The Beechcraft Model 50 Twin Bonanza is a small twin-engined aircraft designed by Beechcraft as an executive transport for the business market. It was developed to fill a gap in Beechcraft's product line between the single-engined Model 35 Bonanza and the larger Model 18. The Twin Bonanza is dissimilar to the Bonanza, being much larger and heavier and using more powerful engines, while in its earliest form having only half the passenger capacity of the Model 18. The Twin Bonanza was first flown on November 15, 1949 after rapid development, begun only in April of that year. The aircraft was first designed to use Franklin engines with superchargers, but engine company owner Preston Tucker diverted all of its aviation resources to support his ill-fated Tucker 48 automobile project, and the aircraft was hastily modified to accept the Lycoming GO-435. However, the engine nacelles were not redesigned to fit the smaller Lycoming, creating unusually generous internal clearances that facilitate engine maintenance. The Model 50's type certificate was awarded in 1951, and production began the same year. The United States Army adopted the Twin Bonanza as the L-23 Seminole utility transport, making it the largest fixed-wing aircraft in its inventory at that time. According to Ralph Harmon, the airplane's designer, during an initial demonstration flight for the Army, Beechcraft test pilot Claude Palmer crashed while trying to land over a 50-foot (15 m) tree line with the aircraft full of soldiers and sandbags. Everyone on board walked away from the crash. The Army was impressed with the structural strength of the Twin Bonanza, eventually purchasing 216 of the 994 examples produced. It was also the first twin-engined aircraft in its class to be offered to the business market, but the Korean War was raging in the early 1950s and the US Army took almost the entire production for 1952 and 1953. The Twin Bonanza is an all-metal low-wing monoplane with a cantilever wing, initially powered by two wing-mounted Lycoming GO-435 piston engines, each with a wooden two-bladed propeller. The cabin seats six people on bench seats, three in the front and three in the rear accessed by a side door on the right side. To gain access to the door a retractable three-tread steps is used. The Twin Bonanza has tricycle landing gear with the nose wheel retracting rearwards and the main landing gears retracting partially into the engine nacelles, leaving the tires exposed to assist in the event of a belly landing. The 260 hp (190 kW) GO-435 was replaced by the 275 hp (205 kW) Lycoming GO-480 in 1954; this engine was subsequently upgraded with fuel injection and then superchargers, increasing power to 295 hp (220 kW) in 1956 and 340 hp (250 kW) in 1957. Despite its name, the Twin Bonanza is a substantially larger and heavier aircraft that is mostly dissimilar to the single-engined Bonanza; the only major shared parts are the front fuselage sides and windows, and on early models, the main cabin door. The Twin Bonanza fuselage is 12 in (30 cm) wider than that of the Bonanza. For details of operational history and fifteen variants, click here.
