NASA AD-1
As NASA AD-1 both an aircraft and an associated flight test program was called, which was conducted between 1979 and 1982 at the NASA Dryden Flight Research Center in Edwards, California. It successfully demonstrated that a single continuous plane wing can be rotated during the flight from zero to 60 degrees oblique to the direction of flight.
The unique angled wings (also called Oblique Wing ) was tested on the small turbine powered subsonic experimental aircraft AD-1 (Ames - Dryden -1).
It flew during the research program 79 times to determine the basic properties of oblique - wing concept and to gather information about the flight characteristics and aerodynamics at various speeds and adjusting angles of the wing.
Background of the project
The oblique - wing concept was originally developed by Robert T. Jones, an aeronautical engineer of the NASA Ames Research Center, Moffett Field, California. As early as 1943 had with such a concept employed ( P.202 project, see also BV 141), but only Jones was able to implement and test this idea into reality the German designer Richard Vogt of Blohm & Voss.
Analytical and wind tunnel studies conducted by Jones in Ames, pointed out that such an aircraft at a speed of up to Mach 1.4 may have substantially better aerodynamic properties than airplanes with conventional ( unswept ) wings.
At high speeds, both the subsonic and the supersonic range, which vanes are up to 60 degrees with respect to the fuselage of the airplane is turned to reach better performances.
The studies showed that this would reduce the air resistance and thus a higher speed and greater range would allow for the same fuel consumption.
At lower speeds (during takeoffs and landings ) of the wings was like a conventional wing perpendicular to the hull and so offered a high level of buoyancy and flight control. When the aircraft is accelerated to higher rates of the wing has been rotated as a whole (as opposed to the swing -wing aircraft ), whereby the air resistance and thus the fuel consumption decreased. The mechanism was designed so that the wing only in one direction, moving forward with the right wing end, could be rotated.
Aircraft
The AD-1 aircraft was delivered in February 1979 at Dryden. The Ames Industrial Corporation of Bohemia, New York, built it as part of a 240,000 U.S. dollar fixed-price contract.
NASA specified the overall design with a geometric configuration which had been investigated by Boeing Commercial Airplanes in Seattle, Washington.
The Rutan Aircraft Factory in Mojave, California, provided the detailed design and stress analysis for the low-speed and low-cost aircraft ( it was internally referred to as the Model 35). The low speed and low cost, limited of course, the complexity of the vehicle and the test frame on the technical feasibility.
The first flight took place on 21 December 1979 with the NASA research pilot Thomas C. McMurtry at the wheel. This steered the aircraft even at its last flight on 7 August 1982.
Another well-known test pilot who was involved in the project, Pete Knight was.
Powered by two small turbojet engines TRS18 -046, which were limited for safety for every 1 kN static thrust at sea level, the aircraft reached a speed of 280 km / h
The AD-1 was 11.8 m long and had a wingspan of 9.8 m in vertical gestelltem wings. It consisted of fiberglass reinforced plastic (FRP ), the surface was separated by rigid foam of the structure. She had a total weight of 2145 lbs and a curb weight of 1450 pounds. A fixed tricycle landing gear, which was mounted close to the fuselage to reduce drag, gave the aircraft on the ground with a height of 2.06 m, a very unusual appearance.
The wing was rotated by an electrically driven gear that was located in the fuselage forward of the engines.
Flight research
The research program to validate the oblique wing concept was typical for all NASA projects with high risk. With the help of each test element of the operation range has been expanded. The basic objective of the AD - 1 project was to investigate the characteristics of an oblique - wing configuration at low speeds.
The AD-1 had its maiden flight the end of 1979. The wing rotation was in the next 18 months piecewise increased until mid-1981, the full 60 -degree angle was reached, however, turned out problems with the flight control by the nonuniform distribution of lift on the wing.
Then the plane was up to his last flight in August 1982 further tested to obtain data for different speeds and wing angle.
The last flight of the AD-1 was not in Dryden instead, but at the annual air show of the Experimental Aircraft Association (EAA ) in Oshkosh, Wisconsin, where it was flown eight times to show off its unique configuration.
After completion of the test program was the AD-1 decommissioned and is now on display at Hiller Aviation Museum in San Carlos, California.
After the end of the flight test program, Jones continued to investigate oblique - wing concepts for long-haul transport aircraft, but with control problems were also at angles above 45 degrees. The fiberglass structure of the wings limited its stiffness, which could only be compensated by a better (and more expensive ) control system otherwise.
Although the AD-1 allowed the completion of the proposed technical objectives, there was still the need for further research in the high subsonic and supersonic region with oblique wing aircraft. Thus, there are currently (until March 2008) is a 25 -month study by Northrop Grumman to this concept, the extensive wind tunnel tests up to Mach 1.3, and then the construction of a demonstrator with 17 m span provides.