From the archives of Bob Montgomery
FELIX WANKEL: It has long bothered engineers to see the use of reciprocating mechanisms in powered units of any sort. To put it bluntly, perfectionist engineers hate the inefficiency of these mechanisms. One such engineer, the German Felix Wankel, was driven throughout his life to produce a more elegant solution and a 'better' internal combustion engine.
A school drop-out, Felix Wankel was a largely self-taught engineer and sometime inventor whose first employment in 1924 was with a Heidelberg bookseller. Quite early in his life he conceived the idea of an engine which would use rotary motion, while at the same time contain positive-displacement sealed chambers, acting like the cylinders of a conventional engine and operating on the four-stroke cycle. Realising that the sealing of the combustion spaces was the key to such an engine, Wankel became an expert on the sealing of combustion spaces and the design of rotary valves for conventional working as a consultant to BMW and Daimler-Benz before and during the second World War.
During this period Wankel used any spare time he had to systematically study rotary engines and published a book which became the standard work on the subject. After several decades of research, Wankel came up with the concept which he persuaded NSU was worth developing. But there were problems. His first Wankel engine rotated bodily, and this was soon found to be impractical. NSU's Dr Walter Froede suggested a fixed housing arrangement and this was tried successfully.
The new engine proved to be easily balanced and as a result very smooth no matter how high the rpm. At the same time it was smaller and lighter than a conventional engine of similar power output. At this point, Felix Wankel bows out of this story, for he disagreed with the direction the project had taken under NSU's patronage. Instead, he set up a research establishment at Lindau and there spent the rest of his life working on other advanced engineering concepts, amply financed by the licence fees on his Wankel engine as car manufacturers around the world experimented with his invention.
NSU introduced a twin rotor Wankel engined car, the NSU Ro 80, to the public in 1967. The Ro 80 was a superb car, but very quickly its unconventional engine exhibited a major weakness. The engine's crucial rotor-tip seals wore at an alarming rate and soon the Ro 80 became notorious for premature loss of performance and reluctance to start. NSU engineers did solve the problem, but not before the Ro 80 had lost all credibility.
Instead, it was left to Toyo Kogyo to develop a rival twin-rotor unit for the Mazda Cosmo. This model saved the rotary concept, proving robust, smooth and highly reliable in use. But no sooner had the Wankel engine survived this crisis when another loomed over the horizon. The design has inherently poor fuel consumption, and was thus particularly badly hit by succeeding global fuel crisis. This problem led GM and Citroën to abandon their own Wankel engine projects after many millions had been spent on them.
In time, all of these problems were solved, but only Mazda has persevered with the Wankel concept. As anyone who has driven a Wankel-engined car will tell you, this is a great shame as the unit first developed by Felix Wankel offers an unforgettably smooth driving experience.
Felix Wankel, whose perseverance over several decades, led eventually led to a successful rotary engine, died in 1988 at the age of 86.