Plane on a treadmill .. to be on Mythbusters

[omgwtfbbq]

drkohler said:

omgwtfbbq said:
you're all getting it wrong! you're all saying "if the plane has no airspeed it won't fly" which is of course true, but you're missing the point that they're trying to slow down a plane with a treadmill. It simply won't work! The plane is pushing against the air. If it were a car it would be stationary. Imagine this scenario then:

You have a car driving at 100 MPH. It's a front wheel drive. The two back wheels are on a treadmill (ok, you'll have to imagine a mobile treadmill here so that the back wheels are on it and the front wheels aren't) and this treadmill is going backwards at 100 MPH. Will the car stay stationary? Of course not! The front wheels are providing the force, the back wheels are simply there for the ride. It doesn't matter how fast those back wheels are spinning, the front wheels will keep the car moving at 100 MPH.

This is the exact same scenario. The plane will move forward because no treadmill in the world can stop a plane from moving.

Oh boy... nobody is trying to slow down anything in that experiment. Now in your car case, put the belt where it belongs, under the FRONT wheels that DEFINE the momentary axis of rotation (it does not make any logic sense to place the belt under the wheels of the free running axle).

Of course the plane can and will stay stationary on the conveyor belt if its forward speed (generated by whatever means) exactly matches that of the belt. Now you can increase both speeds slowly to 'lift-off' speed, If the pilot can balance the plane long enough. At some (probably very high) speed, a propeller plane will lift off although being stationary to an observer standing at the belt. However, in the actual experiment a normal propeller engine might not be able to reach that speed (which is higher than normal 'lift-off' speeds) but the plane lifts off anways because it is probably not running horizontally but with engines slightly inclined giving the accelerated air a downward momentum.

 

Ever watched those fitness freaks running on a treadmill? They do exactly the same, they run just as fast forward as the belt runs backwards to stay in place...

 

Exactly my point! The Front wheels are providing the movement, so putting the treadmill on the back wheels isn't going to slow down anything.

With the plane, what provides the movement? The propellors. By your own admission then, placing a treadmill under the wheels isn't going to slow down anything!

EDIT: to clarify, you said "it does not make any logic sense to place the belt under the wheels of the free running axle". This sums up my position entirely. The wheels on a plane ARE the free running axle.