Originally Posted by
Mechta
We have wind gradient due to friction with the surface in the real world, and wall effect in wind tunnels which is much the same. It is therefore reasonable to assume that a moving conveyor belt would induce some movement in the air above it. Clearly the belt would need to be going a lot faster than normal take off speed to induce an airflow at wing level that is at take off speed, and the comments about tyre speed would apply.
Right, of course. A 40-foot-thick boundary layer...
Here is a hang glider proving the point:
It's proving *a* point, certainly. But sadly I fear not one which is relevant to this question.