page_title: Aerospike engine
section_title: Performance
hierarchical_section_title: Aerospike engine / Performance
caption_attribution_description: Aerospike engine close up Aerospike engine mounted to P-2 (Photo by Kim Garvey)
context_page_description: The aerospike engine is a type of rocket engine that maintains its aerodynamic efficiency across a wide range of altitudes. It belongs to the class of altitude compensating nozzle engines. A vehicle with an aerospike engine uses 25–30% less fuel at low altitudes, where most missions have the greatest need for thrust. Aerospike engines have been studied for a number of years and are the baseline engines for many single-stage-to-orbit designs and were also a strong contender for the Space Shuttle main engine. However, no such engine is in commercial production, although some large-scale aerospikes are in testing phases.
  The terminology in the literature surrounding this subject is somewhat confused—the term aerospike was originally used for a truncated plug nozzle with a very rough conical taper and some gas injection, forming an "air spike" to help make up for the absence of the plug tail. However, frequently, a full-length plug nozzle is now called an aerospike.
context_section_description: 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 revived 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 two-engine setup could be completed. The XRS-2200 produces 204,420 lbf (909,300 N) thrust with an Iₛₚ of 339 seconds at sea level, and 266,230 lbf (1,184,300 N) thrust with an Iₛₚ 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-force (2,410 kN) 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. An engine of this type is on outdoor display on the grounds of the NASA Marshall Space Flight Center in Huntsville Alabama.
  The cancellation of the Lockheed Martin X-33 by the federal government in 2001 decreased funding availability, but aerospike engines remain an area of active research. For example, 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 lbf (4.4 kN) LOX/ethanol aerospike engine. This work on aerospike engines continues; Prospector-10, a ten-chamber aerospike engine, was test-fired June 25, 2008.
  Further progress came in March 2004 when two successful tests sponsored by the NASA Dryden Flight Research Centre using high-power rockets manufactured by Blacksky Corporation, based in Carlsbad, California. The aerospike nozzles and solid rocket motors were developed and built by the rocket motor division of Cesaroni Technology Incorporated, north of Toronto, Ontario. The two rockets were solid-fuel powered and fitted with non-truncated toroidal aerospike nozzles. Flown at the Pecos County Aerospace Development Center, Fort Stockton, Texas, the rockets achieved apogees 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.
caption: CSULB aerospike engine
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