Quote:
Originally posted by Hawk:
How about this.....lets see if this can get to the ALR:

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?
The conveyor is not turning at infinite speed. It is only matching the speed of the aircraft. Hence the conveyor's speed is limited by the aircraft's speed. If the aircraft is not moving, neither is the conveyor. If the aircraft is moving, it's using the air to do so, so no matter how fast the conveyor turns the plane will continue to move relative to a fixed point.

I can't think of any aircraft that have "wheelspeed sensors". Aircraft speed is measured in KIAS, Knots Indicated Air Speed (or mach, but not in this scenario). As air flows into a tube (the pitot tube) it spins a little pinwheel.

If the conveyor spins at triple or quadruple the plane's airspeed or groundspeed, it makes no difference.