Vought F4U Corsair

In February 1938 the US Navy's Bureau of Aeronautics issued two requests for proposals, one for a twin-engined fighter and one for a single-engined type. For the latter it asked for the highest attainable speed, a stalling speed no higher than 70 mph, a range of 1,000 miles and four guns, plus room in the wing for small anti-aircraft bombs, a period notion that envisaged dropping them onto enemy bomber formations.

That June the Navy contracted Vought for a prototype, known in the factory as the V-166B and to the Navy as the XF4U-1, bureau number 1443. Rex Beisel led the design team. After the mock-up was inspected in February 1939, work moved quickly around a prototype of the Pratt & Whitney R-2800 Double Wasp, an 18-cylinder, two-row radial rated at 1,805 hp. It was the first airframe conceived from the outset for that engine, and the result combined the most powerful engine, the largest propeller and probably the biggest wing of any naval fighter yet built.

Lyman A. Bullard Jr. made the first flight on 29 May 1940, which ended in a hurried landing when the elevator trim tabs failed through flutter. On 1 October 1940 the XF4U-1 averaged 405 mph between Stratford and Hartford, becoming the first American single-engine fighter to pass 400 mph. Testing confirmed an excellent climb but also forced requirements to be rewritten: full-power dives reached 550 mph at the cost of damaged control surfaces and panels, and the required spin recovery proved impossible without an anti-spin parachute.

Reports from the war in Europe persuaded the Navy that the planned armament was too light, and in November 1940 it asked for three .50-calibre machine guns in each wing panel. Formal acceptance trials began in February 1941, and on 30 June that year Vought received an order for 584 F4U-1s, which inherited the Corsair name from the company's late-1920s O2U scout biplane.

The F4U was built around the largest engine then available, the 2,000 hp R-2800, turning a three-bladed Hamilton Standard propeller 13 feet 4 inches across. Such a large propeller created a problem: the main gear had to retract rearwards to leave room for the folding wing, and with the chosen wing chord the legs would have been impractically long. The answer was the inverted gull wing, which shortened the struts and let wing and fuselage meet at the lowest-drag angle without root fairings, although the bent wing was heavier and harder to build.

The Corsair was the first Navy aircraft whose undercarriage retracted into fully enclosed wells, the legs rotating through 90 degrees and disappearing behind doors. Oil coolers and supercharger intakes sat in the inner wing, fed through leading-edge openings instead of external scoops. The large aluminium fuselage panels were spot-welded, a new technique that did away with most rivets, yet the Corsair was also the last American fighter to use fabric on parts of the outer wings, the ailerons, the elevators and the rudder.

The production F4U-1 differed considerably from the prototype. Six wing-mounted .50-calibre M2 Browning guns displaced the wing fuel tanks, so a 237-gallon self-sealing tank went in ahead of the cockpit, which moved back by 32 inches. Other additions were 150 pounds of armour, an internal 1.5-inch bullet-proof windscreen, NACA slotted flaps, longer-span ailerons and the 2,000 hp R-2800-8. With its mechanically supercharged engine the F4U-1 was much faster than the Hellcat and only 13 mph slower than the turbocharged Republic P-47 Thunderbolt.

Carrier trials in 1942 uncovered serious faults. The left wing could stall without warning at low speed, and a sudden burst of throttle in a go-around was enough to roll the aircraft over. The cockpit, set far back behind an extremely long nose, left the pilot nearly blind on approach; oil from the cowl flaps sprayed the windscreen, and the oleo struts bounced the aircraft along the deck. Early pilots gave it unflattering names such as "hosenose" and "Widow Maker".

The fixes came one at a time: a small stall strip on the right-wing leading edge evened out the stall, the upper cowl flaps were fixed shut, and a bleed valve in the gear legs ended the bouncing. Meanwhile the more docile, easier-to-build Hellcat had entered service, and the Navy chose it for its carriers. The Corsair went to the Marine Corps, which had no need to land on decks and used it from shore bases to devastating effect. The Navy did not clear the F4U for shipboard use until April 1944, after a longer oleo strut had been fitted.

Demand soon outstripped Vought's capacity. According to the company, the first production Corsair flew on 25 June 1942 and the Navy accepted its first two in July. By the end of 1944 Vought was delivering 300 aircraft a month, one every 82 minutes, and combined output peaked in May 1944 at 596 acceptances in a single month: 254 from Vought, 220 from Goodyear and 122 from Brewster. Vought built 2,814 F4U-1s.

Goodyear built the FG-1 to the same specification and delivered just over four thousand, more than a third of all wartime Corsairs; many of its FG-1As left the line with manually folding wings and no hydraulic mechanism because they were destined for land-based squadrons. Brewster fared far worse. Labour disputes slowed its output, the Navy cancelled the contract in July 1944 after only 735 deliveries, and defective wing fittings led to its F3As being barred from aerobatics. None reached American front-line units.

Twelve F4U-1s of Marine squadron VMF-124 landed at Henderson Field, Guadalcanal, on 12 February 1943. Their debut two days later was the fiasco remembered as the "Saint Valentine's Day Massacre": escorting B-24s over Kahili, the Americans lost ten aircraft, two of them Corsairs, against no more than four Japanese fighters. The Marines learned quickly. By May VMF-124 had the first Corsair ace, Kenneth A. Walsh, who finished the war with 21 victories and stressed that altitude was everything, since the Corsair beat the Zero in every respect except slow-speed manoeuvring and climb.

VMF-214, Gregory "Pappy" Boyington's "Black Sheep", became famous over the stretch of the Solomons known as "The Slot", Boyington scoring 22 kills in the F4U. Three Corsair pilots received the Medal of Honor in the Second World War: Walsh, for two missions in August 1943; Boyington, for a campaign running from September 1943 to January 1944 that ended with his shoot-down and capture over Rabaul; and Robert M. Hanson of VMF-215, posthumously. On the Navy side, VF-17 kept its Corsairs and in November 1943 used them to cover the carrier strike on Rabaul, refuelling aboard Bunker Hill and Essex. The first squadron to operate effectively from an American carrier was VMF-124 itself, aboard Essex in December 1944, when the kamikaze threat demanded more fighters at sea.

From early 1944 the Marines explored the Corsair's potential for close support of amphibious landings. Charles Lindbergh, a civilian adviser for United Aircraft, flew with them to study how to stretch its payload and range, and got airborne with 4,000 pounds of bombs: a 2,000-pounder on the centreline and a 1,000-pounder under each wing. By early 1945 the Corsair had become a fully fledged "mudfighter" delivering bombs, napalm and HVAR rockets, and could even carry the large Tiny Tim rocket. It fought over Palau, Iwo Jima and Okinawa, where infantrymen called it "The Angel of Okinawa".

Figures compiled at the end of the war credit F4Us and FGs with 64,051 operational sorties for the Navy and Marines, 44 per cent of all fighter sorties, of which only 9,581 were flown from carriers. Their pilots claimed 2,140 air victories against 189 losses in air combat, a ratio above 11 to 1, though partly because the type moved into ground attack as the war went on and met fewer enemy fighters. The Corsair also dropped 15,621 short tons of bombs, 70 per cent of all those released by US fighters. Anti-aircraft fire claimed 349 Corsairs and another 692 were lost on non-combat flights, a reminder of how demanding the aircraft was.

Lacking a carrier fighter with enough range, the Royal Navy received its first 95 F4U-1s as the Corsair Mk I in mid-1943, followed by Vought, Brewster and Goodyear batches that brought the total to 2,012 aircraft. To fit its carriers' hangars it clipped 8 inches from each wingtip, which also curbed the aircraft's tendency to float on landing. The British raised the seat, fitted a bulged canopy and adopted the curving approach used with the Seafire, so that they put the Corsair to work from carriers before the US Navy did.

The first unit, 1830 Naval Air Squadron, formed on 1 June 1943. British Corsairs covered the 1944 strikes on the battleship Tirpitz and, with the British Pacific Fleet, attacked targets in South East Asia and Japan. On 9 August 1945 Canadian Lieutenant Robert Hampton Gray attacked Shiogama harbour and sank the escort Amakusa with a 1,000 lb bomb before crashing into the sea; he was awarded Canada's last Victoria Cross posthumously. With no means to pay for their Lend-Lease aircraft, the British pushed many Corsairs overboard off Brisbane at the end of the war.

The Royal New Zealand Air Force received some 424 Corsairs, which equipped 13 squadrons. The first arrived at Espiritu Santo in March 1944, and by late that year the F4U equipped all ten of its Pacific fighter squadrons, used mostly for close support. No. 14 Squadron flew it in Japan with the occupation force until its retirement in 1947.

In July 1944 a Fleet Air Arm Corsair force-landed in Norway and was captured intact by the Germans, who took it to the Rechlin test centre. In 1945 American troops found another F4U in Japan that the Japanese had patched up with fabric and parts from crashed aircraft.

The F4U-4, delivered from early 1945, was the last version to see action in the Second World War. Its 2,100 hp R-2800-18W had a two-stage supercharger and gave 2,450 hp with water-alcohol injection, and it introduced a four-bladed propeller. The earlier F4U-1D had brought water injection and permanent rocket rails, while the F4U-1C swapped the machine guns for four 20 mm cannon. Night fighters carried radar in a pod on the right wing, among them the F4U-2, F4U-4N and F4U-5N, and there were photo-reconnaissance versions too.

The F4U-5, first flown on 21 December 1945, added the R-2800-32(E) engine, automatic supercharger controls, a modernised cockpit and, for the first time, all-metal wings. The AU-1, originally the F4U-6, was a Marine attack version with extra armour, oil coolers moved inboard and a simplified supercharger for low-level work, able to carry 8,200 lb of bombs. Separately, the F2G "Super Corsair" with the huge 28-cylinder Wasp Major was built only in tiny numbers; surplus examples went on to win the Thompson Trophy in 1947 and 1949.

From 1950 to 1953 Corsairs served in Korea as the AU-1, F4U-4B, F4U-4P, F4U-5N and F4U-5NL, nearly always in close support with cannon, napalm, bombs and rockets. The MiG-15 outclassed it in the air, although on 10 September 1952 Marine Captain Jesse G. Folmar shot one down when it made the mistake of turning with him, before he was himself shot down. At night F4U-5Ns hunted convoys, trains and the Po-2 biplanes that harassed United Nations troops; Lieutenant Guy Bordelon of VC-3 became the Navy's only ace of the war and the only American ace in Korea to fly a piston-engined aircraft. Lieutenant Thomas J. Hudner received the Medal of Honor for deliberately crash-landing his F4U-4 beside the downed aircraft of his squadron mate Jesse L. Brown, one of the Navy's first African American aviators, in an attempt to save him.

France needed a close-support aircraft for its carriers, and Vought built the final version, the F4U-7, for it. The prototype flew on 2 July 1952; 94 were built, and the last Corsair of all was rolled out on 31 January 1953. The US Navy paid for them under the Military Assistance Program. Flotille 14F, based at Karouba in Tunisia, was the first unit to receive them.

In Indochina, 14F flew 25 AU-1s passed on by the Marines in 1954 and, in three months that included support of Dien Bien Phu, logged 959 combat sorties. In October 1956 Flotilles 14F and 15F took part in Operation Musketeer at Suez, wearing yellow and black recognition stripes. The Corsair units then deployed to Algeria until 1962 and in July 1961 supported French paratroopers during the Bizerte crisis. The Aéronavale operated 163 Corsairs in all and retired the last in September 1964, as the new carriers Clemenceau and Foch ushered in the jet age.

Corsairs saw combat for the last time in July 1969, in the short war between Honduras and El Salvador, flying with both air forces. On 17 July Honduran Captain Fernando Soto shot down a Cavalier Mustang and two Salvadoran FG-1s, in what are regarded as the last combats between propeller-driven aircraft anywhere.

Infantrymen called the Corsair "The Sweetheart of the Marianas", while naval aviators used less flattering names such as "Ensign Eliminator", for the many training hours it took to master, or the more neutral "Bent-Wing Bird". The Allied story that the Japanese called it "Whistling Death" is not supported by Japanese sources. Connecticut has made it the official state aircraft because of its links with Vought-Sikorsky, Pratt & Whitney and Hamilton Standard.

Among the survivors is the National Air and Space Museum's F4U-1D, bureau number 50375, delivered to the Navy on 26 April 1944. It served with VF-10 aboard Enterprise and with VF-89, then as an instructional airframe for mechanics; during restoration it turned out to carry a fin from another aircraft, a trace of those trainees' work. The museum spent 9,315 hours restoring it, painted it as a VMF-113 Corsair over Eniwetok in 1944, and moved it into its Washington building on the night of 27-28 January 1981.