NASA’s Ames-Dryden-1 (AD-1) aircraft was designed to investigate the concept of an oblique (pivoting) wing. The wing could be rotated about its center pivot so that it could acquire a more efficient angle for each speed at which the aircraft flew. In 1945, NASA engineer Robert T. Jones proposed the idea of converting the entire wing into a hinge pin, which should provide much lighter and more durable designs. It was supposed to turn the wing counterclockwise (as seen from above), i.e. the right wing would turn towards the nose of the aircraft and the right wing towards the tail. The wing of an asymmetrically variable sweep or turn, oblique wing is popularly known as the wing scissors.
Plans for the creation of large supersonic transport aircraft seemed to become a reality. In fact, he was not the discoverer of the rotary wing idea. By 1944, several German companies were developing such aircraft to achieve higher speeds. The first of these was Blohm und Voss with a BV P 202, which later became the Messerschmitt Me P 1109 with two rotary wings, upper and lower.
According to Jones’ calculations, the aircraft with a tilt wing was supposed to increase the takeoff weight of the aircraft by 17 percent or increase the flight range by 29 percent while maintaining the weight of the aircraft. A model wind tunnel test conducted at the Ames Research Center at Moffett Field, California, showed that an aircraft with a similar wing pattern would enable a supersonic speed that would lead to twice the fuel savings compared to aircraft with conventional wings.
During takeoff and on transition from a supersonic barrier. In addition, wind tunnels showed that an aircraft with a scissor wing at speeds up to Mach 1.4 (1.4 times faster than the speed of sound) will have significantly better aerodynamic characteristics than aircraft with conventional wings. A contract was signed with Rutan Aircraft Factory to develop the design of a low-speed aircraft to perform a series of test flights and study this unique flight mode outside the wind tunnel.
The creation of AD-1 began on Rutan Aircraft Factory’s own initiative to meet NASA requirements in December 1975. In December, 1976, Rutan Aircraft Factory reported that they had completed the detailed design of a research aircraft for NASA using VariEze technology. The NASA aircraft turned out to be a small pilot, designed to test the handling characteristics of the future (in 1990s).
NASA chose a design based on a geometric configuration provided by Boeing. The aircraft was manufactured in 15% scale of the planned Boeing transport aircraft. The sloping wing remained perpendicular to the fuselage centerline during low-speed flight and rotated at angles up to 60 degrees as the aircraft speed increased.
The AD-1 design allowed the project to achieve all basic technical tasks. As expected, the aircraft demonstrated aero-elastic phenomena, as well as the connection of pitch and roll motions, which contributed to poor control at sweep angles above 45 deg.
The fiberglass structure has limited the stiffness of the wing, which could significantly improve how the aircraft was controlled. After the completion of the AD-1 project, it was still necessary to investigate an oblique wing at supersonic speeds to evaluate the effect of compression, structural strength, and analysis of flight characteristics at supersonic speeds.
NASA classified the wing scissors project for high-risk projects. They were more interested in the behavior of the aircraft with such a wing at low speeds. Testing continued for 18 months, gradually increasing the wing rotation angle. By mid-1981, the rotation angle was reached at 60 degrees. Final flights of the aircraft were conducted at the annual Experimental Aircraft Association in Oshkosh, Wisconsin, making eight flights there to demonstrate the wing concept. In the tests, the aircraft reached an altitude of 3800 meters.
