Fairchild Republic YA-10A (S/N 71-1370) painted as A-10A (S/N 79-223). Note the angular lower forward edge of the vertical stabilizer, an easy way to distinguish a YA-10A from an A-10A, which has a curved lower forward edge. (U.S. Air Force photo)
The design of the YA-10A had several advantages over its competitor, the Northrop A-9A. The engines were mounted high on the aft fuselage making them less susceptible to foreign object damage when operating on unimproved airfields close to the battle area. The engine location also allowed the entire wing to be used for weapons. Eleven ordnance pylons were fitted to the lower surface of the wing -- three on each outboard wing and five in the center section between the main landing gear. The engines also made it possible for maintenance and rearming "quick turns" with the engines running.
The YA-10 was designed for ease of maintenance, ruggedness and survivability in combat. The aircraft included a number of off-the-shelf components including the use of the General Electric TF34 turbofan, which was originally developed for the US Navy's S-3A Viking. The YA-10 also had many interchangeable parts. The ailerons, rudders, elevators, main landing gear and engines were all usable on either the right or left side of the aircraft. The cockpit was surrounded by a titanium "bathtub" of armor plating. The hydraulic system was triple redundant. There was also an onboard auxiliary power unit to supply compressed air for engine starting.
The fly-off with the A-9A began on Oct. 10, 1972, and concluded on Dec. 9. The competition was held at the Air Force Flight Test Center at Edwards Air Force Base, Calif., and was primarily intended to identify differences in aircraft performance. The two aircraft were equally accurate in weapons delivery and gun tests. The General Electric GAU-8 Avenger 30mm cannon was not ready during this period, so both the YA-10A and A-9A were fitted with the 20mm Vulcan cannon for testing. The YA-10A was flown a total of 138.5 hours during 87 flights while the A-9A was flown 123 times for a total of 146 hours.
Although both aircraft were judged to be acceptable close air support aircraft, the YA-10 was selected based on a number of advantages. The larger wing was easier to access for weapons loading and had more overall space for large ordnance loads. The A-10 had superior ground handling, especially on unimproved fields. The YA-10 was judged closer to an acceptable production version and could be operational in a shorter time. The A-10 was a simpler aircraft, and the USAF was confident it could meet the $1.4 million per aircraft target production cost.
AX fly-off prototype
TECHNICAL NOTES: Armament: One M61A1 20mm cannon with 660 rounds of ammunition and up to 16,000 lbs. of mixed ordnance (bombs, rockets, missiles and dispensers) and/or fuel tanks on 11 external stations Engines: Two General Electric YTF34/F5 turbofans of 9,275 lbs. thrust each Maximum speed: 450 mph/391 knots Cruising speed: 335 mph/291 knots Range: 800 statute miles Service ceiling: 44,200 ft. Span: 55 ft. Length: 52 ft. 7 in. (less boom) Height: 14 ft. 8 in. Weight: 45,600 lbs. maximum takeoff Crew: One
Serial numbers: 71-1369 and 71-1370