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Ehricke, Krafft Arnold
Credit: NASA
Visionary German-American engineer. Protégé of Thiel at Peenemuende; early concepts for nuclear and LOx/LH2 engines. Left von Braun team, developed Centaur at Convair 1956-1964. Prolific output of advanced concepts, but poor program manager.

Born: 1917-03-24. Died: 1984-12-01. Birth Place: Germany.

Ehricke was star-struck by the film Frau im Mond and formed a rocket club at age 12. He became acquainted with Tsiolkovskiy's writings through Shcherschevsky's Die Rakete fuer Fahrt und Flug. He tackled Oberth's Wege zur Raumschiffahrt in his early teens, but the mathematics were still beyond him. Ehricke graduated from the Technical University in Berlin in aeronautical engineering, and took postgraduate courses at the Humboldt University in celestial mechanics and nuclear physics. He was then drafted into the army, and sent in a Panzer division to the Russian front. In common with other aerospace engineers, he was recalled from the front and reassigned to rocket development work at Peenemuende in June 1942.

There he became a protégé of Walter Thiel, head of rocket engine development. In his first year, Ehricke found himself caught up in Thiel's advanced designs. Thiel had plans to test rocket engines of 5,000 to 14,000 kN thrust in mountain gorges in Bavaria. He encouraged Ehricke to continue Thiel's experiments on the use liquid hydrogen/liquid oxygen in small engines for upper stages. Thiel was looking forward to using the nuclear reactor being developed by Heisenberg and Pohl for space propulsion. At his behest Ehricke studied potential propellants for a thermal rocket, and quickly concluded that hydrogen was the best choice.

Thiel was killed in the first British air raid on Peenemunde in October 1943. Thereafter all advanced research was discontinued and all staff were ordered to concentrate on getting V-2 development completed and the missile fielded.

At war's end, Ehricke was part of the convoy that move Peenemuende's records to a secret location, to be used as a bargaining chip by von Braun's team in negotiations with the Americans. Ehricke made his way on foot to his wife and home in Berlin. He wanted to work for the Americans, and hid each time someone knocked on his door, waiting for the right caller. One day his wife answered the door and routinely said, "I don't know where he is." Then she recognized the insignia of a US Army officer and immediately began screaming, "He's here! He's here!"

Ehricke was given a six-month contract, and came to the United States to rejoin the von Braun team as part of the Paperclip operation. Von Braun asked Ehricke to check a Jet Propulsion Laboratory report that concluded that liquid hydrogen/liquid oxygen rockets would have superior performance in all circumstances. Earlier it had been assumed that the weight of the tanks for the low-density hydrogen would overwhelm the superior exhaust velocity of the combination. But JPL showed that lightweight tanks could be built that negated the presumed disadvantage. However the production, storage, and handling of the extremely cryogenic hydrogen were all technical unknowns. Von Braun was tasked by the Army to produce usable military rockets in a short time and shelved the report for the time being.

Ehricke moved with von Braun's team to Huntsville, Alabama in 1950, but chafed under von Braun's conservative technical approach and the southern climate. He moved to Bell to work with Walter Dornberger in 1952. But committed to work on the BOMI manned space bomber and Hustler (later Agena) rocket engine, Dornberger and Bell were mainly interested in high-density storable propellants.

In 1954 Ehricke moved again to Convair to work with Karel Bossart on the Atlas ICBM. Bossart's concept of extremely lightweight balloon tanks was more to Ehricke's liking. Bossart allowed Ehricke to work on advanced space projects using the Atlas as a starting point. By 1956 Ehricke was conducting in-house trade studies on satellite launch vehicles. In October 1957 he visited Air Research and Development Command headquarters. Ehricke had heard of the highly-classified Suntan project - a high-altitude hydrogen-powered aircraft then in an advanced stage of development at Lockheed's Skunk Works. It seemed that the problems of liquid hydrogen production, storage, handling, and use in aerospace vehicles had been covertly solved. However he found no support in the Air Force for his space launch ideas. All that changed a few days later when Sputnik was launched.

A week later, Ehricke was huddled with A G Negro, a Rocketdyne engineer, studying use of a 31 kN pressure-fed liquid hydrogen / liquid rocket engine in a second stage for the Atlas. By the end of October, Negro had sketched out an engine concept with a 4 bar chamber pressure and specific impulse of 410 seconds. By December Ehricke's proposal, "A Satellite and Space Development Plan", was in the Air Force's hands.

Unknown to Ehricke, ARPA already had a secret program for a pump-fed engine of the same class at Pratt and Whitney. Things moved quickly, and by August 1958 Convair had been authorized to proceed with development of their Centaur upper stage for the Atlas using the Pratt and Whitney RL10 engine.

Ehricke proved a better visionary than program manager, however. Centaur ran into multiple technical and quality problems during development. These were so bad that the dual-engine Centaur didn't enter service until after von Braun's S-IV stage, with six RL-10's. Throughout this period Ehricke found time to sketch out a number of advanced concepts for nuclear-powered spacecraft, boosters and manned spent-tank space stations.

After this debacle Ehricke moved on to Rockwell International, where he conducted several advanced studies on space commercialization. During the 1970s, he was a popular speaker on the technical lecture circuit, promoting his concept of "The Extraterrestrial Imperative" (he was to have written a book, but died before it was printed). Ehricke passed away in La Jolla, California. His ashes were sent into space on the first flight of the Celestis mortuary satellite.

Country: Germany, USA. Agency: Convair. Bibliography: 1980, 5350.

1917 March 24 - .
1954 - .
1958 - During the year - . LV Family: Atlas. Launch Vehicle: Atlas D.
1984 December 1 - .

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