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Linear Aerospike Efficiency

KJ_Lesnick

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Efficiency-wise, how does a Linear-Aerospike engine compare to a regular rocket, and a turbojet?

KJ
 

Michel Van

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sorry I overlook this question

The problem with the conventional approach is that the outside air pressure also contributes to confining the flow of the exhaust gasses. At any one altitude, and thus ambient air pressure, the bell can be designed to be nearly "perfect," but that same bell will not be perfect at other pressures, or altitudes. Thus, as a rocket climbs through the atmosphere its efficiency, and thus thrust, changes fairly dramatically, often as much as 30%.
http://en.wikipedia.org/wiki/Aerospike_engine



The annular aerospike engine was the answer to that problem 1960s.
is a engine bell inside out

Rocketdyne's J-2T-250k (for use in Saturn V MLV-V-1 had to use 5 on Saturn MS-II-1 stage)

The annular aerospike engine was in 1960s the no plusultra in SSTO spacecraft like ROMBUS, PEGASUS

later build Rocketdyne XRS-2200 linear aerospike engine as strong contender for the Space Shuttle main engine.
and the X-33 program


the advance ?
A vehicle with an aerospike engine uses 25–30% less fuel at low altitudes
the engine is sorther and lighter as conventional rocket engine.
the annular aerospike engine can used as heatshield for reentry

and WHY are aerospike engine not used ?
lets say Aerospace Industry to conventional in way they build rockets...
 

LowObservable

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On the X-33, the idea was that differential thrust provided control, the engine weight penalty was reduced because it was integrated into the structure, and the aerospike adapted to altitude better than the bell.

Of course it did not work, so you can take it with a grain of salt.
 

mz

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Also, lifting bodies like this have huge base drag that the linear aerospike would have conveniently solved at least partly.
 

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