Oblique wing
An oblique wing (also called a slewed wing) is a
History
The oldest examples of this technology are the unrealized German aircraft projects Blohm & Voss P.202 and Messerschmitt Me P.1009-01 from the year 1944, based on a Messerschmitt patent.[1][2] After the war, constructor Dr. Richard Vogt was brought to the US during Operation Paperclip.[3] The oblique wing concept was resurrected by
In the 1970s, an unmanned propeller-driven aircraft was constructed and tested at Moffett Field.[5] Known as the NASA Oblique Wing, the project pointed out a craft's unpleasant characteristics at large sweep angles.
So far, only one manned aircraft, the
Theory
The general approach is to design an aircraft that performs with high efficiency as the Mach number increases from takeoff to cruise conditions (M ~ 0.8, for a commercial aircraft). Since two different types of drag dominate in each of these two flight regimes, uniting high performance designs for each regime into a single airframe is problematic.
At low Mach numbers induced drag dominates drag concerns. Airplanes during takeoff and gliders are most concerned with induced drag. One way to reduce induced drag is to increase the effective wingspan of the lifting surface. This is why gliders have such long, narrow wings. An ideal wing has infinite span and induced drag is reduced to a two–dimensional property. At lower speeds, during takeoffs and landings, an oblique wing would be positioned perpendicular to the fuselage like a conventional wing to provide maximum lift and control qualities. As the aircraft gained speed, the wing would be pivoted to increase the oblique angle, thereby reducing the drag due to wetted area, and decreasing fuel consumption.
Alternatively, at Mach numbers increasing towards the speed of sound and beyond,
Fundamentally, it appears that no design can be completely optimised for both flight regimes. However, the oblique wing shows promise of getting close. By actively increasing sweep as Mach number increases, high efficiency is possible for a wide range of speeds.
Robert T. Jones theorised that an oblique flying wing could drastically improve commercial air transportation, reducing fuel costs and noise in the vicinity of airports.[6] Military operations include the possibility of a long–endurance fighter/attack vehicle.
NASA OFW airliner research
There have been investigations into an OFW platform being developed into a transcontinental airliner.[7] NASA Ames performed a preliminary design study of a theoretical 500-seat supersonic airliner using the concept in 1991. Following this study, NASA built a small remote-controlled demonstrator aircraft with a 20-foot (6.1m) wingspan. It flew only once, for four minutes in May 1994, but in doing so, it demonstrated stable flight with oblique wing sweep from 35 degrees to 50 degrees. Despite this success, the NASA High Speed Research program, and further oblique wing studies, were canceled.
DARPA Oblique Flying-Wing (OFW) Project
The United States Defense Advanced Research Projects Agency (DARPA) awarded Northrop Grumman a $10.3 million (USD) contract for risk reduction and preliminary planning for an X-plane OFW demonstrator,[8] known as the Switchblade. That program was eventually cancelled, citing difficulties with control systems.
The program aimed at producing a technology demonstrator aircraft to explore the various challenges which the radical design entails. The proposed aircraft would be a pure flying wing (an aircraft with no other auxiliary surfaces such as tails, canards or a fuselage) where the wing is swept with one side of the aircraft forward, and one backwards in an asymmetric fashion.[9] This aircraft configuration is believed to give it a combination of high speed, long range and long endurance.[10] The program entailed two phases. Phase I was to explore the theory and result in a conceptual design, while Phase II covered the design, manufacture and flight test of an aircraft. The program hoped to produce a dataset that can then be used when considering future military aircraft designs.
Wind tunnel tests for the aircraft design were completed. The design was noted to be "workable and robust."[11] The program was concluded before a flight demonstrator was constructed.[12]
See also
References
- TU Darmstadt. pp. 7, 8.
- HAW-Hamburg.de.
- ^ "History of Aerodynamics and Aircraft Design". Scientists & Friends.
- ^ Could This Change Air Travel Forever?. Mustard. 5 January 2024. Retrieved 2024-01-06 – via YouTube.
- Air and Space magazine. 2014-10-06. Archived from the original on 2014-10-08 – via Wayback Machine.
NASA tested the Oblique Wing Research Aircraft in the late 1970s. Its unpleasant flying characteristics at extreme wing-sweep angles discouraged researchers.
- ISSN 0094-5765.
- ^ "Michael Williams blog". Archived from the original on 2006-10-09.
- ^ Warwick, G. "<missing>". Flight International. 169 (5029): 20.
- DARPA.mil. Archived from the originalon 2006-04-21.
- Aerodyn.org. Archived from the originalon 2006-05-14.
- ^ "New Angles: Wind tunnel results point way forward for tailless oblique flying wing study". Aviation Week & Space Technology: 34–35. October 8, 2007.
- ISSN 1059-1028. Retrieved 2024-01-13.
Further reading
- Thinking Obliquely, Larrimer, Bruce I., NASA (2013)
External links
- Oblique Flying Wings: An Introduction and White Paper - Desktop Aeronautics, Inc., 2005