Oblique Wing Airplanes

Investigation of Aerodynamic Characteristics and Stability of Oblique Wing Airplanes

Oblique wing airplanes were investigated for a long time with the promise of combining efficient subsonic as well as supersonic flight characteristics. The first known oblique wing design was the Blohm & Voss P.202, proposed by Richard Vogt in 1942. Further, NASA AD-1 (Ames-Dryden-1) aircraft utilized a wing that could be pivoted obliquely from zero to 60 degrees during flight. The aircraft was flown 79 times during the research program, which evaluated the basic pivot-wing concept and gathered information on handling qualities and aerodynamics at various speeds and degrees of pivot. Further, there has been several test flights to prove the feasibility and performance of oblique wings. NASA Ames also developed an oblique wing airplane from their F-8 digital-fly-by-wire airplane. This design can produce higher lift to drag ratios over a wide range of flying speeds. Such airplanes, however, show large cross-coupling in their control and dynamic behavior which is not present in conventional symmetrical airplanes. Such behavior must be compensated to obtain acceptable handling qualities. Furthermore, R.T. Jones of NASA Ames Research Center has conducted some of the earliest theoretical studies on this subject, beginning in the 1950s. In the present project, first, I will give a historical review of oblique wing airplanes and other oblique wing studies and summarize the results. I will then use XFLR5 software to analyze the characteristics and performance of NASA AD-1 wing (at zero sweep). I will also utilize lifting line theory to analyze the effect of oblique angle on the induced drag. At low speeds, the most efficient lifting surface is a high aspect ratio elliptically loaded wing because drag due to lift is inversely proportional to the aspect ratio. At transonic and supersonic speeds, however, wave drag is the dominant part of the total drag. A significant advantage of oblique wing arrangements for supersonic flight is that they distribute the lift over about twice the wing length compared to a conventional, symmetrically swept wing. This reduces lift dependent wave drag by a factor of 4 and volume dependent wave drag by a factor of 16.