Eugen Sänger

Eugen Sänger

Visionary physicist in the field of rocket propulsion.

Eugen Sänger was born on September 22, 1905, in Prebnitz, Bohemia (then part of Austria-Hungary, now under Prisecnice Lake in the Czech Republic.) Sänger first studied civil engineering at the University of Technology in Graz, Austria, but after reading Hermann Oberth’s The Rocket into Interplanetary Space in 1923, he switched to a course in aeronautics. As aeronautics was not considered a serious subject by his professors, he was not allowed to graduate with a thesis on rockets so instead, he wrote one about experimental airfoil design, graduating in 1931.

In 1932, Sänger began testing rocket engines at the University of Technology in Vienna, where he was an assistant researcher, developing different designs of combustion chambers. Sänger’s influential book Raketenflugtechnik (Rocket Flight Engineering) was published in 1933. This was the first treatise on rocketry by an academic professional and the first scientific study of the concept of space planes. In October 1933, Sänger proposed the development of a rocket-powered hypersonic bomber to the Austrian army, and later that year he began rocket engine tests, exploring various propellants and additives. On February 3, 1934, however, the Austrian Defense Ministry rejected Sänger’s proposed rocket bomber, due to their mistaken belief that liquid rocket engines would never be feasible due to the explosive nature of the chemical reactions involved.

Undeterred, he continued his experiments and by 1935, Eugen Sänger perfected a “regeneratively cooled” liquid-fueled rocket engine that used its own fuel, circulating around the combustion chamber, to control engine temperatures. This engine eventually produced an astounding 10,000 feet per second exhaust velocity, as compared to the later V-2 rocket’s thrust of only 6560 feet per second. In June 1935 and February 1936, Sänger’s articles in the Austrian aviation magazine Flug (Flight) on rocket-powered aircraft attracted wide attention.

In 1936, Sänger accepted a position from the German High Command to be head of the development center for jet engines in Trauen, Germany. The Germans set up a secret aerospace research institute for Sänger to develop and build his “Silverbird,” a manned, winged vehicle that could reach orbit then descend back into the atmosphere. As its proposed range would enable it to reach the United States, it was also known as the “Amerika Bomber.” Sänger had been working on this concept for years and had already begun designing liquid-fuel rocket engines for his proposed space plane.

During World War II, Sänger designed combustion chambers providing a thrust of up to 100 tons as well as working on jet propulsion. He also constructed ramjet engines, which he tested on a Dornier 217 heavy bomber in April 1942. Assisted by physicist Irene Bredt, Sänger continued his research on the Amerika Bomber. The final design of what they called the “Sänger-Bredt Antipodal Bomber” was produced in August 1944, fortunately too late to play a role in World War II.

After the war, with captured designs of the Sänger-Bredt bomber as their starting point, the American government developed the X-15 rocket plane, the X-20 Dynasoar space plane, and the Space Shuttle, while the Soviet Union used Sänger’s data for their Burya and Buran intercontinental cruise missiles. With the exception of the X-15 and the Shuttle, however, all of these projects were eventually canceled.

After the fall of Nazi Germany in 1945, Sänger refused to work for the Americans or the British, and in 1946 he and Irene Bredt moved to France. For the next eight years, they worked for the French government as consultants to what would later be Nord Aviation at Chatillon. Sänger studied problems connected with rocket and large ramjet engines. He and Bredt married in 1951 and continued their work on several French missile programs until the mid 1950s.

In September 1954, West Germany was permitted to resume aerospace research, and Sänger and Bredt returned to their homeland to become director and vice-director, respectively, of their new Institute for the Physics of Jet Propulsion in Stuttgart. In 1961, Sänger and his wife were implicated in a secret Egyptian plan to develop ballistic missiles. Although they denied any involvement Sänger was forced to resign his position as director of the institute in November 1961. Bredt lost her post in June 1962 and their institute was taken over by the West German government. Sänger then took a position with the Junkers Works and from 1961 to 1964 helped design spacecraft.

In 1963, Eugen Sänger became a professor at the Technical University of Berlin but died on February 10, 1964. Irene Bredt survived her husband by nineteen years and was honored with the Hermann Oberth Gold Medal for her body of scientific work in 1970.

Many of Sänger’s visionary proposals have yet to be realized. In the 1950s, he produced a design for a photon rocket that would use gamma rays produced by the annihilation of electrons with positrons for its propulsion, an innovation still under study. His concept of a spacecraft capable of “skipping” off of the earth’s atmosphere has yet to be accomplished, though the American government is planning on producing a “HyperSoar” aircraft that would use this technique, perhaps by as early as 2010. The clearest evidence of Eugen Sänger’s genius is that many of the ideas he proposed in the 1930s are still valid but will require more advances in technology to become reality.