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Pratt & Whitney R-4360

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File:Wasp Major.jpg
Pratt & Whitney R-4360 Wasp Major (sectioned)
File:Pratt & Whitney R-4360 Wasp Major 1.jpg
Pratt & Whitney R-4360 Wasp Major

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 Pratt & Whitney 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 28 cylinder four-row radial engine with each row slightly offset from the previous, forming a semi-helical arrangement (as can be seen in the photograph), to facilitate cooling of the successive rows of cylinders. A mechanical supercharger geared at 6.374:1 ratio to engine speed provided forced induction, while the propeller was geared at 0.375:1 so that the tips did not reach inefficient supersonic speeds.

Although reliable in flight, the Wasp Major was troublesome on the ground.Template:Clarifyme Crankcase oil leaks were very common, as noticeable on many photos of the B-50 Superfortress with long black streaks down each wing. Also it was one of the few engines that could shut down in perfect running order and have something wrong with it the next time it was started up.[citation needed] This required an extensive checklist for start-up and shutdown procedures that could last for more that six hours.

Engine displacement was 4,362.50 in³ (71.5 L), hence the model designation. Initial models developed 3,000 hp (2240 kW), but the final models delivered 4,300 hp (3200 kW) using two large turbochargers in addition to the supercharger. Engines weighed 3,482 to 3,870 lb (1,579 to 1,755 kg), heavy but giving a power to weight ratio of 1.11 hp/lb (1.83 kW/kg), matched by very few engines.

Wasp Majors were produced between 1944 and 1955; 18,697 were built.

A derivative engine, the R-2180, was essentially the R-4360 "cut in half". It had two rows of seven cylinders each, and was used on the postwar Saab 90 Scandia airliner.

Aircraft usage

The Pratt & Whitney R-4360 was 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:


Specifications (R-4360-51VDT)


Related contents

Related development

Comparable engines


Further reading

  • White, Graham (2006). R-4360: Pratt & Whitney's Major Miracle. North Branch, Minn.: Specialty Press. ISBN 1-58007-097-3. 

External links

cs:Pratt & Whitney R-4360 de:Pratt & Whitney R-4360 fi:Pratt & Whitney R-4360 Wasp Major it:Pratt & Whitney R-4360 pl:Pratt & Whitney R-4360

This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article "Pratt & Whitney R-4360".