Ringwing
A ring wing aircraft , also called a ring wing aircraft or coleopter , is an aircraft capable of vertical takeoff with a wing in the form of a cylinder open on both sides and through which the air stream flows, in which the engine is located. Coleopter is an Anglicized form of the French term coléoptère , which means beetle. So far, they have only been planned as experimental aircraft in isolated cases and only actually built and tested in the eponymous model ( SNECMA C.450 Coléoptère) at the end of the 1950s.
construction
In ring-winged aircraft, the wings form a tube that is open at the front and back and encloses the fuselage. In theory, they combine the advantages of a fixed-wing aircraft (speed) with those of a helicopter (vertical take-off and landing). Since the ring wing acts like a ducted propeller and envelops the drive jet, this type of aircraft has a good propulsion efficiency, which makes it particularly suitable for use as a vertical take-off in the version as a stern take-off .
However, the disadvantages are the poor aerodynamic properties and that only aircraft with a small take-off mass can be built. In addition, there are considerable stability problems during take-off and landing as well as during transition , the transition between vertical and horizontal flight. Since an engine failure in these critical phases almost always leads to the loss of the aircraft, ring-wing aircraft are not suitable for civil use.
history
From the summer of 1943, Focke-Wulf and Heinkel investigated the possibilities of a rear-start object protection fighter for the first time with the concept called “ drive wing ”. While the Focke-Wulf design provided for three wings rotating around the fuselage, without a casing, Heinkel used a real ring wing in which two propellers rotating in opposite directions were to be driven by two Daimler-Benz DB 605 D motors (see Heinkel Lerche and Heinkel Wespe ) . None of the designs were implemented by the end of the war.
In the post-war period, SNECMA then developed the C.450 Coléoptère, a ring wing pattern from the previous Atar Valance family. A German group of engine specialists and aircraft manufacturers from Bayerische Motorenwerke and Junkers were involved in the development. After the crash of the only prototype in 1959, the project was discontinued because controlling the aircraft had proven extremely difficult. At the beginning of the 1970s, Dornier created the unmanned reconnaissance platform Aerodyne , which did not go into series production, not least because of technical advances in manned helicopters.
In the USA, Charles Zimmerman from Hiller Helicopters developed the VXT-8, a similar platform as a ring-wing aircraft, which also used a propeller instead of the jet propulsion of the Coléoptère. However, only a dummy was built, as the helicopters with shaft turbines that were introduced in the meantime proved to be more suitable. Zimmerman was also for the construction of Kreisflügler Vought V-173 and Vought Xf5u responsible.
Convair chose the ring wing design for its Model 49 proposal as part of the Advanced Aerial Fire Support System (AAFSS) program. However, the US Army chose the conventional concepts of the Lockheed AH-56 Cheyenne and Sikorsky S-66 as the winner of the competition.
Differentiation from circular winged birds
Horizontal ring wings , such as the Lee-Richards Annular Monoplane , are usually assigned to the circular wing aircraft , as they have very similar aerodynamic properties and differ from the circular wing aircraft only through a wing section in which the pilot's seat and the engine can be located.
See also
Individual evidence
- ^ Heinz AF Schmidt: Lexikon Luftfahrt , Motorbuch Verlag, licensed edition from transpress VEB Verlag für Verkehrwesen, Berlin, 1972, p. 310 f.
- ↑ Otto E. Pabst: Short starter and high flyer. Bernard & Graefe, Koblenz 1984, p. 179
- ↑ Convair Model 49 on aviastar.org