From Wikipedia, the free encyclopedia.
The Pratt & Whitney R4360 Wasp Major was a large radial piston aircraft engine designed and built during World War II. It was the culmination of its maker's piston engine technology, but the war was over before it could power airplanes into combat. It did, however, power the last generation of large piston-engined planes before the jet engine and turboprop took over.
It was a four-row radial engine with 28 cylinders (seven per row); each row was slightly offset from the previous so that they formed a somewhat helical arrangement (as can be seen in the photograph) - this was to permit better cooling of the air-cooled engine. A mechanical supercharger geared at six times engine speed provided forced induction, while the propeller was geared at half engine speed so that the tips did not reach inefficient supersonic speeds.
Engine displacement was 4,360 cubic inches (71.4 litres), hence the model designation. Initial models developed 3,000 hp (2240 kW), but the final models delivered 4,300 hp (3200 kW). Engines weighed 3,482-3,870 pounds, heavy but giving a power-to-weight ratio matched by very few engines.
Wasp Majors were produced between 1944 and 1955; 18,697 were built. They were intended as a new powerplant for the Boeing B-29 Superfortress; Wasp Major-powered Superfortresses were eventually designated B-50. They also powered the Convair B-36 as well as a broad assortment of other aircraft:
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- Boeing XB-44 Superfortress
- Boeing B-50 Superfortress
- Boeing 377 Stratocruiser
- Boeing C-97 Stratofreighter
- Boeing XF8B-1
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- Convair B-36
- Convair XC-99
- Convair A-41
- Curtiss XBTC-2
- Douglas TB2D Devastator
- Douglas C-74 Globemaster
- Douglas C-124 Globemaster II
- Fairchild C-119 Flying Boxcar
- Fairchild C-120 Packplane
- Goodyear F2G
- Hughes XF-11
- Hughes H-4 Hercules ("Spruce Goose")
- Lockheed Constitution
- Martin AM Mauler
- Martin JRM-2 Mars
- Martin P4M Mercator
- Northrop B-35
- Republic XP-72
- Republic XP-12 Rainbow
