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 about 50% larger than the Bonanza, has more powerful engines, and is significantly heavier, while in its earliest form having only half the passenger capacity of the Model 18.

The Twin Bonanza is an all-metal low-wing cantilever cabin monoplane initially powered by two wing-mounted Lycoming GO-435 piston engines each with a wooden two-bladed propeller. The cabin has room for 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 a tricycle landing gear with the nose wheel retracting rearwards and the main landing gears retracting partially into the engine nacelles, this leaves the tire exposed to assist in the event of a wheels-up landing.

VARIANTS

Model 50 - Initial production version powered by two Lycoming GO-435-C2 engines, 13 built (six for the US Army, remainder civilian versions, with the first two production numbers for factory evaluation). As of 2010, only one Model 50 is still registered & flying (serial number H-7).

 Model B50 - Upgraded Model 50 with increased takeoff weight, extra cabin windows and improved cabin heating, 139 built (40 for the US Army).

 Model C50 - Superseded the B50; fitted with 275 hp (205 kW) Lycoming GO-480-F1A6 engines, 155 built (one to United States Air Force).

 Model D50 - Superseded the C50; fitted with 295 hp (220 kW) Lycoming GO-480-G2C6 engines, 154 built (six to US Army).

Model D50A - Upgraded D50 fitted with GO-480-G2D6 engines, 44 built. 

Model D50B - Upgraded D50A with new passenger steps and improved baggage area, 38 built.

 Model D50C - Upgraded D50B with starboard air stair entry door, three rows of seats, improved air conditioning, larger baggage area, 64 built.

 Model D50E - Upgraded D50C with extra portside window, squared-off rear starboard window, pointed nose and 295 hp (220 kW) Lycoming GO-480-G2F6 engines, 47 built.

 Model E50 - Supercharged version of the D50; with increased takeoff weight and 340 hp (250 kW) supercharged GSO-480-B1B6 engines, 181 built (mostly for the US Army).

 Model F50 - Supercharged version of the D50A with GSO-480-B1B6 engines, 26 built including one converted to G50 standard.

 Model G50 – Supercharged version of the D50B with 340 hp (250 kW) IGSO-480-A1A6 engines, increased fuel capacity and increased takeoff weight, one conversion from F50 plus 23 built.

 Model H50 - Supercharged version of the D50C with increased takeoff weight and IGSO-480-A1A6 engines, 30 built.

 Model J50 - Supercharged version of the D50E with 340 hp (250 kW) IGSO-480-A1B6 engines and increased takeoff weight, 27 built.

 Excalibur 800 - A modification designed originally by Swearingen Aircraft and taken over by the Excalibur Aviation Company which re-engines the Twin Bonanza with two 400hp (298kW) Avco Lycoming IO-720-A1A flat-eight engines in a new cowling and revised exhaust system. Other optional improvements were also available.

 L-23 Seminole - Military version

 Source: Wikipedia