Prototype of Hellcat: XF6F-1
The Grumman XF6F-1 marked the beginning of the F6F Hellcat’s development. The first flight occurred on June 26, 1942, with test pilot Selden A. Converse at the controls. The XF6F-1, intended as an upgrade from the earlier F4F Wildcat, initially featured the Wright R-2600-16 Cyclone engine, a 14-cylinder, twin-row radial engine producing 1,600 horsepower at takeoff and 1,200 horsepower at altitude. Despite being a significant improvement over the Wildcat, the XF6F-1’s performance was deemed insufficient, and Grumman quickly switched to the more powerful Pratt & Whitney R-2800 Double Wasp engine for subsequent versions. Key specifications of the XF6F-1:
- Span: 42 feet 10 inches
- Wing Area: 334 square feet
- Length: 33 feet 7 inches
- Height: 11 feet 3 inches
- Propeller: Curtiss Electric 3-blade with cuffs and spinner
- Armament: Six 0.50 cal Browning M6 machine guns mounted in the wings, with 400 rounds per gun
Flight Testing:
Initial flight trials of the XF6F-1 at Bethpage, New York, revealed that while the aircraft performed better than its predecessor, it suffered from excessive longitudinal stability and required significant trim adjustments between flaps up and flaps down configurations. Furthermore, a flutter issue limited its maximum dive speed to 525 mph (845 km/h). These issues were eventually addressed without major changes to the airframe, leading to the final production standard.
Switch to the Double Wasp Engine:
Recognizing the potential for improved performance, Grumman quickly replaced the Wright R-2600 with the Pratt & Whitney R-2800-10W Double Wasp, a much more powerful engine. The second prototype flew on July 30, 1942, featuring this new powerplant. The switch led to the development of the XF6F-3, which became the first production variant.
XF6F-4 Prototype:
The original XF6F-1 was later retrofitted with a two-speed R-2800-27 engine and was redesignated as the XF6F-4, which first flew on October 2, 1942. This model incorporated additional refinements, such as the Hamilton Standard propeller, replacing the original Curtiss Electric type, the elimination of the spinner, and redesigned undercarriage fairings. This version laid the groundwork for the Hellcat’s dominance as a carrier-based fighter in the Pacific Theater during World War II.