Vought Corsair

The Chance Vought Corporation was formed in 1917 and in the inter-war years designed a number of general-purpose biplanes for the US Navy and Marine Corps. By the late 1930s, however, the company was keen to make a name for itself as a builder of fighter aircraft. Chief Engineer Rex B. Beisel and his team came up with two designs, the Model V-166A to be powered by a Pratt & Whitney R-1830 Twin Wasp, and the V-166B with the same manufacturer’s XR-2800 Double Wasp, which was still in the experimental category. Of the two proposals, the US Navy preferred the latter and a contract for the prototype XF4U-1 was issued on 10 February 1939.

To absorb the power of the R-2800 engine, which even in its development stages was producing 1850 hp, a three-blade Hamilton Standard propeller was chosen with a massive 13 ft 4 in diameter. Beisel’s solution to the obvious ground clearance problem that came with such a large propeller, was to adopt an inverted gull-wing, with the undercarriage legs located at the wing’s lowest point. This allowed the undercarriage leg to be shorter and lighter, and by incorporating a 90-degree twist, it could be retracted rearwards to lie within the wing. Further advantages when compared with a more conventional straight wing, were better pilot lookout, reduced drag at the fuselage/wing junction and reduced height with the wings folded.

The XF4U-1 was first flown on 29 May 1940 by Lyman A. Bullard. It was forced to return without its elevator trim tabs, which had departed due to flutter, the first of a number of teething troubles that were to plague the Corsair. The initial armament comprised one 0.303-in gun and one 0.50-in gun in the forward fuselage, together with a single 0.50-in gun in each wing. Combat experience filtering back to the US from Europe led to the Corsair losing its nose-mounted guns and having its outer wings modified to take a total of six 0.5-in guns. The fuel system was radically altered to reduce the possibility of damage from enemy fire, with a large self-sealing tank of 237 US gallons being mounted in the fuselage behind the engine firewall to replace the four tanks previously mounted in the wings. This necessitated the pilot’s cockpit being moved back by 2 ft 8 in.

Early experience with the Corsair was not encouraging, as the aircraft showed a habit of dropping a wing just before the stall. This tendency did not endear it to low-time pilots confronted with the prospect of putting the aircraft down at slow speed on a pitching deck. In the case of an aborted landing, if the throttle was opened too quickly the massive torque from the engine was liable to flick the aircraft out of control. A further problem was that the undercarriage oleos, instead of absorbing the shock, tended to rebound after a firm arrival. This led to a bounce, which could spell disaster with aircraft ranged on the forward deck of a carrier. It would be many months before the US Navy took its Corsairs to sea. As a result, it was left to VMF-124 of the US Marine Corps to introduce the F4U to action at Guadalcanal on 14 February 1943.

In contrast to the US Navy, the FAA showed rather less concern as regards the Corsair’s deck-landing characteristics. The first FAA Corsair squadron was No. 1830, which was formed at the US Navy base at Quonset Point, Rhode Island on 1 June 1943, and seven more squadrons had been equipped by the end of the year. After working up in the USA, the units boarded escort carriers to be shipped to the UK. Corsairs of No. 1834 Squadron aboard HMS Victorious were the first to be used operationally when they took part in attacks on the Tirpitz, which was under repair at Kaafiord in Norway, on 3 April 1944.

The initial batch of 95 Corsair Is (equivalent to the F4U-1) were soon followed by 510 Corsair IIs, a mixed batch of F4U-1A/Ds. These were supplemented by 430 Brewster-built F3A-1As designated Corsair III and 942 Goodyear-built FG-1A/Ds designated Corsair IV. A major modification from the Corsair II onwards, was the clipping of the wing tips so that aircraft could be accommodated in the below-deck hangars of British aircraft carriers with their wings folded. Approximately 5 in was removed from the wing tips, but a further 2½ in had to be taken off due to the use of a longer tailwheel yoke, which was introduced to improve deck handling. Compared with a standard Corsair, the stall speed of the British version with clipped wings was 4–5 kt higher.

On its arrival in the UK, the Corsair was put through its paces at a number of testing establishments, including RAE Farnborough. It was here that Eric Brown flew JT118, an early production Corsair I, in January 1944. He recalled his experiences with the aircraft in his book Wings of the Navy(Airlife, 1987).

The Corsair’s inordinately large proboscis was its most outstanding feature – in the USA it was referred to as ‘Old Hog Nose’. Coupled with its fairly acute and most distinctive ground stance, it imparted an impression of rugged strength rather than aerodynamic refinement. The cockpit was inordinately spacious and tailored for an extremely tall pilot – I subsequently learned that the principal Corsair project pilot was 6 ft 4 in, and one of more modest stature, such as myself, inevitably experienced some discomfort keeping one’s feet on the rudder with the seat adjusted to a height from which what little forward view that existed could be gained. The layout of the cockpit was poor and on the ground the only reasonable view was upward!

The immense R-2800-8 Double Wasp was turned over by hand four or five times, the fuel booster pump was switched ON, the priming switch was flicked several times, the ignition switch activated and the starter cartridge fired. The Double Wasp usually burst into life immediately and with the firing switch depressed and the mixture control moved slowly to AUTO RICH was soon purring with all the smoothness so characteristic of this family of engines. The Double Wasp was opened up to 1,000 rpm to warm up, pressure and magneto checks performed, the flaps lowered and raised, and the revs increased to 1,400, the operation of the two-speed supercharger being checked by moving the control from NEUTRAL to LOW and, after a pause of a few seconds, to HIGH. With the propeller control fully down, the throttle was opened and take-off boost and static rpm checked, the stick being held hard back to contain a strong tendency for the tail to lift.

During taxying the totally inadequate forward view necessitated swinging the nose from side to side, but the tailwheel had to be unlocked which made the Corsair very unstable directionally, necessitating constant use of brakes with the danger of nosing over in the event of too harsh application. For take-off, if trim was correct, the Corsair demonstrated no tendency to swing and unstick was rapid. With 30 degrees flap, such as would be employed for a carrier take-off, and about two-thirds normal fuel at a take-off weight of about 11,150 lb, the Corsair would take-off within 185 yards without wind and about 120 yards into a 15 knot wind.

The speed for maximum climb rate was 125 kts from sea level up to 21,000 ft and the intercooler shutters had to be opened fully, but the cowl gills were only half opened otherwise there was some buffet. Climb was impressive, 10,000 ft being passed in 4 minutes 40 seconds and 20,000 ft in 9 minutes 40 seconds. Above 21,000 ft climb speed was reduced by 3 kts per 2,000 ft, but the two-stage, two-speed supercharger ensured good climbing capability well over 30,000 ft. Once in level flight, the Corsair could be trimmed to a very stable hands-off flying condition. The harmony of control was poor, the elevators being heavy but the ailerons moderately light, enabling the Corsair to be rolled to its maximum rate even at fairly high diving speeds, valuable in the South Pacific as the opposing Zero had poor aileron control at high speeds.

Acceleration was dramatic, and a clean aeroplane with about two-thirds fuel in the main tank only and 200 rounds for each of its six 0.50 in guns could reach a maximum of 342 kts at the critical altitude of 24,000 ft on normal maximum power. At combat power of 1,650 hp at 2,700 rpm (limited to 5 minutes), maximum speed was 343 kts. Stalling characteristics were very poor, with little warning other than the stall warning light on the instrument panel operated by the breakdown of airflow over the centre section. At the stall, the right wing dropped sharply and an incipient spin developed if the control column was not moved smartly forward. If the Corsair stalled in a steep turn it would normally flick out, but recovery was rapid if control column pressure was relaxed quickly. At about 11,500 lb with engine off and all up, the Corsair would stall at 90 kts, and with flaps and undercarriage down at 76 kts, the warning light coming on at 80 kts.

In the deck landing configuration with approach power, the Corsair could demonstrate a very nasty incipient torque stall with dangerously little warning and a simulated deck landing at 80 kts gave very poor view and sluggish aileron and elevator control. A curved approach was necessary if the pilot was to have any chance of seeing the carrier, let alone, the batsman! When the throttle was cut, the nose dropped so that the aircraft bounced on its mainwheels, and once the tailwheel made contact, it proved very unstable directionally, despite the tailwheel lock, swinging either to port or starboard, which had to be checked immediately with the brakes. I tried a baulked landing and discovered that the sudden opening of the throttle at 80 kts also produced the torque stall, but this time the port wing dropped. I needed no more convincing of the US Navy’s wisdom in withholding the Corsair from shipboard operations!

In addition to trials work carried out in the UK, the Corsair was also assessed in the USA by pilots attached to the British Air Commission in Washington. The cockpit layout was considered adequate. The most serious criticism affecting all Corsair Is and early Corsair IIs (in which the fault was made worse by raising the pilot’s seat) was the location of the undercarriage operating lever, which was too far forward and too low down. This meant that the pilot had to bend forwards and down when retracting the wheels, a dangerous procedure when near the ground. In all Corsairs after JT270 (the 171st production aircraft) the lever was moved to a more convenient position. The control column was a little on the short side and, like many other American aircraft, it was positioned too far away from the pilot.

The view forwards when taxying was extremely poor, and was made even worse by opening the gills. With its raised seating position the Corsair II showed a slight improvement, but the view was still far from good. This meant that it was even more important to weave when taxying, but this was made difficult by the aircraft’s directional instability when the tailwheel was free. The Corsair’s ground-handling characteristics could be vicious and selective brake was constantly required to prevent a ground loop developing. This caused the brakes to overheat and fade, and since the pedals were not particularly easy to operate, taxying for some distance could be rather exhausting and was something to be avoided. In practice, the tailwheel had to be locked as much as possible, as in this condition the aircraft ran straight, but this could not be done for any length of time without risk of collision.

Provided that the aircraft had been correctly trimmed, the Corsair showed little tendency to swing on take-off, the run being blind until the tail was up. For a carrier take-off with full flap, however, the tail came up directly the brakes were released. Once airborne, the undercarriage could be raised very quickly, producing a slight nose-up change of trim. The cowling gills were best left at no more than two-thirds open, as considerable buffeting could result. Handling in the climb at 130 kt IAS was quite good, with all three controls being light and responsive. During sustained high-power climbs, there were indications of overheating both of carburettor air and cylinder head temperatures.

The Corsair was very pleasant to fly at cruising speeds, with such low noise levels that some pilots were liable to overboost the engine. Stability was adequate for long-range flights without undue pilot fatigue. In order to avoid excessive fuel consumption and to minimise the danger of CO contamination, the aircraft was normally flown in auto lean whenever possible, or with oxygen in use. The seepage of exhaust gases into the cockpit was one of the major troubles with the Corsair. The main point of entry was around the tailwheel and arrester hook openings, from where the gas was drawn forward by relatively low cockpit pressure. Despite the introduction of a fabric bulkhead behind the radio compartment, excessive CO in the cockpit continued to occur and constituted a considerable danger, to the extent that FAA pilots were instructed to use oxygen at all times.

The flying controls were tested at various speeds. At 200 kt IAS the ailerons and elevators were light and effective, although the rudder was somewhat heavier. When flying at 300 kt IAS the rudder was too heavy to operate without assistance by the trimmer, but the ailerons and elevators, although much heavier to operate than before, still gave good response. At 360 kt IAS the ailerons were just about acceptable, but elevator trim was needed to hold the aircraft in the dive. At this speed the rudder was almost immovable.

When trimmed for the approach with the flaps and undercarriage down, the Corsair was unstable, but a forward pulling spring (tensioned to assist elevator control when the undercarriage was lowered and applicable to nearly all Corsair Is and all Corsair IIs) was brought into action to maintain stick force in the correct sense. There was, however, little change of stick force with reduction in speed, which tended to give a lack of feel to the elevators, and care had to be taken to monitor airspeed when on slow approach. The range of elevator trim provided was adequate for all conditions of flight. The trim changes were as follows:

Increase speed –tail heavy

Increase power –tail heavy

Lower wheels –nose heavy

Lower flaps –

Open gills –

Open shutters –

slightly nose heavy

nose heavy

tail heavy

Directional stability in the air was positive insofar that the aircraft turned correctly on ailerons and elevators alone. However, when a sudden yaw was applied and the rudder released, many oscillations took place before straight flight was eventually resumed. In bumpy air there was a tendency to hunt directionally. An increase in power tended to produce a swing to the left and an increase in speed a swing to the right. At high speeds the rudder trimmer had to be used, owing to the extreme heaviness of the rudder.

The pilot of a Corsair had to be at his sharpest when flying slowly, owing to its sluggish lateral control and lack of feel on the elevators, together with the poor forward view. Adequate control could, however, be maintained when flying in bumpy conditions at around 110 kt IAS, with 30 degrees of flap. At speeds approaching the stall the characteristics of the aircraft were greatly affected by the position of the gills. With the gills even slightly open, considerable warning of the stall was given in the form of buffeting, longitudinal pitching and kicking of the rudder. With the gills closed, there was no warning at all. Observation of wool tufts fitted to the aircraft indicated that the initial breakdown of airflow occurred just outboard of the wing stub, together with disturbance around the cockpit area. The streamlines at the wing tips did not appear to be affected.

The aircraft was comparatively easy to stall with moderate stick force, and it occurred with the control column just aft of central. In all cases, when stalling speed was reached from a steady glide, a wing was liable to drop rather suddenly, followed by the nose, and considerable height could be lost before control was regained. Either wing could go down in a gliding stall, but it was more usually the starboard wing that dropped. This could also occur when landing if the aircraft was held off too high. At a take-off weight of 11,700 lb, the stall speed with the flaps and undercarriage up was 90–92 kt IAS, and 76 kt IAS with the flaps and undercarriage down.

In accelerated stalls a pronounced tendency to flick to the left was noted, although this had been reduced to some extent by fitting a spoiler on the starboard wing. In a 4 g turn, the stall occurred at 140–150 kt IAS and was accompanied by violent buffeting around the cockpit, especially on the left-hand side. Although the Corsair tended to drop a wing at the stall, a spin did not develop unless the control column was held fully back. Should an incipient spin develop, recovery was quick assuming that the pilot took the correct action promptly. If a spin was allowed to progress further, control forces became very high, to the point that the pilot had difficulty in carrying out the necessary recovery procedure.

Aerobatics were performed without difficulty, except that the forward position of the stick meant that the pilot had to reach a long way forward to maintain the correct nose attitude during slow rolls or when flying inverted. Loops were commenced at around 260 kt IAS with an initial acceleration of 4 g, the speed over the top of the loop being approximately 120 kt IAS with the aircraft showing no sign of flicking. There was no abnormal lateral behaviour, although a large change in directional trim with speed, together with the heaviness of the rudder, made accurate manoeuvres difficult and tended to spoil the feel of the aircraft. Rolls off the top of loops could be flown by adding 20–30 kt to that for a normal loop.

The Corsair was dived up to 360 kt IAS, at which speed the ailerons were very heavy and the rudder almost solid. Acceleration was rapid and considerable nose-down and left rudder trim was needed to hold the aircraft straight in the dive. To provide a dive brake, the main wheels could be extended without lowering the tailwheel. This caused some nose-heaviness but the aircraft could be manoeuvred satisfactorily in this condition.

Like many other of its contemporaries, the Corsair ran into problems with compressibility during high-speed dives. A US report seen by the British Air Commission told of a vertical dive being carried out from 37,500 ft. At a speed of 240 kt IAS an incessant pounding commenced and the elevators became immovable. The trimmer was then moved to the full nose-up position and the subsequent recovery from the dive at 13,000 ft was described as ‘very rapid’, which was probably an understatement. At one point prior to recovery, the pilot noticed an indicated airspeed of 430 kt. Considerable damage was caused to the horizontal stabiliser with the horn balance, all of the elevator aft of the spar and outboard of the tab, having broken away. In view of the likelihood of pilots getting into trouble due to compressibility, the US Navy produced a series of limitations for the Corsair in relation to speed and acceleration at various altitudes.

The angle of approach, both with the engine on and off, was adequate and generally the aircraft handled well at 90 kt IAS with the flaps and undercarriage down. The ailerons, although positive, appeared to have a ‘dead area’ covering some 2–3 in of stick movement. During the latter part of the approach, the view ahead deteriorated, but it was possible to see fairly well out of the side. The aircraft had to be held close to the ground at the stall due to the tendency of the right wing to drop suddenly, but apart from this the touchdown was straightforward. Although safely on the ground, the landing was far from over. As soon as the tailwheel was lowered, the aircraft would almost certainly try to swing to either left or right. This required the immediate application of full rudder and brake to correct it. If landing on a runway, this characteristic could be alleviated to some extent by using 30 degrees of flap, by keeping the tail slightly above the three-point attitude and by being gentle at the flare. Once on the ground, any amount of braking could be used and the aircraft stopped quickly. On later machines with the raised cockpit, the air loads on the hood were found to be very high, which made it difficult to open before landing. Care had to be taken when the hood was open to ensure that it was securely locked, otherwise it would slam shut when the aircraft landed.

Flight trials on a Corsair with clipped wings by the US Navy Flight Test Section at Patuxent River showed that there was little difference when compared with the standard wing machine. The take-off run was slightly longer and the lift-off speed was a little higher. It was also noted that the aircraft could be flown off from the three-point attitude without loss of control, unlike the USN/USMC version. It was thought that this might be because of a slight alteration in the angle of attack due to the change in wing tip shape. There was an improvement in the amount of stall warning and the stall was also slightly more symmetrical. The control forces and effectiveness, stability and general flying characteristics were virtually unchanged.

Performance tests could not be carried out by BAC pilots, as the only aircraft available at the time had unpressurised magnetos, which precluded operation at the altitudes needed for an assessment. Figures obtained from Patuxent River were therefore relied on. The aircraft used was F4U-1 No. 02155 at a take-off weight of 11,194 lb. When using its best climb speed at military rated power and with minimum cowl flap, the sea level rate of climb was 2890 ft/min. At the critical altitude of 21,200 ft, the rate of climb in auxiliary high blower was 1840 ft/min and the service ceiling (rate of climb 100 ft/min) was 38,200 ft. The maximum speed at military rated power at sea level was 348 mph TAS, rising to 395 mph TAS in auxiliary high blower at 22,800 ft.

Although intentional spinning was prohibited, the recommended recovery procedures were based on a comprehensive series of spin trials, which showed that the Corsair had slightly different characteristics depending on the direction of spin. Spins to the right were normal, whereas those to the left showed signs of oscillation, with the angle of the nose to the horizon varying from 50 degrees below to level during rotation. As the nose approached the horizon, a tendency for the right wing to drop was noted, but the spin continued to the left. Recovery was possible at any time during the spin, but more time was needed when the nose was near the horizon. The IAS during the spin varied from 0–40/50 kt. In the landing configuration, no difference was noted between spins to the left and right.

Successful recoveries were made after four turns in the clean configuration and one turn with the flaps and undercarriage down. It was essential to apply full opposite control, although the control forces in the spin were extremely high, the rudder requiring about 125–135 lb force before it could be moved to its fullest extent. An improvement in recovery was noted if the ailerons were held against the spin and if necessary the trim tabs could be used to lighten stick loads. The speed of rotation tended to increase just before recovery started, but the controls had to be held in the recovery position until the spin had actually stopped. Care had to be taken to avoid high accelerations during the pull out, and approximately 2000–2500 ft was needed to achieve level flight. If a pilot found himself still in a spin by the time that 3000 ft was passed, it was recommended that he abandon the aircraft.

Patuxent River also carried out a combat evaluation of the F4U-1 Corsair against an F6F-3 Hellcat and a Focke-Wulf Fw 190A-4 in early 1944. The take-off weight for the three aircraft ranged from 8690 lb for the Fw 190 to 12,406 lb for the Hellcat. The Corsair was flown at 11,988 lb. The rate of climb was compared in the speed range 140–200 kt IAS and at altitudes from 200–25,000 ft. The Corsair and the Fw 190 were superior to the Hellcat in the climb at all speeds and altitudes except at 140 kt below 15,000 ft, when the Fw 190 and the Hellcat were about equal. The best climbing speeds of the three aircraft were: Hellcat – 130 kt; Corsair – 135 kt; Fw 190 – 160 kt so it was no great surprise when the Fw 190 began to show marked superiority over the Corsair when it was climbed at higher speeds. This superiority was maintained up to 25,000 ft, by which time the advantage had been gradually reduced so that the two aircraft were virtually equal at that height.

Level speed checks were carried out from 200–25,000 ft, with each aircraft maintaining full power for two minutes in the course of two runs at each height. The Hellcat proved to be the slowest of the three, the advantage between the Corsair and the Fw 190 depending on height. The full results were as follows:


Level accelerations were made at the same heights and initial speeds as in previous tests, and were determined by flying the aircraft in line abreast and applying full power simultaneously. It was found that it was much easier to apply full power in the Fw 190, due to its much simpler throttle operation. Once again, the results were mixed. The Corsair and Fw 190 were superior to the Hellcat at speeds over 160 kt, the Corsair having a slight advantage over the Fw 190 up to 15,000 ft. However, above this height the positions were reversed. At speeds below 160 kt the Hellcat and Fw 190 were about equal.

Rate of roll tests showed that both the Corsair and the Fw 190 were superior to the Hellcat. The Fw 190 rolled with extreme ease, without excessive stick force and showing no tendency to drop its nose. Surprisingly, the rates of roll of the Corsair and Fw 190 were considered to be very similar. This caused a few eyebrows to be raised at the British Air Commission who were well aware of the Fw 190’s capabilities from the trials results that had been made available from the UK. A direct request was made to Vought who supplied their own figures obtained from tests carried out on a standard F4U-1. When compared with British tests, they showed that the Fw 190 had a considerable advantage over the Corsair at all speeds, although this superiority did tend to diminish at the top end of the speed range. The rates of roll (degrees per second, stick force not exceeding 50 lb) were as follows:

IAS – kt at 10,000 ft

F4U-1 Corsair

Focke-Wulf Fw 190A



















* Control deflection on the Corsair was limited by structural limitations at this speed.

There was no doubt as to which aircraft came out on top when it came to turning circles, as both the Corsair and the Hellcat were far superior to the Fw 190 and could follow it in turns with ease at any speed. When the situation was reversed, the German aircraft was unable to follow. The Fw 190 when in a tight turn to the left and near to its stall speed, exhibited a tendency to reverse aileron control and stall without warning. Similarly, when turning to the right, it tended to drop its right wing and nose and end up in a spiral dive. From a head-on meeting, both the Corsair and the Hellcat could be directly behind the Fw 190 in one turn. From a position directly behind, it was possible to turn inside the Fw 190 and be directly behind it once again in about three turns.

The Corsair and Hellcat were also much more manoeuvrable and could follow any manoeuvre attempted by the Fw 190. The Focke-Wulf required a much greater radius in which to loop than either of the American aircraft and tended to stall sharply if it attempted to follow them. In zoom climbs after dives, all three aircraft were about equal.

The American assessment of the Fw 190 was that it was a very simple aircraft to fly in combat and seemed to have been designed for pilot convenience. Not surprisingly, US pilots found the Fw 190 cockpit to be a little cramped after the more luxurious accommodation provided in the Corsair and Hellcat. However, they did appreciate the semi-reclining seat position and high-set rudder pedals, which were excellent for resisting blackout during high ‘g’ manoeuvres. Its lack of stall warning was a major deficiency, particularly if it was pitted against an aircraft that could force it to fly near its stall speed, but overall it was considered to be an excellent interceptor-type aircraft. Given the choice, however, the American pilots would have preferred to fly the Corsair or Hellcat in combat.

In all, 1977 Corsairs were delivered to the FAA and the Royal New Zealand Air Force, forming a total of nineteen and seventeen squadrons respectively. FAA operations continued off the Norwegian coast, but the Corsair was mainly used in the Far East against the Japanese in the Pacific. From April 1944, it was used for fleet air defence during attacks by Barracuda and Avenger aircraft in the island-hopping campaign. The aircraft had its greatest success in FAA service during the attack on oil refineries at Palembang on 24 January 1945, when thirteen Nakajima Ki-44 Tojo fighters were shot down by the Corsairs of Nos 1830 and 1833 Squadrons.

Shortly before the end of the war in the Pacific, strikes were carried out on the main Japanese island of Honshu, during which Lieutenant R.H Gray DSC of the Royal Canadian Naval Volunteer Reserve was awarded the Victoria Cross. Gray was leading No. 1841 Squadron on 9 August 1945 when he sighted several Japanese destroyers near Shiogama and dived to attack. He scored a direct hit with one of his 1000-lb bombs, causing one of the destroyers to blow up and sink. However, his aircraft had already been hit by fire from shore batteries and he was killed when it crashed into the Bay of Onagawa Wan. After VJ-Day the Corsair was rapidly withdrawn from FAA service so that by the end of 1945 only four squadrons remained. The last two squadrons (Nos 1831 and 1851) were disbanded on 13 August 1946.

The Corsair continued to be developed and more advanced versions saw widespread use in the Korean War and in the conflicts in IndoChina. After the F4U-1, the next main variant was the F4U-4, which was powered by an R-2800-18W engine of 2450 hp with water-methanol injection and achieved a top speed of 446 mph. The F4U-5 featured an R-2800-32W engine that developed 2500 hp from a two-stage supercharger, endowing much better performance at altitude with a maximum speed of 462 mph at 31,400 ft. Spring tabs were fitted to the elevators and rudder to ease control loads during high-speed flight. Final variants were the F4U-6 (later known as the AU-1), a specialised ground attack machine with a single-stage supercharged R-2800-83W, and the F4U-7 developed for the French Aeronavale, which utilised the airframe of the AU-1 with the R-2800–18W engine of the F4U-4. The so-called F2G Super Corsair produced by Goodyear was powered by the massive Pratt & Whitney R-4360 Wasp Major (also known as the ‘Corncob’), but poor lateral control and disappointing performance compared with standard production Corsairs led to the project being abandoned after only five aircraft had been built.

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