In the overall picture, I think it is significant that the F4U prototype was in the air
before the Battle of Britain. Much was learned about air combat between May 1940, and June of 1942. It seems to me that Grumman's design being later, was able to capitalize from the start on available combat information and avoid the problems of "catching up" that Vought had to deal with: changing armament and hence the location of fuel tanks, thus being forced to modify the airframe.
Excerpts from Greg Goebel's site
http://www.vectorsite.net/avf4u.htmlF4UOn 1 February 1938, the US Navy issued a request for proposals for a new high-performance single-seat carrier-based fighter that would use the most powerful engine available at the time.
The US Navy ordered a prototype of the Vought design as the "XF4U-1" in June 1938. Armament was planned as two 7.62 millimeter (0.30 caliber) Browning machine guns in the top of the nose, and a single 12.7 millimeter (0.50 caliber) Browning machine gun in each wing, for a total of four guns
Vought engineers completed a full-scale mockup of the XF4U-1 in early 1939 for wind tunnel tests and Navy inspection.
The initial flight of the prototype XF4U-1 was on 29 May 1940.[The plane] demonstrated the design's performance on 1 October 1940, clocking 650 KPH (404 MPH). However, the promise of the type was balanced by continuing difficulties, including some clear handling problems, and the nasty tendency of the Double Wasp engine to catch on fire.
To compound the delays, reports coming back from the war in Europe indicated that an armament of two 7.62 millimeter and two 12.7 millimeter machine guns was too light, and so when the US Navy asked for production proposals in November 1940, heavier armament was specified. The twin 7.62 millimeter Brownings in the nose were eliminated and two 12.7 millimeter Brownings were fitted in each wing.
There was another troublesome consequence: putting all the guns in the wings meant eliminating wing fuel tankage, and so the forward fuselage was stretched by 45 centimeters (18 inches) to include a new self-sealing tank in the center of the fuselage. The fuel tank also meant moving the cockpit back by about 91 centimeters (3 feet), which made it hard for a pilot to see over the nose when taxiing, taking off, or landing. There would never be any way around the long nose, one pilot later recollecting that he used to tell himself after he lined up for the approach: "God, I hope there's nobody on that runway!"
* Formal naval acceptance trials for the XF4U-1 began in February 1941, and the initial Navy production order for 584 "F4U-1s" was placed on 30 June 1941. The type was given the name "Corsair", which had been the name of several prewar Vought aircraft. The first production F4U-1 performed its initial flight on 24 June 1942, once again with Boone Guyton at the controls.
The type quickly underwent a few more improvements, with the number of 12.7 millimeter Brownings in each wing increased to three, for a total of six; the addition of 70 kilograms (155 pounds) of armor around the cockpit and the oil tank, plus an armor glass windscreen and self-sealing fuel tanks; fit of shorter flaps and wider ailerons; and installation of an uprated R-2800-8 Double Wasp engine with a two-stage supercharger and 1,492 kW (2,000 HP) takeoff power to handle the aircraft's increased weight.
The US Navy received its first production F4U-1 on 31 July 1942, with carrier trials beginning on the USS SANGAMON on 25 September 1942.
http://www.vectorsite.net/avf6f.htmlF6FAfter performing wind-tunnel tests on a 16th-scale model, the US Navy ordered two G-50 prototypes on 30 June 1941. The first prototype, the "XF6F-1", was to be powered by a Wright R-2600-10 Cyclone air-cooled, two-row, 14-cylinder radial engine with 1,268 kW (1,700 HP), and the second, the "XF6F-2", was to be fitted with a turbocharged R-2600-16 Cyclone.
Feedback from the British, then flying the Wildcat against the Nazis, and from the US Navy suggested that a more powerful engine was required. The design team, led by Dick Hutton and under the overall direction of vice-president of engineering Bill Schwendler, settled on the Pratt & Whitney (P&W) R-2800 Double Wasp, an air-cooled, two-row, 18-cylinder radial engine in the 1,500 kW (2,000 HP) class. The R-2800 was to power both the Republic P-47 Thunderbolt and the Vought F4U Corsair, but both of these machines had been delayed, and so Grumman was able to get their hands on R-2800 engines.
The initial XF6F-1 "Hellcat" prototype flew on 26 June 1942 with the Cyclone engine and test pilot Bob Hall at the controls. However, the second prototype was actually completed as the "XF6F-3", with the bigger R-2800-10 engine. Hall performed the first flight of the XF6F-3 on 30 July 1942. He had to land the machine on a Long Island farm field on 17 August due to an engine failure.
The only major problem encountered during the test flights was tail flutter, which was fixed by reinforcing the rear fuselage. The lack of major snags was fortunate, since the XF6F-3 had already been ordered into production as the "F6F-3" on 23 May 1942, even before the first flight of the XF6F-1.
The first production F6F-3 performed its initial flight on 3 October 1942, and service deliveries of the type began in early 1943. Following carrier trials, in March 1943 the type reached operational status with Navy fighter squadron VF-9 on the carrier USS ESSEX, with the aircraft painted Navy blue topside and white on the bottom, the standard color scheme for the fighter through the war. Within nine months of the first flight of the production machine, 15 squadrons were equipped with the type. The Hellcat was primarily a Navy machine, the Marines generally preferring the more formidable but demanding F4U Corsair.
Best Regards,
Cement
