Under the designation Northrop YA-9A, the company built two prototypes of a single-seat close-support aircraft as the company's submission for the competitive development phase of the USAF's A-X close-support aircraft competition in late 1972. A cantilever high-wing monoplane, powered by two 2722kg thrust Avco Lycoming ALF 502 turbofan engines, the first of the prototypes made its maiden flight on 30 May 1972. In competitive evaluation the YA-9A lost out to the YA-10A by Fairchild Republic.
Both of the A-9s built were passed on to NASA for further tests and were later retired to museums.
The first of only A-9A built, 71-1367, first flew on May 30, 1972 and at the end of its military career was put on display at the Castle Air Force Base Museum, until its move back to Edwards.
Engines: 2 x Lycoming F-102-LD-100, 33.4kN
Max take-off weight: 18160 kg / 40036 lb
Empty weight: 10318 kg / 22747 lb
Wingspan: 17.7 m / 58 ft 1 in
Length: 16.3 m / 53 ft 6 in
Height: 5.2 m / 17 ft 1 in
Wing area: 54.9 sq.m / 590.94 sq ft
Max. speed: 740 km/h / 460 mph
Cruise speed: 740 km/h / 460 mph
Range w/max.fuel: 4800 km / 2983 miles
Armament: 1 x 30mm machine-guns, 7264kg of bombs and missiles