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And tell me how this "forward progress through the air" is going to occur with a stationary plane and no wind?

Sure, as soon as that plane's propeller (or jets) begin to generate thrust, the conveyor belt is almost irrelevant. (Except for altering the amount of rolling resistance, a minor factor compared to air resistance.)

Planes take off with no wind all the time. You don't need wind to take off. You just need thrust. And the thrust acts against the air, not against the ground.

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Gravity is pulling downward on the plane. Until it has the groundspeed to get some enough lift

Bzzt, wrong again. Groundspeed does not generate lift. Airspeed does.
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Tony Fabris