Pratt & Whitney R-2180-E Twin Wasp E


The Pratt & Whitney R-2180-E Twin Wasp E was a radial aircraft engine developed in the United States by Pratt & Whitney. It had fourteen cylinders in two rows of seven cylinders each. Its only production application was on the post-World War II Saab 90 Scandia airliner.

Design and development

The R-2180-E is effectively a fourteen-cylinder simplification of the twenty-eight cylinder R-4360 Wasp Major engine, basically half of an R-4360 - its cylinders are the same size and displacement as those of the Wasp Major. This is not to say that designing a classic 14 cylinder version of the new engine family required them to first build a 28 cylinder monster and then cut it in half; that is just a convenient way of visualizing the engine. A classic 14 cylinder version of the new engine was certainly proposed as a modest upgrade of the R-1830 even as they were introducing the new 18 cylinder R-2800, long before any serious work went into the radical new approach of stacking four rows of cylinders, which had long been considered impossible due to cooling issues, and when they decided to attempt the 4-row type, they used the plans for the 7 cylinder type banks, due to the impossibility of cooling multiple banks of nine, However, due to the excellent service of the R-1830 and the more pressing need for maximum-power engines for the new types of high performance/heavy weight aircraft, the eighteen cylinder and even more radical 28 cylinder types saw service before the more conventional R-2180. More simply put, the R-2180 is not dependent on the R-4360 in any way for its existence, and would have been designed with or without that engine.
The R-2180-E Twin Wasp E was available in a "power-egg" installation certificated in 1945 for use as an engine upgrade for the Douglas DC-4.

Applications