ChitownRC

Full Version: So a plane is on a conveyer belt......
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the question does say that it keeps up with the speed of the plane, if it doesnt its not much of a myth
The plane absolutely will take off. The plane is being driven by thrust and not by the wheels.

Stand on a treadmill on rollerblades. It takes just as much effort to pull yourself forward no matter how fast the treadmill is moving. (Roughly.... so long as you have good bearings)
FreeRideFrosty Wrote:The plane absolutely will take off. The plane is being driven by thrust and not by the wheels.

Stand on a treadmill on rollerblades. It takes just as much effort to pull yourself forward no matter how fast the treadmill is moving. (Roughly.... so long as you have good bearings)

That was my point. Its not torque through the wheels that moves the plane forwards. If that was the case the plane would never take-off because once the wheels left the ground the plane would slow down and would not stay airborn.
Czech-it-Out Graphics Wrote:the question does say that it keeps up with the speed of the plane, if it doesnt its not much of a myth

Even if the treadmill can hit mach1 speeds it still isn't enough to keep the plane from moving forwards by its own thrust. The planes propulsion system is independent of ground speed.

The friction generated by the wheels on the ground is minimal compared to the wind resistance a plane sees above stall speeds.
I don't think it's going anywhere unless the props push enough air over the wings to generate vertical lift, so long as absolute traction is maintained with the treadmill (whoops conveyor lol).
Ponch Wrote:I don't think it's going anywhere unless the props push enough air over the wings to generate vertical lift, so long as absolute traction is maintained with the treadmill (whoops conveyor lol).

The the issue is that the conveyor can't hold the plane still. The prop does not have to push air over the wings, the prop simply needs to pull the plane forward and the conveyor can't have a big enough effect to stop the plane unless you locked the wheels or applied the brakes.

conveyor belt plane « stereoroid.com Read this article, all valid points. Then watch Mythbusters tonight. Smile
Youtube is the friend. Here is a practicle application showing that despite the speed of the treadmill the little RC plane still has enough power to accelerate.

Note that the little plane probably can't exceed 7mph in level flight.



Though the RC plane couldn't take off because of the guideline it still demonstrates that the plane was capable of accelerating even with the treadmill moving against the plane. Were it not on a guide wire it probably would have lifted off.
you're missing my point though, there is no conveyor that can overcome the acceleation of the plane. The wheels are not applying the thrust to the ground, aiding in the planes advancment in one direction. if the plane does not overcome the speed of the conveyor then it will not take off. If the conveyor keeps the plane at 0 velocity it cannot take off. So unless they have a conveyor that can completely keep up with planes speed then the myth really isnt busted.
Didn't prove anything...Kid was in the way for the important part Rolleyes
doesnt prove anything becuase the plane has a faster ground speed than the treadmill
It can still take off if its a turbine style.
think about this too. So when the plane lands the wheels are stationary, does that mean the plane will stop when it hits the ground?

The plane will take off.
HELLL YEAH ITS ON MYTHBUSTERS FINALLY

and yes, the plane will take off.
Czech.... the conveyor will never under any circumstance hold the plane stationary.
so then there is no myth, if you can't hold it still no matter what speed it is going then it will always be able to take off
It would have no effect. The plane is not dependant on traction from the belt. It will move forward as normal. minus the drag from the wheels spinning.
Guaranteed that the only effect the tread will have on the plane is the actual drag created by the friction.
yeah i would say it would take off... I base this on no facts or even any higher thought process, i just think it would. Dont much care but thats what i think
Quote:Official reply:
"Adam? Jamie? Dan? Someone step up and tell us what happened tonight."

Dear all,

As wbarnhill called out, I thought I should step in to what is rapidly becoming a hornet's nest. I will try to calm things down but I don't hold out much hope!

First up, for those concerned that this story has been cancelled, don't worry, planes on a conveyer belt has been filmed, is spectacular, and will be part of what us Mythbusters refer to as 'episode 97'. Currently that is due to air on January 30th.

Secondly, for those very aggrieved fans feeling "duped" into watching tonight's show, I can only apologise. I'm not sure why the listings / internet advertised that tonight's show contained POCB. I will endeavour to find out an answer but for those conspiracy theorists amongst you, I can assure you that it will have just been an honest mistake. At one point
several months ago, POCB was going to be part of Airplane Hour. Somewhere, someone has mistakenly posted the wrong listing. It will have been a genuine mistake but nonetheless it was a mistake which is unacceptable. As said I will try to find out what went wrong and hope that you will see fit to forgive the team at Discovery.

Thanks in advance,

Dan

Official reply to a fan. Guess we have to wait for Jan 30th to find out their verdict.

Still say the plane will take off. An airplanes thrust has nothing to do with ground speed.
I'm going to change to "will shoot off the runway and crash into the side of the building they're in."
I going to say that the plane will spontaniously explode just prior to lift off and the conveyor belt will double backflip onto Jamie.
and pieces of schrap will slice buster into 3rds!
Czech-it-Out Graphics Wrote:but ideally if the treadmill holds it from advancing its motion in any direction it will not take off. you asked for the answer in an ideal situation Smile


Theoretical situations are tough to understand, but pyshics are pyshics. No lift (airfoil wings) no flight.

If an aircraft does not have sufficient airflow over the wing surface to produce lift, it will not fly. This is demonstrated by small aircraft landing into a strong headwind....small planes can actaully land flying backwards if the windspeed is greater than the minimum flight speed in still air.

Without data to define the "plane", it's impossible to calculate if the plane could fly based on prop wash over the wings...

Good brainteaser.
The episode is finally being aired this Wed. Bout time!
It's on now!
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