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Originally Posted by fleaofsc
Ok, then yah, I did agree with you... thats what I thought you were getting at. We can safely know that we are right.
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The situation you and Maine are describing does nothing to explain if the plane will take off. To attain the friction balance point, the engines must be significantly throttled back. Any plane, whether on a treadmill, or runway cannot take off without take-off thrust.
You have only proven that the plane will not take off due to lack of power. That is not what this myth is about.
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Originally Posted by roastbeef
i still maintain my theory that the plane would not take off.
there is very significant resistance against the free spinning wheels.
pretend you have a toy car on a treadmill. the treadmill is on, and you are holding it in place. the moment you let go of the car, it will immediately begin to 'slow' and fall off the back of the treadmill pretty quickly.
the same applies to an airplane. even though the airplane is moving by creating thrust, the engines are still working to keep the plane from falling off the back of the treadmill. the engines can not create and infinant amount of trust, and therefore, can not create enough thrust to overcome the resistance against the spinning wheels. im willing to bet the turbines would burn up too.
in a perfect world where there was no friction, the plane would take off. if there was no friction, the toy car on the treadmill would remain stationary when you let go, also.
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As you are holding the toy car in place on the moving treadmill, take a sense of the force needed to resist the moving conveyor. Now imagine what force will be needed to accelerate the toy car to take-off speed. This is about 150 mph. Imagine holding this toy car out your car window at 60 mph. How much force will you need to keep it from flying away? Imagine if you held the car out the window of a car going 150 mph. Get the idea? The force needed to hold a toy car at 150 mph against rushing air is the same force needed to accelerate the car to 150 mph. This force is orders of magnitude larger than the force needed to hold the car against the motion of the treadmill.
But you say, as the toy car accelerates, the treadmill drag goes up also. It goes up some, but not as dramatically as air drag. If the treadmill were running at 60 mph, would you expect the force need to hold the car in place to be the same as in 60 mph rushing air?
The frictional traction forces at the plane-treadmill interface are trivial when compared against the massive forces generated by the engines to acccerate the plane to take-off speed.
