Pratt & Whitney R-2800 Double Wasp
A powerhouse 18-cylinder radial that defined late-WWII air power and later powered advanced commercial transports. It delivered exceptional horsepower for its size while maintaining durability in both combat and civilian service. The R-2800 proved that piston engines could reach remarkable performance limits before jets took over.
Key Specifications
Type
Year Built
18-cylinder, two-row air-cooled radial piston engine
1937
Horsepower
2,000–2,800 hp at ~2,700 rpm
Weight
~2,350 lb (1,066 kg)
Power-to-Weight Ratio
~1.0–1.2 hp/lb (variant dependent)
Fuel
Aviation gasoline (high-octane)
Cooling System
Ignition
Construction
Manufactuer
Air-cooled with finned cylinders
Dual magneto ignition system
Forged steel crankshaft, aluminum alloy crankcase, steel cylinder barrels with aluminum cooling fins
Pratt & Whitney Aircraft
Engineering Significance
•The R-2800 powered some of the fastest and most capable piston-driven aircraft ever built. In commercial aviation, it enabled higher cruise speeds and greater payload capacity on postwar airliners like the DC-6 and Constellation, helping airlines expand long-range passenger service before the jet age.
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•The Double Wasp demonstrated the practical limits of large air-cooled radial engine development, producing up to 2,400 horsepower in later variants while maintaining operational reliability. Its two-stage, two-speed supercharging system enabled strong high-altitude performance above 25,000 feet, a critical requirement for both long-range bombers and high-performance transports. Advances in aluminum alloys, sodium-cooled exhaust valves, and refined fin geometry improved thermal dissipation, allowing sustained high power settings without catastrophic overheating. In many ways, it represented the technical and mechanical peak of piston-era radial engineering just before gas turbine engines reshaped commercial aviation.
Notable Aircrafts
•Douglas DC-6
•Convair 240/340/440
•Lockheed Constellation
(only for test purposes)
•P-47 Thunderbolt
•F4U Corsair
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