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Vought A-7DE Upgraded fuslage 30%+300%=330%_AV

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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 is 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.


Contents
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.[2] 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.[2]

In December 1962, the Sea-Based Air Strike Forces (SBASF) study group started examining detailed performance and cost evaluations on the topic.[2] 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.[2] 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.[2] A particular emphasis was placed on the accurate delivery of weapons, which would reduce the munitions costs per target.[3]

On 17 May 1963, these criteria were formulated into a draft requirement, known as VAL (Heavier-than-air, Attack, Light).[3] On 29 May 1963, the request for proposals (RFP) associated with the requirement was issued.[2] To minimize costs, all proposals had to be based on existing designs.[3] 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.[3]

All bids were received by September 1963 and the evaluation process was completed in early November of that year.[2] 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.[2] On 19 March 1964, Vought received a contract from the Navy for the manufacture of the initial batch of aircraft, designated A-7.[3] On 22 June 1964, the mock-up review took place.[2] In 1965, the A-7 received the name Corsair II; Vought had previously produced two aircraft known as "Corsair". During the 1920s, they had produced the O2U Corsair biplane scout and observation aircraft; 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; the obscure O2U was not considered, which is why the name "Corsair III" was not adopted.

Into production


The first A-7 mock-up in 1964

On 27 September 1965, the first A-7A performed the type's maiden flight.[2][4] 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 250 lb (110 kg) and twelve 500 lb (230 kg) 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.[5]

The flight test programme 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 programme 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.[6] On 14 October 1966, enough aircraft had been delivered to the Navy that the first squadron could be formed.[2] 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.[7]

The June 1964 contract had ordered the completion of seven development aircraft and 35 production-standard fighter bombers.[8] 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.[8] 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.[8] 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.[8] The adoption of a British engine caused some political controversy on both sides of the Atlantic.[6]

During 1967, the Navy decided to cancel its order for the A-7B, resulting in 257 aircraft less of this variant being constructed.[6] 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.[9] On 25 November 1968, the first A-7E conducted its first flight; a total of 535 aircraft of this variant would be manufactured.[10] 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.[11] During 1983, the final delivery of a new-build A-7 took place.[1]

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 15,000 lb (6,800 kg) of bombs or other equipment.[5] According to Gunston and Gilchirst, there were no common structural features shared between the two aircraft despite their visual similarity and shared heritage.[2]

The A-7 had fully powered flight controls, as did the F-8.[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.[8] 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.[8]




VA-147 was the first operational USN A-7 squadron, in 1967.

To achieve the required range, initial versions of the A-7 were powered by a single Pratt & Whitney TF30-P-6 turbofan engine, which produced 11,345 lbf (50.47 kN) of thrust.[3] It had replaced the afterburner-equipped Pratt & Whitney J57-P-20A turbojet engine of the F-8.[5] The same engine had also powered several other combat aircraft of the era, including the General Dynamics F-111 Aardvark and early Grumman F-14 Tomcats. The TF30-P-6 did not require an afterburner for its subsonic role.[2]

Later versions of the A-7 used different engines; according to Gunston and Gilchrist, this was largely due to production difficulties in keeping up with numerous military and civil demands.[8] These new powerplants included the more powerful Pratt & Whitney TF30-8 and the Allison TF41-A-2 engines, a licensed model of the Rolls-Royce Spey engine. The TF41 corrected issues that had troubled initial A-7 operations, such as severe compressor stalls and low thrust.[8] The Air Force A-7D had self-contained starting using internal batteries and a gas turbine starter. The Navy A-7E used an air turbine starter driven by an external air supply.

Air was fed to the engine through ducting from a simple nose inlet, similar to that on the F-8, despite the potential hazard it posed to flight deck personnel.[8] An aerial refueling probe was mounted on the righthand side of the nose.[8] Two cannon were installed on the underside of the nose. For self-defense against aerial threats, the A-7, in addition to the cannon, had a mounting for AIM-9 Sidewinder air-to-air missiles on either side of the fuselage.[8] Later variants had the two cannon replaced with a single M61A1 Vulcan rotary cannon, along with other improvements.[8] To reduce vulnerability to ground fire the flying control hydraulic systems were triplicated, other systems duplicated and much of the fuselage had armor protection.[12]

The A-7 was fitted with an AN/APQ-116 radar, later followed by the AN/APQ-126, which was integrated into the ILAAS digital navigation system. The radar also fed an IBM navigation and weapons delivery computer which made possible accurate delivery of bombs from a greater stand-off distance, greatly improving survivability compared with faster aircraft such as the McDonnell Douglas F-4 Phantom II.[13] It was the first U.S. aircraft to have a modern head-up display, (made by Marconi-Elliott),[14] now a standard instrument, which displayed information such as dive angle, airspeed, altitude, drift and aiming reticule. The integrated navigation system also had another innovation—the projected map display system (PMDS) which accurately showed aircraft position on two different map scales.[15]

The A-7 had more modern avionics and systems than contemporary aircraft. This included data link capabilities that, among others, provided "hands-off" carrier landing capability when used with its approach power compensator (APC) or auto throttle. Other notable and advanced equipment was a projected map display located just below the radar scope. The map display was slaved to the inertial navigation system and provided a high-resolution map image of the aircraft's position superimposed over TPC/JNC charts. Moreover, when slaved to the all-axis auto pilot, the inertial navigation system could fly the aircraft "hands off" to up to nine individual waypoints. Typical inertial drift was minimal for newly manufactured models and the inertial measurement system accepted flyover, radar, and TACAN updates.[16]

Operational history
Introduction and early operations
Initial operational basing/homeporting for USN A-7 squadrons was at NAS Cecil Field, Florida for Atlantic Fleet units and NAS Lemoore, California for Pacific Fleet units. This was in keeping with the role of these bases in already hosting the A-4 Skyhawk attack squadrons that would eventually transition to the A-7.




Lynn Garrison in a Chance Vought F4U-7 Corsair leads A-7 Corsair IIs of VA-147, over NAS Lemoore, California on 7 July 1967 prior to the A-7's first deployment to Vietnam on USS Ranger. The A-7A "NE-300" is the aircraft of the Air Group Commander (CAG) of Attack Carrier Air Wing 2 (CVW-2).

From 1967 to 1971, a total of 27 US Navy squadrons took delivery of four different A-7A/B/C/E models. The Vought plant in Dallas, Texas, employed up to 35,000 workers who turned out one aircraft a day for several years to support the navy's carrier-based needs for Vietnam and SE Asia and commitments to NATO in Europe. In 1974, when USS Midway became the first and only aircraft carrier to be homeported in Yokosuka, Japan, two A-7A squadrons assigned to Carrier Air Wing Five (CVW-5) were moved to NAF Atsugi, Japan. In 1976, these squadrons (VA-93 and VA-56) finally transitioned to the much more advanced A-7E model.[citation needed] Six Naval Reserve attack squadrons would also eventually transition to the A-7, operating from NAS Cecil Field, Florida; NAS Atlanta/Dobbins ARB, Georgia; NAS New Orleans, Louisiana; NAS Alameda, California and NAS Point Mugu, California. An additional active duty squadron stood up in the 1980s, Tactical Electronic Warfare Squadron 34 (VAQ-34) at NAS Point Mugu, operating twin-seat TA-7C and EA-7L aircraft with both a pilot and a naval flight officer in an adversary electronic warfare role.[17]

Pilots of the early A-7s lauded the aircraft for general ease of flying (with the exceptions of poor stability on crosswind landings and miserable stopping performance on wet runways with an inoperative anti-skid braking system) and excellent forward visibility but noted a lack of engine thrust. This was addressed with A-7B and more thoroughly with A-7D/E. The turbofan engine provided a dramatic increase in fuel efficiency compared with earlier turbojets—the A-7D was said to have specific fuel consumption one sixth that of an F-100 Super Sabre at equivalent thrust. An A-7D carrying twelve 500 lb (230 kg) bombs at 480 mph (770 km/h) at 33,000 ft (10,000 m) used only 3,350 lb (1,520 kg) of fuel per hour. Typical fuel consumption at mission retrograde during aircraft carrier recovery was approximately 30 pounds per minute (14 kg/min) compared to over 100 pounds per minute (45 kg/min) for the Phantom F-4J/N series.[18] The A-7 Corsair II was tagged with the nickname "SLUF" ("Short Little Ugly Fucker") by pilots.[19]

Southeast Asia carrier use


A-7Bs of CVW-16 on USS Ticonderoga in 1968

In Vietnam, the hot, humid air robbed all jet engines of power, and even the upgraded A-7D and A-7E fell short of their required power levels when serving in these conditions. Takeoff rolls were lengthy, and fully armed aircraft struggled to reach 500 mph (800 km/h). For A-7A aircraft, high-density altitude and maximum-weight runway takeoffs often necessitated a "low transition", where the aircraft was intentionally held in "ground effect" a few feet off the runway during gear retraction, and as much as a 10 mi (16 km) departure at treetop altitude before reaching a safe flap-retraction speed. (A-7A wing flap systems were either fully extended or fully retracted. The A-7A flap handle did not have the microswitch feature of later models that permitted the flaps to be slowly raised by several degrees per tap of the flap handle as airspeed slowly increased during max-weight takeoffs.

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