Aerospike Engine - Performance

Performance

Rocketdyne conducted a lengthy series of tests in the 1960s on various designs. Later models of these engines were based on their highly reliable J-2 engine machinery and provided the same sort of thrust levels as the conventional engines they were based on; 200,000 lbf (890 kN) in the J-2T-200k, and 250,000 lbf (1.1 MN) in the J-2T-250k (the T refers to the toroidal combustion chamber). Thirty years later their work was dusted off again for use in NASA's X-33 project. In this case the slightly upgraded J-2S engine machinery was used with a linear spike, creating the XRS-2200. After more development and considerable testing, this project was cancelled when the X-33's composite fuel tanks repeatedly failed.

Three XRS-2200 engines were built during the X-33 program and underwent testing at NASA's Stennis Space Center. The single-engine tests were a success, but the program was halted before the testing for the 2-engine setup could be completed. The XRS-2200 produces 204,420 lbf (909,300 N) thrust with an I_sp of 339 seconds at sea level, and 266,230 lbf (1,184,300 N) thrust with an I_sp of 436.5 seconds in a vacuum.

The RS-2200 Linear Aerospike Engine was derived from the XRS-2200. The RS-2200 was to power the VentureStar single-stage-to-orbit vehicle. In the latest design, seven RS-2200s producing 542,000 pounds of thrust each would boost the VentureStar into low earth orbit. The development on the RS-2200 was formally halted in early 2001 when the X-33 program did not receive Space Launch Initiative funding. Lockheed Martin chose to not continue the VentureStar program without any funding support from NASA.

Although the cancelling of the X-33 program was a setback for aerospike engineering, it is not the end of the story. A milestone was achieved when a joint academic/industry team from California State University, Long Beach (CSULB) and Garvey Spacecraft Corporation successfully conducted a flight test of a liquid-propellant powered aerospike engine in the Mojave Desert on September 20, 2003. CSULB students had developed their Prospector 2 (P-2) rocket using a 1,000 lb_f (4.4 kN) LOX/ethanol aerospike engine. This work on aerospike engines is ongoing; Prospector-10, a ten-chamber aerospike engine, was test-fired June 25, 2008.

Further progress came in March 2004 when two successful tests were carried out at the NASA Dryden Flight Research Centre using small-scale rockets manufactured by Blacksky Corporation, based in Carlsbad, California. The aerospike nozzles and solid rocket motors were developed and built by Cesaroni Technology Incorporated. The two rockets were solid-fuel powered and fitted with non-truncated toroidal aerospike nozzles. They reached an apogee of 26,000 ft (7,900 m) and speeds of about Mach 1.5.

Small-scale aerospike engine development using a hybrid rocket propellant configuration has been ongoing by members of the Reaction Research Society.