A Rolls-Royce RB.50 Trent on a test rig at Hucknall, in March 1945 Propellers lose efficiency as aircraft speed increases, which is why turboprops are not used on higher-speed aircraft. However, turboprops are far more efficient than piston-driven propeller engines. The world's first Turboprop was the 'Jendrassik CS-1' designed by Gyorgy Jendrassik. It was produced and flown briefly in Czecho-Slovakia between 1939 and 1942. The aircraft it was fitted to was the Varga XG/XH twin-engined Recconaisance bomber. Not surprisingly the engines proved very unreliable. For more info. visit "Podklady", a Czech Aircraft drawing site (Czech text). Jendrassik had also produced a small scale turboprop of 75 kW in 1937. (Added By Peter Butt 03/12/05)
The first British turboprop engine was the Rolls-Royce RB.50 Trent, a converted Derwent II fitted with reduction gear and a Rotol 7' 11" five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 - the sole "Trent-Meteor" - which became the first relataively reliable turboprop powered aircraft. From their experience with the Trent, Rolls-Royce developed the Dart, which became one of the most reliable turbprop engines ever built. Dart production continued for more than fifty years. For info on Trent go to Rolls-Royce Heritage Trust) The first American Turboprop was the General-Electric T-31. A European consortium is currently developing the 11000shp TP400-D6 turboprop for the Airbus A400M military transport. The engine is all-axial and has a two shaft core, with a free power turbine mounted on a third coaxial shaft. Residual thrust on a turboshaft is avoided by: a) further expansion in the turbine system and/or b) truncating and turning the exhaust through 90degrees, to produce two opposing jets. Apart from the above and the remote location of the gearbox, there is very little difference between a turboprop and a turboshaft.
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