July 31, 2007

Fairey Jet Gyrodyne helicopter

The Jet Gyrodyne was a modification of the second prototype Fairey Gyrodyne aircraft registered G-AJJP. The Jet Gyrodyne was built specifically to develop the pressure-jet rotor drive system used on the later Fairey Rotodyne. The appearance of the Jet Gyrodyne is part way between a small aeroplane and a helicopter. A helicopter-type cabin is the front of the aircraft. The engine, an Alvis Leonides 9 cylinder radial, is in the middle of the fuselage. Above the engine is a two bladed rotor. There is a simple tailplane with no tail rotor as might be expected on a helicopter. Two short wings carry rear facing wingtip propellors and also the main wheels of the tricyle undercarriage.

The engine performs two functions; the first is to power, through gearboxes, the two wingtip propellors, the second is to drive two superchargers (taken from Rolls-Royce Merlin engines) whose output goes up through the rotor blades and exhausts through jets at the tips of the rotors. At the jets the compressed air is mixed with fuel and burnt to give more power. As this means of powering the rotor gave no reaction torque, a separate tail rotor was not needed. The rotor jets could be used to power the rotor for vertical takeoff and landing and for the rest of the time, the rotor would autorotate like an autogyro giving lift but not needing power while the forward drive came from the wingtip propellors.

The Fairey Jet Gyrodyne was a British experimental compound autogyro built by the Fairey Aviation Company that incorporated helicopter, gyrodyne and autogyro characteristics. The Jet Gyrodyne was the subject of a Ministry of Supply research contract to gather data for the follow-up design, the Fairey Rotodyne.

Tethered flights at White Waltham were followed by the first free flight in January 1954, but a full transition from vertical to horizontal flight was not achieved until March 1955. System proving continued and by September 1956, 190 transitions and 140 autorotative landings had been completed.

Although scheduled for scrapping in 1961, the Jet Gyrodyne (serial XD759 later XJ389) survived and today is displayed at the Museum of Berkshire Aviation, on loan from the RAF Museum collection.

Source: Wikipedia

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