This document contains summary design notes on the Russian AJAX hypersonic aircraft, as described by Alexander Szames in the December 2001 issue of Air Et Cosmos. AJAX is a uniquely proposed design that incorporates MHD (magnetohydrodynamic) technology to further increase the hypersonic speed. It is a proposed Russian competitor to the "Aurora" project...

AJAX has a dual skin which serves as a thermochemical reactor for the fuel, which utilizes aerodynamic heating to break the fuel down into a mixture of olefin & hydrogen. This mixture enters a magnetoplasma-chemical engine located beyond the combustion chamber. As the fuel enters this chamber, the MHD generator brakes flow to an optimum speed and also generates electrical power, which is used to later re-accelerate the flow as well as ionize incoming air into a plasma. This is believed to increase the aircraft's speed by up to 10-30%, as well as effectively dissipate aerodynamic heating on the aircraft's skin. The plasma itself is believed to form a cloud around the aircraft, which serves as a means of reducing boundary-layer airflow for increased performance and may potentially reduce or eliminate the aircraft's radar-signature as well. In 1993, an expert commission of scentists analyzed the design and found it consistent with contemporary science & aerospace design principles. [more on AJAX]

"The illustration clearly shows an over-under inlet geometry. However, I do not think it is the conventional over-under inlet where one system is closed as the other opens (turbojet and ramjet) There is probably some type of variable ramp system ahead of the gas turbine engine, and a MHD generator ahead of that that keeps the flow into the gas turbine below maximum Mach number. The turbojet could be a supersonic turbojet or a high throttle ratio turbojet that can be run at Mach three or so inlet conditions. My interpretation of the geometry is shown below. The ramp angles as estimates made from rotating the illustration into a side view. This ramp geometry conforms to the inlet geometry shown in the previous Szames article. The highest Mach number that that appears possible with the cowl angle shown is about Mach 12, with perhaps Mach 10 having more stability margin. That implies the flight Mach number could be in the 12 to 14 range." - Prof. Paul Czysz

Related: Aurora & Beyond (PDF), Paul Czsyz Video Interview, Paul Czysz Audio Interview, AJAX and Magnetohydrodynamics, Hypersonic MHD Implementation, Hypersonic Technical Data, Russian AJAX Technical Analysis, Space - The Final Design Frontier, Model 176 Hypersonic Shuttle, Hypersonic Design Notes, 2025 and 2050 Military Aerospace Vehicles