This week's MythBusters episode was awesome! They tackled the amazingly controversial topic of whether or not an airplane can take off while on a conveyor belt. And, I have to say, the results at first surprised me, until it all finally clicked. When it did click, I went "Oh! Oh! Oh! DUH!!!!!" Before I explain...
*** SPOILER ALERT *** SPOILER ALERT ***
So, alrighty, here's the deal...
People argue that a plane won't take off on a conveyor belt that's moving the same speed as the plane because they mistakenly believe that the plane's propulsion is the same mode as that of a ground-based vehicle. After all, if you put a car on a conveyor belt moving forward at the same speed as the belt, it stays in one places.
As a result of this logic, people then argue that air will not flow over the wings of the plane, meaning that no lift will occur, and thus the plane won't take off.
The error in logic is in the first paragraph above. An airplane does not propel itself to takeoff speed by apply force against the ground with the wheels. Instead, a plane applies force against air using the propeller or a jet or turbine engine. Therefore, the force of the tires against the ground has absolutely no bearing on whether or not the plane will take off. It is strictly a matter of getting the engine applying enough force to air that it will propel itself at a high enough speed to cause adequate lift.
This experiment was very interesting and it was all based on one major fault in logic that the masses were making (including the ultralight pilot in the show!): airplanes do not rely on forward propulsion at takeoff generated by the wheels. They rely on thrust pushing/pulling the airplane through the air until enough lift can be generated, completely independent of the movement of the ground underneath the plane.
Very cool! :)
