F4F Grumman Wildcats
Grumman’s first monoplane fighter actually began as a biplane, the XF4F-1 ordered March 2, 1936. After the Brewster XF2A-1 monoplane and more powerful engines became available, the XF4F-1 contract was replaced by Grumman’s XF4F-2 monoplane design on July 28, 1936. The original specification promised a top speed of 257 mph at sea level and 280 mph at 9,000 feet.
Powered by a 900-hp Pratt & Whitney R-1830-66 with a single-stage supercharger, the XF4F-2 was first flown September 2, 1937, by Robert Hall at Bethpage and was delivered to Anacostia on December 23. Like the Brewster, it was an all-metal mid-wing monoplane using the new NACA 230 airfoil section and rounded tips. The wheels, however, were retracted by 30 turns of a hand crank, as on the older biplanes. Two .50-caliber guns protruded from the cowling top with provisions for two more in the wings and two 116-pound bombs could be hung under the wings.
Although the XF4F-2 in its original form made a crash landing in April and lost the 1938 production contract to Brewster, in October 1938 the aircraft was ordered rebuilt with the Navy’s first engine with a two-stage, two-speed supercharger, the XR-1830-76 developing 1,000 hp at 19,000 feet with 100-octane fuel. Redesignated XF4F-3 and fitted with a larger, square-tipped wing and redesigned tail, that Grumman flew on February 12, 1939. A Curtiss propeller replaced the original Hamilton, with two .30-caliber guns in the nose and a pair of .50-caliber guns added in the wings.
In June 1939, the XF4F-3 was tested in NACA’s full-scale wind tunnel and the raised stabilizer and squared tail of the production shape was established. A new specification for the production F4F-3 promised a top speed of 343 mph and a contract for 54 (later 78) was placed on August 8, just before World War II began. In October, the French Navy was allowed to order 81 Grummans, but with a commercial Cyclone engine.
The first F4F-3 was delivered on February 24, 1940, with a twin-row R-1830-76 and Curtiss propeller, and the second F4F-3 tried a nose spinner. Both were armed with two .30-caliber nose guns and two .50-caliber wing guns aimed with a telescopic sight. An order issued in April had the third and fourth aircraft delivered on July 2 as XF4F-5s with single-row Wright R-1820-40 Cyclones, the same engine used on the Brewster fighters.
Just as the Navy allowed Brewsters to go to Finland in exchange for later models, the G-36A model ordered for the French Navy was allowed to precede the rest of the F4F-3 order. Powered by a Wright R-1820-G205A Cyclone, the G-36A first flew on May 11, 1940, with French markings, and provisions for cockpit armor and six 7.5-mm Darne guns, two in the nose and four in the wings, to be fitted in France.
Britain took over the contract in June, named the
G-36A the Martlet I, and installed four .50-caliber wing guns and reflector sights. From July to October, 81 Martlets, less 10 lost at sea, were sent to the Royal Navy, where the first replaced No. 804 Squadron’s Gladiator biplanes. Their first German Ju 88 bomber kill scored on Christmas Day was also the first by American fighters flown by British pilots.
Deliveries resumed on the F4F-3, now with four .50-caliber wing guns and 1,720 rounds, and nose guns deleted. The usual wing racks for two 116-pound bombs remained, and 155 pounds of 3/8-inch pilot armor were authorized in December 1940, to be added when available. The first standardized, heavier, F4F-3 was delivered November 26, 1940, and 18 went to a Ranger squadron, VF-4 (later VF-41), and the rest to VF-72 and VF-71 on the new Wasp. All 78 F4F-3s on this contract were completed by February 1941 and served on the Navy’s Atlantic side.
Mass production had been ordered by the Navy on August 8, 1940, and 100 G-36Bs (Martlet II) were ordered for Britain on October 1. These contracts added a 25-pound bullet-proof windshield and a self-sealing main tank, which reduced fuel capacity from 160 to 147 gallons. A 62-pound radio, oxygen, and a life raft were provided, but the old flotation bags were gone.
Sufficient two-stage supercharged engines were lacking, so a substitute was found in the single-stage R-1830-90 Wasp on the XF4F-6 first tested on October 26. Despite a sacrifice of high-altitude performance, this engine was used in the new Navy contract’s first 95 aircraft, designated F4F-3A and delivered from March 8 to May 28, 1941, and on the G-36B. The F4F-3A served VMF-111 at Quantico and VF-6 on the Enterprise, but the first 30 were shipped as lend-lease for Greece.
When that country was overrun in April, the shipment was halted at Gibraltar and those F4F-3As became the Royal Navy’s Martlet III and were first used in North Africa by 805 Squadron on July 23, 1941. The first ten G-36Bs (Martlet II) for the Royal Navy were also completed in March, but 90 were delayed until they could have the folding wings of the F4F-4 model.
From May to September 1941, 107 more F4F-3s followed with the two-stage R-1830-86 Twin Wasps in modified cowls with more flaps, but without the upper air intake. Most F4F-3 aircraft had to be delivered without tank protection, until enough sealing bags became available in December. Not until December 1941 did the Navy replace the old telescopic sight with the reflector sight on all Navy fighters. Officially named the Wildcat by the Navy on October 1, these Grummans equipped 10 of the 13 Navy and Marine fighter squadrons in December 1941.
Folding wings, reducing span from 38 to 14 feet, enabled the Navy to double the number of Wildcats placed on a carrier and the first with this feature was the XF4F-4, the 54th aircraft from the first F4F-3 contract. Flown April 14, 1941, it had the R-1830-76, six wing guns, and power folding. Lighter manual folding wings with six .50-caliber guns, were next built on the 90 Martlet IIs delivered with R-1830-S3C4G Wasps and Hamilton props from August 1941 to April 1942. The first 35 were sent to the United Kingdom, 19 were lost at sea, and 26 were shipped to a Royal Navy station in India. Six embarked on HMS Audacity, the first British escort carrier, destroyed five Fw 200C bombers from September 20 to December 21, 1941.
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