The plane will never take off. If the conveyor is moving in the opposite direction as the forward motion of the plane, the plane is essentially standing still. If there is no air movement over the wings, there is no lift. A plane will not lift off without airflow. The jets only act to push the plane forward fast enough through the air to generate enough lift to get the plane off the ground. Prop planes opperate under the same guidelines only the prop pushes/pulls the plane through the air to generate lift on the wings. So no airflow (forward motion) no flying.