Plane on a treadmill

N

nakedpeanut

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nakedpeanut said:
Hahahaha I honestly can't believe people battle to understand this concept!

Imagine a car (in neutral) attached to a winch on the same treadmill.
The winch, similar to a planes propeller applies a force on the vehicle separate to that of the treadmill on the FREE spinning wheels and moves the vehicle forwards!

In the case of the plane, it will move forward, resulting in moving air over the wings which creates lift..
Crappy drawing:
View attachment 394800
Click to expand...

nakedpeanut said:
Dude..

FREE SPINNING WHEELS!!!
The wheels will speed up proportionally and thus match the delta of the planes velocity and that of the treadmill!!

Stationary
Plane = 0 m/s
Treadmill = -50m/s
----------------------
Wheels = 50m/s

Plane moving
Plane = 50m/s
Treadmill = -50m/s
----------------------
Wheels = 100m/s


(using negative to show direction)
Click to expand...

I dunno what more people need to understand this..
 
K

Klipdrif

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I understand the concept and I know why we are all missing each other. There are some assumptions being made that qualifies the point that the treadmill does nothing i.e. 0 friction bearings etc. If we take the extremes both parties will win. Heaven built wheel bearings = plane wins. Opel corsa powered propeller + rusted bearings = treadmill wins. . There is way too much varables in this thing to simply say x or y will happen. Okey im out now
 
Sinbad

Sinbad

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Klipdrif said:
I understand the concept and I know why we are all missing each other. There are some assumptions being made that qualifies the point that the treadmill does nothing i.e. 0 friction bearings etc. If we take the extremes both parties will win. Heaven built wheel bearings = plane wins. Opel corsa powered propeller + rusted bearings = treadmill wins. . There is way too much varables in this thing to simply say x or y will happen. Okey im out now
Click to expand...

failure to admit you're wrong = get in the corner.
 
N

nakedpeanut

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You'd only need 0 friction bearings to ensure the plane stays stationary if there is no thrust being produced by the propeller blades.
As soon as there is thrust > the bearing friction you'll have forward movement of the plane.

Klipdrif said:
I understand the concept and I know why we are all missing each other. There are some assumptions being made that qualifies the point that the treadmill does nothing i.e. 0 friction bearings etc. If we take the extremes both parties will win. Heaven built wheel bearings = plane wins. Opel corsa powered propeller + rusted bearings = treadmill wins. . There is way too much varables in this thing to simply say x or y will happen. Okey im out now
Click to expand...
 
Ho3n3r

Ho3n3r

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Klipdrif said:
I understand the concept and I know why we are all missing each other. There are some assumptions being made that qualifies the point that the treadmill does nothing i.e. 0 friction bearings etc. If we take the extremes both parties will win. Heaven built wheel bearings = plane wins. Opel corsa powered propeller + rusted bearings = treadmill wins. . There is way too much varables in this thing to simply say x or y will happen. Okey im out now
Click to expand...

In no world will a plane have a Corsa powered propeller and rusted bearings. That plane would not be allowed to enter any official airspace.
 
O

oober

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Trick is in the theoretical wheel bearings which cancels out a 100% of the treadmill's backwards force yes.

They will just spin x times faster to compensate for the backwards motion. In the real world where there is some friction in the wheel bearings the plain will start to move backwards after a time if the engines are not creating a forward force.

Only a forward moving plain will take off.

If there was a lot of friction in the wheel bearings being translated to the plain itself then it would need to cancel out that force first to move forward before taking off.
 
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Klipdrif

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Ho3n3r said:
In no world will a plane have a Corsa powered propeller and rusted bearings. That plane would not be allowed to enter any official airspace.
Click to expand...
Hence the word extremes. We are deciding an outcome without calcs. Wheel bearing friction force vs thrust.

Please dont discount the effects of friction. I believe this theoretical treadmill will quickly speed-up those wheels red hot.

I am simply saying nobody is really wrong i.e. I agree that it is very plausible to get a plane moving forward using earth as the reference on a treadmill that matches wheelspeed. Its relative motion. BUT in the realworld i would route for the treadmill to win the force fight. I think the wheels will spin up to some unusual speed, bearing would sieze and some catastrophe will insue.
 
bwana

bwana

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Klipdrif said:
Hence the word extremes. We are deciding an outcome without calcs. Wheel bearing friction force vs thrust.

Please dont discount the effects of friction. I believe this theoretical treadmill will quickly speed-up those wheels red hot.

I am simply saying nobody is really wrong i.e. I agree that it is very plausible to get a plane moving forward using earth as the reference on a treadmill that matches wheelspeed. Its relative motion. BUT in the realworld i would route for the treadmill to win the force fight. I think the wheels will spin up to some unusual speed, bearing would sieze and some catastrophe will insue.
Click to expand...
If you're allowed to have a theoretical treadmill that can do this we're allowed theoretical wheels and bearings that can cope. :p
 
Sinbad

Sinbad

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Klipdrif said:
Hence the word extremes. We are deciding an outcome without calcs. Wheel bearing friction force vs thrust.

Please dont discount the effects of friction. I believe this theoretical treadmill will quickly speed-up those wheels red hot.

I am simply saying nobody is really wrong i.e. I agree that it is very plausible to get a plane moving forward using earth as the reference on a treadmill that matches wheelspeed. Its relative motion. BUT in the realworld i would route for the treadmill to win the force fight. I think the wheels will spin up to some unusual speed, bearing would sieze and some catastrophe will insue.
Click to expand...

Lol so you think wheel bearings that can handle takeoff speed won't handle double take off speed?
 
Ho3n3r

Ho3n3r

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Klipdrif said:
Hence the word extremes. We are deciding an outcome without calcs. Wheel bearing friction force vs thrust.

Please dont discount the effects of friction. I believe this theoretical treadmill will quickly speed-up those wheels red hot.

I am simply saying nobody is really wrong i.e. I agree that it is very plausible to get a plane moving forward using earth as the reference on a treadmill that matches wheelspeed. Its relative motion. BUT in the realworld i would route for the treadmill to win the force fight. I think the wheels will spin up to some unusual speed, bearing would sieze and some catastrophe will insue.
Click to expand...

I think you're discounting the effects of a plane's thrust a bit tbh...
 
supersunbird

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If there is no air moving over the wings it wont take off.

Even if it has the biggest rocket engine, if the treadmill belt moves at the same speed as the planes wheels but in the opposite direction, the plane will just roll along.
 
bwana

bwana

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supersunbird said:
If there is no air moving over the wings it wont take off.

Even if it has the biggest rocket engine, if the treadmill belt moves at the same speed as the planes wheels but in the opposite direction, the plane will just roll along.
Click to expand...

:wtf: Seriously? After all this?
 
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