what mythbusters *SHOULD* have done.

[gsh]

Airplane on conveyor belt. As with many word problems, the exact wording becomes important, so google "plane conveyor belt" hit "I'm feeling lucky" and get:


Here's the original problem essentially as it was posed to us: "A plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?"

Mythbusters showed two examples of the plane taking off, and declared the myth busted. However, I don't think they did the myth right. The basic physics is that as long as the plane isn't moving with respect to the wind, there is no lift. However, as long as the plane's propeller is providing thrust, there will be an acceleration of the plane. Any conveyor belt that doesn't accelerate doesn't describe what is listed in the myth. As long as the belt accelerates to match (and cancel) the acceleration of the plane, the plane doesn't generate lift. Eventually the conveyor belt reaches its maximum velocity, stops accelerating, the plane surges forward, starts generating lift, and then can take off.

What, me OCD on this issue?

Comments

[whitebird.livejournal.com]

And now, how much wind velocity is generated under/over the wings as the conveyor belt travels under the plane? There is a variety of ground effects with wind which could easily come into play for increasing the amount of lift the plane is subjected to while on the conveyor.