Focke-Achgelis FA 269
A Nazi German Tiltrotor "Heliplane". Conceived as a single-seat fighter, the Fa 269 project resulted from a design study order issued by the Reich Air Ministry to Focke-Achgelis in 1941. The order called for a local defence fighter which would combine the VTOL capabilities of a helicopter with the speed and economy of a conventional fixed-wing aircraft.
A large amount of wind tunnel testing was undertaken, along with work on gearboxes, drives and power-pivoting mechanisms, and a full-scale mock-up of the aircraft was built, but much of this was destroyed by Allied bombing raids and all work was shelved in 1944 when Focke-Achgelis estimated that there was little likelihood of a practical prototype being available before 1947.
Focke revived the design in the early 1950s on behalf of Brazil's Centro Técnico Aeroespacial (CTA), at the time the air force's technical center, who had contracted him to develop a Convertiplane, the "Convertiplano". The Convertiplano was built using the fuselage and wings of a Supermarine Spitfire Mk 15, which was believed to be one delivered to Argentina as a sales example. Britain refused to supply the Armstrong Siddeley Double Mamba engine originally selected and the design was altered to accept a mid-mounted 2200 hp Wright engine instead as used in the Lockheed Constellation, which necessitated a redesign of the transmission due to the increase in weight and vibration. Some 40 workers and US$8 million were devoted to the project, and more than 300 takeoffs were achieved.
A mid-wing monoplane, the Fa 269 was to have been powered by a single BMW 801 air-cooled radial engine buried in the fuselage behind the cockpit, which was to have driven transverse drive shafts in the leading edges of the fixed wing, the shafts turning three-bladed rotors via synchronised gearboxes. The plane of rotation of the rotors would have been capable of being swivelled through 80° using angled extension shafts.
It was proposed that the Fa 269 would adopt a high angle of attack when at rest using extremely long undercarriage units. For vertical take-off, the rotors would be lowered so that their plane of rotation was parallel with the ground. For translation to conventional flight following take-off, the extension shafts were to pivot to the rear, the rotors then behaving as pusher propellers.
Specifications (Fa 269)
- Kovacs, Joseph (April-September 2003). "Uma Breve História das Atividades do Prof. Focke no Brasil". ABCM engenharia 9 (2): pp. 17-22.
- Springmann, Enno; Gottfried Hilscher (1997). Focke: Flugzeuge und Hubschrauber von Heinrich Focke 1912-1961. Aviatic-Verlag GmbH. ISBN 3925505369.
- Nowarra, Heinz (1985-1988). Die Deutsche Luftrüstung 1933-1945. Bernard & Graefe. ISBN 3-7637-5464-4.
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