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Old 03-06-2006, 10:26 PM
David Simmons David Simmons is offline
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Join Date: Nov 2001
Posts: 12,684
Originally Posted by zut
Well, I prefer "the realm of a thought experiment" to "a fantasy world scenario," but, yeah, we're talking about a situation that isn't really testable on a real aircraft given real-world limitations.
I've been thinking over this thought experiment in my spare time. Since I am retired I have a lot of spare time.

I think it's a lousy thought experiment. Such experiments are those that you can do theoretically but not practically. I don't think you can even do this one theoretically.

Take the case where the only force opposing the engine thrust is the acceleration of the wheels. In order to stop the plane indefinitely you must constantly accelerate the wheels and that is not possible.

In the case where viscous friction is also included the scenario would be to run the wheel speed up until wheel acceleration force plus the viscous friction force balances the thrust. If the acceleration is then stopped the force immediately becomes merely the friction force and the plane moves forward. If the acceleration is not stopped the plane moves backward but here again you can't maintain constant acceleration indefinitely.

I think BR#2 is a loser.