Wankel auf dem Prüfstand: Ursprung, Entwicklung, und Niedergang eines innovativen Motorenkonzeptes (review)

This book by Ulrich Ch. Knapp is a history of the Wankel rotary engine from a German perspective. Instead of reciprocating pistons, the Wankel uses a rotor for the conventional four-stroke process of most gasoline-powered engines. Beginning in the mid-1960s, Wankel engines were used in cars, boats, and pumps. But the only Wankel-powered automobile today is a Mazda sports car. While the Wankel engine is very compact, delivers unparalleled smooth power, and easily revs up, its shortcomings are low mileage and serious exhaust pollution. Both are consequences of the oddly shaped, moving combustion chamber that does not allow for efficient combustion.

Felix Wankel (1902–1988) was a school dropout with no engineering education. In 1922 he organized a militant forerunner to the SA, and in 1926 he formally joined the Nazi Party. Upset by the personal vanities of some Nazi fat cats, he left the party in 1932 and was even a political prisoner for a few months after the Nazis' rise to power in 1933. This did not affect his anti-democratic attitude, and throughout the Nazi years he courted party leaders all the way up to Hitler to find support for his engineering experiments. His main supporter and advisor from the early 1930s until well after World War II was Wilhelm Keppler, economic adviser to the Nazi government, SS leader, undersecretary of state "for special tasks," and in the end a convicted war criminal.

Bored by his job as an insurance agent, Wankel began developing rotary engines in the late 1920s in a small workshop. His experience with rotary valves earned him a number of research contracts for aircraft engines. The breakthrough for a workable rotary engine only came in the 1950s. While major automobile firms turned a cold shoulder, Wankel found support at NSU, a small manufacturer of motorcycles and subcompact cars. NSU was to develop the Wankel engine into an automobile power plant, first in a little "spider" and eventually in a (European) full-size limousine. Financially more important—and certainly more profitable—was licensing by NSU and Wankel. Virtually all major engine and auto manufacturers took a Wankel license in the late 1960s and early 1970s. The first licensee in America was Curtiss-Wright; the most promising was General Motors. But with the exception of Mazda, all of this came to nothing. The rise of oil prices after 1973 killed the low-mileage Wankel. And, more than Knapp admits, tightening pollution restrictions eventually sealed the fate of this ingenious little engine. Felix Wankel himself had been smart enough to sell his engineering firm in 1972—a year before gas prices skyrocketed—to Lonrho, a British conglomerate, for 100 million deutschmarks.

There is a school of Wankel enthusiasts who claim that a "piston cartel" among major car manufacturers obstructed the development of a superior technology. Knapp debunks all the conspiracy theories. He convincingly shows that it was the fundamental shortcomings of the rotary engine and the simultaneous improvement of traditional piston engines that made auto manufacturers turn away as they had previously done with gas turbines. Knapp is very good in showing how it took an innovative group of engineers at the periphery of auto manufacture to venture into a groundbreaking new technology in the first place. He follows this group and eventually finds some of them at Audi, designing a small diesel engine for Volkswagen. Diesels yield the best mileage in cars and were felt to be a godsend in the face of rising oil prices. America quickly gave up on diesel-powered autos, but in continental Europe they currently have a market share of more than 50 percent. Diesels were the answer to high fuel costs, while Wankels gave an idea of how silent a car could be. The combination of the two characteristics was the R&D path of the European car industry. Wankel engines were not ineffective, as Knapp shows, they just turned up...