Air moving horizontally over wings creates lift.

A stationary plane (relative to the earth) on a conveyor belt has no air moving on the wings. Therefore, the conveyor belt speed, in fact is moot.

On the other hand, slamming on the landing gear brakes on a conveyor belt moving under the plane at takeoff speed could well catapault a properly configured (flaps etc.) plane into the air because it would go from zero relative speed to take off speed almost instantly. (Think aircraft carrier launch)

But if the plane is sitting with engines at an idle on the moving conveyor belt it will probably be a short bumpy flight since the engines can't spool up in time to keep it flying.

I mean, you can launch a VW off an aircraft carrier but it ain't gonna fly far...

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A stationary plane (relative to the earth) on a conveyor belt has no air moving on the wings.

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Is the plane chained down or something while it is on the belt?

The conveyor is moot if they dont buy it from me!

www.wwcannon.com

Holy carp they're showing the myth tonight

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Episode Detail: Airplane Hour - MythBusters
Adam and Jamie try to land a jet on a runway in varying weather conditions; meanwhile, Kari, Tory and Grant investigate skydiving myths, including catching up with someone in freefall. Also: a myth about an airplane on a conveyor belt.

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HAHA I bet all you idiots who thought it would take off feel pretty stupid

im pretty sure it didnt air tonight

http://dsc.discovery.com/fansites/mythbusters/mythbusters.html

Go there, click on the "preview controversial myth"...shows about what they're going to do for the myth.

The conveyor is moot!

Wow, that's a big piece of meat!!!!!!!

that's what she said

The airplane would take off but crash with all dead.

The Africanized bees that built an enormous net under the conveyor belt would swarm up and attack the aircraft plugging up the intake air. By the time the aircraft gets up to altitude, everyone on board has passed out from lack of oxygen. The airplane will continue on because of the autopilot until it runs out of gas and crashes.

planes need lift to fly...

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planes need lift to fly...

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Nice use of the popcorn. No one bite!!!

THE POPCORN IS MOOT!!!!!!!!!!!!!!!

I love it that nobody can decide......are we talking about the conveyor speed being takeoff, and the plane remaining stationary, or is the plane moving forward at takeoff speed while traveling on a conveyor moving the opposite direction.

Tell you what, find me a conveyor big enough to hold my R/C plane, we can test it our selves...

____________________________________________________________
Proudest member of the Fightin Texas Aggie class of 08 Beat the h*** outa tu A Whoop!!!.
= texags

One factor that no one seems to consider is the friction between the wheels and the conveyor belt.

With a light plane, the friction will be very low. If the friction between the wheels and the conveyor are less than the friction of the wheel bearings, the wheels will slide across the conveyor which will render the conveyor moot and allowing the plane to take off. With a full-size (read, heavy) plane, the friction between the wheels and the conveyor will be greater than the friction of the wheel bearings and the wheels will just spin in place preventing any movement of the plane relative to the surrounding air and the plane will not take off.

Flame away

OK I'll bite, I'm bored this morning. Friction has been mentioned numerous times but for the sake of the question it is mostly a non factor because it does not completely relate to the heart of the question. Wheel to belt friction is the force that could keep the plane stationary (short of chaining the plane down which has never been apart of the scenario.) As has been explained, if the belt is moving backwards, the plane will have to exact some amount of forward thrust to remain in it's stationary position.

However, if the belt is moving backward at 50 mph and the plane is stationary, does that not void the question entirely? The questions is if a belt moves backwards in relation to the speed of the plane, will it take off. Can an object have a determined speed if it is not moving? So if the plane is stationary then the belt speed is 0. If the plane speed is 50mph, the belt speed will be 50mph in the opposite direction. Granted, the thrust issued buy the plane to reach 50 mph is greater on the belt then if on a normal runway (this is where the friction comes in.)

Further, the only people that claim the plane remains stationary or even bring the subject up are ones who do not understand the belt to plane relationship and who have yet to figure out a plane does not propel itself forward by power to the wheels.

the friction is moot

tu is moot!!!

I don't get it.

Narcolepsy?

so did it air? and if so, did anyone see it?

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So if the plane is stationary then the belt speed is 0...

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I always assumed that the "speed" of the conveyor was whatever the "speed" of the plane would be if there was no conveyor. Basically, some sort of sensor that would speed up the conveyor belt to compensate whenever any motion of the plane were detected in relation to the ground beyond the conveyor belt. If the friction between the wheels and the conveyor belt isn't broken, the wheels would spin at the speed of the conveyor belt and the plane would not take off. If, however, the force of friction between the conveyor and the wheels is broken, then the conveyor becomes moot and the plane moves (and ultimately takes off) regardless of the speed of the conveyor belt because there is no longer a "connection" between the two.

I am done, again.

Merry Christmas.

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With a full-size (read, heavy) plane, the friction between the wheels and the conveyor will be greater than the friction of the wheel bearings and the wheels will just spin in place preventing any movement of the plane relative to the surrounding air and the plane will not take off.

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Ff = uN where u is itty bitty...and N ~= W

So, THAT can't be it...

But, it's obvious that the only propulsion available to all aircraft is the propulsive force provided by the wheels. THAT'S why the aircraft can't take off:

The conveyor belt renders the wheel propulsion moot!

Unless the wheels can move the airplane forward, the airplane will stay stationary!!!!! This is the fundamental misunderstanding everyone has about airplanes....

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short of chaining the plane down which has never been apart of the scenario.

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As a side note, have y'all ever seen an F-16 doing a static engine runup test while the F-16 is pointed right at your building? It is a little disconcerting to say the least...

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The questions is if a belt moves backwards in relation to the speed of the plane, will it take off.

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Nowhere in the question is the speed of the conveyor stated to be relative to the aircraft.

The conveyor remains moot!

horn likes this thread

Horn liking this thread is moot...

Wow. 40 pages of "the conveyor is moot" followed by someone saying the same thing with different words explaining that the plane will take off, followed by other random posts, followed by "random posts are moot", followed by someone disagreeing with fancy explanation, followed by "the conveyor is moot" (in no particular order)

This is simultaneously the greatest and worst thread of all time.

[This message has been edited by putmeincoach (edited 12/27/2007 1:56p).]

You missed the other ones didn't you?

there's this thing called inertia. the plane would just sit there.

^
For about 5 seconds.

It really depends on who's "driving" the conveyor belt system.