Hi Italian....
"That's hard to define. I think it's easy to see that a jet pushes as it accelerates a flow of air behind it at a higher velocity. But a propeller actually pulls 50% and pushes 50%. Consider a prop that accelerates the local flow velocity by 100 m/s. There will be a 50 m/s increase by the time the air reaches the propeller and the last 50 m/s increase will happen somewhere down stream of the propeller. So with either a Cessna 182 or a Piaggio Avanti II, they both pull AND push. "
A turbojet does the same push/pull...
In extreme cases, the intake can produce well over half of the thrust of the exhaust.
In such a case, the exhaust can be redirected to flow against the a/c forwards, and the aircraft will still fly. A jet engine is full of propellors
Put propellers in a tube, and spin them, will there be thrust? Yes.
Power these propellers with an engine that drives them mechanically, still, thrust.
Inject fuel behind the propellers, and ignite it. Thrust.
Last edited by Lyman; 26th Jul 2012 at 00:56.