The Vickers is an English gun, belt-fed, water-cooled, recoil-operated. It can shoot from 300 to 500 shots a minute. Since all the shells are in a belt it can be fired continuously until the 500 shots have been used up. Its water-cooled devices were dispensed with on the aeroplanes.
The German Maxim is similar to the Vickers. The Lewis shoots .33 and Vickers and Maxim .30 ammunition. In the beginning of the war the Colt gas-operated gun was also used on aeroplanes, as were also the Hotchkiss and Benet-Mercier. The first gun shooting 400 shots a minute was similar to the Vickers.
Owing to the ease with which the cotton-belts containing the cartridges on Vickers guns jam, it was used only for fixed positions in front, whereas the Lewis was employed in the observer’s nacelle and other positions which required sudden change in the aim. As many as half a dozen machine-guns were mounted on some of the large bombers in the last days of the war.
Many attempts to mount cannon on aircraft have been made, but owing to the recoil, the room necessary for mounting and manipulating, and the speed with which the gunner and the target move through the air, not much success was attained.
Captain Georges Guynemer, the first great French flier to down more than fifty Hun planes, is credited with mounting a one-pounder on his Nieuport, single-seater. It could not shoot through the propeller, so it was arranged to shoot through the hub. The gun was built into the crank-case, the barrel protruding two inches beyond the hub. It is said that Guynemer brought down his forty-ninth, fiftieth, fifty-first, and fifty-second victims with this type of gun; but because of the fifty pounds extra weight above that of the machine-gun it was an impediment.
Attempts to use on aeroplanes the Davis non-recoil gun, invented by Commander Davis of the United States navy, have not been entirely successful. The two-pounder is 10 feet long, weighs 75 pounds, and shoots 1.575 shell with a velocity of 1,200 feet a second. The 3-inch Davis fires a 12-pound shell and weighs 130 pounds.
Several other guns have been used, and with the increase in the size of planes there ought to be much increase in the size of aeroplane guns.
CHAPTER VII
DEVELOPMENT OF THE LIBERTY AND OTHER MOTORS
DEBATE IN REGARD TO ORIGIN OF LIBERTY MOTOR—LIBERTY-ENGINE CONFERENCE, DESIGN, AND TEST—MAKERS OF PARTS—HISPANO-SUIZA MOTOR—ROLLS-ROYCE—OTHER MOTORS