Quote:
Originally Posted by Tallyn  Yeah, but what force does the treadmill exert on the plane? Beyond the normal (perpendicular) force, none, except for a minor amount of friction spinning the wheels. Essentially all of the energy from the engine goes to moving the plane forward through the air. |
Wrong, Objects in motion wish to remain in motion, objects at rest wish to remain at rest.
Turning on a treadmill that a plane is
resting on, will not spin the wheels in a real world scenario, the only way the wheels would spin is in a frictionless world.
Again, the engine does NOT move the plane forwards through the air, it creates sufficient force to overcome the friction of the wheels, thus moving the plane along the ground until the necessary lift on the wings is achieved. This is why a headwind is favorable for takeoffs, and why steam catapults can make a fighter take off on shorter distance on an aircraft carrier. These are additional positive forces, where a treadmill working against the plane would be like a negative force like extreme tailwind. It is very very possible that a strong enough tailwind can prevent takeoff as well.
This is real world shit where they plan which end of a runway to start at for takeoff depending on the direction of the winds.
Runways are paved, and they're not uphill for a reason. Planes have wheels instead of square blocks for tires all for a fucking purpose. The purpose being so that the plane achieves sufficient ground speed which in turn creates enough air current over the wings for liftoff.
In real world scenarios, a steam catapult aids in that ground speed, a headwind aids in the increased air current over the wings. Conversely a tailwind hinders air current over the wings or a fictional moving runway in the wrong direction would achieve an similar negative effect. It is entirely possible that a tailwind could be strong enough theoretically to render takeoff impossible. Well, not on Earth because of the limitations of our weather, but you get the idea.
