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physics

Airplane on a Conveyor Belt

So here’s the question of the day:

“A plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?”

Personally, my first thought was that the plane would not take off because it wouldn’t have enough lift without moving up to speed relative to the ground. But after thinking about what it is that actually causes a plane to lift off, the wind going around the wings, I wasn’t so sure.

The wheels in planes aren’t generally what cause the plane to move forward, it’s the suction of wind through the propeller or engines. Presumably the plane would pull the same amount of wind whether or not it was riding the conveyor belt, therefore, I think it would take off.

While you’re taking a moment to think about this problem, let me tell you that tonight the Mythbuster’s are putting this question to rest once and for all. Will a plane on a conveyor belt take-off? (We’ll see tonight, but I think yes).

Update: here is the clip:


[Mythbusters – Plane on a Conveyor Belt – YouTube]

The Mythbusters official channel has uploaded the full episode:

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