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Lewis Gun Extras – Scarff Ring

The Lewis gun was one of the most widely used machine guns fitted to Allied WW1 aircraft. It was lightened and modified to fire 900-1000 rounds per minute, and had a 97 round magazine. Once Interrupter gear was invented, the gun was used by the observer for self protection, with one or two guns fitted to a Scarff ring. This animation also looks at the problems of aiming in aerial warfare.
Apart from the problem of vibration from the aircraft, and the target’s manoevering, it is also necessary to aim where the target will be when the bullets reach him. The ‘Aim off’ varies depending on the direction the target is flying. An added problem for the observer firing a gun out the side is that the bullets also inherit the aircraft’s velocity. For this reason, a special sight ‘the Norman vane’ was introduced to automatically correct for the component of aircraft speed added to the bullet.

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