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View Poll Results: Will it Fly?
Yes 184 45.54%
No 220 54.46%
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Nov 28, 2005, 09:25 AM
Registered User
Poll

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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Nov 28, 2005, 09:37 AM
INDORUS EXPARAMINTO
SPEED-E-FLYER's Avatar
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
Nov 28, 2005, 09:41 AM
Frequent Flyer
wattsup_kz's Avatar
The thrust will result in the same airspeed as without the conveyor, so it can take off.
Last edited by wattsup_kz; Nov 28, 2005 at 09:48 AM. Reason: changed my answer
Nov 28, 2005, 09:41 AM
Registered User
yes
Nov 28, 2005, 09:50 AM
I love HAM
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?
Nov 28, 2005, 09:51 AM
Sam Talley
Ranger13's Avatar
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.
Nov 28, 2005, 09:53 AM
Flap chap
snakeX2's Avatar
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
Nov 28, 2005, 09:59 AM
Registered User
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
Nov 28, 2005, 10:02 AM
Flap chap
snakeX2's Avatar
Haha, bet those who put 'NO' feel silly now .

James,
Nov 28, 2005, 10:05 AM
Registered User
thermal's Avatar
As the wheels supply no thrust the plane will take off whether the conveyor moves or not.
Nov 28, 2005, 10:10 AM
Modeller Dilettante
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.
Nov 28, 2005, 10:10 AM
Closed Account
If you started with the brakes of the plane on would the conveyor belt still move ?.
Nov 28, 2005, 10:13 AM
Yep I got another one.
mohillbilly's Avatar
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"
Nov 28, 2005, 10:21 AM
Registered User
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.
Nov 28, 2005, 10:22 AM
Closed Account
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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