A-9A
The Northrop A-9A was a large ground-attack aircraft which was designed in competition with the A-10 in the mid 1970's for the A-X requirement. The Air Force requirement for a dedicated Close Air Support (CAS) / ground attack aircraft included the ability to operate from short unimproved runways, have a long loiter time over the battlefield area, and have a relatively high cruise speed to get from the home field to the battle field. The winner of the A-X fly-off would incorporate the 30mm GAU-8 cannon into production aircraft, but the gun was under parallel development during the A-X competition and wasn't ready for flight testing during the fly-off between October and December 1972.
Models underwent basic aerodynamic testing and evaluation in Arnold Engineering Development Center's 16-foot transonic propulsion wind tunnel in 1971. The first flight of the A-9A was on 30 May 1972 and the fly-off competition ran between 10 October and 9 December 1972.
The A-9A was a high wing, twin engine, single place aircraft. Designed to provide extremely stable platform for bombing accuracy and for exceptional maneuverability, the plane had large flight control surfaces. The engines were specifically designed for the project by Lycoming. Each of the YF102-LD-100 turbofans developed 7,500 lbs. of thrust at maximum power. It was also designed to be extremely durable and rugged since most of its flight time was to be spent close to the ground, in range of enemy guns. Like the A-10, it carried many "hard points" for weaponry beneath its wings. Offensive firepower consisted of a 20mm "Vulcan" cannon and up to 16,000 lbs. of ordnance carried on 10-12 external wing stations. The underwing pylons could carry almost all arms in Air Force inventory. All flight control systems were backed up by identical systems and all vital areas were protected with aluminum alloy armor of 1.25 to 2.5 inches.
The Air Force selected the A-10 as the winner of the A-X fly-off on 18 January 1973. Although it was not chosen for production, the A-9A was a formidable aircraft in its own right. The two prototype A-9A's were transferred to NASA for flight testing before being retired. One A-9A is currently in the March Field Museum at March Air Force Base. The other is on display at the Castle Air Museum in California.
