re: Can this 747 take off?

My interpretation in this rolling-friction-counter-force model was that the tread goes fast enough that the center axle as zero velocity. The vectors at the top and bottom of the wheel would be equal and opposite.

I posed a thought experiment earlier with a small toy plane with no engines on needing to be held in place to keep from falling off the back of a running household treadmill. Obviously there is a force transmitted tangentially to a free rolling object to send it off the back of a treadmill, no? And could there not theoretically be a tremendously fast treadmill that could produce enough of this tangential force to counteract the thrust?