Philosophical Society of Washington

Light-Gas Gun Satellite Launchers

Harold E. Gilreath,
Johns Hopkins University Applied Physics Laboratory

2122nd Meeting Abstract
Friday, November 3, 2000 at 8:15 p.m.


The complexity and high cost of getting into space recently motivated a request by the Defense Advanced Research Projects Agency for an assessment of the technical and economic feasibility of using a distributed-injection light-gas gun (DI LGG) to launch small satellites. In this kind of launcher, the basic idea is to maintain a moderate pressure force on the projectile over a very great distance by adding mass and energy behind it as it moves along an evacuated launch tube — as opposed to starting the launch at extremely high but rapidly falling pressure associated with conventional guns. The DI LGG approach is attractive because it may offer a way to improve payload fraction by an order-of-magnitude compared to conventional launch systems. While the idea of shooting things into space with a gun dates from the days of Jules Verne, this lecture provides a look at the proposition in the glare of both technical and economic reality. After reviewing the history of space gun concepts, the presentation will examine the technical feasibility of both the launcher and the launch vehicle, discuss the major drivers of launch costs, and define the circumstances under which a gun launch business might provide an attractive total mission cost relative to current systems.

About the Author:

HAROLD E. GILREATH is a Principal Staff Research Engineer at the Johns Hopkins University Applied Physics Laboratory (JHU/APL). He received B. S. (1964), M. S. (1966), and Ph. D. (1968) degrees in aerospace engineering from the University of Maryland, where he also taught courses in aerodynamics and propulsion.

He joined JHU/APL in 1968 as a member of the Hypersonic Propulsion Group and first conducted theoretical and experimental research on advanced missile propulsion systems. He became a member of APL's Submarine Technology Department at its inception, where he established the Wave Physics Group. This group conducted research and field exercises concerned with submarine detection. He later became the Chief Scientist for the Department, working on special projects over a wide range of technical areas.

He presently works in the Milton S. Eisenhower Research and Technology Development Center. Over the years his investigations there have touched on a variety of interesting topics, including oceanic internal waves, hypersonic propulsion, radioacoustic detection systems, drag reduction, ammonia-fueled engines, groundwater mechanics, flapping-wing flight, and light-gas gun satellite launchers. At the moment his interest is focused primarily on technologies associated with unmanned vehicles.

He has served on dozens of U. S. Government panels, planning committees, and working groups, as well as on numerous committees and boards at the Applied Physics Laboratory, including the JHU/APL Advisory Board. He is the author of more than forty technical papers and reports, and has won five publication awards. He is also a member of Tau Beta Pi, Phi Kappa Phi, and Sigma Xi.


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