gave it.
[Illustration: How an object dropped from the Woolworth Building would
increase its speed in falling]
It was really a very difficult matter to hit a rapidly moving airplane;
and even if it were hit, there were few spots in which it could be
mortally wounded. Hundreds of shots could go through the wings of an
airplane without impairing its flying in the least. The engine, too,
could be pretty well peppered with ordinary bullets without being
disabled. As for the men in the machine, they furnished small targets,
and even they could be hit in many places without being put entirely
out of business. And so the dangers of air scouting were not so great
as might at first be supposed.
One of the most vulnerable spots in the airplane was the gasolene-tank.
If that were punctured so that the fuel would run out, the airplane
would have to come to the ground. Worse still, the gasolene might take
fire and there was nothing the aviator dreaded more than fire. There
were occasions in which he had to choose between leaping to earth and
burning to death, and the former was usually preferred as a quicker and
less painful death. In some of the later machines the gasolene-tank
could be pitched overboard if it took fire, by the throwing of a lever,
and then the aviator could glide to earth in safety.
THE SELF-HEALING GASOLENE-TANK
One of the contributions which we made to military aëronautics was a
gasolene-tank that was puncture-proof. It was made of soft rubber with
a thin lining of copper. There are some very soft erasers on the market
through which you can pass a lead pencil and never find the hole after
it has passed through, because the rubber has closed in and healed
the wound. Such was the rubber used in the gasolene-tank. It could be
peppered with bullets and yet would not leak a drop of gasolene, unless
the bullet chanced to plow along the edge of the tank and open a long
gash.
The Germans used four different kinds of cartridges in their aircraft
guns. The first carried the ordinary bullet, a second type had for its
bullet a shell of German silver filled with a phosphor compound. This
was automatically ignited through a small opening in the base of the
shell when it was fired from the gun and it left a trail of smoke by
which the gunner could trace its course through the air and correct his
aim. At night the bright spot of light made by the burning compound
would serve the same purpose. Such a bullet, if it hit an ordinary
gasolene-tank, would set fire to its contents. The bullet would plow
through the tank and out at the opposite side and there, at its point
of exit, is where the gasolene would be set on fire. Such incendiary
bullets were repeatedly fired into or through the rubber tanks and the
hole would close behind the bullet, preventing the contents from taking
fire. The two other types of bullets referred to were an explosive
bullet or tiny shell which would explode on striking the target and
a perforating steel bullet which was intended to pierce armor or
penetrate into vital parts of an airplane engine.
Machines with which artillery-spotting was done were usually manned
by a pilot and an observer, so that the latter could devote his
entire attention to noting the fire of the guns and signaling ranges
without being hampered by having to drive the machine. These machines
were usually of the pusher type, so that the observer could have an
unobstructed view. They did not have to be fast machines. It was really
better for them to move slowly. Had it been possible for them to stop
altogether and hover over the spot that was being shelled, it would
have been a distinct advantage. That would have given the observer a
chance to note with better accuracy the fall of the shell. Like the
scout, the spotter had to be a fast climber, so that it could get out
of the range of enemy guns and run away from attacking planes.
GIANTS OF THE SKY
The largest war-planes were the bomb-dropping machines. They had to be
capable of carrying heavy loads of explosives. They were usually slow
machines, speed being sacrificed in carrying-capacity.
The Germans paid a great deal of attention to big bomb-dropping
machines, particularly after their Zeppelins proved a failure. Their
huge Gothas were built to make night raids on undefended cities. The
Italians and the British retaliated with machines that were even
larger. At first the French were inclined to let giant planes alone.
They did not care to conduct long-distance bombing-raids on German
cities because their own important cities were so near the battle-front
that the Germans could have done those places more harm than the French
could have inflicted. Later they built some giant machines, although
not so large as those of the Italians and the British.
The large triplane Capronis built by the Italians held a crew of
three men. They were armed with three guns and carried 2750 pounds of
explosives. That made a useful load of 4000 pounds. The machine was
driven by three engines with a total of 900 horse-power.
The big British plane was the Handley-Page, which had a wing-spread of
125 feet and could carry a useful load of three tons. These enormous
machines conducted their raids at night because they were comparatively
slow and could not defend themselves against speedy battle-planes. The
big Italian machines used "search-light" bombs to help them locate
important points on the ground beneath. These were brilliant magnesium
torches suspended from parachutes so that they would fall slowly and
give a broad illumination, while the airplane itself was shielded from
the light by the parachute.
But these giants were not the only bombing-machines. There were smaller
machines that operated over the enemy's battle-line and dropped bombs
on any suspicious object behind the enemy lines. These machines had to
be convoyed by fast battle-planes which fought off hostile airmen.
HOW FAST IS A HUNDRED AND FIFTY MILES PER HOUR?
In naval warfare the battle-ship is the biggest and heaviest ship
of the fleet, but in the air the battle-planes are the lightest
and the smallest of the lot. They are one-man machines, as a rule,
little fellows, but enormously speedy. Speed is such an important
factor in aërial warfare that there was a continuous struggle between
the opposing forces to produce the faster machine. Airplanes were
constantly growing speedier, until a speed of 150 miles per hour was
not an uncommon rate of travel. It is hard to imagine such a speed as
that, but we may gain some idea if we consider a falling object. The
observation platform of the Woolworth Building, in New York, is about
750 feet above the ground. If you should drop an object from this
platform you would start it on a journey that would grow increasingly
speedy, particularly as it neared the ground. By the time it had
dropped from the sixtieth story to the fifty-ninth it would have
attained a speed of nearly 20 miles per hour. (We are not making any
allowances for the resistance of the air and what it would do to check
the speed.) As it passed the fiftieth story it would be traveling as
fast as an express-train, or 60 miles per hour. It would finally reach
the ground with a speed equal to that of a fast battle-plane--150 miles
per hour.
The battle-plane was usually fitted with a single machine-gun that was
fixed to the airplane, so that it was brought to bear on the target
by aiming the entire machine. In this the plane was something like a
submarine, which must point its bow at its intended victim in order to
aim its torpedo. The operator of the battle-plane simply drove his
machine at the enemy and touched a button on his steering-lever to
start his machine-gun going.
SHOOTING THROUGH THE PROPELLER
Now, the fleetest machines and the most easily manoeuvered are those of
the tractor type, that is, the ones which have the propeller in front;
but having the propeller in front is a handicap for a single-seater
machine, for the gun has to be fired through the propeller and the
bullets are sure to hit the propeller-blades. Nevertheless the French
did fire right through the propeller, regardless of whether or not
the blades were hit; but at the point where they came in line with
the fire of the gun they were armored with steel, so that there was
no danger of their being cut by the bullets. It was calculated that
not more than one bullet in eighteen would strike the propeller-blade
and be deflected from its course, which was a very trifling loss;
nevertheless, it was a loss, and on this account a mechanism was
devised which would time the operations of the machine-gun so that the
shots would come only when the propeller-blades were clear of the line
of fire.
[Illustration: Machine-Gun mounted to Fire over the Blades of the
Propeller]
[Illustration: Courtesy of "Scientific American"
Mechanism for Firing Between the Blades of the Propeller
The cam _B_ on the propeller shaft lifts the rod _C_, rocking the angle
lever _D_ which moves the rod _E_ and operates the firing-piece _F_.
Firing may be stopped by means of lever _H_ and Bowden wire _G_. _I_ is
the ejection-tube for empty cartridges.]
[Illustration: It would take a Hundred Horses to Supply the Power for a
Small Airplane]
A cam placed on the propeller-shaft worked the trigger of the
machine-gun. This did not slow up the fire of the machine-gun. Quite
the contrary. We are apt to think of the fire of the machine-guns as
very rapid, but they usually fire only about five hundred rounds per
minute, while an airplane propeller will make something like twelve
hundred revolutions per minute. And so the mechanism was arranged to
pull the trigger only once for every two revolutions of the propeller.
FIGHTING AMONG THE CLOUDS
There was no service of the war that began to compare with that of
the sky fighter. He had to climb to enormous heights. Air battles
took place at elevations of twenty thousand feet. The higher the
battle-plane could climb, the better, because the man above had a
tremendous advantage. Clouds were both a haven and a menace to him.
At any moment an enemy plane might burst out of the clouds upon
him. He had to be ready to go through all the thrilling tricks of a
circus performer so as to dodge the other fellow and get a commanding
position. If he were getting the worst of it, he might feign death and
let his machine go tumbling and fluttering down for a thousand feet or
so, only to recover his equilibrium suddenly and dart away when the
enemy was thrown off his guard. He might escape into some friendly
cloud, but he dared not hide in it very long, lest he get lost.
It is a peculiar sensation that comes over an aviator when he is flying
through a thick mass of clouds. He is cut off from the rest of the
world. He can hear nothing but the terrific roar of his own motor and
the hurricane rush of the wind against his ears. He can see nothing but
the bluish fog of the clouds. He begins to lose all sense of direction.
His compass appears to swing violently to and fro, when really it is
his machine that is zig-zagging under his unsteady guidance. The more
he tries to steady it, the worse becomes the swing of the compass. As
he turns he banks his machine automatically, just as a bicyclist does
when rounding a corner. He does this unconsciously, and he may get
to spinning round and round, with his machine standing on its side.
In some cases aviators actually emerged from the clouds with their
machines upside down. To be sure, this was not an alarming position
for an experienced aviator; at the same time, it was not altogether a
safe one. A machine was sometimes broken by its operator's effort to
right it suddenly. And so while the clouds made handy shelters, they
were not always safe harbors.
To the battle-plane fell the task of clearing the air of the enemy. If
the enemy's battle-planes were disposed of, his bombing-planes, his
spotters, and his scouts could not operate, and he would be blind. And
so each side tried to beat out the other with speedier, more powerful,
and more numerous battle-planes. Fast double-seaters were built with
guns mounted so that they could turn in any direction.
THE FLYING TANK
The Germans actually built an armored battle-plane known as the flying
tank. It was a two-seater intended mainly for attacking infantry and
was provided with two machine-guns that pointed down through the floor
of the fuselage. A third gun mounted on a revolving wooden ring could
be used to fight off hostile planes. The bottom and sides of the
fuselage or body of the airplane from the gunner's cockpit forward
were sheathed with plates of steel armor. The machine was a rather
cumbersome craft and did not prove very successful. A flying tank was
brought down within the American lines just before the signing of the
armistice.
AMERICA'S HELP
Our own contribution to the war in the air was considerable, but we had
hardly started before the armistice brought the fighting to an end.
Before we entered the war we did not give the airplane any very serious
consideration. To be sure, we built a large number of airplanes for the
British, but they were not good enough to be sent to the front; they
were used merely as practice planes in the British training-schools. We
knew that we were hopelessly outclassed, but we did not care very much.
Then we stepped into the conflict.
"What can we do to help?" we asked our allies, and their answer gave us
a shock.
"Airplanes!" they cried. "Build us airplanes--thousands of them--so
that we can drive the enemy out of the air and blind his armies!"
It took us a while to recover from our surprise, and then we realized
why we had been asked to build airplanes. The reputation of the United
States as a manufacturer of machinery had spread throughout the world.
We Americans love to take hold of a machine and turn it out in big
quantities. Our allies were sure that we could turn out first-class
airplanes, and many of them, if we tried.
Congress made an appropriation of six hundred and forty million dollars
for aëronautics, and then things began to hum.
A BIRTHDAY PRESENT TO THE NATION
The heart of an airplane is its engine. We know a great deal about
gasolene-engines, especially automobile engines; but an airplane engine
is a very different thing. It must be tremendously powerful, and at the
same time extremely light. Every ounce of unnecessary weight must be
shaved off. It must be built with the precision of a watch; its vital
parts must be true to a ten-thousandth part of an inch. It takes a very
powerful horse to develop one horse-power for a considerable length
of time. It would take a hundred horses to supply the power for even
a small airplane, and they would weigh a hundred and twenty thousand
pounds. An airplane motor of the same power would weigh less than three
hundred pounds, which is a quarter of the weight of a single horse.
It was this powerful, yet most delicate, machine that we were called
upon to turn out by the thousand. There was no time to waste; a motor
must be designed that could be built in the American way, without any
tinkering or fussy hand-work.
Two of our best engineers met in a hotel in Washington on June 3,
1917, and worked for five days without once leaving their rooms. They
had before them all the airplane knowledge of our allies. American
engine-builders offered up their trade secrets. Everything was done
to make this motor worthy of America's reputation. There was a race
to have the motor finished by the Fourth of July. Sure enough, on
Independence Day the finished motor was there in Washington--the
"Liberty motor," a birthday present to the nation.
Of course that did not mean that we were ready at once to turn out
Liberty motors by the thousand. The engine had to undergo many tests
and a large number of alterations before it was perfectly satisfactory
and then special machinery had to be constructed before it could be
manufactured in quantity. It was Thanksgiving Day before the first
manufactured Liberty was turned out and even after that change upon
change was made in this little detail and that. It was not until a year
after we went to war that the engine began to be turned out in quantity.
There was nothing startlingly new about the engine. It was a composite
of a number of other engines, but it was designed to be turned out in
enormous quantities, and it was remarkably efficient. It weighed only
825 pounds and it developed over 420 horse-power. Some machines went
up as high as 485 horse-power. An airplane engine weighing less than 2
pounds per horse-power is wonderfully efficient. Of course the Liberty
was too heavy for a light battle-plane (a heavy machine, no matter how
powerful, cannot make sharp turns), but it was excellent for other
types of airplanes and large orders for Liberty engines were made by
our allies. Of course we made other engines as well, and the planes to
carry them. We built large Caproni and Handley-Page machines, and we
were developing some remarkably swift and powerful planes of our own
when the Germans thought it about time to stop fighting.
FLYING BOATS
So far we have said nothing about the seaplanes which were used in
large numbers to watch for submarines. These were big flying boats in
which speed was not a very important matter. One of the really big
machines we developed, but which was not finished until after the war,
was a giant with a 110-foot span and a body or hull 50 feet long.
During the war seaplanes carried wireless telephone apparatus with
which they could call to destroyers and submarine-chasers when they
spotted a submarine. They also carried bombs which they could drop on
U-boats, and even heavy guns with which they could fire shell.
A still later development are the giant planes of the N. C. type with a
wing-spread of 126 feet and driven by four Liberty motors. They carry a
useful load of four and a half tons.
[Illustration: (C) Underwood & Underwood
The Flying-tank--an Armored German Airplane designed for firing on
troops on the march]
Early in the war, large guns were mounted on airplanes, but the shock
of the recoil proved too much for the airplane to stand. However,
an American inventor produced a gun which had no recoil. This he
accomplished by using a double-end gun, which was fired from the
middle. The bullet or shell was shot out at the forward end of the
gun and a dummy charge of sand was shot out at the rear end. The sand
spread out and did no damage at a short distance from the gun, but care
had to be taken not to come too close. These non-recoil guns were made
in different sizes, to fire 1-1/2-inch to 3-inch shell.
THE AUTOMATIC SEAPLANE
Another interesting development was the target airplane used for the
training of aërial gunners. This was a small seaplane with a span of
only 18-1/2 feet, driven by a 12-horse-power motor, the whole machine
weighing but 175 pounds. This was sent up without a pilot and it would
fly at the rate of forty to fifty miles per hour until its supply of
gasolene gave out, when it would drop down into the sea. It afforded a
real target for gunners in practice machines.
[Illustration: (C) Underwood & Underwood
An N-C (Navy-Curtiss) Seaplane of the type that made the first flight
across the Atlantic]
Early in the war an American inventor proposed that seaplanes be
provided with torpedoes which they could launch at an enemy ship. The
seaplane would swoop down out of the sky to within a short distance of
the ship, drop its projectile, and fly off again, and the torpedo would
continue on its course until it blew up the vessel. It was urged that
a fleet of such seaplanes protected by a convoy of fast battle-planes
could invade the enemy harbors and destroys its powerful fleet. It
seemed like a rather wild idea, but the British actually built such
torpedo-planes and tested them. However, the German fleet surrendered
before it was necessary to blow it up in such fashion.
AIRPLANES AFTER THE WAR
With the war ended, all the Allied powers have large numbers of
airplanes on their hands and also large numbers of trained aviators.
Undoubtedly airplanes will continue to fill the skies in Europe and we
shall see more and more of them in this country. Even during the war
they were used for other purposes than fighting. There were ambulances
on wings--machines with the top of the fuselage removable so that a
patient on a stretcher could be placed inside. A French machine was
furnished with a complete hospital equipment for emergency treatment
and even for performing an operation in case of necessity. The flying
hospital could carry the patient back to the field or base hospital
after treatment.
Mail-carrying airplanes are already an old story. In Europe the big
bombing-machines are being used for passenger service between cities.
There is an air line between Paris and London. The airplanes carry from
a dozen to as many as fifty passengers on a single trip. In some cities
here, as well as abroad, the police are being trained to fly, so that
they can police the heavens when the public takes to wings. Evidently
the flying-era is here.