by Louis Bruchiss
With World War II being dominated more and more by fighting aircraft of all kinds, it is quite natural that the interest of our readers is centered on military airplanes. It is even more natural that this interest fixes itself more specifically on the equipment of military aircraft; the weapons with which they fight and defend themselves.
In recent years the performance characteristics of airplanes have been radically improved, reliable flying at tremendous speeds has been attained, more powerful engines have increased the range and useful load capacities, multiengined ships have appeared that equal in speed and maneuverability and surpass in other qualities the pursuit ships of a few years ago.
To expert and layman alike, the status of the fighting apparatus in use is eagerly sought; a very pertinent question that is asked is: "What aircraft weapons are there, what effect are they having now and what will the future bring?"
A brief review of what has preceded since the airplane became a military tool is not amiss here.
Even in the beginning of the first world war, airplanes, balloons and dirigibles were employed for observation purposes, liason work and, in isolated instances, for smoke screen effects. The first war planes were merely army cooperation units, observing and directing artillery fire and taking air photos of enemy terrain. The planes were light, slow, and generally unreliable. Development, meaning improvements fostered by wartime urgency, was rapid, however. Belligerent airplanes naturally wanted each other out of the air. Early world war Hyers had only pistols as weapons, and these really were for ground use in case of emergency. It was discovered that it was possible to shoot witli a pistol, and eventually with a rifle, at an enemy plane. Whether any hits were scored by these weapons is not recorded. The results, however, must have been discouraging, for light machine guns made their appearance in short order; the first mounted on swivel posts in rear observation cockpits, and sometimes high enough to fire ahead of the upper wing outside the propeller circle. Single-seater fighters had their machine gun mounted in this manner, and the pilot was forced to stand up to fire his gun. This was not too difficult in 1914 vintage planes. In a modern fighter, even an exposed cockpit is unthinkable.
Ever since the airplane first made its appearance, it was predicted that it would be utilized to drop bombs.
Confidence in this mission was quite high, despite the fact that innumerable difficulties had to be overcome. Early planes, constructed as they were of light, open framework materials, and powered by comparatively low output and none too dependable engines, had very little useful load capacity. In demonstration aviation meetings, these planes often dropped bags of flour and oranges in simulated bombing attacks.
The first aerial bombs were crude hand made affairs, built in cylindrical metal containers, and even in glass bottles, which airmen simply threw over the side at enemy troops. Among bombing material were steel darts feathered at the end to be thrown over in showers, and they were effective if they ever hit personnel. They were soon discontinued in 1914, and then in November of that year, grenades and incendiaries were used in the Battle of Mons. Early bombs were almost as dangerous to the crew and plane carrying them as to the enemy who was to receive them. Bombs could explode prematurely before hitting the target, and "duds," were common.
The Italians dropped real bombs from airplanes in their campaign in Tripoli in 1912. These first bombs were converted from some other type of ammunition, and being small, were effective only against personnel. But as the size and lifting capacity of the airplane increased, the number of bombs that could be carried increased, until either a significant group of small bombs could be carried, or one single large mass of explosive.
The first bombs made in the United States during the last war were based on a French design, known as the Gros Andreau bombs, which were brought here in July 1917. At first the design and manufacture of three types was undertaken, the 25-lb., 50-lb., and 100-lb. demolition bombs. These were all of streamlined design. By 1918 our army had specified bombs in additional weights up to 1,100-lb.
Our first fragmentation bombs were made from rejected 3-inch artillery shells, weighing 17-lb. Later fragmentation bombs were based on the "British Cooper bomb of 25-lb., a streamlined missile.
Bombs were made in streamlined body form because it was thought that the ballistics would be favorably affected, that a more accurate trajectory would be assured. Bombs in free flight, however, are not shells rotating at high speed, propelled with tremendous force through rifled gun barrels. Actually, streamlining oi bombs did nothing to improve their trajectory characteristics and later day practice is to make them in cylindrical form. This simplifies manufactuie.
From an embryonic stage at the beginning of the first world war, airplane armament advanced so rapidly that at the end of the war in 1918, all the weapons existing today liad passed through the early stages of experimentation. Guns of 37-mm. bore were experimentally mounted by the French to fire through the propeller hub of the Flispano-Suiza engine. The French ace, Guynemer, and the American fiver, Norman Prince, tried this installation for a time, as did Fonck.
A number of victories were recorded before the Germans even discovered that shell guns were being used, as few pilots who were shot down with the cannon ever returned to explain. The reason that the use ol large bore shell firing guns was discontinued was due to the fact that mountings were poor, gun and ammunition too heavy, firing rate very slow and recoil excessive. Unless a direct hit was made with the first shot, the enemy would bank around and riddle the cannon-equipped plane with machine gun fire. In the last war, machine gun bullets were extremely effective, as the pilot and most of the plane was quite vulnerable.
Pilots in the last war had no armor protection, although they often bewailed the lack of it. The limited useful load of the fighting planes of that time did not permit the carrying of heavy armor. Some pilots surreptitiously took along stove lids to place on their seats, and other odd pieces of metal plate. Free type parachutes were not developed until the war had ended, and the types used by balloon ists and aerial daredevils were not, suitable for fighting pilots. Pilots must jump out of their planes in a hurry if incendiaries fired their exceptionally vulnerable gas tanks, when wing coverings were ripped off, or when wounded and the necessity of making a crash landing was imminent.
Of the two types of aircraft guns, fixed and free, both were used as soon as machine guns were installed on planes in 1914. Fixed guns were mounted alongside the fuselage on twin-engined planes; on the British B.E. type of tractor plane, even at an angle to the line of flight, so that fire would clear the propeller arc. This meant that the pilot had to maneuver his plane in one direction and fire in another. To obviate this great disadvantage, the French aviator Garros, and several other world war flyers, used fuselage mounted machine guns firing straight through the propeller without any form of interrupter gear. Steel plates fixed to the leading edges of the propeller blades deflected a certain percentage of the bullets. This method was generally unsatisfactory.
The most radical and important development in air weapons was the synchronizing gear which enabled the machine guns to be mounted flush with the fuselage in front of the pilot and fire through the propeller blades. The gun mechanism was geared with the engine so that shots were spaced nearly between the whirling blades.
Vickers began experimenting with interrupter mechanism as early as 1915, and several types were sent out on Bristol fighters in the following year. The German mechanism was far superior, having been developed by Anthony H. G. Fokker in a three day period in 1915.
Fokker accomplished his ingenious feat with a mechanical device that locked the firing mechanism of the gun as each propeller blade approached the line of lire. When the blade passed this point, the gun began firing again, assuming that the trigger was held down meanwhile. In this system, cams and push rods connected to the engine operated the firing mechanism. But in 1916, Georges Constantinesco, a Rumanian engineer, assisted the British in building an efficient interrupter or synchronizing mechanism based on the hydraulic system.
During the last war, A. L. Nelson developed a mechanical interrupter gear for the U. S. army, which was highly successful, although the war ended before many of them saw service. Mr. Glenn D. Angle, as an engine expert, collaborated in the development of this device, which formed the basis for all later U. S. synchronization gear.
Modern versions are very similar, with improvements only in the apparatus used. A pneumatic system has also functioned satisfactorily, although the hydraulic method of allowing small impulse generators attached to the engine to control pulsations of oil under pressure has also proved efficient. Synchronization limited the rate of fire of the machine guns then just as it does today. In 1914-1918, however, the engine r.p.m. was lower, and this, coupled with a machine gun rate of fire lower than on free guns, resulted in a total cyclic firing rate that was quite low.
Aircraft guns in the last war were standard land machine guns, usually fitted with speeding up equipment or recoil increasers which built up the rate of fire. In land guns a high firing rate is not always desired. In the air the higher the firing rate, the better. The free guns used by rear gunners and observers were also converted land guns, but because the hanging cartridge belts interfered with the movements of the gunner, the British adopted the Lewis gun as their free gun, and still use it today as the standard movable gun.
The mounting of free guns in rear cockpits and forward cockpits of twin engined ships was a great problem in 1914. Simple swivel post mountings were unsatisfactory, and in an attempt to improve mountings, an experimental airplane was supplied to each R.F.C. squadron, so that any ideas that the pilots had could be tried immediately. W. 0. Scarff, R.N.A.S., developed a ring type mounting that was highly efficient, and taken as standard equipment during the war. A modified form of Scarff mounting is still being used, supplanted only by power turrets.
The war's end saw a complete stop to armament development. Aircraft stagnated for a time, and it was only by dint of hard work on the part of enthusiastic flyers and farsighted business men that commercial aviation helped to keep the flame of flying alive. The progress of the past decade requires no repetition. Both airplanes and the weapons which make them military machines have reached a stage that necessitates the air forces taking a leading place as a military arm, with ground and sea forces cooperating on an equal footing.
1 comment:
it is quite natural that the interest of your readers is centered on military airplanes. It is even more natural that this interest fixes itself more specifically on the equipment of military aircraft, the weapons with which they fight and defend themselves.
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