Grumman F6F Hellcat
In early 1941 Grumman designers had been studying the next generation, using one of the much more powerful engines that were available, such as the 1,600-hp Wright R-2600 Cyclone 14 or the 2,000-hp Pratt & Whit-ney R-2800 Double Wasp.
The fuselage was made much bigger, with a cross-section no longer circular but resembling a pear-shape. The huge squarish wing was lowered, partly to keep the landing gear reasonably short and still provide ground clearance for the larger propeller. The main landing gears were moved out to the wings, retracting rearwards with the wheels turning to lie flat just in front of the slotted flaps. The outer wings, with six 0.5-in guns, folded about skewed hinges as before. The overall impression was one of strength, accentuated by the blunt nose, with ducts for the oil cooler and supercharger intercooler under the engine.
Contracts for the prototypes were placed on June 30, 1941, which meant that reports of aerial combat in Europe played a part in the design, and the first prototype, designated XF6F-1 and powered by a 1700-hp Wright R-2600-10 Cyclone, flew for the first time on June 26, 1942 from the Bethpage, Long Island factory, piloted by Selden A Converse. In the same month, a Zero had been forced down in the Aleutians and captured, so that further lessons could be incorporated, and the revised prototype, now designated XF6F-3 (another prototype, XF6F-2, later XF6F-4, was also built), made its first flight on 26 June 1942, powered by the R-2800. The bigger engine was the obvious choice, and — even though Grumman was building a completely new Plant 3 in order to make the new fighter — mass production got under way with amazing rapidity. Even as the factory was being built, assembly lines of F6F-3s took shape inside it, the first coming off the line and into the sky on 4 October 1942.
Orders for production F6F-3s had been placed in May 1942, and by the end of the year the first examples were being delivered to US Navy Squadron VF-9 on the newly-commissioned USS Essex.
Designed to outperform the Zero in everything but manoeuvrability - achieved in the A6M only at the expense of heavy armament and armour protection for the pilot and fuel tanks - the F6F-3 was powered by a Pratt & Whitney R-2800-10W Double Wasp 18 -cylinder air-cooled two-row radial engine with water injection. Construction was simple and robust for case of both production and maintenance, an all-metal semi-monocoque with stressed skin incorporating armour protection for the pilot and a turnover structure. The wings used the characteristic Grumman folding system, pivoting about the front spar and folding back parallel with the fuselage, leading edge down. The operation was carried out manually, the locking pins being operated hydraulically from the cockpit and made safe by hand. The six 0.50-in (12.7-mm) machine-guns, mounted just outboard of the break line, were thus accessible with the wings folded. The main undercarriage legs also rotated through 90degs to retract backwards into wing wells, covered by plates attached to the legs.
Compared with the Wildcat, the F6F-3 had 800 hp more power, was 97 km/h (60 mph) faster and had two more guns with almost double the ammunition (400 rounds per gun). Although considerably heavier, the Hellcat could climb to 4572 m (15000 ft) in under eight minutes and had a service ceiling of over 8230 m (37000 ft). Compared with the Zero it was faster, better armed and far more resistant to battle damage.
In order to concentrate on the Hellcat, Grumman sub-contracted production of the Wildcat and the TBF Avenger to General Motors, and deliveries to both the US Navy and Marine Corps and the Fleet Air Arm, which named the type Hellcat I, mounted rapidly.
Named Hellcat, the F6F-3 was almost right from the start, the only major modifications being to tilt the engine slightly downwards, simplify the main landing-gear fairings and fit a Hamilton propeller with no spinner. Then production really rolled, starting with 4,403 F6F-3s, including 16 converted as F6F-3E night-fighters with an APS-4 radar pod on the starboard wing and 205 F6F-3N night-fighters with an APS-6 radar in a pod on the starboard wing. Late Dash-3s had the R-2800-10W rated at 2,200hp with water injection, and a flat bul-letproof windshield.
During 1944 the F6F-3 (an eventual total of 4646) was replaced on the production lines by the F6F-5, using the same engine but with modified cowling and windshield and improvements to the control surfaces with spring-tab ailerons, strengthened tail surfaces, additional armour behind the pilot and a waxed high-gloss skin finish.
Armament was increased, with fittings for a 454-kg (1000-lb) bomb under each wing centre section, racks for six rockets under the outer wings and, on later models, the inboard machine-guns replaced by 20-mm cannon. The F6F-5 carried a search radar as the F6F-5E. This was the final production version of the Hellcat, a total of 7860 being produced by November 1945, including 1189 F6F-5N night-fighters with wing-podded APS-6, photographic-reconnaissance (F6F-5P) versions, and 930 FAA Hellcat IIs.
The F6F-5K was a long-range radio-controlled pilotless drone conversion of the Hellcat. The modification was undertaken by the Naval Aircraft Modification Unit at Johnsville. Several were used in the Bikini operations.
The remaining variant was the F6F-6, powered by a 2100-hp R-2800-18W, which first flew in mid-1944, but only two were built.
At the same time as the Hellcat began to enter service, the US Navy's new Essex Class fleet carriers and Independence Class light carriers were coming into commission, and new aircraft and new carriers saw their first operational use in the summer of 1942 in a strike against the Japanese-held Marcus Island. Alongside the Avenger torpedo bomber and Dauntless dive-bomber and in partnership with the later F4U Corsair fighter, Hellcats fought their way across the Pacific as the island-by-island drive towards Japan continued.
Some late F6F-5s had two 20-mm cannon and four 0.5-in guns. The overall figure of 7,870 included 1,529 F6F-5N night fighters and about 200 conversions as F6F-5P photo aircraft. The totals for the F6F, like, those for the F4F, correct many that have been accepted since 1945.
In combat with the F6F, the Zero was at an enormous disadvantage. The unarmoured fuel tanks of the Japanese fighter were easily ignited by a short burst from the Hellcat's six Brownings, and the Zero's superior manoeuvrability was outweighed by the American fighter's greater power and strength. Their most dramatic combat came in the Battle of the Philippine Sea, a carrier battle fought at extreme range on June 19/20, 1944. In the course of this epic encounter, 402 Japanese aircraft were destroyed, while six Hellcats were lost in the vicinity of the Japanese fleet and a further 17 splashed down with empty fuel tanks on the return journey. This decisive victory was known as the 'Marianas Turkey Shoot' by the US Navy and Marine pilots.
As well as flying from carriers, F6Fs were operated by shore-based US Marine squadrons. The type also distinguished itself in Fleet Air Arm service, flying anti-shipping strikes off the Norwegian coast, providing fighter cover during night attacks on the German battlecruiser Tirpitz, and becoming the standard FAA fighter in the Pacific. The Royal Navy received over 900 Hellcats including approximately 70 night fighters. These were designated F Mk II and NF Mk II. US Navy carrier-borne Hellcats claimed a total of 4947 enemy aircraft shot down-over 75% of all US Navy combat victories of the Second World War, and with a kill-to-loss ratio of over 19: 1. The virtual annihilation of Japanese naval aviation represented the successful completion of the Hellcat's mission.
The Fleet Air Arm received 252 Hellcat Is (F6F-3), 930 Hellcat IIs (F6F-5) and 80 Hellcat NF.IIs (F6F-5N). Some were modified as FR.IIs (fighter-reconnaissance) or as unarmed PR.IIs. The com-bat record of the Hellcat speaks for itself. Though it did not get into action until 31 August 1943 this fighter destroyed 5,155 (not 4,947) of the US Navy total carrier-based score of 6,477 against the Japanese. Though perhaps not entirely typical, it gives a flavour of the F6F’s long-awaited ascendancy to note that in its first big battle, in the Kwajalein/Roi area on 4 December 1943, 91 F6F-3s met approximately 50 A6M Zeros and destroyed 28 for the loss of two aircraft.
After the war Hellcats continued in service, some as camera-equipped F6F-5Ps, others as F6F-5K target drones and -5D drone directors. One of their last and least-known missions came during the Korean war, by which time they were obsolete as fighters. Remote controlled F6F-5Ks, filled with explosives, were launched from USS Boxer by Guided Missile Unit 90 in six attacks against North Korean targets, the first attack being carried out on August 28, 1952. The -5Ks were guided during the attacks by Douglas AD-2D Skyraider drone director aircraft.
The F6F-5 was the last operational version of the Hellcat, which was finally withdrawn from production in November 1945. The 10,000th Hellcat was delivered to the US Navy in March 1945 and final production amounted to 12,275.
Span:13.06 m (42ft 10 in)
Length:10.24 m (33 ft 7 in)
Gross weight: 5643 kg (12441 lb)
Maximum speed: 604 km/h (375 mph).
Engine: 1 x Pratt & Whitney R-2800-10W Double Wasp, 1491kW / 1973 hp
Max take-off weight: 6991 kg / 15413 lb
Empty weight: 4152 kg / 9154 lb
Wing loading: 46.13 lb/sq.ft / 225.0 kg/sq.m
Wingspan: 13.06 m / 42 ft 10 in
Length: 10.24 m / 33 ft 7 in
Height: 4.11 m / 13 ft 6 in
Wing area: 31.03 sq.m / 334.00 sq ft
Max. speed: 330 kts / 612 km/h / 380 mph
Cruise speed: 146 kts / 270 km/h / 168 mph
Service Ceiling: 11370 m / 37300 ft
Range w/max.fuel: 1329 nm / 2462 km / 1530 miles
Armament: 6 x .50in / 12.7mm machine-guns, 2 x 454kg bombs or 6 x 127mm missiles