History
Background
_(7911148090).jpg)
The development of conventionally armed attack aircraft in the United States stagnated after World War II,[6] as design efforts for tactical aircraft focused on the delivery of nuclear weapons using high-speed designs such as the McDonnell F-101 Voodoo and Republic F-105 Thunderchief.[7] As the U.S. military entered the Vietnam War, its main ground-attack aircraft was the Korean War-era Douglas A-1 Skyraider. A capable aircraft for its era, with a relatively large payload and long loiter time, the propeller-driven design had become relatively slow, vulnerable, particularly to ground fire, and incapable of providing adequate firepower. The U.S. Air Force and Navy lost some 266 A-1s in action in Vietnam, largely from small-arms fire.[8][9]
The lack of modern conventional attack capability prompted calls for a specialized attack aircraft.[10][11] On 7 June 1961, the Secretary of Defense Robert McNamara ordered the USAF to develop two tactical aircraft, one for the long-range strike and interdictor role, and the other focusing on the fighter-bomber mission. The former was the Tactical Fighter Experimental (TFX) intended to be a common design for the USAF and the US Navy,[12] which emerged as the General Dynamics F-111 Aardvark, while the second was filled by a version of the U.S. Navy‘s McDonnell Douglas F-4 Phantom II. While the Phantom went on to be one of the most successful fighter designs of the 1960s and proved to be a capable fighter-bomber, its short loiter time was a major problem, as was its poor low-speed performance, albeit to a lesser extent. It was also expensive to buy and operate, with a flyaway cost of $2 million in FY1965 ($20.4 million today), and operational costs over $900 per hour ($9,000 per hour today).[13]
After a broad review of its tactical force structure, the USAF decided to adopt a low-cost aircraft to supplement the F-4 and F-111. It first focused on the Northrop F-5, which had air-to-air capability.[9] A 1965 cost-effectiveness study shifted the focus from the F-5 to the less expensive A-7D variant of the LTV A-7 Corsair II, and a contract was awarded. However, this aircraft doubled in cost with demands for an upgraded engine and new avionics
