Axial jet engines work sort of like this..
The big fan at the front sucks in air which then tries to squeeze out the back. But on it's way out it has to pass through a fan blade on the same shaft as the front fan, turning it and thus making the front fan suck in more air..
..they just need to throw some fuel (or fast-pedalling bicylist) in every now and then to keep things going.
The big fan at the front sucks in air which then tries to squeeze out the back. But on it's way out it has to pass through a fan blade on the same shaft as the front fan, turning it and thus making the front fan suck in more air..
..they just need to throw some fuel (or fast-pedalling bicylist) in every now and then to keep things going.