Armament

by Maj Franklin C Wolfe

Holder of the DFC. Major Wolfe was born in Colorado. Oct 4. 1902. He joined Army Aviation in 1925. Graduate of Air Corps Technical School. he is rated senior pilot and ls chief. Wright Field Armament section.

Any military airplane is only as good as its punch. US Army aircraft machine guns, bombs and cannon can deliver the world's deadliest punch.

The war abroad has necessitated rearming American-built fighting planes, bringing about changes in design to allow heavier armament — more and heavier caliber guns, hydraulic- and electrically-operated gun turrets for bombers, leak-proof gasoline tanks and added armor plating. These factors are vitally important in increasing planes' combat effectiveness. Getting these improvements onto our warplanes and doing the job quickly has created a difficult problem for Army Air Forces' armament experts and the Ordnance Department.

Working together, Wright Field's Armament Laboratory, of the Experimental Engineering Section, Air Corps Materiel Division, and the Army's Ordnance Department are producing results that make American fighting planes among the most formidably-armed aircraft in the world.

Armed aircraft date back to the early days at College Park, Maryland in 1909 when the Wright brothers were training America's first military aviators — among them Maj Gen. Henry H Arnold, today Chief of the US Army Air Forces. Here, the first machine gun was carried on an airplane and fired at a ground target. Crudely fashioned bombs were carried aloft and dropped. During the US Army's campaign against Villa in 1916, the first-known incident of aerial bombardment took place when pilots with an US Air Service squadron sent to the Texas border made a bomb from a tin can filled with explosives and dropped on the outlaw bands in their hideouts. These were the first known incidents of arming the airplane for combat purposes.

Progressive steps in making the airplane an effective military weapon were made during the World War period. Both Ger- mans and Allies introduced new methods of equipping their fighting planes with machine guns and bombs. As early as 1915 German observers, flying over Paris, fired rifle shots at French aircraft they encountered. The French retaliated by giving pilots rifles and revolvers. These were not very effective, but they produced the first aerial combats. Later, machine guns, some mounted on the wing and shooting over the propeller, and others located at various positions on the airplane were introduced. These soon were synchronized to fire through the propeller and, from then on, Germans and Allies both increased the fire power of their aircraft. The French used the first cannon, a 37-mm Hotchkiss, on the Voisin airplane. Guynemer, the French ace, used a similar cannon, firing through the propeller shaft of a Hisso engine in his Spad airplane. It proved effective against balloons and other aircraft. Leak-proof gasoline tanks and armor-plating also were introduced during this period but they came too late; the war was over before much could be done about their practical application.

Records of these experiments which took place during the World War were shelved in War Department files until recent years when the current war has brought them out again. Today US fighting planes are being equipped with the latest armament features: the Bell Airacuda utilizes two 37mm cannon mounted in its two engine nacelles. Both the Bell Airacobra (P-39) and Lockheed P-38 mount cannon and .30- and .50-caliber machine guns. In addition, US medium and heavy bombers now are utilizing hydraulic and electric gun turrets mounting .50-caliber guns.

Problems concerned with putting these features on our fighting planes are many. Chiefly they are the worries of the Armament Laboratory. But engineers in the Armament Laboratory rely on the cooperation they get from the Army Ordnance Department, which controls all US arsenals and furnishes bullets, shells, bombs and guns that are installed on the airplanes.

The Armament Laboratory is divided into several units, all under the Experimental Engineering section. These include the Bombing, Fire Control, Specifications, Service Liaison and Photo units. The Fire Control Unit is divided into two sections, one for flexible guns, the other for fixed. Each unit has its own separate function.

The Bombing Unit develops bomb sights, racks, releases and all mechanisms pertaining to the installation of such equipment in airplanes. Engineers of this unit also are charged with obtaining the bombs themselves from the Ordnance Department.

Our Air Forces use two types of bombs — fragmentation and demolition. These may weigh anywhere from 17 to 2,000 pounds (the largest now being used). They range in price from $25 to $5,000. The type bomb used and its weight depend entirely upon the nature of its objective.

The fragmentation bomb, which seldom weighs more than 500 pounds, is used on missions aimed at ground troops or supply movements. These bombs are timed so that they explode several hundred feet in the air scattering shrapnel over a large area. Some, however, do not explode until they strike the ground or some other object. They contain sufficient powder to blow the shell to pieces and scatter the heavy metals — but not as much of the explosives as the demolition bombs.

Demolition bombs weigh between 100 and 2,000 pounds. As the name implies, this bomb is for demolishing an objective. There are three kinds: armor-piercing, semi-armor-piercing and general purpose. The armor-piercing bomb is used against objectives like a battleship, which has heavy 16-inch armor to protect it. These generally are in the 1,000- to 2,000-pound category. Smaller demolition bombs are used against factories, supply trains, ammunition dumps. They carry a great amount of explosives. Testing and installing these bombs in the airplanes is one of the tasks facing the Bombing Unit.

There are two methods of releasing bombs from aircraft today; the Bombing Unit developed both. By means of electrically-controlled selective panels, a bombardier can release bombs one at a time or in salvo. Bombs now are carried inside bombers, doing away with the idea of hanging them underneath the fuselage or wings. Racks have been designed that serve as "cradles" for the bombs inside the bombers' fuselages. This helps lessen drag and increases bombers' speed.

Another development of the Bombing Unit is the bomb sight. The Army has created some of the most accurate sights in the United States. Coordinating — by means of delicate and intricate instruments — speed, trajectory, wind velocity and other important factors such as weight, shape, size, American bomb sights are considered the world's best. The development of these sights accounts for US Air Forces' relying chiefly on precision bombing.

Working with the Photo Unit, Bombing Unit engineers also have designed flash flare bombs which produce light equivalent to more than 7,000,000,000 candle power for night photographic work. The flare is working so effectively that cameramen are making night pictures as good as daylight pictures, thus changing the whole of military operations.

Guns for bombers and fighters are the responsibility of the Fire Control Unit. The creation of revolving gun turrets. as used by the British so effectively to defend their bombers, has caused the Fire Control Unit to study both fixed guns that go on fighters and flexible guns that go in turrets.

There are three companies in the U.S. today making armor-plated, glass-enclosed turrets for US bombers. The turrets are equipped with special sights and have mounts for as many as four heavy machine guns. Those which are located underneath the fuselage telescope outward so that guns are fired from almost any angle. Special design of turrets, application of guns and installation on aircraft have been developed by the Flexible Gun Unit of the Fire Control organization.

Fixed guns are those mounted on fighter planes generally in the nose or wings. All machine guns are .30- and .50-caliber Brownings.

The .30- and .50-caliber guns fire about 1,000 rounds per minute. Quick bursts have been found very effective in combat. Fighters are being designed to carry about 1,500 rounds per loading. Planes using cannon carry several hundred rounds per loading.

One of the most difficult problems facing the Fire Control Unit is shell ejection. Used shells must be ejected from guns as rapidly as they are fired. Engineers have designed various methods, still are working to perfect new ones.

On one experimental type airplane the shells were ejected falling directly into the backwash of the propeller and were thrown against the ship's elevator surfaces, ripping them apart and interrupting control. Such experiences are all part of the experimental program of the Fire Control Unit.

Nose guns and wing guns on U.S. fighters are fired individually or all at one time. A special selector panel has been designed that allows the pilot to fire any gun he chooses. This firing mechanism is controlled electrically. Panels were developed by the Fixed Gun Unit.

The Service Liaison Unit of the Armament Laboratory keeps in constant contact with all tactical units in continental US and its possessions. Whenever there is trouble that develops with gun installation mechanism, engineers from this unit are responsible for smoothing it out and getting the mechanism to work properly. Sometimes they find the trouble is universal for this particular type airplane. Then they must re-design complete gun installations for this particular type, a process which sometimes takes several months. More often they find that the trouble lies not with the installation mechanism but with the gun itself, in which case they turn the matter over to the efficient Army Ordnance Organization.

Armament engineers are faced with still another problem — armor plating; the Armament Laboratory is responsible for armoring all US fighting planes. At present armament engineers are using various thicknesses of plating which will stop .30- and .50-caliber shells. They also develop leak-proof gasoline tanks, now being fitted in all US planes. These are the finest in the world.

The progressive steps of getting guns onto warplanes starts with the Specifications Unit. Acting upon the direction of Army strategists who desire certain gun mounts, these engineers draw up specifications for the new type guns that are desired and send them to the Ordnance Department and to plane designers. This is necessary because we have learned that we must design our planes around their guns, not the guns around the planes. Literally we are building guns and putting wings on them.

The words of Nathan Bedford Forrest, Civil War general, who said: "He what gets there fustest with the mostest guns, wins" are very much alive.

This article was originally published in the September, 1941, issue of Flying and Popular Aviation magazine, vol 29, no 3, pp 91-94, 214, 216.
The original article includes a thumbnail portrait of the author and 10 photos.
Photos are not credited, but are probably from USAAC.