The Grumman F6F Hellcat

began life as a concept for an improved F4F Wildcat fighter, with studies beginning in early 1938, and gradually evolving by early 1940 into a concept with the company designation "G-50". By that time, the aircraft no longer looked like a modified Wildcat, basically having become a "clean sheet" design based on the Wildcat but with little or no parts commonality.

After 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 also planned to power both the Republic P-47 Thunderbolt and the Vought F4U Corsair fighters, but both of these machines had been delayed, and so Grumman was able to get their hands on R-2800 production.

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, but the development effort continued with little disruption, though Seldon Converse soon replaced Hall as the test pilot.

Neither prototype was armed. 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, over a month before the first flight of the XF6F-1. There was a war on, and improved fighters were needed even if some risks had to be taken.

Production began at a new Grumman plant in Bethpage, New York, with the fighter going down the assembly line before the buildings were completed. 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.

The Hellcat's angular lines were intended to help make it easy to manufacture. It was a barrel-shaped fighter of mostly metal construction with a flush-riveted skin, though the ailerons were fabric covered. The aircraft was fitted with a roomy cockpit that provided the pilot with an excellent forward view though a poor rear view, and with a "razorback" canopy that slid backwards to open. The straight-edged, square-tipped wings were manually folded up and back along the sides of the fuselage in good Grumman fashion. According to Grumman legend, the concept had been dreamed up by Leroy Grumman using a paperclip and a pink gum eraser.

There were significant differences from the Wildcat as well:

• Although both the Hellcat and the Wildcat had "taildragger" landing gear, the details were entirely different. The Wildcat's main gear retracted into the fuselage, using a hand crank, and had a notoriously narrow track. The Hellcat's main gear were mounted in the wings, retracting backward and rotating 90 degrees to lie flat. The Hellcat also had a retractable solid-rubber tailwheel, with all three gear hydraulically actuated -- a welcome change for pilots who found cranking up the landing gear tiresome.
• The Hellcat had a low-mounted wing, instead of the Wildcat's mid-mounted wing. The new landing gear scheme dictated the shift in the wing's position.
• The Hellcat was simply bigger, with more armor, firepower, and fuel. Armor included a bulletproof windscreen and 96 kilograms (212 pounds) of cockpit armor, as well as armor around the oil tank and cooler under the engine.

  Armament consisted of six 12.7 millimeter (0.50 caliber) Browning machine guns, three mounted in each outboard section of the wing with 400 rounds per gun, instead of the (typical) four 12.7 millimeter Brownings of the Wildcat.

  The Hellcat was fitted with three self-sealing fuel tanks: one with a capacity of 227 liters (60 US gallons) under the pilot's seat, and one in each wing with a capacity of 331 liters (87.5 US gallons), for a total of 889 liters (235 US gallons) -- over twice the fuel capacity of the Wildcat. The F6F-3 could also carry a 568 liter (150 US gallon) centerline drop tank, though most F6F-3 production had no provisions for carrying any other external stores.

The big Double Wasp engine drove a three-bladed, constant-speed Hamilton Standard Hydromatic propeller with a diameter of 3.99 meters (13 feet 1 inch), though the XF6F-3 had used a Curtiss Electric propeller. The XF6F-3 had also featured a large prop spinner, but this item didn't make it into production aircraft. The engine was set three degrees off the center axis of the aircraft, giving the machine a tail-down attitude in flight. The Hellcat used a "stinger" type arresting hook, like that of the Wildcat, that discreetly retracted straight back into the extreme tail.

 GRUMMAN F6F-5 HELLCAT:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                13.06 meters        42 feet 10 inches
   wing area               31.03 sq_meters     334 sq_feet
   length                  10.24 meters        33 feet 7 inches
   height                  3.99 meters         13 feet 1 inch

   empty weight            4,190 kilograms     9,238 pounds
   normal loaded weight    6,990 kilograms     15,415 pounds

   max speed at altitude   610 KPH             380 MPH / 330 KT
   service ceiling         11,370 meters       37,300 feet
   range                   1,520 kilometers    945 MI / 820 NMI
   _____________________   _________________   _______________________

The Hellcat no doubt came as a nasty surprise to Japanese pilots, since it looked enough like a Wildcat to be confused for one at a distance, but was a substantially more dangerous adversary, every bit as tough as the Wildcat but faster and more heavily armed. It was still no match for the Zero in terms of agility and couldn't outclimb the "Zeke", but the Hellcat could almost always escape by going into a dive. Any competent Hellcat pilot who understood his machine's advantages and the Zeke's weaknesses had the upper hand.