were V-1710-6, -17, -31, 35, -37, -47, -59, -63, -83, -85, -93, -103, -109, -117, -125, -127, -129, -133,-135 and -137, producing at 3000 rpm. Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.6:1 depending on altitude rating. These engines were a complete redesign, and did not share many components with the earlier engine series. Almost all components were interchangeable with later series engines and the V-3420, and could be assembled as right hand or left hand turning engines in either pusher or tractor applications. "F" series engines were designed for late model pursuit aircraft, and are identified by the compact external spur gear-type reduction gear box. Military models were V-1710-27, -29, -39, -45, -49, -51, -53, -55, -57, -61, -75, -77, -81, -87, -89, -91, -95, -99, -101, -105, -107, -111, -113, -115, -119, producing at 3000 rpm. The V-1710-101, -119 and -121 models has an auxiliary supercharger, some with a liquid-cooled aftercooler. Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.60:1 depending on altitude rating. These engines had either a six or twelve weight crankshaft, revised vibration dampeners that combined to allow higher engine speeds, SAE #50 propeller shaft, and higher horsepower ratings. The "E" series and "F" series engines were very similar, the primary difference being the front crankcase cover, which was interchangeable between the two series engines. "G" series engines were designed for high-altitude pursuit aircraft, and are identified by the auxiliary supercharger with a Bendix "Speed-Density" fuel control. Military models were V-1710-97, -131, -143, -145, and -147, producing at 3000 rpm. Supercharger gear ratios were: 7.48:1, 7.76:1, 8.10:1, 8.80:1 and 9.60:1 depending on altitude rating. These engines were equipped with an SAE #50 propeller shaft and a single power lever to regulate engine performance, reducing the pilot's workload when managing this very complex engine. "H" series engines were to use a two-stage supercharger driven by a two-stage air-cooled power recovery turbine. The engine was to have an aftercooler and port-type fuel injection. This variant, however, was never built. Applications Bell FM-1 Airacuda Bell FL Airabonita Bell P-39 Airacobra Bell P-63 Kingcobra Boeing XB-38 Flying Fortress Curtiss P-40 Warhawk Curtiss-Wright XP-55 Ascender Curtiss XP-60A Curtiss P-37 Douglas XB-42 Mixmaster Douglas DC-8 Lockheed P-38 Lightning North American A-36 Apache North American F-82 Twin Mustang North American P-51 Mustang T29 Heavy Tank (trial) Engines on display An Allison V-1710-51 is on public display at the Aerospace