A-X Attack Fighter - Fly-Off

Pierre Sprey wrote the requirements for the A-X fly-off. The USAF issued the final RFP in May 1970. Four months later, the USAF selected Northrop and Fairchild to build A-X prototypes for a fly-off competition - the Competitive Prototype Phase [CPP]. The A-X program was the first to conduct a competitive prototype fly-off, something that Secretary of the Air Force John McLucas strongly advocated. In a lengthy competition the Northrop A-9A and Fairchild A-10A were pitted against each other in flyoff contests throughout 1972.

The prototype contract costs were estimated to be $28 million for Northrop and $41.1 million for Fairchild-Hiller. The DOD-selected acquisition report for the A-X as of June 30, 1971, estimated the competitive flyoff phase to be $84.5 million. The total research, development, test, and evaluation costs were estimated to be $281.2 million.

The Air Force spent approximately $2.5 million to test A-X fuel tank replicas for survavability / vulnerabllity duriag CPP. These tests were performed on realistic production configuration sections of the A-9 and A-10 aircraft. The cost was not included as part of total program cost because the testing was separately funded. SPO offaclals stated that test results also applied to other aircraft, since test data had never been acquired for the specific enemy projectiles used in the tests.

The CPP was conducted against a set of performance goals with minimum design constraints imposed by the Goverrmmnt. The competing contractors were encouraged to seek ways of reducmng unit costs below the $1.4 millon goal us well as reducing the operatzonal and support costs while keeping system performance degradation to a minimum. The contractors were requested to submit budgetary estimates for production of 600 aircraft at a peak rate of 20 per month stated in 1970 dollars as part of their full-scale development proposals.

The Air Force flight evaluation of the prototype aircraft was conducted at the Air Force Flight Test Center, Edwards Air Force Ease, California, between October and December 1972. Representatives from the Air Force Flight Test Center, Tactical Air Command, Logistics Command; and Training Command participated in the evaluation of the weapons delivery, performance, and operational utility of each aircraft.

The flight schedules were arranged so that each of the aircraft were flown at the same time and under the same cond.itions on identical‘ missions. In addition, the Air Force pilots rotated between the aircraft thereby compensating for differences in individual pilots. The competing contractors informed us that in their opinion the flight evaluation was conducted fairly and objectively.

Although the A-10 fell short of some performance goals established at the beginning of the program, the Air Force concluded that it was more suitable for the A-X close air support mission than the A-9. For example, the A-lo’s high-fuselage engine mounting reduced the likelihood of engine damage from foreign objects while operating on unimproved runways. Its wide pylon spacing provided more armament carrying flexibility and enhanced armament loading. In addition, the Air Force rated the A-10 as easier to maintain than the A-9.

The Air Force also determined that the A-10 was the most survivable candidate. For example, it survivability was en- Ilanced by the redundancy and wide separation of critical flight control elements, and by the combination of passive fire protection measures provided. The engine location and firewall protection also reduced the overall aircraft vulnerability to an engine fire.

The Air Force considered the extent of and the risk associated with changes required to the prototype aircraft design to make it suitable for production. The key factor that favored the A-10 in this area was the similarity of the prototype to the proposed production configuration. Because of this similarity the A-10 prototype aircraft can be used more extensively during developmental flight tests than could the A-9 prototype. This will allow Fairchild to start their flight test effort almost immediately thereby providing more time for developmental testing and operational evaluation prior to the production decision.

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