Originally Posted by
megan
Ken: in reality no jet engine puts "propellers in a tube."
It does if you consider the loads imposed by the various components..... The compressor is providing 33% of the total thrust load, a prop in a tube.
You missed the entire point of my post. It has nothing to do with "the loads imposed" or even "thrust generated". Yes, the intake system can provide a considerable amount of thrust. But it does so NOT because the blades in the intake system are accelerating the air, but because the blades are compressing the air and then the constriction of the casing acts as a nozzle to accelerate the air. Propeller blades directly accelerate air. The blades in the jet engine are compressors, not accelerators. Propeller blades and jet engine blades behave similarly from a pilot perspective (they provide thrust), but employ fundamentally different principles.
You noted that the SR-71 inlet/diffuser provides a lot of thrust. That is NOT because the inlet/diffuser has a bunch of little propellers in the tube accelerating the air. A fundamentally different principle is being employed.