The F4U-1A in World War II
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Development
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Despite the proven and exceptional combat capability of the F4U-1, it became apparent there was still room for improvement. Numerous modifications and upgrades were performed both in the factory during the manufacturing process and in the field by ground crews looking to correct several perceived issues with the aircraft, as well as further improve it against increasing performance in its Japanese opponents. The results of these modifications would lead to what has now been classified as the F4U-1A.
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A numerical distinction between the 1A and earlier -1 is somewhat deceptive, as the F4U's early development after the design was accepted for full production was more of a series of minor upgrades than any one definitive model version. Rather, the designation was a later one to encompass all F4U-1s after a specified BuNo that incorporated all of a specific set of design improvements. The most significant visual distinction, and the one that is generally accepted to be the definitive line between the -1 and 1A, is in the canopy and cockpit. The F4U-1A raised the pilot's seat and replaced the -1's "birdcage" framed canopy with a partial bubble canopy, retaining only two frames on either side and a distinctive metal hood over the pilot's head. As a result overall visibility was greatly increased. The difference was most significant looking out over the aircraft's long nose thanks to the raised position of the pilot. This was also a significant first step in clearing the way for the Corsair to be designated as fit for carrier use, as it partially addressed one of the Navy's chief concerns.
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The cowling was slightly redesigned with the permanent removal of the top cowl flaps. Most ground crew permanently jammed this set of flaps in place because when opened the engine tended to throw oil straight back on the windscreen and blinding the pilot. The remaining flaps running the circumference of the cowling were retained. The F4U-1 possessed an open window in the floor of the cockpit which the pilot could look through. This was replaced by a metal plate in the 1A, though the cockpit would remain floorless except for the guide rails for the rudder pedals until the development of later models. The cockpit also went through a minor redesign due to the elevated pilot's position and change in the canopy frame. The glass of the Mk.8 gunsight was removed, and instead was replaced by a large sheet of glass bolted to the frame of the windscreen. Further improvements to visibility while on the ground resulted from a redesign of the tail wheel, extending the strut slightly and raising the tail more.
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One improvement first introduced in later BuNo's of the F4U-1 upgraded the Pratt and Whitney R-2800-8 with the 8(W) model. This version of the R-2800 increased available horsepower through the use of water-methanol injection, boosting engine output by 250hp. The 1A replaced the Hamilton Standard prop utilized by the -1 with a more effective paddle prop, which possessed greater blade chord than the earlier type. This resulted in a significant improvement in lateral acceleration and sustained rate of climb.
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Perhaps the most significant modification of the 1A was the addition of a small wedge-shaped spoiler to the leading edge starboard wing. This was introduced in an attempt to alleviate the Corsair's vicious stall characteristics by increasing drag on the starboard wing. In the F4U-1, engine torque from the big R-2800 would cause the left wing to enter a stall before the right and causing the Corsair to snap hard over to port during an accelerated stall. The intent of the spoiler was to induce the right wing into a stall at higher speeds and help balance the aircraft and ease the big fighter's tendency to spin, though some observations suggest the spoiler may have been most effective at easing the minds of inexperienced pilots. The wicked stall and spin behavior suffered by the Corsair (a characteristic not unique among high-performance propeller-driven aircraft) would never be completely remedied.
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With its numerous refinements, the F4U-1A became the primary fighter of the United States Marine Corps from mid- to late-1943, through the end of 1944. However, much as with the earlier -1, tinkering by both Vought and ground crews in the combat area didn't end, and numerous refinements would continue to be made that would lead directly to the next major variant.
Unit Deployment
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The F4U-1A would see combat with many Marine Corps, as well as Navy fighter squadrons, from the middle of 1943 through the end of 1944. Most F4U-1's were updated in the field, where practical, while others were transitioned over. Perhaps the two most famous squadrons to operate the F4U-1A were VF-17, the Jolly Rogers, and the legendary Black Sheep of VMF-214.
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While VF-12 soon replaced their Corsairs for Hellcats, The Jolly Rogers elected to keep their F4Us instead. They completed carrier trials and were initially assigned to the USS Bunker Hill, CV-17. Their operating record from the deck of the carrier proved that the F4U could indeed be flown safely and effectively off the flat-tops, however citing the logistical issues of maintaining a squadron of Corsairs in a fleet dominated by the more docile F6F VF-17 was ordered ashore and served most of its tour of duty staging from island bases in the South Pacific. The Jolly Rogers had not seen the last of the Bunker Hill, as during supporting operations during attacks on Rabaul VF-17 helped provide air cover for the carrier while her own aircraft were engaged, landing to refuel and rearm aboard the carrier, and reaffirming that the F4U could operate as a carrier-borne fighter.
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F4U-1As were also flown by VMF-214, led by Major Greg Boyington during operations beginning in August, 1943. VMF-321 Hell's Angels, VMF-121 and VMF-111 all flew the 1A from island bases throughout the Pacific. VMF-321 also flew combat operations from the decks of USS Kwajalein. Much like the earlier -1, the environment and supply and maintenance situation in the South Pacific were exceptionally hard on aircraft, and even after a few weeks of combat, many aircraft showed heavy signs of wear. Multiple squadrons assigned to one base would often share aircraft between them from a pool of whatever planes were available, and it was exceptionally rare for an individual pilot to have his own plane (the Jolly Rogers were one of the only squadrons operating in the Pacific which had this luxury). Boyington was known to intentionally select the most battered-looking aircraft on the flight line.
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An F4U-1A of VMF-111 also became the only individual combat aircraft in history to receive a citation in her own "name" for her combat service. "Ole 122" completed 100 bombing missions against Japanese targets in the Pacific, logging in excess of 80,000 miles and 400 hours of flight time without having to return to base for mechanical failure.
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“In accomplishing her 100 missions, Corsair No. 122 logged more than 400 hours flying time, her total hops, including tests and reconnaissance flights, reached an amazing total of 178. Built for air combat, Corsair 122 proved her versatility by accepting 1000-pound bombs slung from her belly, and without strain or protest developed into the hottest dive bomber with wings. Were there blood in her fuel line instead of 100 octane, she would be wearing the Purple Heart, for the patch on the leading edge of her wing attests the accuracy of Japanese antiaircraft fire. She has covered all the Japanese based in the Marshall Islands like the morning dew.”