The LTV A-7 Corsair II is an American carrier-capable subsonic light attack aircraft designed and manufactured by Ling-Temco-Vought (LTV).
The A-7 was developed during the early 1960s as replacement for the Douglas A-4 Skyhawk. Its design was derived from the Vought F-8 Crusader; in comparison with the F-8, the A-7 is both smaller and restricted to subsonic speeds, its airframe being simpler and cheaper to produce. Following a competitive bid by Vought in response to the United States Navy's (USN) VAL (Heavier-than-air, Attack, Light) requirement, an initial contract for the type was issued on 8 February 1964. Development was rapid, first flying on 26 September 1965 and entering squadron service with the USN on 1 February 1967. By the end of that year, A-7s were being deployed overseas for the Vietnam War.
Initially adopted by USN, the A-7 proved attractive to other services, soon being adopted by the United States Air Force (USAF) and the Air National Guard (ANG) to replace their aging Douglas A-1 Skyraider and North American F-100 Super Sabre fleets. Improved models of the A-7 would be developed, typically adopting more powerful engines and increasingly capable avionics. American A-7s would be used in various major conflicts, including the Invasion of Grenada, Operation El Dorado Canyon, and the Gulf War. The type was also used to support the development of the Lockheed F-117 Nighthawk.
The A-7 was also exported to Greece in the 1970s and to Portugal in the late 1980s. The USAF and USN opted to retire their remaining examples of the type in 1991, followed by the ANG in 1993 and the Portuguese Air Force in 1999. The A-7 was largely replaced by newer generation fighters such as the General Dynamics F-16 Fighting Falcon and the McDonnell Douglas F/A-18 Hornet. The final operator, the Hellenic Air Force, withdrew the last A-7s during 2014.
Development Origins In 1960, officials within the United States Navy (USN) began to consider the need to replace its existing fleet of Douglas A-4 Skyhawk, a light attack aircraft. At that time, it was not clear that the A-4 would eventually remain in production until 1979; furthermore, according to aviation authors Bill Gunston and Peter Gilchrist, some figures believed there to be an unmet requirement for a more capable attack platform that could routinely attain supersonic speeds, carry heavier payloads, and fly further than its predecessors. Proponents of a new attack aircraft included Secretary of Defense Robert McNamara, who urged the Navy's consideration on the matter.
In December 1962, the Sea-Based Air Strike Forces (SBASF) study group started examining detailed performance and cost evaluations on the topic. The group analyzed a total of 144 hypothetical aircraft to support their findings. According to Gunston and Gilchrist, a major finding from these studies was that a subsonic aircraft would achieve superior performance to a supersonic one. By foregoing a supersonic capability, the airframe could be smaller, cheaper, and easier to manufacture; considerably larger quantities of such an attack platform could be procured over a supersonic counterpart. Development speed was also increased by sticking to subsonic speeds, which was a further advantage. A particular emphasis was placed on the accurate delivery of weapons, which would reduce the munitions costs per target.
On 17 May 1963, these criteria were formulated into a draft requirement, known as VAL (Heavier-than-air, Attack, Light). On 29 May 1963, the request for proposals (RFP) associated with the requirement was issued. To minimize costs, all proposals had to be based on existing designs. Accordingly, Vought, Douglas Aircraft, Grumman and North American Aviation chose to respond. The Vought proposal was based on their successful F-8 Crusader fighter and sharing a similar configuration; however, it had a shorter airframe with a rounded nose, giving the aircraft a "stubbier" appearance.
All bids were received by September 1963 and the evaluation process was completed in early November of that year. On 8 February 1964, funding for VAL was approved by Congress, enabling the programme to proceed; three days later, Vought's submission was selected as the winner. On 19 March 1964, Vought received a contract from the Navy for the manufacture of the initial batch of aircraft, designated A-7. On 22 June 1964, the mock-up review took place. In 1965, the A-7 received the name Corsair II; Vought had previously produced three aircraft known as "Corsair". During the 1920s, they had produced the O2U Corsair biplane scout and observation aircraft and the SBU Corsair scout bomber of the 1930s. During World War II, the firm made the successful F4U Corsair. The name Corsair II reflects the well-known F4U Corsair, which famously served as a capable fighter bomber in World War II and the Korean War. It was supposed to establish a lineage between the aircraft from the same manufacturer and intended for the same ground attack role.
Into production
On 27 September 1965, the first A-7A performed the type's maiden flight. On 2 November 1965, Vought publicly demonstrated the first pair of A-7As to 1,000 guests; test pilot John Conrad demonstrated the aircraft's ability to perform rapid rolls even while laden with a payload of six and twelve bombs. A Navy spokesperson acknowledged the A-7's ability to carry double the bombload of an A-4E, or the same payload over twice its maximum distance.
The flight test program proceeded at a relatively rapid pace, during which no major setbacks were uncovered or meaningful delays were incurred. According to Gunston and Gilchrist, there were some naval officials that sought to slow the program down so that the A-7's avionics systems could be revised for greater capabilities, but this preference had been overridden by a perceived urgency to getting the type into service. On 14 October 1966, enough aircraft had been delivered to the Navy that the first squadron could be formed. The first A-7 squadrons attained operational status on 1 February 1967; these were able to commence overseas combat operations in the escalating Vietnam War during December of that year.
The June 1964 contract had ordered the completion of seven development aircraft and 35 production-standard fighter bombers. A follow-up contract, placed during September 1965, ordered 140 more aircraft. A third contract for 17 aircraft led to a total of 199 A-7A aircraft being manufactured. As the original version was found to be underpowered, a large order for 196 aircraft of the improved A-7B variant, equipped with the more powerful Pratt & Whitney TF30-8 engine, was placed. Further variants of the type would be ordered, including the A-7D for the United States Air Force (USAF), during 1966. Partially due to a shortage of engines, the Allison TF41-A-2, a licensed derivative of the Rolls-Royce Spey engine, powered the A-7D. The adoption of a British engine caused some political controversy on both sides of the Atlantic.
Further development
United States Air Force A-7D
The United States Army has not been permitted to operate fixed-wing combat aircraft since the establishment of an independent United States Air Force (USAF) in 1947. To meet its need for close air support of its troops in South Vietnam, the Army pressured the Air Force to procure a specialized subsonic close air support fixed-wing aircraft that would suit its needs better than the general-purpose supersonic aircraft that the USAF preferred.Munzenmaier 2009.
The Vought A-7 seemed to be a relatively quick and inexpensive way to satisfy this need. However, the USAF was initially reluctant to take on yet another Navy-designed aircraft, but Secretary of Defense Robert McNamara was insistent. On 5 November 1965, Secretary of the Air Force Harold Brown and USAF Chief of Staff General John P. McConnell announced that they had decided to order a version of the Corsair II, designated A-7D, for the Tactical Air Command.
The A-7D differed from the Navy's Corsair II in several ways. For one, the USAF insisted on significantly more power for its Corsair II version, and it selected the Allison TF41-A-1 turbofan engine, which was a license-built version of the Rolls-Royce Spey. It offered a thrust of , over greater than that of the TF30 that powered the Navy's Corsair IIs. Other changes included a head up display, a new avionics package, and an M61A1 rotary cannon in place of the two single-barreled 20-mm cannon. Also included was a computerized navigation/weapons delivery system with AN/APQ-126 radar and a head-up display.
Two YA-7D prototypes were completed with TF30-P-6 engines, and the first of these flew on 6 April 1968. The first Spey-powered A-7D (67-14854) flew for the first time on 26 September 1968. The seventeenth production aircraft introduced a provision for boom flight refueling in place of the Navy's retractable starboard-side probe/drogue system, with the boom receptacle being on the top of the fuselage behind the cockpit and offset to port.
Improved A-7E
The Navy was sufficiently impressed with the increased power offered by the A-7D Spey engine used by the Air Force, and decided to use this engine for its own version of the Corsair II. The designation A-7E was assigned, and this version was to succeed the A-7B in production. However, there were delays in the deliveries of the TF41-A-2 engine specified for the A-7E, so the first 67 aircraft of the order were delivered with the TF30-P-8 engine. These aircraft had all of the other improvements planned for the A-7E, including the improved avionics and the M61 rotary cannon, and were re-designated A-7C after delivery.
During 1967, the Navy decided to cancel its order for the A-7B, resulting in 257 aircraft less of this variant being constructed. Taking its place, the A-7E, the definitive model of the aircraft, was specified and placed into production. This variant integrated several of the improvements of the USAF's A-7D, including the TF41 engine and much of its avionics; however, the engine was revised for slightly more thrust and the communications modified for compatibility with naval systems. On 25 November 1968, the first A-7E conducted its first flight; a total of 535 aircraft of this variant would be manufactured. During the 1970s and 1980s, several specialised models, such as the TA-7C for training and EA-7L for electronic warfare, were developed as well. During 1983, the final delivery of a new-build A-7 took place.
Design The LTV A-7 Corsair II was a carrier-capable subsonic attack fighter. It was a derivative of the Vought F-8 Crusader, an earlier fighter; compared to the Crusader, it had a shorter, broader fuselage, and a longer-span wing but without the Crusader's variable-incidence feature. The A-7's wing was not only larger but had reduced sweepback, as well as six pylons with the carriage of up to of bombs or other equipment. According to Gunston and Gilchrist, there were no common structural features shared between the two aircraft despite their visual similarity and shared heritage.
The A-7 had fully powered flight controls, as did the F-8. However, conventional outboard ailerons were used (instead of the drooping ailerons mounted inboard of the wing-fold of the F-8 and doubling as flaps when flaps were deployed), along with large slotted flaps on the wing's inboard area; the wing fold was between the flaps and ailerons. The wing leading edge was fixed and had a dog-tooth discontinuity. A large air brake was fitted on the underside of the aircraft. The three-unit landing gear retracted into the fuselage; the twin-wheel nose gear was steerable and stressed for catapult-assisted take-offs.