Plumbob Machinbird
I'm having a problem understanding the mechanism which would make your air-dam theory slow the aircraft.
Any force acting on the air blown forward would blow the air backward. How would this be transmitted to the airframe?
pattern-is-full
Newton is turning in his grave.....
If you could increase the thrust of an engine by fitting it backwards and then bouncing it off something then fighters would have done it long ago.