A-7 Corsair II
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The Ling-Temco-Vought A-7 Corsair II was a light attack aircraft based on the F-8 Crusader. The A-7 was one of the first combat aircraft to feature a head-up display (HUD), doppler-bounded inertial navigation system, and a turbofan engine. It served with both the United States Navy and the United States Air Force, and later with the Air National Guard. It was also exported to South Vietnam (during the Vietnam War), Greece (in the 1970s), Portugal, and Thailand (in the late 1980s).
Development
In 1962, United States Navy began preliminary work on VAX (Heavier-than-air, Attack, Experimental), a replacement for the A-4 Skyhawk with greater range and payload. A particular emphasis was placed on accurate delivery of weapons to reduce the cost per target. The requirements were finalized in 1963 and in 1964 the Navy announced the VAL (Heavier-than-air, Attack, Light) competition. Since the upcoming General Dynamics F-111B was supposed to fulfill the advanced strike role, the NAL was intended to be only an interim solution. To minimize costs, all proposals had to be based on existing designs. Vought, Douglas Aircraft, Grumman, and North American Aviation responded. The Vought proposal was selected as the winner on 11 February 1964, and on 19 March the company received a contract for the initial batch of aircraft, designated A-7. In 1965 the aircraft received the popular name Corsair II, after Vought's highly successful F4U Corsair of World War Two.The A-7 was based on the F-8 Crusader fighter but had a shorter, broader fuselage, and a larger wing. The Crusader's variable incidence wing was deleted. To achieve the required range, A-7 was powered by a Pratt & Whitney TF-30-Р-6 turbofan shared with the F-111 producing 11,345 lbf (50.5 kN) of thrust. Since supersonic performance was not required, the engine was not fitted with an afterburner. The aircraft was fitted with an AN/APQ-116 radar integrated into the ILAAS digital navigation and weapons computer. It was one of the first aircraft to have a modern heads-up display HUD which displayed information such as dive angle, airspeed, altitude, drift, and aiming reticle. The integrated navigation system allowed for another innovation -- the projected map display system (PMDS) accurately showed aircraft position on two different map scales.
The A-7 enjoyed the fastest and most trouble-free development period of any American combat aircraft since the second world war. The YA-7A made its first flight on 27 September 1965, and began to enter Navy squadron service late in 1966. The first Navy A-7 squadrons reached operation status on 1 February 1967, and began combat operations over Vietnam in December of that year.
Production of Corsairs continued through 1984. A total of 1,569 aircraft were built.
Operational history
Pilots of the early A-7s lauded the aircraft for general ease of flying (with the exception of poor stability on cross-wind landings) 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 six times less than F-100 Super Sabre at equivalent thrust. An A-7D carrying 12x 500 lb (227 kg) bombs at 480 mph (775 km/h) at 33,000 ft (10,000 m) used only 3,350 lb (1,500 kg) of fuel per hour. The integrated weapons computer provided highly accurate bombing with CEP of 60 ft (20 m) regardless of pilot experience. The doppler navigation system required a mere 2.5 minutes on the ground for partial alignment, a big improvement over 13 minutes required in F-4 Phantom II. In addition, the A-7 required only 11.5 man hours of maintenance per mission resulting in quick turnaround and high number of combat-ready aircraft. In Vietnam, the hot, humid air robbed even upgraded A-7D and A-7E of power. Takeoff rolls were lengthy and fully-armed aircraft struggled to reach 500 mph (800 km/h). Pilots quipped that the Corsair "is not very fast, but it sure is slow" (Higham 1978).-->The first US Navy A-7As were deployed to Vietnam in 1967 with VA-147 Argonauts aboard USS Ranger (CVA-61). The aircraft made their first combat sortie on 4 December 1967. In the following months, VA-147 made around 1,400 flights losing only one aircraft. In January 1968, USS Ranger participated in the incident surrounding the capture of USS Pueblo (AGER-2) in the Sea of Japan by North Korea. Improved A-7B arrived in Vietnam in early 1969, with A-7E following in 1971.
The USAF A-7Ds were also widely used in Vietnam with 354th Tactical Fighter Wing, Korat RTAFB, Thailand, entering action in October 1972. The aircraft attacked targets as far as 500 mi (800 km) from airbases, extensively utilizing mid-air refueling. The A-7Ds were quickly assigned the "Sandy mission" of providing air cover for rescue of downed pilots. Taking over for A-1 Skyraiders (hence the name "Sandy"), the A-7's higher speed was somewhat detrimental for escorting the helicopters but the aircraft's high endurance and durability were an asset and it performed admirably. On 18 November 1971, Major Colin A. Clarke led a successful mission near Thanh Hoa to rescue a downed F-105 Wild Weasel crew. The mission lasted a total of 8.8 hours during which Clarke and his wingman took a number of hits from 13 mm (0.51 cal) anti-aircraft fire. For his actions in coordinating the rescue, Clarke was awarded the Air Force Cross, the USAF's second-highest medal. The A-7D flew a total of 12,928 combat sorties during the war with only 4 losses -- the lowest of any US fighter in the theatre. The aircraft was second only to B-52 Stratofortress in the amount of ordnance dropped on Hanoi and dropped more bombs per sortie with greater accuracy than any other US attack aircraft.
USAF Corsair IIs were phased out of front-line service by the late 1970s, many aircraft passing to the Air National Guard. The 4450th Tactical Group stationed at Nellis AFB, NV had the unique distinction of being the last active USAF unit to operate the A-7D Corsair II. Navy aircraft were gradually replaced by the F/A-18 Hornet in the 1980s. The last US Corsairs were retired not long after Operation Desert Storm where the A-7Es of squadrons VA-46 and VA-72 operated from the aircraft carrier USS John F. Kennedy. Some surplus aircraft were then passed to Greece and Portugal, where they remain in service.
The A-7 Corsair II was tagged with the nickname "SLUF" (Short Little Ugly Fucker) by pilots.
Variants
- A-7A - First production version. Early USN Corsair IIs had two 20 mm Colt Mk 12 cannons with 250 rounds per gun. Maximum ordnance, carried primarily on the wing pylons, was theoretically 15,000 lb (6,804 kg), but was limited by maximum takeoff weight, so the full weapon load could only be carried with greatly reduced internal fuel. 199 built.
- A-7B - Uprated TF30-P-8 engine with 12,190 lbf (54.2 kN) of thrust. In 1971, surviving A-7B were further upgraded to TF30-P-408 with 13,390 lbf (59.6 kN) of thrust. 196 built.
- A-7C - first 67 production A-7E with TF30 engines.
- TA-7C - two-seat trainer version for US Navy, 24 converted from A-7B, 36 from A-7C. Upgraded to A-7E standard in 1984.
- A-7D - In the footsteps of recently adopting another Navy design, the F-4 Phantom II, USAF requested a version of A-7 for Tactical Air Command to fulfill the need for an inexpensive close-air support replacement for A-1 Skyraider. On 5 November 1965 the USAF announced that it would purchase a version of the A-7, designated the A-7D. The most important difference from Navy versions was adoption of the Allison TF41-A-1 turbofan, a license-built version of British Rolls-Royce Spey. With 14,500 lbf (64.5 kN) of thrust, the engine offered a considerable boost in performance. In addition, avionics were upgraded, internal armament was changed to a single 20 mm M61 Vulcan gatling cannon, and the in-flight refueling method was changed from probe-and-drogue to the boom. The YA-7D prototype with TF30 flew on 6 April 1968, with the first TF41 aircraft taking to the air on 26 September 1968. The aircraft were later updated to carry the Pave Penny laser spot tracker to add the capability to drop guided bombs. 459 built.
- A-7E - the Navy was so impressed with the performance gain of USAF A-7D that they ordered their own version with the TF41 engine. The first prototype flew on 25 November 1968. In 1986, 231 A-7E were equipped to carry the LANA (Low-Altitude Night Attack) pod which projected amplified light image on the HUD and, in conjunction with radar, provided terrain following down to 460 mph (740 km/h) at 200 ft (60 m). 529 built (not counting 67 A-7C).
- YA-7F (A-7D Plus, A-7 Strikefighter) - In 1985, USAF requested proposals for a fast strike aircraft because of concerns that A-10 Thunderbolt II was too slow for interdiction. The design called for a new engine, either the Pratt & Whitney F100 or General Electric F110. LTV responded with a supersonic version of A-7 powered by a F100-PW-220 with 26,000 lbf (115.7 kN) of thrust. To accommodate the new engine, the fuselage was lengthened about 4 ft (1.22 m). New fuselage sections were inserted in both the forward and aft fuselage - a 30 in (76 cm) section in front of the wing and an 18 in (46 cm) section behind the wing. The wing was strengthened and fitted with new augmented flaps, leading edge extensions and automatic maneuvering flaps. The vertical stabilizer height was increased about 10 in (25 cm). Ironically, the end result resembled the F-8 Crusader from which the A-7 was originally derived. Two A-7D were modified, the first one flying on 29 November 1989 and breaking the sound barrier on its second flight. The second prototype flew on 3 April 1990. The project was cancelled in favor of the F-16 Fighting Falcon.
- A-7G - proposed version for Switzerland, none built
- A-7H - Modified A-7E for Greece without air-refuelling capability, 60 built.
- TA-7H - two-seat trainer version for Greece
- EA-7L - 8 TA-7C modified into electronic aggressor aircraft used by VAQ-34, upgraded to A-7E standard in 1984
- TA-7K - two-seat trainer version for Air National Guard, 30 built
- A-7P - rebuilt ex-Navy A-7A for Portugal
- TA-7P - two-seat trainer version for Portugal
- YA-7E or YA-7H - two-seat prototypes built by Ling-Temco-Vought as a private venture.
Operators
- Greece, Portugal, Thailand, United States (Air Force, Navy),
- Also see List of units using the A-7 Corsair II
Specifications (A-7D)
References
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