French-Russian Analysis of Kholod Dual-Mode Ramjet Flight Experiments

Abstract

Development of operational, civilian or military, application of the hypersonic airbreathing propulsion depends of two key points: development of needed technologies for the propulsion system as a low weight, high robustness fuel -cooled structure for the combustor, capability to predict with a reasonable accuracy and to optimize the aero -propulsive balance (or generalized thrust -minus -drag balance). The most part of the technology development effo rt can be led with available ground test facilities and classical numerical simulation (thermics, mechanics …). On the contrary, the extreme sensitivity of the aero -propulsive balance when the flight Mach number increases on one hand, and the correspondin g limited capability of ground test facilities to represent right flight conditions on the other hand make mandatory a flight experiment to demonstrate the feasibility of a positive aero -propulsive balance. The recent record autonomous flight of American X 43 -A solved this question at Mach 7, then at Mach 10. Recently, the Australian HyShot non -autonomous flight at Mach 8 was considered by some observers as a very interesting step to compare flight and ground test operation of an academic supersonic combusti on experiment. In 1993/1995, such a first flight test program was performed by the Central Institute of Aviation Motors from Moscow (CIAM) with France at lower Mach number, but with a more realistic engine : Kholod experiment used a liquid hydrogen active ly cooled dual -mode ramjet. This program was based on a hydrogen fueled axisymetrical engine placed on top of a Russian SA5 missile during the whole flight. It follows a Russian -only successful flight experiment at Mach 5.6 in 1991.