Rotary Engine

History of Rotary

Engineering History
The Birth of the Rotary Engine
Young Wankel's Dream

The rotary engine was invented by a German named Felix Wankel in 1957. About 40 years before its invention, 17-year-old Wankel had an improbable dream in the summer of 1919 which led to the idea of the rotary engine. In the dream, he went to a concert in his own handmade car. He even remembers boasting to his friends in the dream; "my car has a new type of engine: a half-turbine half-reciprocated engine. I invented it!" When he woke up in the morning, he was convinced that the dream was a premonition of the birth of a new type of gasoline engine. At the time, he had no fundamental knowledge about internal combustion engines, but he intuitively believed that an engine could achieve four strokes--intake, compression, combustion, and exhaust--while rotating. This intuition actually triggered the birth of the rotary engine, which had been attempted countless times by people all over the world since the 16th century. The rotary engine, which converts rotary motion directly into driving force, has an almost perfectly smooth operation; it also meets the most stringent technical standards. This dream and intuition went on to steer his entire life.

In 1924, at the age of 22, Felix Wankel established a small laboratory for the development of the rotary engine, where he engaged in research and development. During World War II, he continued his work with the support of the German Aviation Ministry and large civil corporations, both of which believed that the rotary engine would serve the national interest once it was fully developed. They held that the rotary engine, if exploited to its full potential, could help move the German nation and its industries toward greatness.

The First Wankel Engine

After the war, Wankel established the Technical Institute of Engineering Study (TES) and continued his work on the research and development of the rotary engine and the rotary compressor for commercial use.

One prominent motorcycle manufacturer, NSU, showed a strong interest in Wankel's research. NSU was proud of its acclaimed engineering capabilities, and at the time won many World Grand Prix championships. It was not long before Wankel and NSU created a partnership for the development of the rotary engine. At first, both Wankel and NSU focused on an engine with a trochoid housing as being the most feasible. Before they had any success, however, NSU completed development of its rotary compressor and combined it with the Wankel-type supercharger. With this installed, an NSU motorcycle set a new world speed record in the 50cc class, marking a top speed of 192.5 km/h. In 1957, Wankel and NSU completed a prototype of the type DKM rotary engine, which combined a cocoon-shaped rotor housing with a triangular rotor.

The DKM proved that the rotary engine was not just a dream. The structure, however, was complicated because the trochoid rotor housing itself rotated, making this type of rotary engine impractical. A redesigned KKM with a static rotor housing was completed a year later in 1958. Although it had a rather complicated cooling system that included a water-cooled housing with an oil-cooled rotor, this new KKM was the forerunner of the modern Wankel rotary engine. Thirty-nine years had already passed since young Felix Wankel had first dreamed of the rotary engine.


Related information

Felix Wankel

Felix Wankel
In 1957, in cooperation with NSU, Dr. Wankel completed the type DKM engine. It was the world's first prime mover by rotating motion alone. In 1958, he completed a more practical type KKM that became the basis of the current rotary engine.

How a Rotary Engine Works

Watch an easy-to-understand animated explanation of how a rotary engine works.