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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 21 November 2010, was produced in FY 2010 under the Advanced Aerospace Weapons System Applications (AAWSA) Program. It reviews propulsion concepts that use plasmas and magnetohydrodynamics. It finds the Ajax MHD energy bypass concept meaningless below Mach 12 but calls a reverse energy bypass with a Virtual Cowl potentially practical. It also predicts that electric propulsion will become standard for spacecraft.
“Jet Propulsion Laboratory”4 pages
UNCLASSIFIED/ ,'F811. 8FFl@llltt 1!1!11!! 9HL"i' pressure, Pamb is the ambient/environmental pressure, Piet is the jet-kinetic power (thrust power) produced by the engine, and Peiect is the electrical (or other external source) power supplied to the propulsion system. For air-breathing systems the mass flow rate of the fuel is very small relative to the mass flow rate of the air. Note that an air-breathing system can never fly faster than its exhaust velocity. Rockets, because they carry an onboard oxidizer, do not have this restriction and, therefore, have no flight-speed limits. The jet power for high-speed air- breathing engines is larger than the equivalent jet power for a rocket due to the inlet and is the difference of two large numbers. Large power levels are required for aircraft and launch vehicles. For example, an SR-71 cruising at Mach 3.2 produces a thrust of 24,700 lbf (110 kN) and a jet power of 104 MW. Climb and maneuver thrust is much higher. Similarly, an RLl0 rocket engine produces 15,000 lbf (66.7 kN) thrust at an lsp of 433 seconds, and has a jet power of 142 MW. By comparison, a Nimitz class nuclear aircraft carrier propulsion system is 194 MW, and the Hoover dam produces about 2000 MW. Therefore, any electric system replacing these applications must be capable of processing a lot of power. Spacecraft propulsion systems are typically hundreds of watts to tens of kW. This, in addition to powerplant weight issues, is a primary reason why electric propulsion systems are currently being used on spacecraft and not on aircraft. Historically, electric thrusters for spacecraft were available for flight decades before the power systems. 12 Figure 1. Electrothermal Arcjet Thruster. Photograph of a 30-kW arcjet thruster being tested at the Jet Propulsion Laboratory. 13 7 UNCLASSIFIED/f8R 8ffl@IIIIL ~91!! 8HLV
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 32 pages are in the text index: search them above, or from the library's search.