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This Defense Intelligence Reference Document, dated 21 November 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under its Advanced Aerospace Weapons System Applications (AAWSA) Program. It reviews propulsion concepts that use weakly ionized plasmas and magnetohydrodynamics for hypersonic flight and spacecraft. It concludes that the Ajax MHD energy bypass concept is meaningless below Mach 12. A reverse energy bypass with a Virtual Cowl is judged potentially practical, and electric propulsion is expected to become standard for spacecraft.
From the source: Release of 2026-09-18 Incident: 11/21/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys magnetohydrodynamic (MHD) and plasma-based concepts for air-breathing propulsion, onboard power generation, and aerodynamic control, arguing that such systems could in principle extend aerospace performance beyond the limits of conventional chemical propulsion and control surfaces. The report reviews concepts including MHD acceleration, flow control, inlet control, onboard power generation, drag reduction, and plasma-generated “virtual” aerodynamic surfaces, while giving particular attention to hypersonic applications such as scramjet power extraction, reentry vehicles, global-strike gliders, and aero-assisted orbital maneuvers. However, it emphasizes major practical constraints, especially extreme power requirements, system weight and complexity, and the difficulty of achieving useful ionization in colder air at lower hypersonic speeds; on that basis, it argues that Ajax-style MHD bypass concepts, in which energy is extracted from the airflow upstream and reintroduced downstream through an electromagnetic system, are not meaningful below about Mach 12, while treating the “virtual cowl” and related reentry applications as more plausible. The document presents plasma and MHD aerospace systems as a technically serious but highly demanding field whose nearer-term promise lies in specialized hypersonic control, power generation, and reentry applications rather than a fully realized air-breathing propulsion system.
UNCLASSIFIED/ /FAR OFFICI CIs. W&i e ..tv thrust (Fth) is produced from each mass unit of propellant. The thrust efficiency (ll ) is a measure of how much of the power/energy that is available results in directed kinetic energy (thrust power) in the flow. The thrust density is a measure of how much thrust is produced per unit cross-sectional area, Ac (area perpendicular to the flow direction). Although the thrust density is a packag ing issue for spacecraft, it is critical for air vehicles where drag is present. The thrust-to-power measures the acceleration efficiency. Traditiona lly a trade exists between fuel/propellant efficiency and thrust-to-power (speed vs. economy). The fina l parameter is the specific mass or weight (mass)-to-power ratio. In most cases the efficiencies improve with the size of the system (economy of scale). Measures of performance are fundamenta lly different between air-breathing and rocket systems due to the inlet on the air-breathing system . Rocket Air-Breathing FIB = m, ue - m(/ u + A e (Pe - panil ) = ,,;J(l +f)u.- u] + A. (P. - P anti ) = ThrustI = _ F....=lh'-- Thrust l sp - ---------- SP - fuel weight flow rate propeJlant weight flo w rate F,h u cq = = 0 m, g o o o fuel mass flow rate __ mJ TSFC = ------ Thrust F111 . p jel = 1/2 m, u;q = 1/2 F,1, I SP 8 0 . p 1/2 ( ,,;, u;q _,,;au2) 1] = ½ ·er = F,h l sp 8 0 _ 112 m, u;q 1] =___!!!_ = ---'------'-- P,,/ect 2 P,,,,cr P ,/ec, P e,ec/ P,,,c, Above, m0 is the mass flow rate of the air, mI is the mass flow rate of the fuel, m, is the exit flow rate, go is the acceleration of gravity (reference po int, Earth), Ue is the nozzle exit velocity, u is the flight/vehicle velocity, Ueq is the equivalent exit velocity, Ae is the nozzle exit cross-sectional area, Pe is the nozzle exit UNCLASSIFIED/Peft. err1e1111t ~9E 8,.L?/ 6
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Official release, from the pursue 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.