The components of this engine are an air intake, a hinged air diverter, an annular ram air conduit, a low pressure propellant seal, a centrifugal impeller with integral propellant lines, a toroidal combustion chamber (TCC), and a truncated aerospike ramp. The aerospike ramp provides altitude compensation at all altitudes, and the centrifugal impeller delivers subsonic air, fuel, and oxidizer to the TCC.
During hovering and subsonic flight, the centrifugal impeller sucks air into the engine and flings it outward toward the TCC, compressing it in the process. High-pressure air and centrifugally pressurized liquid hydrogen is then injected into the TCC for combustion and expansion onto the aerospike ramp.
At supersonic speeds, ram air is diverted directly to the TCC, bypassing the impeller completely by means of the air diverter(s). Ram action provides the necessary compression before injection into the chamber. LH2 is still injected through the impeller assembly by continuous rotation of the engine, which spins in air as well as in space.
Rotation of the engine is accomplished by small thrust cells within the TCC. The proper angular speed of the engine is maintained by controlling the thrust or angle of these cells. This, in turn, controls propellant pressurization and main engine thrust levels.
All propellants except ram air are delivered to the combustion chamber through the centrifugal impeller. These propellants include subsonic air, fuel, and liquid oxidizer, each of which is pressurized by the impeller. Liquid propellants are delivered to the impeller through a low pressure seal located at the axis of the rotating engine, where centrifugal forces cannot disturb the flow of low-pressure propel-lants. Fuel and (if required) LOX then flow through internal tubes in the impeller, where they are pressurized just before entering the TCC.
One advantage of this design is that the entire engine rotates as a unit. Therefore the only moving part is the engine itself. Rotation accomplishes several things at once: (1) it allows air to be used as a propellant-oxidizer in the atmosphere as it is sucked in and pressurized by the impeller; (2) it acts as a pump for the liquid propellants; (3) it pressurizes the propellants prior to their delivery to the combustion chamber; and (4) it slightly increases the pressure of the ram air because of centrifugal force in the transverse component of the annular ram air conduit. Another advantage of this design is that the impeller is protected from melting at supersonic velocities because ram air is diverted away at those speeds. Yet it still provides pressurized propellants to the combustion chamber by centrifugal operation at all speeds, in the atmosphere and in space. All of these attributes would allow this engine to fulfill its role as a power plant for an advanced spaceplane, incorporating as it does elements of the ramjet, turbojet, and aerospike rocket engine.
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