Vought F4U Corsair F4U-1A

The F4U-1A was never ordered as such by the U.S. Navy. The designation was coined to tell mid- and late-production F4U-1 Corsairs apart from the early aircraft with the famous "birdcage" canopy, and its use was allowed internally by the manufacturers. Behind that label, however, lay a set of changes that solved many of the problems that had delayed the Vought fighter's entry into service.

The early F4U-1s suffered from poor visibility: the heavily framed canopy, the low seat and the long nose of the Double Wasp engine, with the aircraft sitting nose-high, made it hard to see straight ahead while taxiing on deck. On top of that, the main undercarriage made the aircraft bounce on landing. So although the Corsair was declared ready for combat at the end of 1942, the Navy initially cleared it only for land bases until the carrier qualification issues were worked out.

The F4U-1A introduced a new, taller and wider canopy with only two frames, very close to the Malcolm hood fitted to some British fighters, together with a simplified windscreen. The new design allowed the semi-elliptical flank windows behind the headrest to be omitted. The pilot's seat was raised by about 18 centimetres and the tailwheel strut lengthened by about 15 centimetres; combined with the new canopy, these changes gave the pilot much better visibility over the long nose. The bombing window under the cockpit was also deleted.

On the leading edge of the right wing, just outboard of the gun ports, a stall strip about 15 centimetres long was added, curing the wing's tendency to stall asymmetrically. The main undercarriage oleo struts were improved and eliminated bouncing on landing. With all this, the F4U-1As became the first truly carrier-capable Corsairs.

The F4U-1A kept the armament of six 12.7 mm Browning machine guns in the wings. Fuel was split between the main tank ahead of the cockpit, of about 900 litres, and an unarmoured, non-self-sealing tank of about 230 litres in each wing. It was the first Corsair version able to carry a drop tank under the centre section, which markedly extended its ferry range. One of the late F4U-1As was fitted on trial with an R-2800-8W engine with water injection; the results were satisfactory and many F4U-1As were later fitted with that engine, the same one that became standard on the F4U-1D. The version's top speed was 671 km/h, which the -1D would raise to 684 km/h. Many Marine Corps squadrons had the arrester hooks removed, as they operated from land.

The F4U-1A reached front-line units at the height of the Solomon Islands campaign, where the Corsair became famous in Marine hands. One of the best-known aircraft of this version is the F4U-1A of Major Gregory "Pappy" Boyington, commander of VMF-214, the "Black Sheep", which fought over the stretch of the Solomons known as "The Slot". Boyington was credited with 22 kills flying the F4U. The visibility and undercarriage improvements of the -1A arrived just as the Navy was trying to bring the Corsair back onto its decks.

The Royal Navy had first received 95 birdcage F4U-1s, called Corsair Mk I. Vought then delivered 510 blown-canopy F4U-1As and F4U-1Ds, designated Corsair Mk II in British service; the final 150 were equivalent to the F4U-1D, although the British did not designate them separately. Of these, 360 were F4U-1As. To operate from British carriers, with their lower hangars, about 20 centimetres were clipped from each wingtip.

The Royal Navy had solved several of the Corsair's problems on its own: a bulged canopy similar to the Malcolm hood, a raised seat, upper cowl flaps wired shut to divert oil spray away from the windscreen, and the curved approach borrowed from the Seafire, which kept the deck in sight until the last moment. As a result it cleared the Corsair for carrier operations before the U.S. Navy did: it had been operating the Mk I since 1 June 1943, when 1830 Naval Air Squadron was commissioned and assigned to HMS Illustrious. The Mk IIs, together with Goodyear's Mk IVs, formed the bulk of the Fleet Air Arm's Corsair squadrons, which numbered eighteen by the end of the war and served in both Europe and the Pacific.