Page:Aircraft in Warfare (1916).djvu/144

§ 68 velocity of the projectile is round about 12 to 1, and this gives the angle of lead necessary to aim in front of the objective from a fixed mounting. When firing from another aeroplane moving in the opposite direction, the angle of lead will be six to one more or less, a considerably greater allowance than is known in any other branch of gunnery. With the highest muzzle velocity and slow-moving aircraft the angle of lead under these conditions is about 1 in 15. The angle of lead given by a pigeon-shot when the bird is flying fast across the line-of-sight is about 1 in 20, and even here the demand, under the stress of competition, is for higher and higher velocity. This may be taken as a sure indication of what may be expected in the eventual future of aeronautical gunnery. 102