I have to disagree with the consensus of this thread in three areas...
If the conveyor belt is going 170 mph in a backwards direction, and the plane engines are providing enough thrust for the the plane to go forward at 170 mph, then the plane would actually be sitting still and would have no forward movement with regards to other stationary objects. There would also be no air movement over the wings, unless the wind was blowing.
[quote] The only thing that the conveyor belt does is makes the wheels spin faster, so the plane is going 100 mph forward, the conveyor belt 100 mph backwards, meaning the wheels are spinning at 200 mph.
In the example I gave above, the wheels of the plane would be moving at 170 mph, not 340 mph. There is no force that would double the speed of the wheels. The conveyor belt is going backwards at 170 mph, and the plane wheels are going forward at the same speed. 170 - 170 = 0, which is the speed of the aircraft.
I'm a pilot, and the answer is yes.
Forward movement of an aircraft is caused by the thrust of its propeller or jet, not by it's wheels like that of a car. Therefore, the movement of the conveyor in no way affects the aircraft's ability to move forward relative to its position through the air which is what generates lift and allows for flight.[/quote]
No offense, but si
nce the plane is sitting still relative to the air surrounding the wings, there would be no lift, and this plane has no chance of taking off. The rotation speed required for takeoff must be in relation to the air moving across the wings. I think this is called "indicated airspeed". So with a 20 mph headwind, you'd only need 150 mph of actual land speed. But with no aircraft speed, you might need ~ 170 mph headwind to take off.
This would be a completely different story if we were talking about a plane specifically designed for vertical takeoff...