Early life and jet development
Born in Dessau, Germany, Ohain earned in 1933 a PhD in physics, with his thesis on an optical microphone to record sound directly to film, at the University of Göttingen, then one of the major centers for aeronautical research, having attended lectures by Ludwig Prandtl.Constant, Edward. "Genesis N + 1: The origins of the Turbo-Jet revolution" Retrieved: 1 August 2010. In 1933, while still a student, he conceived what he called "an engine that did not require a Propeller (aeronautics), propeller". After receiving his second degree in Physics and Aerodynamics in 1935, Ohain became the junior assistant of Robert Pohl, Robert Wichard Pohl, then director of the Physical Institute of the University. In 1936, while working for Pohl, Ohain registered a patent on his version of a jet engine, ''Process and Apparatus for Producing Airstreams for Propelling Airplanes''. Unlike Frank Whittle's Power Jets WU design with its axial flow turbine, Ohain used a radial in-flow turbine to go with a centrifugal compressor, placing them back-to-back with an annular combustion space wrapped around the rotor. While working at the University, Ohain used to take his sports car to be serviced at a local garage, Bartles and Becker. There he met an automotive mechanic, Max Hahn, and eventually arranged for him to build a demonstration model of his engine for . The completed model was larger in diameter than Whittle's fully working engine of 1937, although much shorter. Ohain took the model to the University for testing but ran into problems with combustion of the petrol fuel, which took place mostly after the turbine, sending flames shooting out from the exhaust duct. The lack of combustion before the turbine contributed to the engine being unable to run without the assistance of the electric motor which subsequently overheated. According to von Ohain, "My interest in jet engines began in about 1933. I found that the elegance of flying was spoiled by the enormous vibrations and noise from the piston engine/propeller combination. I came to the conclusion that a constant work process, i.e. constant compression, combustion, expansion, would have great advantages. Thus I chose a quite simple engine, a radial compressor with a radial turbine." However, the model he and Max Hahn built and tested in the courtyard of the Institute showed the combustion chamber needed further development. As a consequence, Pohl and von Ohain decided to approach Heinkel as someone who "doesn't back away from new ideas".Heinkel
In February 1936, Pohl wrote to Ernst Heinkel, telling him about Ohain's design and its possibilities. Heinkel arranged a meeting between his engineers and Ohain, during which he argued that the current "garage engine" would never work, but that the concept upon which it was based was sound. The engineers were convinced, and in April Ohain and Hahn began working for Heinkel at the Marienehe airfield outside Rostock, in Warnemuende. Working with Engineer Gundermann and Hahn in Special Development, von Ohain states: "Under pressure of aiming to bring a combustion chamber of unknown endurance to flight readiness, I came upon the idea of separating the turbine problem from the combustion chamber problem by using hydrogen fuel. As a physicist, I knew of course that the diffusion and combustion speed of gaseous hydrogen was substantially greater than that of petrol." A study of the model's airflow resulted in several improvements over a two-month period. Encouraged by these findings, Ohain produced a new prototype that would run on hydrogen gas supplied by an external pressurised source. The resulting Heinkel-Strahltriebwerk 1 (HeS 1), German for Heinkel Jet Engine 1, was built by hand-picking some of the best machinists in the company, much to the chagrin of the shop-floor supervisors. Hahn, meanwhile, worked on the combustion problem, an area in which he had some experience. The engine was extremely simple, made largely of sheet metal. Construction, by the blacksmith in his village, started late in the summer of 1936 and was completed in March 1937. Two weeks later the engine was running on hydrogen, but the high temperature exhaust led to considerable "burning" of the metal. The tests were otherwise successful, and in September the combustor was replaced and the engine was run on gasoline for the first time. Running on gasoline caused the combustor to clog up. Although the engine was never intended to be a flight-quality design, it proved beyond a doubt that the basic concept was workable, and Ohain had at last caught up with Whittle. With vastly more funding and industry support, Ohain would soon overtake Whittle and forge ahead. In February 1937, the turbine was running on a test stand. According to von Ohain, "We were now working on a machine capable of powering an aircraft, the forerunner of the He-S3B. I had intended to put the combustion chamber between the compressor and the turbine, as we had done with the hydrogen unit, but Hahn suggested putting it ahead of them, which was an excellent idea." The He-S3 turbine was test flown by Erich Warsitz and Walter Künzel in a Heinkel He 118, providing additional throttled thrust to the conventional engine. While work on the HeS 1 continued, the Pohl-Ohain team had already moved on to the design of a flight-quality engine, the Heinkel HeS 3, HeS 3. The major differences were the use of machined compressor and turbine stages, replacing the bent and folded sheet metal, and a re-arrangement of the layout to reduce the cross-sectional area of the engine by placing the annular combustor in an extended gap between the compressor and turbine. The original turbine was too small to work efficiently. In the beginning of 1939, the He-S3A was fitted into the He 178 airframe for a standing display at Roggentin on 3 July 1939. Yet this turbine was still not powerful enough for flight. According to von Ohain, "We experimented with various combinations to modify the compressor diffuser and turbine nozzle vanes to increase thrust sufficiently to qualify the aircraft for the first flight demonstration. We found that a small diffuser behind the engine with a collar and splitter to divert flows functioned better than a high speed flow through the entire tube. The final result of the changes was the He-S3B." A new design, the Heinkel HeS 3, HeS 3b was proposed, which lengthened the combustor by placing the forward part of it in front of the compressor outer rim. While not as small as the original HeS 3 design, the 3b was nevertheless fairly compact. The 3b first ran in July 1939 (some references say in May), and was air-tested under the Heinkel He 118 dive bomber prototype. The original 3b engine soon burned out, but a second one was nearing completion at about the same time as a new test airframe, the Heinkel He 178, which first flew on 27 August 1939, the first jet-powered aircraft to fly by test pilot Erich Warsitz. Heinkel had applied, May 31, 1939, for a patent: US225619"When I saw Whittle's patent I was almost convinced that it had something to do with boundary layer suction combinations. It had a two-flow, dual entrance flow radial flow compressor that looked monstrous from an engine point of view. Its flow reversal looked to us to be an undesirable thing, but it turned out that it wasn't so bad after although it gave some minor instability problems ... Our patent claims had to be narrowed in comparison to Whittle's because Whittle showed certain things." He then somewhat understandably justified their knowledge of Whittle's work by saying: "We felt that it looked like a patent of an idea ... We thought that it was not seriously being worked on."
Post-World War II
In 1947, Ohain was brought to the United States by Operation Paperclip and went to work for the United States Air Force at Wright-Patterson Air Force Base. In 1956 he was made the Director of the Air Force Research Laboratory, Air Force Aeronautical Research Laboratory and by 1975 he was the Chief Scientist of the Aero Propulsion Laboratory there. During his work at Wright-Patterson, Ohain continued his own personal work on various topics. In the early 1960s he did a fair amount of work on the design of gas core reactor rockets which would retain the nuclear fuel while allowing the working mass to be used as exhaust. The engineering needed for this role was also used for a variety of other "down to earth" purposes, including centrifuges and pumps. Ohain would later use the basic mass-flow techniques of these designs to create a fascinating jet engine with no moving parts,Hans von Ohain et alAwards
During his career, Ohain won many engineering and management awards, including (among others) the American Institute of Aeronautics and Astronautics (AIAA) Goddard Astronautics Award, the United States Air Force Exceptional Civilian Service Award, Systems Command Award for Exceptional Civilian Service, the Eugene M. Zuckert Management Award, the Air Force Special Achievement Award, and just before he retired, the Citation of Honor. In 1984–85, Ohain served as the Charles A. Lindbergh Chair in Aerospace History, a competitive senior fellowship at the National Air and Space Museum. In 1991 Ohain and Whittle were jointly awarded the Charles Stark Draper Prize for their work on turbojet engines. Ohain was elected a member of the U.S. National Academy of Engineering (NAE). Ohain was awarded the Ludwig-Prandtl-Ring from the Deutsche Gesellschaft für Luft- und Raumfahrt (German Society for Aeronautics and Astronautics) for "outstanding contribution in the field of aerospace engineering" in 1992. In 1982, Ohain was inducted into the International Air & Space Hall of Fame at the San Diego Air & Space Museum.Death
Ohain died in Melbourne, Florida, in 1998, aged 86. He was survived by his wife and four children.See also
* List of German inventors and discoverers * Nathan C. Price * Frank WhittleReferences
;General *External links