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Will the plane fly...?

 
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Will the plane fly?
Yes
46%
 46%  [ 6 ]
No
53%
 53%  [ 7 ]
Total Votes : 13

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LuckySe7ens
"Cowboys"


Joined: 20 Aug 2005
Posts: 35

PostPosted: Sat Jun 17, 2006 8:08 am    Post subject: Will the plane fly...? Reply with quote

I saw this posted on several message boards, and the variance in answers, and everyone's insistence that they are correct is downright humorous... so I though I'd give it a try here... please don't cheat and search google or anything like that... I'll chime in after a few responses...


A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

Will the plane fly? Why or why not?
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Ranman
"A Set of Mop Squeezers"


Joined: 31 Aug 2005
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PostPosted: Sat Jun 17, 2006 8:59 am    Post subject: Reply with quote

I voted no.

Due to the fact that since the forward motion of the plane would be "canceled out" by the conveyor the air passing over the wing (required for lift) would be lost.
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drneau
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PostPosted: Sat Jun 17, 2006 11:28 am    Post subject: Reply with quote

Ranman wrote:
I voted no.

Due to the fact that since the forward motion of the plane would be "canceled out" by the conveyor the air passing over the wing (required for lift) would be lost.


Bingo.
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rastapete
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PostPosted: Sat Jun 17, 2006 12:18 pm    Post subject: Reply with quote

Of course it will. The fact that the wheels are spinning doesn't stop the air from doing it's thing w.r.t. lifting the wings.

PS Just for information, I've read a couple of threads on other forums on this topic.
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drneau
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PostPosted: Sat Jun 17, 2006 1:35 pm    Post subject: Reply with quote

rastapete wrote:
Of course it will. The fact that the wheels are spinning doesn't stop the air from doing it's thing w.r.t. lifting the wings.

PS Just for information, I've read a couple of threads on other forums on this topic.


True. Wheels would just be spinning at a speed of (conveyor * 2).
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LuckySe7ens
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PostPosted: Sat Jun 17, 2006 2:53 pm    Post subject: Reply with quote

Here's the explanation that more technically explains it:

The wheels of the plane are pretty-much free-moving, there is some friction that will cause a little resistance, but for the most part, they are free-moving. Even though the conveyor is moving backwards at the speed the plane is moving forward, the jet engines are acting upon air in order to move the plane forward, and they don't have to counter the negative speed of the conveyor belt moving backwards.

So, the wheels wont quite reach speed of conveyor * 2, but it'll be pretty close to that... and in a perfect system without any friction, it would be that exactly.
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MaxPower
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PostPosted: Mon Jun 19, 2006 9:09 am    Post subject: Reply with quote

LuckySe7ens wrote:
Here's the explanation that more technically explains it:

The wheels of the plane are pretty-much free-moving, there is some friction that will cause a little resistance, but for the most part, they are free-moving. Even though the conveyor is moving backwards at the speed the plane is moving forward, the jet engines are acting upon air in order to move the plane forward, and they don't have to counter the negative speed of the conveyor belt moving backwards.

So, the wheels wont quite reach speed of conveyor * 2, but it'll be pretty close to that... and in a perfect system without any friction, it would be that exactly.


Yep - the force used to move the plane is not transmitted via the wheels. If, however, it was, then the plane would stand in place like a tread mill.

Max
I think I had this once on a mechanics test or something...
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LA_Rounder
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PostPosted: Mon Jun 19, 2006 11:43 am    Post subject: Reply with quote

think about those belts at the airport. ever notice that when you walk fast down one of them, the wind around you is way stronger than when you walk normally?

i think this is the same. the conveyor action has little to no effect on the air passing over the wings, even though the plane would not appear to be moving at all.
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MaxPower
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PostPosted: Mon Jun 19, 2006 11:57 am    Post subject: Reply with quote

LA_Rounder wrote:
think about those belts at the airport. ever notice that when you walk fast down one of them, the wind around you is way stronger than when you walk normally?

i think this is the same. the conveyor action has little to no effect on the air passing over the wings, even though the plane would not appear to be moving at all.


Not to sound elitest, but that's funny. Reread what you wrote, and tell me if it still makes sense...

Max
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rastapete
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PostPosted: Mon Jun 19, 2006 1:44 pm    Post subject: Reply with quote

MaxPower wrote:

Not to sound elitest, but that's funny. Reread what you wrote, and tell me if it still makes sense...

Max


Max, you don't have to worry.
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MaxPower
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PostPosted: Tue Jun 20, 2006 6:12 am    Post subject: Reply with quote

Thank ya!

Max
Still a rocket scientist... I think.
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