Mobycat, please explain how the conveyor belt applies force to the aircraft. Do you agree with the following statement?

-- The force the conveyor belt applies to the aircraft is due to friction in the wheel bearings and deformation of the tires making them not perfectly circular. --

If we agree on the above statement then the aircraft needs to extert enough force (engines pushing against the atmosphere) to overcome the conveyor belt's force before the plane can move. I think it's been established that once the plane generates enough lift via. airspeed that it can take off.

So, if you agree with the above (and please post your arguments if you don't) then the critical issue is how much force the conveyor can exert on the plane.

Since the conveyor can only exert force through friction in the bearings and wheel deformation there is no way it can extert enough force to overcome the jet's engines. If it could that would mean that jet's would never take off in the first place because they wouldn't be able to get moving, which obviously is not the case. The most that could happen would be that as the jet accellerates the wheels will be spinning at 2x the normal speed, which might cause some slight additional resistance. The only way the jet won't take off is if the wheel bearings fail because they are subjected to speeds outside of their design parameters.

On a side note, when people talk about the jet's "speed" are you talking air speed or ground (wheel) speed? If we are talking air speed then the jet would need to first move relative to the air to induce movement in the conveyor. If the argument is that the conveyor can extert enough force to stop the jet then we wind up with the jet's engines on full and neither it or the conveyor moving at all, which makes absolutely no sense.

- Matt