Pratt & Whitney R-4360
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Wasp_Major.jpg
The Pratt & Whitney R-4360 Wasp Major was a large radial piston aircraft engine designed and built during World War II. It was the last of the Wasp family and 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 successive rows of cylinders. 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 in³ (71.4 L), 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 to 3,870 lb (1,600 to 1,800 kg), heavy but giving a power to weight ratio matched by very few engines.
The engine was commonly nicknamed the Corncob, since its multiple, staggered rows of cylinders made it resemble one.
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:
- Sud-Est SE-2010 Armagnac
- Boeing XB-44 Superfortress
- Boeing B-50 Superfortress
- Boeing 377 Stratocruiser
- Boeing C-97 Stratofreighter
- Boeing XF8B-1
- Aero Spacelines, Inc. Pregnant Guppy and Mini Guppy
- Convair B-36
- Convair XC-99
- Convair A-41
- Curtiss XBTC-2
- Douglas TB2D Skypirate
- 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 Mars
- Martin P4M Mercator
- Northrop B-35
- Republic XP-72
- Republic XF-12 Rainbow
References
- Pratt & Whitney page on the R-4360 (http://www.pratt-whitney.com/about_history_classic_r4360.asp)
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