FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1950
1950 - 1588.PDF
2l8 FLIGHT "The 1930 Westland single-seater had the gun arranged to fire obliquely upwards ..." (This type met a 1927 specification). Fighter Armament ... During 1917-19 (and again later) the Germans pursued another solution to increase fire-density. Since gun syn- chronization greatly reduced rate of fire, engine-operated guns were developed. In such guns, the loading and firing is per- formed by engine power, i.e., independently of the energy of the propellant in the cartridge. At least three types were under active development in Ger- many The main principle was that of a crank with the breech-block forming a reciprocating piston. As the gun worked in synchronization with the engine, no special gear to actuate the trigger was required. It was found that such "motor-guns" were lighter, and fired at a much greater rate, than any ordinary machine gun. The Siemens motor-gun, able to fire 2,400 rqunds per minute from two barrels, was the only one to progress to operational trials: it produced an air victory at the first attempt; but during a subsequent attack the gun began to swell alarmingly, on accouut of a rapid accumulation of unfired cartridges in the case of the mechanism, and the pilot did his best to reach earth again in a hurry. Such guns, of course, needed perfect ammunition, and would not tolerate "hang-fire" cartridges. With electrically ignited ammunition, the motor-gun would have been more practical. Of the Fokker-Luebbe motor-gun and its derivatives, an improved version was placed at the Air Ministry's disposal during 1938, but failed to raise interest; perhaps it was not even tested. Fokker himself held that his own gun design, with a terrific rate of fire, was the only intercepter weapon worth while installing. During 1918. incidentally, the Austrian authorities decided to adopt the Gebauer motor-gun as their principal fighter weapon; in later comparative tests, however, it was found less efficient than those of Siemens and Luebbe. As regards ammnnition, international conventions, concluded before 1914, prohibited the use of explosive ammunition and "spreading" bullets in rifles and machine guns of up to 19 mm calibre; this agreement was generally adhered to up to about 1936. In other directions, three important develop- ments became general: the incendiary bullet, the tracer bullet, and the armour-piercing bullet. The first arose' from the necessity to ignite the combustible gas-filling of airships, and originated in this country. Later it was found that incendiary bullets could ignite fuel tanks, and thus white-phosphorus-filled bullets were generally adqpted. They were prone to self-ignition when stored close to the engine, however, and their ballistic properties differed from those of ordinary ball ammunition. The tracer bullet conveyed an immediate advantage in air combat. In spite of some ballistic difference, tracers were soon found indispensable, and they were retained until auto- matically computing sights rendered them superfluous. The armour-piercing (steel-core) bullet was originally intended for ground attack. In air combat it was employed to cause engine damage, and for use against the metal or armoured aircraft which came into use during 1918. In the first place, the introduction of shell-guns as fighter armament was due to the desire to attack objectives on both land and sea. In air combat, the use of flatter trajectories and with explosive shells allowed attack over ranges which the target aircraft could not cover with defensive fire. Britain, France and Germany share equally in the early history of airborne shell-guns. British interest, however, soon petered out. There was an American aircraft gun, too, the recoilless Davis; it fired at both ends, to the discomfiture of designers and gunners. The 20 mm single-shot C.O.W. shell-gun, tested at Farn- borough in 1913 in a F.E.3, showed that firing of such a weapon would not impair aircraft stability, but that an auto- malic gun was required. A 2-pdr Vickers, too, was tested, but' the airframe of the Farman used for the experiment threatened to disintegrate. In January, 1914, a 37 mm semi- .automatic Vickers was installed in a special Short " Gun- \ Carrier" seaplane and fired in flight. During the 1914-18 \ war, 1- and ij-pdr automatic C.O.W. shell-guns were tried in >^pfsin pushers and found practical. A few of the 20 mm guns were even operationally employed in France, installed in F.E.2bs, for nightly ground attacks. Till 1930, further experiments were made with 37 mm auto- matic C.O.W. and Vickers guns. The interest then evaporated, and the shell-gun experts turned for some nine years into sleeping beauties. Even for air combat, a serious attempt had been made to provide an intercepter with a 37 mm shell-gun. This 1930 Westland single-seater had the gun arranged to fire obliquely upwards to clear the airscrew. When the gunnery experts were aroused to appreciate the fact that a war was impending, all they could discover was the Hispano gun. In France, secret firing trials -with a 37 mm Hotchkiss single-shot gun had been made from a Voisin biplane as early as the autumn of 1913; but when a shell was accidentally put into a very civilian hostel, the secrecy, too, was exploded. The experience gained was exploited during 1915, and a Voisin squadron with 37 mm Puteaux single-shot shell-guns was operationally employed for ground attack and, occasionallv, also for air combat. The mounting was semi-flexible, permit- ting adjustment in elevation by 30 deg either way. Against German fighters, however, these two-seaters proved helpless; several were brought down, proving that ability to fire over long ranges is useless if it is not matched by adequate fire density and aircraft performance. One of these Voisins carried a naval gun of 47 mm calibre, also of Puteaux design. On the whole, the Voisin-Puteaux combination, with a rate of fire of about one shot per minute, did not prove a success. Guynemer suggested, in 1916, the installation of a shell-gun in single-seaters, for air combat over long range as well as for attacks on the German submarines then based at the Flanders coast. The suggestion was taken up by Marc Birkigt of Hispano-Suiza. He modified the 37 mm Puteaux gun for single-hand loading by the pilot in flight, shortened the barrel (at the expense of muzzle velocity), and placed it between the cylinder blocks of a geared Hispano-Suiza eight- cylinder engine so that the gun could fire through the hollow airscrew shaft and hub (incidentally, a 1912-13 idea of F. Schneider and Daimler). The gun was elastically attached to the crankcase by way of a recoil spring and a hydraulic recoil brake. The 220 h.p. Hispano tnoteur canon thus created was installed in several single-seater types (British and French), notably Spad biplanes. In July, 1917, Guynemer succeeded in shooting down a German aircraft at 200 yards " Marc Birkigt of Hispano-Suiza . . . modified the 37 mm Puteaux gun for single-hand loading by the pilot in flight . .. and placed it between the cylinder blocks of a geared eight-cylinder engine ..." An early Hispano moteur canon is illustrated.
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
