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The X-31 is an experimental aircraft for research and testing of new technologies with the aim of improving the manoeuvrability of fighter planes through thrust vectoring

Thrust vectoring and the aerodynamic rudder are controlled automatically by the digital flight control system. Because of the prohibitive cost of developing a vectoring nozzle for three-dimensional thrust vectoring, this task is performed by three thrust-deflecting “paddles” behind the engine. This permits tactical manoeuvres at a 70-degree angle of attack, far beyond the stall angle of conventional aircraft. The X-31 is one of the legendary US series of experimental ‘X-planes’, and was developed, built and tested under a German- American cooperative programme involving EADS (previously MBB and Dasa), Boeing (previously Rockwell International), the German Federal Office for Defence Technology and Procurement (BWB), the US agencies DARPA and NASA, and the US Navy. To keep costs down, components of existing aircraft were used. The use of advanced materials, for instance carbon fibre composites in the forward section of the fuselage and the wings, optimised the structure and reduced the weight of the aircraft. Two planes were built, and the first flight took place in 1990. In both programmes, more than 400 flying hours were logged between 1990–1995 and 2001–2003 at Edwards Air Force Base, California, and the Naval Air Station, Patuxent River, Maryland. One plane crashed in 1995 because of ice forming in the pitot tube, which caused the flight control system to malfunction. The test programme was continued with the second plane, with the last flight carried out on April 29, 2003.

    Technical specifications:

    • Manufacturer: European Aeronautic Defence and Space Company (EADS), Munich and Boeing Aerospace, Chicago, USA, 1990
    • Wingspan: 7.26 m
    • Length: 14.85 m
    • Empty weight: 5175 kg
    • Take-off weight: (max.) 7300 kg
    • Maximum speed: Mach 1,3 at an altitude of 11,000 m  
    • Rate of climb: 218.4 m/s
    • Power plant: General Electric F404 GE400 turbojet engine
    • Thrust: 71.17 kN