Quote:
Originally Posted by MWS
And thanks for adding one of the classic engineering brain experiments to the mix. LOL. I've always contended that a model plane on a treadmill won't take off (it's not moving through the air, hince no pressure change and no lift) BUT you said jet. A jet engine moves air, so even if the wing isn't moving through a medium, the jet is moving air over the wing producing *some* lift. Would it be enough to take off? Doubtful, but reason would say that if it DID move enough volume of air to sufficiently reduce pressure, then lift would occur. Think of a model plane in a wind tunnel...the planes forward motion (same as with the treadmill) would be zero, but relative speed through the air would still create lift...theoretically if the fan in the wind tunnel was mounted on a sufficiently sized wing, it would lift itself. With that, back to our regularly scheduled programming...  |
Well...
An aircraft engine (model or full size) moves air, not the wheels. Once inertia on the treadmill is overcome, the amount of forward thrust to balance the forces of the tread on the wheels is minuscule.
If one is arguing that forward thrust is applied only to overcome that tread to wheel friction and hold the plane stationary, then it won't lift off. However, the amount of power needed to hold it stationary is tiny.
For example, if the plane needs to be moving forward at 60mph to take off, and treadmill is moving at 60mph in the opposite direction, the amount of power needed to take off would be almost exactly the same as it would without the treadmill.
The Mythbusters did it.
https://m.youtube.com/watch?v=YORCk1BN7QY
What were we talking about?
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