Plane on a conveyor revisited Options

[james]

Dragging up the past a bit - TV show Mythbusters ran it's much anticipated episode with a practical experiment version of this question on it a couple of nights ago over in the US.

I don't know when it will come on over here but for the curious Kottke liveblogged it and also links to another good explanation from a guy with a Sc.D. in Nuclear Science and Engineering (whatever that is).

And for the hard of attention and understanding - yes of course it takes off.

[Jeffers]

The plane will only take off if there is airflow over the wings.
If the plane is stationary then there is no airflow. It doesn't matter how fast its wheels are spinning.

Imagine standing behind the plane and pushing on it while the treadmill increased in speed. The wheels are doing Mach 4 but the plane is just sitting there as you are negating the tendency for the plane to move backwards. Massive speed in the wheels but the plane is not going to just start "flying". The only way the plane will lift off is if you start pushing on it enough to get it going forward at such a speed that lift was generated. This would then move the plane forward (as shown in the Mythbusters clip where the plane was moving through the air faster than the ground was moving underneath it) therefore providing lift.

That is the question is it not?
Will the plane take off? (While it is on a treadmill)

The answer is no if there is no forward movement providing airflow which in turn provides lift.

Now you could make it lift off the ground with no engines while the plane was stationary and chained to a post but you would need some seriously big fans ( a la Wind tunnel) to provide the airflow over the wings. It would then be, in effect, a giant kite.

Jeff