AD-1

AD-1. The AD-1 was a unique experimental aircraft designed and flown by NASA to investigate the flight characteristics of an oblique wing configuration. Conceived by aeronautical engineer Robert T. Jones at the NASA Ames Research Center, the aircraft featured a single wing that could pivot on its center point to angles up to 60 degrees during flight. This research program aimed to gather data on the potential efficiency benefits of oblique wings for future high-speed transport aircraft.

Design and development

The design and development of the AD-1 was driven by theoretical studies, primarily by Robert T. Jones, which suggested an oblique wing could offer superior aerodynamic efficiency at high subsonic and low supersonic speeds compared to traditional swept-wing designs. The program was managed by the NASA Ames Research Center in California, with the airframe constructed by the Burt Rutan-led company Rutan Aircraft Factory due to their expertise in building lightweight, composite experimental aircraft like the VariEze. The AD-1 was a small, subscale research vehicle made primarily from fiberglass and foam to minimize weight and cost. Its most distinctive feature was the single-piece wing, pivoted by an electric motor in the center fuselage, which allowed the pilot to adjust the sweep angle from zero to 60 degrees in flight. The aircraft was powered by two small turbojet engines and featured a fixed tricycle landing gear. The cockpit was equipped with instruments to monitor structural loads and flight parameters, transmitting data to engineers on the ground during test flights.

Operational history

The AD-1's operational history consisted entirely of its NASA flight test program. The aircraft, bearing NASA tail number N805NA, made its first flight on 21 December 1979 at the Dryden Flight Research Center (now the Armstrong Flight Research Center) with NASA pilot Thomas C. McMurtry at the controls. Over the next three years, a series of test pilots, including John Manke and William H. Dana, flew the aircraft to gradually expand its flight envelope and wing-sweep angles. The program successfully demonstrated that the oblique wing concept was mechanically feasible and controllable in flight. However, pilots reported increasingly poor handling qualities, including significant adverse yaw and reduced control authority, as the wing was pivoted to angles beyond 45 degrees. The final flight of the AD-1 occurred on 7 August 1982, after which the aircraft was retired, having fulfilled its research objectives. Data from the program contributed to ongoing studies in aeroelasticity and unconventional aircraft configurations but did not lead directly to a production aircraft.

Aircraft on display

Following the conclusion of its flight research program, the sole AD-1 was placed into storage. It is now part of the permanent collection of the Hiller Aviation Museum in San Carlos, California. The aircraft is displayed as a static exhibit, allowing the public to view its unique oblique wing design firsthand. Its preservation at this museum highlights its role in the history of American aviation experimentation and NASA's research into advanced flight concepts.

Specifications (AD-1)

* **Crew:** 1 * **Length:** 38 ft 8 in (11.8 m) * **Wingspan:** 32 ft 3 in (9.8 m) at 0° sweep * **Height:** 6 ft 3 in (1.9 m) * **Wing area:** 93 sq ft (8.6 m²) * **Empty weight:** 1,450 lb (658 kg) * **Gross weight:** 2,000 lb (907 kg) * **Powerplant:** 2 × Microturbo TRS 18 turbojet engines, 220 lbf (0.98 kN) thrust each * **Maximum speed:** 200 mph (322 km/h, 173 kn) * **Service ceiling:** 12,000 ft (3,700 m)

Category:United States experimental aircraft 1970–1979 Category:NASA aircraft Category:Canard aircraft Category:Ames Research Center Category:Oblique-wing aircraft