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View Poll Results: Will it Fly?
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Old Nov 28, 2005, 09:25 AM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
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Something to think about.....Will it Fly?

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?
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Old Nov 28, 2005, 09:37 AM
INDORUS EXPARAMINTO
SPEED-E-FLYER's Avatar
Springfield, Missouri, United States
Joined Jul 2002
4,202 Posts
What?
Wheels don't make an airplane fly.
Airspeed verses ground speed.
Maybe I don't have a clear picture of what you're talking about.

Larry
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Old Nov 28, 2005, 09:41 AM
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Kalamazoo, MI USA
Joined Aug 2003
2,892 Posts
The thrust will result in the same airspeed as without the conveyor, so it can take off.
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Last edited by wattsup_kz; Nov 28, 2005 at 09:48 AM. Reason: changed my answer
Old Nov 28, 2005, 09:41 AM
Registered User
Joined Aug 2005
19 Posts
yes
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Old Nov 28, 2005, 09:50 AM
I love HAM
Joined Nov 2005
725 Posts
I answered yes. but... If the plane starts to roll forward, the belt will start to move backwards. As a reaction, the wheels will have to turn harder to keep up with the plane, leading to an increased speed of the belt. At takeoff speed (say 120 kts), the speed of the belt will be also 120 kts and the wheels will spin at 240 kts equevalent, which may cause them to fail. Does this sound reasonable?
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Old Nov 28, 2005, 09:51 AM
Sam Talley
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Nashville, TN
Joined May 2003
299 Posts
Yes, it will fly.

Suppose the plane's wheels are replace by powerful magnets with the north-seeking poles of the magnets pointing down. Suppose the conveyor belt is replaced conveyor belt composed of a series of electromagnets (imagine a cobblestone belt of magnets) with the north-seeking poles pointing up. The two sets of magnets will repel each other, levitating the plane. The propeller begins to turn pulling the plane forward and the belt begins to move at the same speed in the opposite direction. The plane's ground speed will increase and the plane will take off.

The only difference is that in the original setting the wheels appear "tied" to the ground. If fact they are not. The wheels will rotate at twice the rate that they would if the conveyor belt was stationary.
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Old Nov 28, 2005, 09:53 AM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
1,934 Posts
The wheels can be concidered somewhat detached from the airframe; i.e. the wheels could be moving freely with the conveyor belt moving in the opposite direction but the plane would still be stationary.
When the plane is in motion, the wheels will move accordingly, probably spinning faster, but the plane should still be able to take off under airspeed as it would normally would. I am probably wrong but some others have put 'yes' too. Reason please. And perhaps a practicle test would be nice. Actually, its not a bad science project, thanks for the idea

James,


Edit- P.S. looks like we all replied at the same time
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Old Nov 28, 2005, 09:59 AM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
Wow this filled up fast.

Many forums are debating this right now. So i threw it on this one.

I believe the answer is yes. So far its been on car forums and others, but i wanted it on a forum with some pilots.

http://www.naplesracing.com/thread.p...tuser=0&page=1

http://forum.physorg.com/index.php?showtopic=2417&st=0

http://community.discovery.com/group...7451937218/p/1

http://videos.streetfire.net/player....D-D6BA1A43A06B
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Old Nov 28, 2005, 10:02 AM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
1,934 Posts
Haha, bet those who put 'NO' feel silly now .

James,
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Old Nov 28, 2005, 10:05 AM
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thermal's Avatar
Maryland's eastern most shoreline
Joined May 2004
566 Posts
As the wheels supply no thrust the plane will take off whether the conveyor moves or not.
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Old Nov 28, 2005, 10:10 AM
Modeller Dilettante
Vancouver
Joined Sep 2005
422 Posts
No, it won't take off.

If the conveyor belt is exactly matching the wheel rotation in the opposite direction, the plane will remain stationary relative to the air around it. Most of the thrust will be transfered to the movement of the conveyor belt through friction with the wheels. Therefore no airspeed at all, no lift.
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Old Nov 28, 2005, 10:10 AM
Registered User
Usta Bee's Avatar
Joined Jul 2004
3,765 Posts
If you started with the brakes of the plane on would the conveyor belt still move ?.
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Old Nov 28, 2005, 10:13 AM
Yep I got another one.
mohillbilly's Avatar
Springfield, Mo.
Joined Jan 2005
2,529 Posts
as far as the magnets go you could actually not have to make it move if the north/south was in the right config. just set the plane balanced on the field then give a push/thrust. It could then accelerate on the "field"
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Old Nov 28, 2005, 10:21 AM
Registered User
Boynton Beach, FL
Joined Jul 2005
402 Posts
Quote:
Originally Posted by Usta Bee
If you started with the brakes of the plane on would the conveyor belt still move ?.
No. The belt only moves when the wheels try to.
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Old Nov 28, 2005, 10:22 AM
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Joined Jul 2004
3,765 Posts
This whole conveyor belt thing reminds me of the Sanger Silverbird/ America bomber (only they were gonna use rockets)....

http://www.luft46.com/misc/sanger.html
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