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Saturday, March 12, 2011

Grumman F6F Hellcat

F6F Hellcat
A U.S. Navy Grumman F6F-3 Hellcat
Role Fighter aircraft
Manufacturer Grumman
First flight 26 June 1942
Introduced 1943
Retired 1960 Uruguayan Navy[1]
Primary users United States Navy
United States Marine Corps
Royal Navy
French Navy
Produced 1942–1945
Number built 12,275
Unit cost $35,000 in 1945[2]
The Grumman F6F Hellcat was a carrier-based fighter aircraft developed to replace the earlier F4F Wildcat in United States Navy (USN) service. Although the F6F bore a family resemblance to the Wildcat, it was a completely new design powered by a 2,000 hp Pratt & Whitney R-2800. Some tagged it as the "Wildcat's big brother".[3] The Hellcat and the Vought F4U Corsair were the primary USN fighters during the second half of World War II.
The Hellcat was the first USN fighter for which the design took into account lessons from combat with the Japanese Zero.[4] The Hellcat proved to be the most successful aircraft in naval history, destroying 5,271 aircraft[5] while in service with the U.S. Navy and U.S. Marine Corps (5,163 in the Pacific and eight more during the invasion of Southern France, plus 52 with the Royal Navy's Fleet Air Arm during World War II).[6] Postwar, the Hellcat aircraft was systematically phased out of front line service, but remained in service as late as 1954 as a night fighter in composite squadrons.

Contents

  • 1 Design and development
  • 2 Operational history
  • 3 Variants
  • 4 Operators
  • 5 Survivors
  • 6 Specifications (F6F-5 Hellcat)

Design and development

Grumman F6F-3 Hellcats in tricolor camouflage, red outline on US insignia indicate picture was taken circa June–September 1943[7]
Grumman F6F-3 Hellcat on the flight deck of USS Yorktown (CV-10) prior to take off, having its wings extended
Grumman was working on a successor to the F4F Wildcat well before the Japanese attacked Pearl Harbor. While the F4F was a capable fighter, early air battles revealed the Japanese A6M Zero was more maneuverable and possessed a better rate of climb than the F4F. The F4F did have some advantages over the Zero. Wildcats were able to absorb a tremendous amount of damage compared to the Zero, and had better armament. The F4F was also much faster in a dive than the Zero, an advantage Wildcat pilots used frequently to elude attacking Zeros.
These advantages carried over into the F6F and, combined with other improvements, created a fighter that outclassed the Zero almost completely. The contract for the prototype XF6F-1 was signed on 30 June 1941. The F6F was originally to be given the Wright R-2600 Cyclone engine of 1,700 hp (1,268 kW), but based on combat experience of F4F Wildcat and Zero encounters, Grumman decided to further improve their new fighter to overcome the A6M Zero's dominance in the Pacific theater.[3] Grumman installed the Pratt & Whitney R-2800 Double Wasp 2,000 hp (1,500 kW) estimating a 25% increase in performance would result.[3] The first Cyclone-equipped prototype (02981) flew on 26 June 1942 while the first Double Wasp-equipped aircraft, the XF6F-3 (02982) had its first flight on 30 July 1942.
Proposed at the same time as the first Hellcat prototypes, the XF6F-2 incorporated a turbo-supercharger, but performance gains were only slight and until fleet demands for improvements in speed arose, this variant, along with the two-speed supercharger-equipped XF6F-3, languished. However, later F6F-4 and F6F-5 variants did benefit from these initial development programs.
Like the Wildcat, the Hellcat was designed for ease of manufacture and ability to withstand significant damage. A total of 212 lb (96 kg) of cockpit armor was fitted to aid pilot survival, as well as a bullet-resistant windshield and armor around the engine oil tank and oil cooler.[8] Self-sealing fuel tanks further reduced susceptibility to fire and often allowed damaged aircraft to return home. The U.S. Navy's all-time leading ace, Captain David McCampbell USN (Ret) scored all his 34 victories in the Hellcat. He once described the F6F as "...an outstanding fighter plane. It performed well, was easy to fly and was a stable gun platform. But what I really remember most was that it was rugged and easy to maintain."[9]
The first production aircraft off the line, designated F6F-3s, flew on 3 October 1942 with the type reaching operational readiness with VF-9 on USS Essex in February 1943.[8]
Two night fighter sub-variants of the F6F-3 were also developed. The F6F-3E, converted from standard -3 frames, featured the AN/APS-4 radar in a fairing in the starboard wing. The later F6F-3N, first seen in July 1943, was fitted with the AN/APS-6 radar in a similar fairing. By November 1943, Hellcat night fighters had seen their first action.[10] Fitting AN/APS-6 radar fairings to F6F-5s resulted in the night fighter F6F-5N, and a small number of standard F6F-5s were also fitted with camera equipment for reconnaissance duties as the F6F-5P.[11]
Folded wing of F6F at the Cradle of Aviation Museum
Instead of the Wildcat's narrow-track undercarriage retracting into the fuselage requiring awkward hand-cranking by the pilot, the Hellcat had hydraulically-actuated undercarriage struts set wider and retracting backward, twisting through 90° into the wings,[12] exactly as the Chance Vought F4U Corsair's landing gear did. The wing was low-mounted instead of mid-mounted and folded the same way as the later versions of the Wildcat, allowing the Hellcat to take on a compact, tucked-in appearance on a flight deck.[13]
Standard armament on the F6F consisted of six .50 in (12.7 mm) M2 Browning air-cooled machine guns with 400 rpg; later aircraft gained three hardpoints to carry a total bombload in excess of 2,000 lb (900 kg). The center hardpoint also had the ability to carry a single 150 gal (568 l) disposable drop tank. Six 5 in (127 mm) HVARs (High Velocity Aircraft Rocket)[14] could be carried; three under each wing.[15]
The next and most common variant, the F6F-5, featured improvements such as a more powerful R-2800-10W engine housed in a slightly more streamlined engine cowling, spring-loaded control tabs on the ailerons, deletion of the rear-view windows behind the main canopy, an improved, clear view windscreen with a flat armored-glass front panel replacing the curved plexiglass panel and internal armor glass screen and numerous other minor advances.[12][16] Another improvement in the F6F-5 was the availability of more potent armament than the standard six .50 in (12.7 mm) machine guns. Trials with cannon-armed Hellcats were not followed up by a production version; although all F6F-5s could carry an armament mix of a pair of 20 mm (.79 in) Hispano cannon, one mounted in each of the inboard gun bays, with a minimum of 220 rpg, along with two pairs of .50 in (12.7 mm) machine guns, with 400 rpg, this configuration was only used on many later F6F-5N night fighters.[17]
Two F6F-5s were fitted with the 18-cylinder 2,100 hp (1,567 kW) Pratt and Whitney R-2800-18W two-stage blower radial engine which was also used by the F4U-4 Corsair. The new Hellcat variant was fitted with a four-bladed propeller and was called the XF6F-6. The aircraft proved to be the best performer in the series with a top speed of 417 mph (671 km/h).[12] The war ended before this variant could be mass-produced.[18]
The last Hellcat rolled out in November 1945, the total production figure being 12,275, of which 11,000 had been built in just two years.[19] This impressive production rate was credited to the sound original design, which required little modification once production was underway.

Operational history

F6F-3 on the USS Yorktown, May 1943. Non-specular blue-grey over light-grey scheme.
The Hellcat first saw action against the Japanese on 1 September 1943 when fighters off the USS Independence shot down a Kawanishi H8K "Emily" flying boat.[20] Soon after, on 23 and 24 November, Hellcats engaged Japanese aircraft over Tarawa, shooting down a claimed 30 Mitsubishi Zeros for the loss of one F6F.[20] Over Rabaul, New Britain, on 11 November 1943, Hellcats and Corsairs were engaged in day-long fights with many Japanese aircraft including A6M Zeros, shooting down nearly 50 aircraft.[20]
When trials were flown against a captured Zero Type 52, they showed that the Hellcat was faster at all altitudes. The F6F outclimbed the Zero marginally above 14,000 ft and rolled faster at speed above 235 mph. The Japanese fighter could out-turn its American opponent with ease at low speed and enjoyed a slightly better rate of climb below 14,000 ft. The trials report concluded:
“Do not dogfight with a Zero 52. Do not try to follow a loop or half-roll with a pull-through. When attacking, use your superior power and high speed performance to engage at the most favourable moment. To evade a Zero 52 on your tail, roll and dive away into a high speed turn.” [21]
Hellcats were involved in practically all engagements with Japanese air power from that point onward. It was the major U.S. Navy fighter type involved in the Battle of the Philippine Sea, where so many Japanese aircraft were shot down that Navy aircrews nicknamed the battle The Great Marianas Turkey Shoot. The F6F accounted for 75% of all aerial victories recorded by the U.S. Navy in the Pacific.[22] Radar-equipped Hellcat night fighter squadrons appeared in early 1944.
Navy and Marine F6Fs flew 66,530 combat sorties (45% of all fighter sorties of the war, 62,386 sorties were flown from aircraft carriers)[23] and destroyed 5,163 (56% of all Naval/Marine air victories of the war) at a cost of 270 Hellcats (an overall kill-to-loss ratio of 19:1).[24] The aircraft performed well against the best Japanese opponents with a 13:1 kill ratio against Mitsubishi A6M, 9.5:1 against Nakajima Ki-84, and 3.7:1 against the Mitsubishi J2M during the last year of the war.[25] The F6F became the prime ace-maker aircraft in the American inventory, with 305 Hellcat aces.[N 1]That being said, it must be noted that the U.S. successes were not only attributed to superior aircraft, but also because they faced increasingly inexperienced Japanese aviators from 1942 onwards, as well as having the advantage of ever-increasing numerical superiority.
In the ground attack role, Hellcats dropped 6,503 tons (5,899 tonnes) of bombs.[24]
The British Fleet Air Arm (FAA) received 1,263 F6Fs under the Lend-Lease Act; initially it was known as the Grumman Gannet Mark I. The name Hellcat replaced it in early 1943 for the sake of simplicity, the Royal Navy at that time adopting the use of the existing American naval names for all the U.S.-made aircraft supplied to it, with the F6F-3 being designated Hellcat F I, the F6F-5, the Hellcat F II and the F6F-5N, the Hellcat NF II.[N 2] They saw action off Norway, in the Mediterranean and in the Far East. A number were fitted with photographic reconnaissance equipment similar to the F6F-5P, receiving the designation Hellcat FR II.[27] The FAA Hellcat units experienced far fewer opportunities for air-to-air combat than their USN/Marines counterparts; a total of 52 enemy aircraft were shot down during 18 aerial combats from May 1944 to July 1945. 1844 Naval Air Squadron, on board HMS Indomitable of the British Pacific Fleet was the highest scoring unit, with 32.5 kills.[28]
FAA Hellcats, as with other Lend-Lease aircraft, were rapidly replaced by British aircraft after the end of the war, with only two of the 12 squadrons equipped with the Hellcat at VJ-Day still retaining Hellcats by the end of 1945.[29] These two squadrons were disbanded in 1946.[29] In British service, the Hellcats proved to be a match even for the main Luftwaffe fighters, the Messerschmitt Bf 109 and Focke-Wulf Fw 190.
Postwar, the Hellcat was succeeded by the F8F Bearcat which was smaller, more powerful and more maneuverable than the Hellcat, but entered service too late to see combat in World War II.[30] The Hellcat soldiered on in a number of second line USN duties including training. In late 1952, Guided Missile Unit 90 used F6F-5K drones, each carrying a 2000 lb bomb, to attack bridges in Korea; flying from USS Boxer, radio control was from an escorting AD Skyraider.[31] The French Aéronavale was equipped with F6F-5 Hellcats and used them in Indochina. The Uruguayan Navy also used them until the early 1960s.[32]

Variants

XF6F-1 in 1942.
F6F-3N night fighter with AN/APS-4 radar.
XF6F-4 with R-2800-27 Double Wasp.
XF6F-1
First prototype, powered by a two-stage 2,000 hp (1,491 kW) Wright R-2600-10 Cyclone 14 radial piston engine.
XF6F-2
Second prototype, powered by a turbocharged Wright R-2600-16 Cyclone radial piston engine.
XF6F-3
The first XF6F-1 prototype revised and fitted with a two-stage supercharged 2,000 hp (1,491 kW) Pratt & Whitney R-2800-10 Double Wasp radial piston engine.
F6F-3
Single-seat fighter, fighter-bomber aircraft, powered by a 2,000 hp (1,491 kW) Pratt & Whitney R-2800-10 Double Wasp radial piston engine.
Gannet Mk. I
British designation of the F6F-3 Hellcat; later redesignated Hellcat F Mk.I.
F6F-3E
Night fighter version, equipped with an AN/APS-4 radar in a fairing on the starboard outer wing.
F6F-3N
Another night fighter version, equipped with a newer AN/APS-6 radar in a fairing on the starboard outer wing.
XF6F-4
One F6F-3 fitted with a two-speed turbocharged 2,100 hp (1,567 kW) Pratt & Whitney R-2800-27 Double Wasp radial piston engine.
F6F-5 Hellcat
Improved version, with a redesigned engine cowling, a new windscreen structure with an integral bullet proof windscreen, new ailerons and strengthened tail surfaces; powered by a 2,200 hp (1,640 kW) Pratt & Whitney R-2800-10W (-W denotes Water Injection) radial piston engine.
Hellcat F Mk II
British designation of the F6F-5 Hellcat.
F6F-5K Hellcat
A number of F6F-5s and F6F-5Ns were converted into radio-controlled target drones.
F6F-5N Hellcat
Night fighter version, fitted with an AN/ APS-6 radar. Some were armed with two 20 millimeter (0.79 in) AN/M2 cannon in the inner wing bays and four 0.50 in (12.7 mm) M2 Browning machine guns in the outer.
Hellcat NF Mk. II
British designation of the F6F-5N Hellcat.
F6F-5P Hellcat
Small numbers of F6F-5s were converted into photo-reconnaissance aircraft, with the camera equipment being fitted in the rear fuselage.
Hellcat FR Mk II
This designation was given to British Hellcats fitted with camera equipment.
XF6F-6
Two F6F-5s that were fitted with the 2,100 hp (1,566 kW) Pratt & Whitney R-2800-18W radial piston engine, and four bladed propellers.
FV-1
Proposed designation for Hellcats to be built by Canadian Vickers; cancelled before any built.[33]

Operators

A Fleet Air Arm Hellcat F.I
 France
 United Kingdom
 United States
 Uruguay

Survivors

A relatively large number of Grumman F6Fs are survivors, either in museums or in flyable condition. In order of Bu.No. they are:[34]
F6F-3K in the Steven F. Udvar-Hazy Center
Airworthy
Display
Restoration

Specifications (F6F-5 Hellcat)

Aircraft captains ready VF-82 Grumman F6F-5 for launch from USS Bennington (CV-20) off Okinawa in May 1945. Late-war production F6F-5 show the overall Glossy Sea Blue
Postwar service: A bright orange F6F-3K target drone
F6F-5P of VP-23 crashes on USS Princeton (CVL-23).
Data from Quest for Performance,[56]Jane’s Fighting Aircraft of World War II[57]Standard Aircraft Characteristics[58]
General characteristics
Performance
Armament
  • Guns:
    • either 6× 0.50 in (12.7 mm) M2 Browning machine guns, with 400 rpg, (All F6F-3, and most F6F-5)
    • or 2 × 20 mm (.79 in) cannon, with 225 rpg
    • and 4 × 0.50 in (12.7 mm) Browning machine guns with 400 rpg (F6F-5N only)
  • Rockets:
    • 6 × 5 in (127 mm) HVARs or
    • 2 × 11¾ in (298 mm) Tiny Tim unguided rockets
  • Bombs: up to 4,000 lb (1,814 kg) full load, including:
    • Bombs or Torpedoes:(Fuselage mounted on centreline rack)
      • 1 × 2,000 lb (907 kg) bomb or
      • 1 × Mk.13-3 torpedo;
    • Underwing bombs: (F6F-5 had two additional weapons racks either side of fuselage on wing centre-section)
      • 2 × 1,000 lb (450 kg) or
      • 4 × 500 lb (227 kg)
      • 8 × 250 lb (110 kg)
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