Northrop YA-9

YA-9
Role	Attack aircraft
Manufacturer	Northrop
First flight	30 May 1972
Status	Canceled
Primary user	United States Air Force NASA
Number built	2

The Northrop YA-9 was a prototype attack aircraft developed for the United States Air Force A-X program. The YA-9 was passed over in preference for the Fairchild Republic YA-10 that entered production as the A-10 Thunderbolt II.

Criticism that the U.S. Air Force did not take close air support seriously prompted a few service members to seek a specialized attack aircraft. In the Vietnam War, large numbers of ground-attack aircraft were shot down by small arms, surface-to-air missiles, and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. Fast jets such as the North American F-100 Super Sabre, Republic F-105 Thunderchief, and McDonnell Douglas F-4 Phantom II proved for the most part to be ineffective for close air support. The Douglas A-1 Skyraider was the USAF's primary close air support aircraft.

In mid-1966, the U.S. Air Force formed the Attack Experimental (A-X) program office. On 6 March 1967, the Air Force released a request for information to 21 defense contractors for the A-X. The objective was to create a design study for a low-cost attack aircraft. Discussions with A-1 Skyraider pilots operating in Vietnam and analysis of the effectiveness of current aircraft used in the role indicated the ideal aircraft should have long loiter time, low-speed maneuverability, massive cannon firepower, and extreme survivability; an aircraft that had the best elements of the Ilyushin Il-2, Henschel Hs 129 and Skyraider. While turboprop engines were requested in the initial request, by May 1969, requirements had changed to specify use of turbofan engines.

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