Harry Julian Allen
Encyclopedia
Harry Julian Allen also known as Harvey Allen, was an aeronautical engineer and a Director of the NASA
Ames Research Center, most noted for his "Blunt Body Theory" of re-entry aerodynamics which permitted successful recovery of orbiting spacecraft. His technique is still used to this day.
. He attended Stanford University
, receiving a Bachelor of Arts
in engineering in 1932 and an Aeronautical Engineer professional degree in 1935. In 1936, he joined the NACA
's Langley Memorial Aeronautical Laboratory
. In 1940, he moved to the Ames Research Laboratory, where he served as Chief of the Ames Theoretical Aerodynamics Branch (starting in 1941), Chief of the High-Speed Research Division (starting in 1945), Assistant Director for Astronautics (starting in 1959), and finally Center Director (1965-1969).
, supersonic
and hypersonic
flow. When the United States
became interested in the design of ballistic missiles, Allen began research in the dynamics and thermodynamics of atmospheric reentry
, as well as the effects of radiation
and meteorite
s on space 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". Earlier ballistic missiles, developed by both the United States and the Soviet Union
, featured long nose cones with very narrow tips, which had relatively low drag
when entering the atmosphere at high speeds. However, Allen demonstrated that a blunt body, although it had greater drag, would have a detached shock 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 ablative heat shield
s that protected the astronauts of the Mercury
, Gemini and Apollo programs as their space capsules re-entered the atmosphere.
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
Ames Research Center, most noted for his "Blunt Body Theory" of re-entry aerodynamics which permitted successful recovery of orbiting spacecraft. His technique is still used to this day.
Career
Allen was born in Maywood, IllinoisMaywood, Illinois
Maywood is a village in Proviso Township, Cook County, Illinois, United States. It was founded on April 6, 1869 and organized October 22, 1881. The population was 26,987 at the 2000 census.-Overview:...
. He attended Stanford University
Stanford University
The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San...
, receiving a Bachelor of Arts
Bachelor of Arts
A Bachelor of Arts , from the Latin artium baccalaureus, is a bachelor's degree awarded for an undergraduate course or program in either the liberal arts, the sciences, or both...
in engineering in 1932 and an Aeronautical Engineer professional degree in 1935. In 1936, he joined the NACA
National Advisory Committee for Aeronautics
The National Advisory Committee for Aeronautics was a U.S. federal agency founded on March 3, 1915 to undertake, promote, and institutionalize aeronautical research. On October 1, 1958 the agency was dissolved, and its assets and personnel transferred to the newly created National Aeronautics and...
's Langley Memorial Aeronautical Laboratory
Langley Research Center
Langley Research Center is the oldest of NASA's field centers, located in Hampton, Virginia, United States. It directly borders Poquoson, Virginia and Langley Air Force Base...
. In 1940, he moved to the Ames Research Laboratory, where he served as Chief of the Ames Theoretical Aerodynamics Branch (starting in 1941), Chief of the High-Speed Research Division (starting in 1945), Assistant Director for Astronautics (starting in 1959), and finally Center Director (1965-1969).
Research
Allen was interested in the full range of aerodynamics research, and made contributions to the study of subsonic, transonicTransonic
Transonic speed is an aeronautics term referring to the condition of flight in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil that are concurrently below, at, and above the speed of sound in the range of Mach 0.8 to 1.2, i.e. 600–900 mph...
, supersonic
Supersonic
Supersonic speed is a rate of travel of an object that exceeds the speed of sound . For objects traveling in dry air of a temperature of 20 °C this speed is approximately 343 m/s, 1,125 ft/s, 768 mph or 1,235 km/h. Speeds greater than five times the speed of sound are often...
and hypersonic
Hypersonic
In aerodynamics, a hypersonic speed is one that is highly supersonic. Since the 1970s, the term has generally been assumed to refer to speeds of Mach 5 and above...
flow. When the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
became interested in the design of ballistic missiles, Allen began research in the dynamics and thermodynamics of atmospheric reentry
Atmospheric reentry
Atmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line,...
, as well as the effects of radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
and meteorite
Meteorite
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...
s on space 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". Earlier ballistic missiles, developed by both the United States and the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
, featured long nose cones with very narrow tips, which had relatively low drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
when entering the atmosphere at high speeds. However, Allen demonstrated that a blunt body, although it had greater drag, would have a detached shock wave
Shock wave
A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries energy and can propagate through a medium or in some cases in the absence of a material medium, through a field such as the electromagnetic field...
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 ablative heat shield
Heat shield
A heat shield is designed to shield a substance from absorbing excessive heat from an outside source by either dissipating, reflecting or simply absorbing the heat...
s that protected the astronauts of the Mercury
Mercury program
Mercury Program might refer to:*the first successful American manned spaceflight program, Project Mercury*an American post-rock band, The Mercury Program...
, Gemini and Apollo programs as their space capsules re-entered the atmosphere.
Awards and honors
- Fellow of the American Institute of Aeronautics and AstronauticsAmerican Institute of Aeronautics and AstronauticsThe American Institute of Aeronautics and Astronautics is the professional society for the field of aerospace engineering. The AIAA was founded in 1963 from the merger of two earlier societies: the American Rocket Society , founded in 1930 as the American Interplanetary Society , and the Institute...
- Fellow of the Royal Aeronautical SocietyRoyal Aeronautical SocietyThe Royal Aeronautical Society, also known as the RAeS, is a multidisciplinary professional institution dedicated to the global aerospace community.-Function:...
of Great Britain - Fellow of the American Astronautical SocietyAmerican Astronautical SocietyFormed in 1954, the American Astronautical Society is an independent scientific and technical group in the United States dedicated to the advancement of space science and exploration. AAS supports NASA's Vision for Space Exploration and is a member of the Coalition for Space Exploration and the...
- Fellow of the Meteoritical SocietyMeteoritical SocietyThe Meteoritical Society is a non-profit scholarly organization founded in 1933 to promote research and education in planetary science with emphasis on studies of meteorites and other extraterrestrial materials that further our understanding of the origin and history of the solar system.The...
- Member of the National Academy of EngineeringNational Academy of EngineeringThe National Academy of Engineering is a government-created non-profit institution in the United States, that was founded in 1964 under the same congressional act that led to the founding of the National Academy of Sciences...
- Sylvanus Albert Reed Award of the Institute of the Aerospace Sciences (predecessor of the AlAA) (1955)
- Wright Brothers Lectureship of the Institute of the Aerospace Sciences (1957)
- Distinguished Service Medal of the NACA (1957)
- Airpower Trophy of the Air Force AssociationAir Force AssociationThe Air Force Association is an independent, 501 non-profit, civilian education organization, headquartered in Arlington, Virginia...
(1958) - NASA Medal for Exceptional Scientific Achievement (1965)
- Daniel Guggenheim MedalDaniel Guggenheim MedalThe Daniel Guggenheim Medal is an American engineering award, established by Daniel and Harry Guggenheim. The medal is considered to be one of the greatest honors that can be presented for a lifetime of work in aeronautics...
awarded by AlAA, ASME, and SAE (1969)