Harry Julian Allen | |
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| Born | (1910-04-01)April 1, 1910 |
| Died | January 29, 1977(1977-01-29) (aged 66) |
| Nationality | American |
| Citizenship | U.S. |
| Occupation | Aeronautical engineer |
| Years active | 1936-1969 |
| Employer | Ames Research Center |
| Known for | Blunt Body theory |
Harry Julian Allen (April 1, 1910 – January 29, 1977), also known asHarvey Allen, was anaeronautical engineer and a Director of theNASAAmes Research Center, most noted for his "Blunt Body" theory ofatmospheric entry which permitted successful recovery of orbiting spacecraft.[1] His technique is still used to this day.
Allen was born inMaywood, Illinois on April 1, 1910.[1] He attendedStanford University, receiving a Bachelor of Arts in engineering in 1932 and an Aeronautical Engineer professional degree in 1935. In 1936, he joined theNACA'sLangley Memorial Aeronautical Laboratory. In 1940, he moved to the Ames Research Laboratory, where he served as Chief of the Ames Theoretical Aerodynamics Branch (1941-1945), Chief of the High-Speed Research Division (1945-1959), assistant director for Astronautics (1959-1965), and finally Center Director (1965-1969).[1]
Allen was interested in the full range of aerodynamics research, and made contributions to the study ofsubsonic,transonic,supersonic andhypersonic flow.[2] When the United States became interested in the design of ballistic missiles, Allen began research in the dynamics and thermodynamics ofatmospheric reentry, as well as the effects ofradiation andmeteorites onspace vehicles. His most significant contribution in this area was the idea of using a blunt nose for reentry vehicles, otherwise known as his "Blunt Body" theory.[2] Earlier ballistic missiles, developed by both the United States and theSoviet Union, featured long nose cones with very narrow tips, which had relatively lowdrag when entering the atmosphere at high speeds. However, Allen demonstrated that a blunt body, although it had greater drag, would have a detachedshock wave which would transfer far less heat to the vehicle than the traditional shape with its attached shock wave. Excessive heating was the greatest concern in the design of ballistic missiles and spacecraft, since it could melt their surface; the blunt body design solved this problem. Allen's theory led to the design of ablativeheat shields that protected the astronauts of theMercury,Gemini andApollo programs as their space capsules re-entered the atmosphere.[2]
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