A comment in the hover text of the latest XKCD led me to look up this thought experiment:
A plane is standing on a large treadmill or conveyor belt. 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?Which led me to lots of argument, the inevitable Wikipedia article, and a comprehensive explanation from an exasperated blogger.
So you see it's worth reading these sites so often. They lead me to further edumacation!
Although again, perhaps icanhascheezburger is a bit of an exception.
2 comments:
The wikipaedia harticle is correct. A plane's wings must have "airspeed" in order to generate lift. Airspeed is measured as the air moving with respect to the aircraft.
With the aircraft being stationary on a conveyour belt that does not move with respect to the surrounding air, the aircraft has zero airspeed and therefore zero lift. Answer: no it would not take off.
The plane is not stationary.
How do you think a plane goes from take off speed to cruising speed? Obviously the wheels have nothing to do with that.
The plane goes from stop to take off speed the same way. And the wheels have no real effect in that either. and the Conveyor can only affect the wheels. Therefore the conveyor makes no difference to a plane.
Therefore it takes off as normal.
Post a Comment