Riscram™ Rocked Ignited Supersonic Combustor Ramjet. Propulsion system for hypersonic aircraft with supersonic combustor. Mach 0 to 30 - Earth Sea Level to Space Exosphere.
This invention relates to a propulsion system for hypersonic aircraft configured to operate from a fixed point to hypersonic steady state speed and from an altitude at sea level to an altitude which comprises the terrestrial exosphere. More specifically, this invention relates to a propulsion system for hypersonic aircraft having a supersonic combustor which is ignited by a rocket, in other words, a propulsion system for hypersonic aircraft having a supersonic RAM combustor which is ignited by a rocket.
The engine was studied for two-stage reusable satellite launch vehicle. This launcher was designed to orbit payloads of up to 500 kg to low orbits (LEO). Two RISCRAM™ jet engines  power the first stage that is fully reusable. They aspirate atmospheric air and allows speeds of up to Mach 6, below 30 km, and Mach 15 above 40 km of altitude. The second stage is powered by a solid rocket motor that carries the payload at the orbital speed of Mach 24. In this work are presented details of the concept of the vehicle and an economic feasibility analysis of system operation. Launch cost estimative are made and compared to the values of the current satellite launchers that are not reusable. The conclusion of the article is that the proposed system would be able to reduce by an order of magnitude the cost of placing the kilogram of payload in low orbit.
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 RISCRAM patent -> " Engine for hypersonic aircrafts with supersonic combustor" WO 2016157224 A1