Plane on a Treadmill

[cmoneyr]

So the plane can take off now if it is not moving at all simply because it has free rotating wheels? What you all are not understanding is that THE PLANE CANNOT MOVE FASTER THAN THE TREADMILL! Talk about pushing it all you want, etc etc, but if you push the plane/thrust/whatever, the treadmill MUST also increase in speed, the plane is NOT moving, there is no wind whatsoever to create lift. I really don't know how I can be any more clear.

htown, i'm beginning to think you're a lost cause because you obviously don't understand how a plane works, among other things. YES, as the plane increases speed so does the treadmill, BUT, the only thing that changes is the speed of rotation of the wheels. Do you understand that.

Can you understand, please tell me, that on a treadmill, a plane going 10 mph may have wheels rotating at 20mph? Does that even make sense to you?

 

[twittkop]

It WOULD be moving if the car was going 10mph and the treadmill was going 5mph. but the myth is about these 2 moving the SAME SPEED.

The car would be moving 5mph with respect to the stationary ground and the treadmill would be moving 5mph in the opposite direction. This is exactly what the myth is about.

 

[jdoggivjc]

Forgive me my ignorance, but wouldn't it be true to say that the force of gravity will be acting on the plane regardless of thrust. I know that those who believe that the thrust of the plane would overcome the speed of the treadmill, allowing the plane to gain lift and therefore take off. But if gravity continues to act on the plane, and the treadmill can match the speed of the wheels, then there is no lift. Maybe I am misunderstanding the arguments for lift off, but I think that they are forgetting about the force of gravity that keeps the wheels on the ground (thrust is trying to move the plane forward, not up, the movement of the air over the wings provides lift).

Oh, Well.

The only way the treadmill can match the speed of the wheels is if there is absolutely no thrust acting on the plane. If the treadmill is moving, and there is no thrust on the plane, the wheels will freely rotate at the exact same speed as the treadmill and the plane will move nowhere. The moment you apply any thrust to the plane is the moment the plane starts moving, and then the wheels start rotating faster than the treadmill at a speed of the opposite speed that the treadmill is moving plus the speed that the plane is moving.

 

[htownclone]

Can you understand, please tell me, that on a treadmill, a plane going 10 mph may have wheels rotating at 20mph? Does that even make sense to you?

absolutely it makes sense. do you understand that no matter how fast the wheels are turning and how fast the plane is traveling that the treadmill is always going the same speed as the plane?

 

[Clonefan94]

The treadmill is irrelevant. It has nothing to do with the speed of the airplane. Air pressure is what determines the speed of the plane. The wheels would just do more RPMs than what would normally be seen with a relative stationary earth.

 

[htownclone]

Tthe wheels will freely rotate at the exact same speed as the treadmill and the plane will move nowhere. The moment you apply any thrust to the plane is the moment the plane starts moving, and then the wheels start rotating faster than the treadmill at a speed of the opposite speed that the treadmill is moving plus the speed that the plane is moving.

This is wrong, the myth says that the PLANE...not the wheels...is moving at the same speed of the treadmill. Just forget about the wheels, the plane is not advancing on the treadmill because it cannot go faster.

 

[DaddyMac]

The only way the treadmill can match the speed of the wheels is if there is absolutely no thrust acting on the plane. If the treadmill is moving, and there is no thrust on the plane, the wheels will freely rotate at the exact same speed as the treadmill and the plane will move nowhere. The moment you apply any thrust to the plane is the moment the plane starts moving, and then the wheels start rotating faster than the treadmill at a speed of the opposite speed that the treadmill is moving plus the speed that the plane is moving.

Want to try that one again?

 

[jdoggivjc]

htown - do you understand this concept -

When you are standing in a plane that is flying at 100 mph, and you walk down the aisle at 5 mph, how fast are you moving - 5 mph or 105 mph?

 

[mjlane]

The treadmill is irrelevant. It has nothing to do with the speed of the airplane. Air pressure is what determines the speed of the plane. The wheels would just do more RPMs than what would normally be seen with a relative stationary earth.

Exactly. This is the point that htown is hung up on, that the treadmill and plane are going the same speed. True, they most definitely will be, but it really doesn't matter. If the treadmill was going 1/2 the speed of the plane or 2x the speed of the plane, it's all irrelevant.

 

[twittkop]

absolutely it makes sense. do you understand that no matter how fast the wheels are turning and how fast the plane is traveling that the treadmill is always going the same speed as the plane?

Exactly. The plane will be going x mph and the treadmill will be going x mph in the opposite direction, so the wheels will be going 2x mph.

 

[jbhtexas]

absolutely it makes sense. do you understand that no matter how fast the wheels are turning and how fast the plane is traveling that the treadmill is always going the same speed as the plane?

The treadmill or conveyor or whatever it is, is stationary. The treadmill or conveyor belt is what is moving.

 

[cmoneyr]

absolutely it makes sense. do you understand that no matter how fast the wheels are turning and how fast the plane is traveling that the treadmill is always going the same speed as the plane?

Yes, now we agree apparently, but I think your still not seeing what that will accomplish.

The plane moves 50mph forward, the treadmill goes 50mph backwards, the wheels spin at 100mph. Net movement is the plane moving 50mph forwards.

 

[htownclone]

htown - do you understand this concept -

When you are standing in a plane that is flying at 100 mph, and you walk down the aisle at 5 mph, how fast are you moving - 5 mph or 105 mph?

It depends on the reference point once again. To a reference point that is stationary on the ground it would be 105mph, to a reference point on the plane moving 100mph it would be 5mph.

 

[jdoggivjc]

Want to try that one again?

What do you mean? That's exactly how it works. Take whichever model that's been listed here - the rollerblade on the treadmill, the shopping cart on the treadmill, the toy truck on the treadmill, the die cast car on the sheet of paper.

 

[htownclone]

What do you mean? That's exactly how it works. Take whichever model that's been listed here - the rollerblade on the treadmill, the shopping cart on the treadmill, the toy truck on the treadmill, the die cast car on the sheet of paper.

THEY ABSOLUTELY WOULD MOVE. Unless they are someone attached to something stationary off of the belt, they will move off the back of the treadmill.

 

[DaddyMac]

What do you mean? That's exactly how it works. Take whichever model that's been listed here - the rollerblade on the treadmill, the shopping cart on the treadmill, the toy truck on the treadmill, the die cast car on the sheet of paper.

Some thrust needs to be present to keep the plane stationary.

If you park a plane on this enormously large treadmill (no thrust), and being movement of the treadmill, the plane WILL move.

With any of those examples you listed - a force of you holding the rollerblade in place, you holding the rope, is being exerted.

Just setting a rollerblade on a moving treadmill and letting it go will not mean the rollerblade will remain stationary.

 

[jdoggivjc]

It depends on the reference point once again. To a reference point that is stationary on the ground it would be 105mph, to a reference point on the plane moving 100mph it would be 5mph.

Then why is it so hard for you to understand that a plane that is moving at +50 mph on a treadmill that is moving -50 mph will still move forward at +50 mph, but the wheels will rotate at +100 mph to compensate for the fact that the plane is going to move forward at +50 mph?

 

[htownclone]

Yes, now we agree apparently, but I think your still not seeing what that will accomplish.

The plane moves 50mph forward, the treadmill goes 50mph backwards, the wheels spin at 100mph. Net movement is the plane moving 50mph forwards.

But there is no air pressure whatsoever on the wings, which is what causes lift.

 

[jdoggivjc]

Some thrust needs to be present to keep the plane stationary.

If you park a plane on this enormously large treadmill (no thrust), and being movement of the treadmill, the plane WILL move.

If you consider gravity thrust, then yes, thrust is acting on the plane.

 

[htownclone]

If you consider gravity thrust, then yes, thrust is acting on the plane.

gravity would keep that plane on the belt, and as the belt moves backwards, it would move off the treadmill.