Regional airliner were replaced by progressively longer-range designs. In the immediate post-war era these were typically Douglas DC-3s, although even the De Havilland Dragon Rapide biplane airliner remained in service for some time. This "hand-me-down" process of supplying aircraft continued with designs like the Convair 440, Douglas DC-6 and Vickers Viscount also serving in this role while the first jets were introduced. By the mid-1950s, demand for even more economical designs led to the production of the first custom feederliners. These were almost always turboprops, which had fuel economy on par with piston engine designs, but had far lower maintenance costs. Often
Vickers machine gun Vickers E.F.B.1 biplane, which was probably the world's first purpose-built combat aeroplane. However, by the time the production version, the Vickers F.B.5, had entered service the following year, the armament had been changed to a Lewis gun. During World War I, the Vickers gun became a standard weapon on British and French military aircraft, especially after 1916. Although heavier than the Lewis, its closed bolt firing cycle made it much easier to synchronize to allow it to fire through aircraft propellers. The belt feed was enclosed right up to the gun's feed-way to inhibit effects from wind. Steel disintegrating-link ammunition