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AX Close Air Support Project

Posted 12/31/2008 Printable Fact Sheet

The attack designation was dropped in 1947, and the attack mission was absorbed by other aircraft classes, primarily fighters and bombers. The USAF strategic doctrine of the 1950s and 1960s was based upon the mass retaliation and mutually assured destruction theories of nuclear warfare. Most bombers developed during this period were designed primarily as nuclear weapons delivery vehicles. Additionally, fighters were developed as high altitude interceptors, air superiority fighters or fighter-bombers. Most fighters were capable of delivering nuclear weapons. The Close Air Support and ground attack missions were considered secondary roles for these fighters and bombers.

During the Southeast Asia War, it became clear that the USAF was in need of a dedicated CAS aircraft. Many aircraft were used successfully in the CAS/ground attack role in Vietnam, but all had limitations. For example, the Douglas A-1 and LTV A-7 were used effectively; however, the A-1s were getting old, and the A-7 did not have the maneuverability to operate at low altitudes in confined areas.

A number of fighters (and fighter-bombers) were used as well. The McDonnell Douglas F-4, North American F-100, Republic F-105 and General Dynamics F-111 were all moderately effective ground attack aircraft, but like the A-7, they lacked the maneuverability to operate in very close proximity to friendly troops under enemy attack. A number of cargo aircraft were modified for use as side firing gunships. The Douglas AC-47, Fairchild AC-119 and Lockheed AC-130 were used effectively in the interdiction and ground attack roles, particularly at night. Finally, the USAF used some modified trainer aircraft in the counter insurgency and ground attack roles; two examples are the North American T-28 and Cessna A-37.

In addition to the Air Force's need for a dedicated CAS aircraft, the Army was fighting for development of its own specialized aircraft: the AH-56 Cheyenne helicopter. The AV-8 Harrier was also being considered for a dedicated CAS role. Interservice rivalry was particularly intense during this time, but the USAF persisted because of the role "to furnish close combat and logistic air support to the Army" was outlined in the Unified Command structure publication (JCS 2) giving the CAS mission responsibility to the Air Force.

The need for a CAS and ground attack aircraft designed specifically for those roles was apparent and in the spring of 1970, the AX System Program Office was established at the Aeronautical Systems Division at Wright-Patterson Air Force Base, Ohio. On May 8, 1970, the AX SPO issued a request for proposal to 12 aircraft manufacturers. Six of the 12 companies who received the RFP responded with proposals: Boeing, Cessna, Fairchild Hiller, General Dynamics, Lockheed and Northrop. On Dec. 18, 1970, the Northrop and Fairchild Hiller entries were selected for prototype construction. The USAF intended to test the prototype aircraft in a "Fly Before Buy" competition.

Because the AX aircraft would be used primarily in support of ground troops, the Army had significant input into the necessary characteristics of the aircraft. The AX needed "to perform in close coordination with ground troops, in a high intensity, small-arms fire environment, and for extended periods of time with a high payload. The requirement for fast response to Army needs is to be met three ways: 1) the aircraft will have short takeoff and landing (STOL) characteristics and rugged landing gear which will permit it to operate from unimproved landing fields; 2) it will have a long loiter time, giving it the capability to remain over the battlefield where it will be on call at a moment's notice; and 3) the aircraft will have a rather high cruise speed to allow rapid deployment from home field to battle area, or from one battle area to another. The AX should be able to take off and land from 2,000-foot runways" (Armed Forces Journal, October 1970).

One of the primary requirements of the AX RFP was the ability to carry the GAU-8 30mm cannon; however, this weapon did not exist at the time and a separate RFP for the GAU-8 was issued on Nov. 16, 1970.

On March 1, 1971, the Northrop AX prototype was designated A-9 and the Fairchild Hiller AX prototype was designated A-10. In June the GAU-8 competitive design and prototype construction contracts were awarded to General Electric and Philco Ford.

The A-10 prototype flew for the first time on May 10, 1972, followed by the A-9's first flight on May 30, 1972. The fly-off competition was held between Oct. 10, and Dec. 9, 1972. On Jan. 18, 1973, the Fairchild Hiller (Fairchild Republic by this time) entry was declared the winner and a $160 million contract was signed for 10 pre-production aircraft (YA-10) on March 1. The contract awarded for the development and construction of 32 General Electric TF34 turbofan engines was also signed on March 1.

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