I had an idea once which I'd like to go into a little. It involves how a fan or propeller draws in air verses only providing thrust. The idea is/was to cut down on aerodynamic drag and resistance a propeller imposes once the craft is up to speed. By having a remote fan/propeller air intake like a jet or even a NACA inlet; in-line tandem fans which are located down a serpentine duct would provide thrust. The first fan/propeller would act to drawn air into the air intake plenum feed duct; the second fan would kick it up a notch. Much like a compressor. The second fan might rotate in the same direction or be counter-rotating; it does not matter at this point. I would also use additional duct length to straighten the flow in lieu of stator vanes AFTER THE LAST FAN. All this together is aerodynamic and quiet if not the last word in weight control or efficiency margins. I'm not claiming this is a new idea or invention, do a search on "cold jet" or "cold thrust", pre-WWII Italy had an example or two, and of course there was Henri COANDA in 1910. Example the Davis Wing: http://members.cox.net/rebid/DavisWing.html Note: The inlet may not always face the direction of motion in my example, it could be at a right angle. This might also be used in a hovercraft, not just an aircraft. What do I need to know or reference to pull off such a configuration?