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 aircraft was first designed to use Franklin engines with superchargers, but the engine company owner, Preston Tucker, diverted all of its aviation resources to support his ill-fated Tucker 48 automobile project. The aircraft was hastily modified to accept the Lycoming GO-435, but the engine nacelles were not redesigned to fit the smaller Lycoming, creating unusually generous internal clearances that facilitate engine maintenance. and production began the same year. The Twin Bonanza is one of only a few light twin-engined civil aircraft certificated in the utility category, and was the first production light aircraft to feature shoulder belts.

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 wider than that of the Bonanza.

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 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.

The Beechcraft Model 65 Queen Air and Model 90 King Air are both direct descendants of the Model 50 Twin Bonanza. All three aircraft share the same basic wing design, as well as landing gear, flaps, instrument panels, fuel cells, and more. The Queen Air added a larger cabin to the design, while the later King Air added turbine power and pressurization. Twin Bonanza production ended in 1963 while the King Air was under development.

Design

The Twin Bonanza is an all-metal low-wing monoplane with a cantilever wing and retractable tricycle landing gear, initially powered by two wing-mounted geared Lycoming GO-435 piston engines, each with a wooden two-bladed propeller. The standard cabin seats six people on bench seats, three in the front and three in the rear, and several other seating configurations were offered, including club seating and a three-person sideways-facing couch. Early models had a single right-hand door above the wing, accessed by trailing edge steps, while later aircraft added a rear airstair door with retracting steps. The GO-435 was replaced by the Lycoming GO-480 in 1954; this engine was subsequently upgraded with fuel injection and then superchargers, increasing power to in 1956 and in 1957. The Twin Bonanza has been plagued by a reputation for slow cruise speed, poor fuel economy and high engine overhaul costs relative to other six to eight-seat light piston twins; this has historically kept resale values low, but many owners praise its reliability, good outwards visibility, stable flying qualities and generous interior space, particularly when the three-wide seats are not fully occupied.

Variants

thumb|Beechcraft J50 Twin Bonanza

;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 and flying (serial number H-7). As of June 2016, Serial Number H-7 is owned by W. Hulsey Smith through his holding company Archangel Technologies, LLC, as part of the Archangel Collection.

;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 Lycoming GO-480-F1A6 engines, 155 built (one to United States Air Force).

;Model D50: Superseded the C50; fitted with 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 airstair 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 Lycoming GO-480-G2F6 engines, 47 built.

;Model E50: Supercharged version of the D50; with increased takeoff weight and 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 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 IGSO-480-A1B6 engines and increased takeoff weight, 27 built.

;Model K50: Unbuilt variant. Serial numbers KH-1 through KH-38 were allocated for this variant.

thumb|The Excalibur 800 modification

;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 400 HP (298 kW) 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

Operators

Military operators

;:Chilean Air Force (5 x C50, 4 x D50)

;:Swiss Air Force (3 x E50)

Specifications (D50)

frameless|right|3-view line drawing of the Beechcraft L-23A Seminole

See also

References

Further reading

  • Aviation Media, Inc. Wonderful World of Flying. New York: Aviation Media, Inc, 1992.
  • Beech Aircraft Corporstion. Beechcraft Bonanza. Wichita, Kan. : Beech Aircraft Corp., 1947.
  • Beech Aircraft Corporation. The Story of Beechcraft. Wichita, Kan., 1969.
  • Beech Aircraft Corporation. The World of Beechcraft. Wichita, Kan. : Beech Aircraft, 1973.
  • Christy, Joe. Beechcraft Guide: Bonanza, Debonair, Musketeer. New York : Modern Aircraft Series, 1962.
  • McDaniel, William Herbert. The History of Beech. Wichita, Kan. : McCormick-Armstrong Co. Pub. Division, 1982.
  • Pelletier, Alain J. Beech Aircraft and Their Predecessors. Annapolis, MD. : Naval Institute Press, 1995.
  • Ward, Richard I. Beechcraft Twin Bonanza, Craft of the Masters: The Story of the Beech Civilian Model 50 & Military L-23/U8. Destin, FL. : Aviation Heritage, 1996.
  • Wixey, Kenneth E. Beechcraft. Stroud: Tempus, 1999.