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Pratt & Whitney’s R-1340 is The Only Aircraft Engine to be Designated an Historic Landmark

The Wasp Engine’s Great Leap Forward

Advances in propulsion are what drive aviation development. Innovative airplanes almost always start with innovative engines, and the airframes follow. In 2016, the American Society of Mechanical Engineers celebrated just such an engine. The society designated the Pratt & Whitney R-1340 Wasp a technology landmark, the organization’s highest award, because the Wasp singlehandedly brought about a leap forward in aircraft performance and economics. The tale of its development is still fascinating.

Wasp no. 1 never flew, but the Navy bought 200 after ground tests. (NASM (2014-04858))

The story can be told as a series of meetings among ambitious young designers, dealmakers with burning needs, and inflexible government contractors. The Wasp’s manufacturer, Pratt & Whitney, was at the time a humble machine tool company with no connection whatsoever to aviation. Thanks to a risky bet on an unproven technology, today it’s one of the world’s dominant builders of airplane engines.

At the center of the Wasp’s creation was Frederick Rentschler, scion of a well-connected Ohio industrial family. The family probably assumed that the dutiful son, who’d grown up working in their foundry, would one day inherit and run the family automobile engine manufacturing firm. And he might have done just that if it had not been for World War I. The Princeton graduate enlisted, and in 1917, as a first lieutenant in the aviation section of the U.S. Army Signal Corps, he was tasked with inspecting Hispano-Suiza engines built under license from France by the Wright-Martin Company in New Brunswick, New Jersey, and Long Island City, New York.

Young Rentschler found the work fascinating. These engines were not that different from those he was familiar with in automobiles: reciprocating pistons and cylinders arranged in rows, with liquid coolant circulating through the engine block and a radiator to dump excess heat. As the war wound down, Wright-Martin’s output tapered off, and Rentschler rejoined civilian life. For a time he ran Wright Aeronautical Corporation as president, until the board of directors, mostly bankers, decided not to reinvest profits for future engine development as he wished. In his mind, without investment in product development, the company was doomed. He resigned and spent months, including some time in a hospital due to illness, pondering the aircraft propulsion industry and how to jolt it from complacency.

Vought O2U-1s and Boeing F2B-1s—all Wasp-powered—aboard the USS Saratoga. (NASM (Si-95-2267a))
 The industry was at that time deeply invested in liquid-cooled engines, primarily large V-12s producing in excess of 400 horsepower. It was the conservative, low-risk solution for an aircraft engine, despite its well-known drawbacks: The required cooling system added weight and complexity, and radiators and coolant lines were vulnerable to battle damage, leakage, and subsequent engine failure.

Read more at http://www.airspacemag.com/flight-today/why-the-wasp-is-wonderful-180967115/#efYeFtu5fj6dueul.99