Research Aircraft
Even after the development of powered aircraft, gliders have been built for research. The NASA Paresev Rogallo flexible wing is an example that was built to investigate alternative methods of recovering spacecraft. Although this application was abandoned, publicity inspired hobbyists to adapt the flexible wing airfoil for modern hang gliders.
Unpowered flying wings are another type of aircraft that have been built for aerodynamic research. Examples are the Horten flying wings, the scaled glider version of the Armstrong Whitworth A.W.52 jet powered flying wing and the Baynes Bat (to give information for a planned military glider).
In contrast to the flying wings, lifting bodies have been also developed using unpowered prototypes. Although the idea can be dated to Vincent Justus Burnelli in 1921, interest increased as an alternative for returning spacecraft. Traditional space capsules have very little control over where they land, whereas a steerable craft using wings would have more options. The lifting bodies use the fuselage itself to generate lift without employing the usual thin and flat wing. The objective of the lifting body is to minimize the drag and structure of a wing for very high supersonic or hypersonic flight as might be experienced during the re-entry of a spacecraft. This can be compared with a flying wing that seeks to minimise drag at subsonic speeds by eliminating non-lifting surfaces. Examples of type are the Northrop HL-10 and Martin-Marietta X-24.
Read more about this topic: Glider Aircraft
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