Uses
Ram accelerators have been proposed as a cheap method to get payloads into space. Impulsive launched projectiles need some means to circularize their trajectory for orbit insertion, so rockets, such as those designed in Project HARP, are typically incorporated into the projectiles. Using rockets for upper stages, it is believed that a launch cost of less than $500 (US dollars, 2004) per kilogram can be attained. Using a tether or space tug would further reduce launch costs.
The main competitors to a ram accelerator for direct space launch applications are two-stage gas guns (SHARP), multiple sidewall injection gas guns (JVL), railguns and coilguns. Ram accelerators are currently used primarily for research into supersonic combustion. The scram cannon science fiction weapon was inspired by ram accelerators.
As of July 2007, the Ballistic Flight Group has been promoting commercial investment into the ram accelerator technology.
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