[RedDevil]

Funny that even a professor is convinced it cannot work and bets on that it can't be proven to work. I would really want to accept that bet!

Then there's the question how much proof the professor would need to accept defeat. He is no doubt very clever - and clever people have the mental weaponry to find all kinds of intricate loops and excuses to dismiss what they don't want to agree with.

While if you figure it out it feels very rewarding indeed.

In a nutshell, the energy needed to push the air back over a certain distance is less than the energy obtained by the wheels rolling a greater distance over the ground, as the force on the propeller and the wheels is about equal.