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post #1 of (permalink) Old 01-05-2006, 04:47 PM Thread Starter
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Default Move Over Seinfeld - All About Nothing

Imagine a plane is sat on the beginning of a massive conveyor belt/travelator type arrangement, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
There is no wind.
Can the plane take off?

Explain why it can, or cannot, take off?

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post #2 of (permalink) Old 01-05-2006, 04:52 PM
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Want us to do your homework for you or what?
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post #3 of (permalink) Old 01-05-2006, 04:53 PM
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Is this your math homework?
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post #4 of (permalink) Old 01-05-2006, 04:58 PM
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I'll say no it won't take off.If the conveyer is under the planes wheels, then no amount of engine thrust will allow the plane to move, and so no lift will be created under the wings. there needs to be a presure difference from the top of the wings and from under the wings to create lift.
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post #5 of (permalink) Old 01-05-2006, 05:07 PM
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no, because it would sit in the same spot.
Can't remember exactly how it works, but air moving faster over the top of the wing than what is under allows a plane to fly.
A lift can only occur when there is a relative difference between an object and air. With no movement there is no air flow... or something like that

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post #6 of (permalink) Old 01-05-2006, 05:12 PM
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Or would there be enough disturbance in the air simply because of the wheels moving against the conveyor belt(something like that, can't explain my thought any better than that), creating high pressure under the wing, and low pressure above the wing, therefore the plane would lift?



Hhhhmmmm (scratches head now, and waits for the answer... meanwhile google, ya, google knows everything!)

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post #7 of (permalink) Old 01-05-2006, 05:23 PM
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aaahhh haaaaa!!![8D]

I was right the second time, though my theory might not have been exact

http://txfx.net/2005/12/08/airplane-on-a-conveyor-belt/

thankyou google knowitall

nope, there's a lot of debate over this. I'll wait for the answer..

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post #8 of (permalink) Old 01-05-2006, 06:41 PM
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I think the plane would still take off - the speed of the plane vs. the air is the only relevant factor - the speed of the wheels irrelevant. My thoughts without looking for answers elsewhere
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post #9 of (permalink) Old 01-05-2006, 06:51 PM
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This sounds like a problem for the Mythbusters .
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post #10 of (permalink) Old 01-05-2006, 07:09 PM
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ok, on the conveyor belt, the plane is still moving. it just isn't moving relative to the ground. but it builds up a velocity. therefore it does take off

conversely, it would also take off if the plane itself had no engines and it was accellerated forwards by the conveyor belt. but once airborne, it would crash back to earth as once off the conveyor no engines would accellerate it.

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post #11 of (permalink) Old 01-05-2006, 07:20 PM
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I say it takes off. What the wheels are doing have no relevance since engine power is not directed to the wheels like a typical motor vehicle. It uses thrust. The wheels are only suppourting the weight of the plane and allowing it to break the friction with the runway.The wheels will be spinning much faster at take off however.
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post #12 of (permalink) Old 01-05-2006, 08:02 PM
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Quote:
quote:Originally posted by Jimbo
My thoughts without looking for answers elsewhere
Hey I gave both my answers BEFORE googling, of which never really gave a me a real answer anyway.

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post #13 of (permalink) Old 01-05-2006, 08:04 PM
 
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I say it won't take off! If I'm on a running type exercise machine in a gym and I hold my arm straight out to the side, would I feel any wind or any noticeable air flow hitting my hand? This would be no different than the plane example. Unless I'm really missing something here. I better read it again.

Ok, the above is assuming you were asking if the belt alone would allow the plane to take off, and there would be no engine thrust.

Definately it would take off with engine thrust. The wheels' RPM would just be faster than normal (forward movement from thrust + conveyor belt turning the wheels).
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post #14 of (permalink) Old 01-05-2006, 08:09 PM
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The plane is not driven by the wheels but jet engines like jeffster said.The platform on which the vehicle sits is meaningles as long as there are no hindrances or friction.If you attached a jet engine to your back and got on your treadmill you would feel wind because the treadmill would be far behind you and there would be a hole in your wall.
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post #15 of (permalink) Old 01-05-2006, 08:19 PM
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There needs to be airflow across the wing to generate lift. The plane can have all the thrust it wants, but if there's no relative air movement over the wing, then no dice.

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