Felix Wankel

German engineer and inventor

• Born: August 13, 1902
• Birthplace: Lahr, Germany
• Died: October 9, 1988
• Place of death: Lindau, West Germany (now in Germany)

As early as 1924, Wankel began to sketch models for rotary piston engines. In 1929 he obtained his first patent for an engine that has a reciprocating piston housed in a horizontal cylinder, the earliest Wankel engine, that has since been perfected to the point that it can power automobiles and other motorized vehicles.

Early Life

Felix Wankel (FAY-lihks VAHN-kehl) was born in Lahr, in the southwestern reach of Germany near the Alsace province of France, practically on the Swiss border. His father, Rudolf, a forest commissioner killed in the first month of World War I, left his wife, Gerty Heidlauff Wankel, and his twelve-year-old son, Felix Heinrich, to fend for themselves. They were financially comfortable. Their security, however, was sufficiently eroded by the raging postwar inflation that nineteen-year-old Wankel lacked the means to continue his education beyond the secondary level.

Wankel, leaving Lahr and its stolid people behind him, moved to Heidelberg and was employed there by a publisher of scientific books. Within three years, he had opened a mechanical shop and begun his early work with motors. He quickly learned the need for precision and meticulous craftsmanship in mechanical work. He began to dwell on the problem of finding more efficient engines than those then in common use: gas turbines, diesel engines, free-piston engines, steam engines, electrically powered engines, fuel cells, Stirling engines, and combinations of these.

By 1924, he had conceived the basic idea for the Wankel engine. Working from his sketches of it, he eventually forged models that represented a dramatic departure from all engines of the past. The concept of such an engine was not new; mechanics and engineers had puzzled over the idea for more than a century, but Wankel was the first to conceive of a model that would work and that, providing the requisite power to propel vehicles, could function economically without undue wear.

The concept behind Wankel’s engine was that energy could be conserved if an engine were developed that rotated rather than pumped vertically. Because the wheels of vehicles are round, the energy from piston-driven engines, once it is produced, must be converted to a rotary motion. Wankel found this conversion, with its accompanying loss of energy, inefficient.

The practical problem he had to solve was that of developing a working model of an engine that, housed in a horizontal chamber, would seal the gap created by the motion of the rotor. In piston engines, the only gap that has to be sealed is that between the piston rod and the walls of the cylinder into which it plunges. Wankel realized that if a rotor is packed into its chamber too tightly, it loses energy through friction. If the rotor is packed too loosely, the seal is not tight, so the cylinder leaks energy. Wankel packed the rotor in various materials, none of which worked.

Life’s Work

Unable to support himself from his workshop in Heidelberg, Wankel continued to work for a publisher of scientific books until 1926. By 1927, he had a detailed working sketch of his engine, but he had not solved the sealing problem. Despite this, he had progressed sufficiently by 1929 to obtain his first patent for a rotary engine.

The sealing problem, however, continued to plague Wankel for the next two decades. The substantial reputation he gained for his work grew during World War II, when he served Germany by working on torpedoes, although this work diverted him from his main purpose. As Adolf Hitler was rising to power, Wankel joined the Hitler Youth Movement, as did the woman he married. He remained a supporter of the dictator during the early years of Nazism but fell from grace, was arrested, and was imprisoned soon after he broke from the Nazi Party in 1932.

Wilhelm Keppler, a staunch supporter of Hitler, had become an enthusiastic advocate of Wankel and his invention. Through his intervention and that of the chief engineer of Daimler-Benz, Otto Nibel, Wankel was released from prison in 1933 and returned to his experimental work, now with Daimler-Benz, quitting a year later when he had a dispute with the general manager. He then went to work for Bayerischen Motoren Werke (BMW) in Munich, assigned to develop a piston engine with rotary valves.

The basic sealing problem Wankel encountered was that the seal edge in his previous designs was too wide. Every means he conceived of for sealing the cylinder resulted in lost energy and rapid wear, rendering the engine impractical.

Wankel’s personality was such that people could not work easily with him, resulting in his usually having to attack problems independently that several minds working harmoniously might have resolved more quickly than Wankel alone could. Keppler, realizing his protégé’s potential, used his influence to help Wankel receive a government subvention in 1936 that enabled him to establish a workshop that grew into an institute in the island town of Lindau, Bavaria, at Lake Constance, where he would settle permanently. At the lake this man of average height, his hair growing thin and his eyes obscured behind thick glasses, proceeded with his solitary work.

Finally, after experimenting with various materials, Wankel devised thin strips of metal that represented a major step toward resolving the persistent sealing problem. His wartime work with the Goetz corporation, which made piston rings, added another possibility to Wankel’s means of sealing his motor. Goetz developed an ultrastrong metal alloy, IKA, that would figure prominently in the development of sealing devices for rotary engines.

Wankel overcame another crucial obstacle when he discovered that he could use the gas pressure built up in the engine as the gas tries to escape to work for rather than against sealing it. He used this gas buildup to put pressure on the seals, thereby fixing them tightly enough to prevent significant leakage and obviating the need for springs beneath the plates of his engine.

At the war’s end in 1945, the French occupied Lindau. Wankel was arrested, his institute disbanded, and most of the thousands of sketches for his engine destroyed. This seeming disaster turned into a blessing for Wankel, who was now forced to rethink his work from the beginning, unhindered by the lingering ghosts of his past work. By 1951, when he reestablished his institute, he began the tedious, gargantuan task of classifying the thousands of possible configurations for his engine, not publishing his results until 1963. By January, 1954, however, he had drawn the design for rotary engines that finally powered automobiles in the 1970’s. It consisted of a double circle housing for a rotor with three convex sides, a fat, triangular figure rotating within a figure eight.

During the 1950’s, automotive manufacturers in Japan, the United States, Germany, and France grew interested in Wankel’s experiments, and with their help the first Wankel rotary engines stood endurance tests in 1959. Because such engines could deliver acceptable power economically with minimal air pollution, the idea was appealing to automobile manufacturers and environmentalists alike. The Wankel, half the weight of conventional six-cylinder engines but capable of delivering more power, had potential popular appeal.

General Motors committed fifty million dollars to buying the Wankel license but had difficulty bringing rotary-engine cars into production. Meanwhile, however, Toyo Kogyo of Japan produced an economically viable rotary engine car, the Mazda R-100 and later the Mazda RX-2, for the American market. The first of these cars reached the United States in May, 1970. Despite early customer skepticism and some negative reports, they enjoyed considerable popularity in the geographically limited market in which Toyo Kogyo first marketed them. Soon, Mazda’s rotary engine models ranked fourth in sales in the markets where they were sold.

The only problem to emerge was that Wankel engines did not endure. Often the entire engine had to be replaced before thirty thousand miles. Enthusiasm for the Wankel engine waned as the end of the 1970’s approached. Although several major automotive manufacturers bought the license to manufacture the engine, the piston engine still dominates the automobile industry.

Significance

Despite its present lack of popular acceptance, the Wankel engine holds many appealing possibilities, particularly in its ability to produce sufficient power to propel automobiles smoothly and quietly at high speeds with much less air pollution than conventional engines create and with relatively modest consumption of fuel.

Wankel became rich because he ensured that his early patents were airtight. Subsequent patents more than thirty of them between 1955 and 1958 alone were carefully drawn to protect Wankel’s financial interests fully. His arrangement with the Necharsulm Strickmachinene Union (NSU), for example, gave him 40 percent of the profits from NSU’s rotary engines, even though Wankel had been on NSU’s payroll when he developed them. Despite his wealth, Wankel always lived frugally and was not renowned for his beneficence, although he founded a refuge for dogs and cats and contributed money to cancer research.

Bibliography

Ansdale, Richard F. The Wankel RC Engine. New York: A. S. Barnes, 1968. This book by Wankel’s translator is definitely for specialists although valuable general information can be gleaned from it. Ansdale’s writing style is often unclear, resulting in an unnecessary complexity in a book whose subject is itself complex and highly technical in many of its essential aspects.

Burstall, Aubrey F. A History of Mechanical Engineering. New York: Pitman, 1963. This book provides as solid a brief overview of Wankel and his work as any in print. Although written with an audience of engineers in mind, the book is not so technical as to bewilder more general readers. It makes a reasonable, well-focused starting point for those unfamiliar with Wankel and his inventions.

Faith, Nicholas. Wankel: The Curious Story Behind the Revolutionary Rotary Engine. New York: Stein & Day, 1975. Faith’s is the most accessible source for readers who do not require a highly technical approach. His exposition is lucid and appealing. Faith avoids scientific jargon, often defining key terms in context. His research is thorough and accurate. He is totally in control of all the basic writing by and about Wankel to the mid-1970’s. The index is extensive and useful.

Hege, John B. The Wankel Rotary Engine: A History. Jefferson, N.C.: McFarland, 2001. A history of Wankel’s invention, including information about Wankel, his experiments at NSU, and his work at Daimler-Benz.

Inman-Hunter, Marcus C. Rotary Valve Engines. New York: Hutchinson’s Scientific and Technical, 1951. This book pays considerable homage to Wankel although it was published before his ideas had progressed to the point of making rotary engines reasonable alternatives to conventional piston engines. The book is interesting primarily for its historical review of Wankel’s work at a time when the practicality of his inventions was questionable.

Norbye, Jan P. The Wankel Engine: Design, Development, Applications. Randor, Pa.: Chilton, 1971. Norbye, automotive editor of Popular Science Monthly, has produced a highly detailed book on the Wankel engine, profuse with clear, helpful illustrations. The book is more technical than Faith’s, but it is generally comprehensible to nonspecialists. Norbye has an encyclopedic knowledge of the engines in general use and understands them technically. Although his emphasis is on engines rather than on the man, Norbye provides substantial biographical information.

Wankel, Felix. Rotary Piston Machines. Translated by Richard F. Ansdale. London: Iliffe Books, 1965. Wankel’s own book provides an excellent resource for the specialist but is not valuable for beginners because it tends to be overly technical. Much of the material in this book is replicated in Ansdale’s book cited above, but neither book is recommended for the novice.