That plane, and it taking off.

[PurdueRy]

Originally posted by: DLeRium

Originally posted by: NanoStuff

Originally posted by: JujuFish

Originally posted by: NanoStuff
Ok well... did you consider that if the wheels start spinning faster, the belt also starts moving back faster?

This would place a torque on the wheels, spinning them even faster.

It wouldn't because the belt is moving in direct proportion to the wheels of the plane. So the belt only accelerates if the wheels rotate faster, and the wheels will rotate faster if thrust is applied to the plane. 'Torque' would only be applied to the wheels by the belt if the belt attempted to rotate faster than the wheels.

This is shown by the fact that the plane has to apply thrust in order for the belt to move. If the plane sits still, so does the belt, as such it does not attempt to accelerate the wheels itself, only compensate.

Originally posted by: DLeRium
You do realize that the conveyor belt provides 0 force if you assume the bearings are close to frictionless...

No I don't because it's not true.

How is that not true. When you use rollers in statics classes, you assume only upward forces only. No horizontal forces. Frictionless bearings = 0 force by the conveyor belt. The only force on the wheels results in pure rotation and 0 translational force. Thus your energy by the conveyor belt is stored only in rotational energy and none of it goes into KE = 1/2mv^2.

^ absolutely correct. Lets see if someone wants to point out your "obvious" flaws in physics without backing it up with anything :roll:

 

[NanoStuff]

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: JujuFish

Originally posted by: NanoStuff

Originally posted by: JujuFish

Originally posted by: NanoStuff
Ok well... did you consider that if the wheels start spinning faster, the belt also starts moving back faster?

This would place a torque on the wheels, spinning them even faster.

It wouldn't because the belt is moving in direct proportion to the wheels of the plane. So the belt only accelerates if the wheels rotate faster, and the wheels will rotate faster if thrust is applied to the plane. 'Torque' would only be applied to the wheels by the belt if the belt attempted to rotate faster than the wheels.

No, once thrust is applied, the plane will move forward. The conveyor will attempt to move faster in order to match the wheels, and in doing so, will apply a torque to those wheels.

Even if we assume that it does infact apply torque, the plane still won't take off if the belt always matches the rotation of the wheels. Regardless of what forces are in play, if the wheel does not rotate faster than the belt, the wheel does not advance forward.

The wheels DOES rotate faster than the belt...double it in face. YOU interpreted the question incorrectly when you decided to make the post. If you look at this question around the internet it CLEARLY says the speed of the plane itself. Not the rotation speed of the plane. As if this was not true, as has been mentioned, you would introduce a situation that is unstable.

so....plane starts moving when engines turn on...lets say 1 MPH....treadmill moves 1 MPH backwards...wheels rotate at 2 MPH...plane takes off.

I didn't interpret the question incorrectly, I'm well aware of the question you're referring to. What I failed in however was wording the question unclearly, this is why there are now two interpretations to the question, one in which the plane takes off (as you describe), and the other where it does not; in which case the belt is moving in reverse twice as fast as in the original question.

 

[PurdueRy]

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: JujuFish

Originally posted by: NanoStuff

Originally posted by: JujuFish

Originally posted by: NanoStuff
Ok well... did you consider that if the wheels start spinning faster, the belt also starts moving back faster?

This would place a torque on the wheels, spinning them even faster.

It wouldn't because the belt is moving in direct proportion to the wheels of the plane. So the belt only accelerates if the wheels rotate faster, and the wheels will rotate faster if thrust is applied to the plane. 'Torque' would only be applied to the wheels by the belt if the belt attempted to rotate faster than the wheels.

No, once thrust is applied, the plane will move forward. The conveyor will attempt to move faster in order to match the wheels, and in doing so, will apply a torque to those wheels.

Even if we assume that it does infact apply torque, the plane still won't take off if the belt always matches the rotation of the wheels. Regardless of what forces are in play, if the wheel does not rotate faster than the belt, the wheel does not advance forward.

The wheels DOES rotate faster than the belt...double it in face. YOU interpreted the question incorrectly when you decided to make the post. If you look at this question around the internet it CLEARLY says the speed of the plane itself. Not the rotation speed of the plane. As if this was not true, as has been mentioned, you would introduce a situation that is unstable.

so....plane starts moving when engines turn on...lets say 1 MPH....treadmill moves 1 MPH backwards...wheels rotate at 2 MPH...plane takes off.

I didn't interpret the question incorrectly, I'm well aware of the question you're referring to. What I failed in however was wording the question unclearly, this is why there are now two interpretations to the question, one in which the plane takes off (as you describe), and the other where it does not; in which case the belt is moving in reverse twice as fast as in the original question.

Look on the internet. The only person who wrote the question that way is YOU. All over the internet it clearly says "Matches spped of plane". If you are so troubled by the confusion, the only person you have to blame is yourself. You agree the plane WILL takeoff in the case that is POSSIBLE and can be tested...therefore the answer is YES

Not to mention: in your original post you said the SPEED THE WHEELS MORE FORWARD. This quite clearly means linear speed since you specified a direction. The only confusion came from when you added your own opinion in a follow up post.

 

[NanoStuff]

Originally posted by: DLeRium

Originally posted by: NanoStuff

Originally posted by: JujuFish

Originally posted by: NanoStuff
Ok well... did you consider that if the wheels start spinning faster, the belt also starts moving back faster?

This would place a torque on the wheels, spinning them even faster.

It wouldn't because the belt is moving in direct proportion to the wheels of the plane. So the belt only accelerates if the wheels rotate faster, and the wheels will rotate faster if thrust is applied to the plane. 'Torque' would only be applied to the wheels by the belt if the belt attempted to rotate faster than the wheels.

This is shown by the fact that the plane has to apply thrust in order for the belt to move. If the plane sits still, so does the belt, as such it does not attempt to accelerate the wheels itself, only compensate.

Originally posted by: DLeRium
You do realize that the conveyor belt provides 0 force if you assume the bearings are close to frictionless...

No I don't because it's not true.

How is that not true.

Because 'close to frictionless' is not frictionless as one example. I'm sure that will make sense to you if you think about it for a moment.

 

[ThePresence]

I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

 

[PurdueRy]

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

 

[NanoStuff]

Originally posted by: PurdueRy
Look on the internet. The only person who wrote the question that way is YOU..

http://discuss.futuremark.com/forum/sho...Number=5975420&page=&view=&sb=&o=&vc=1
http://www.straightdope.com/columns/060203.html

However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation."

THINK before you post, I beg of you. K, thx 🙂

 

[NanoStuff]

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

It wouldn't take up less room. The effective take off distance would be the same, it would just require more power to take off.

On the other hand if you reverse the scenario and have the belt accelerate the plane FORWARD, now you have a conveyor belt that does some good.

 

[PurdueRy]

Originally posted by: NanoStuff

Originally posted by: PurdueRy
Look on the internet. The only person who wrote the question that way is YOU..

http://discuss.futuremark.com/forum/sho...Number=5975420&page=&view=&sb=&o=&vc=1
http://www.straightdope.com/columns/060203.html

However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation."

THINK before you post, I beg of you. K, thx 🙂

"This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

The original question in the second link puts the question this way. So you found one example where someone specified speed of the wheels...which isn't necessarily rotational speed. It depends where you are measuring from. Speed of the wheels measured from the center? Then all is fine and the situation is possible.

Stop being such a immature person and realize that the question is posted all around the internet as the SPEED of the PLANE as this is the situation that is possible and move on.

 

[AlienCraft]

Originally posted by: D1gger

Originally posted by: LoKe

Originally posted by: msparish

Originally posted by: LoKe
Then can someone explain this to me real quick? I don't feel like digging in the other thread :

If the plane and conveyor are moving at the exact same speed, meaning, the plane isn't moving, is air still being moved?

The plane still moves, despite the conveyor belt. A plane doesn't get its thrust through the wheels. The wheels will just be rotating at twice their normal speed.

But I mean, if the planes wheels were matching the speed of the conveyor belt, it's practically the same as the plane being completely stationary on a cement floor. It's not actually moving, and no additional wind is being pushed under the wings.

You are working under the assumption that the wheels are what drive the plane forward, but that is simply not the case. The props or jet engine create the thrust that move the plane forward, regardless of the speed the wheels are spinning. Under your thinking, the minute a plane left the runway, and the wheels stopped spinning (which they do) the plane would fall out of the sky. Since planes do not generally fall out of the sky, it must be that the thrust comes from the engines working in the air, not the engines thrusting against the earth or the wheels providing force.

You're ignoring the effect of gravity at the inital stages of establishing thrust. Gravity is pushing down on the plane even as the wheels turn. Only when the thrust forward exceeds the friction holding it down it does it roll forward, ONLY then air is flowing over the wing.

A jet does not cause a plane to fly by sucking air across the wing. It does it by PUSHING it through the air. That push forward must greater than the force of gravity.
Since the mythical conveyor belt is able to accelerate infinitely, the plane is not rolling therefore there is ZERO airflow across the wing. No forward motion =No airflow otw. No airflow otw = no lift. No lift = no flight.

Forward motion is what gets air flowing over the wings. If that conveyor belt then starts turning in the reverse direction, gravity re-asserts as the predominate force and airflow ceases.

This is why cars (Formula1 and NASCAR) have ground effect aerodynamics calculated in so as to keep the wheels on the track. YES, once the wheels leave the ground, the lift is reduced and they come back down, but thatwsould have an oscillation adverse effect on performance.

 

[PurdueRy]

Originally posted by: AlienCraft

Originally posted by: D1gger

Originally posted by: LoKe

Originally posted by: msparish

Originally posted by: LoKe
Then can someone explain this to me real quick? I don't feel like digging in the other thread :

If the plane and conveyor are moving at the exact same speed, meaning, the plane isn't moving, is air still being moved?

The plane still moves, despite the conveyor belt. A plane doesn't get its thrust through the wheels. The wheels will just be rotating at twice their normal speed.

But I mean, if the planes wheels were matching the speed of the conveyor belt, it's practically the same as the plane being completely stationary on a cement floor. It's not actually moving, and no additional wind is being pushed under the wings.

You are working under the assumption that the wheels are what drive the plane forward, but that is simply not the case. The props or jet engine create the thrust that move the plane forward, regardless of the speed the wheels are spinning. Under your thinking, the minute a plane left the runway, and the wheels stopped spinning (which they do) the plane would fall out of the sky. Since planes do not generally fall out of the sky, it must be that the thrust comes from the engines working in the air, not the engines thrusting against the earth or the wheels providing force.

You're ignoring the effect of gravity at the inital stages of establishing thrust. Gravity is pushing down on the plane even as the wheels turn. Only when the thrust forward exceeds the friction holding it down it does it roll forward, ONLY then air is flowing over the wing.

A jet does not cause a plane to fly by sucking air across the wing. It does it by PUSHING it through the air. That push forward must greater than the force of gravity.
Since the mythical conveyor belt is able to accelerate infinitely, the plane is not rolling therefore there is ZERO airflow across the wing. No forward motion =No airflow otw. No airflow otw = no lift. No lift = no flight.

Forward motion is what gets air flowing over the wings. If that conveyor belt then starts turning in the reverse direction, gravity re-asserts as the predominate force and airflow ceases.

This is why cars (Formula1 and NASCAR) have ground effect aerodynamics calculated in so as to keep the wheels on the track. YES, once the wheels leave the ground, the lift is reduced and they come back down, but thatwsould have an oscillation adverse effect on performance.

The conveyor belt does not accelerate to infinity. We already disregarded this case as this is not the way it is predominantly posted accross the internet. It matches the speed of the PLANE. Not the rotational speed of the wheels.

 

[NanoStuff]

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: PurdueRy
Look on the internet. The only person who wrote the question that way is YOU..

http://discuss.futuremark.com/forum/sho...Number=5975420&page=&view=&sb=&o=&vc=1
http://www.straightdope.com/columns/060203.html

However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation."

THINK before you post, I beg of you. K, thx 🙂

"This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

The original question in the second link puts the question this way. So you found one example where someone specified speed of the wheels...which isn't necessarily rotational speed. It depends where you are measuring from. Speed of the wheels measured from the center? Then all is fine and the situation is possible.

Stop being such a immature person and realize that the question is posted all around the internet as the SPEED of the PLANE as this is the situation that is possible and move on.

Relax your ego there for a moment and realize that I'm not the first person to bring up the alternate scenario. I wish I was, but it has been discussed before.

Furthermore, I don't give a ballsack as how to how it was posted 'all around the internet'. I posted a question that you yourself agree makes sense, so there's no reason for this.

 

[PurdueRy]

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: PurdueRy
Look on the internet. The only person who wrote the question that way is YOU..

http://discuss.futuremark.com/forum/sho...Number=5975420&page=&view=&sb=&o=&vc=1
http://www.straightdope.com/columns/060203.html

However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation."

THINK before you post, I beg of you. K, thx 🙂

"This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

The original question in the second link puts the question this way. So you found one example where someone specified speed of the wheels...which isn't necessarily rotational speed. It depends where you are measuring from. Speed of the wheels measured from the center? Then all is fine and the situation is possible.

Stop being such a immature person and realize that the question is posted all around the internet as the SPEED of the PLANE as this is the situation that is possible and move on.

Relax your ego there for a moment and realize that I'm not the first person to bring up the alternate scenario. I wish I was, but it has been discussed before.

Furthermore, I don't give a ballsack as how to how it was posted 'all around the internet'. I posted a question that you yourself agree makes sense, so there's no reason for this.

See post in other thread

We are all cool, lets just discuss the OP where it was all about linear speed. :thumbsup:

 

[AlienCraft]

Originally posted by: newmachineoverlord

Once the pilot fires up the engines, the plane moves forward at pretty much the usual speed relative to the ground--and more importantly the air--regardless of how fast the conveyor belt is moving backward. This generates lift on the wings, and the plane takes off. All the conveyor belt does is, as you correctly conclude, make the plane's wheels spin madly.

The obvious flaw here is that the above is basically assuming that the plane is not resting on the conveyor. Imagine the planes engines are off. In this case, the conveyor pushes the plane backwards until it falls off the conveyor. Turning the engines on just allows the plane to keep pace with the conveyor, meaning that the plane is completely stationary relative to the ground and the air, but has a forward velocity relative to the belt.

Thus it depends how the problem is phrased. If the conveyor is moving at a rate that keeps the plane stationary relative to the wind, there will be no lift, and hence, no takeoff. A plane must have forward motion relative to the air in order to take off. If it is only moving relative to the conveyor belt, and not the wind, as the problem implies, there is no lift and it cannot takeoff.

I should point out some caveats with this interpretation: It assumes that the engine does not directly force air over the wings. This assumption is probably valid for most jet engines, but probably not for propeller based light aircraft. In the case of such light aircraft where the propellor not only generates thrust but also forces air to pass over the wings, a completely vertical takeoff is possible.

edited typo

This is the correct interpretation of airflight.
Jets DO NOT SUCK, they PUSH. You must overcome the effect of gravity as rolling resistance to cause air to flow over the wings.
A Propellor PULLS it's way through the air. It asserts it force and will cause the plane to "float" even if tethered down. This is the only way the problem would be "true". Since the OP specified a JET, the answer is NO.

 

[NanoStuff]

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: PurdueRy
Look on the internet. The only person who wrote the question that way is YOU..

http://discuss.futuremark.com/forum/sho...Number=5975420&page=&view=&sb=&o=&vc=1
http://www.straightdope.com/columns/060203.html

However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation."

THINK before you post, I beg of you. K, thx 🙂

"This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

The original question in the second link puts the question this way. So you found one example where someone specified speed of the wheels...which isn't necessarily rotational speed. It depends where you are measuring from. Speed of the wheels measured from the center? Then all is fine and the situation is possible.

Stop being such a immature person and realize that the question is posted all around the internet as the SPEED of the PLANE as this is the situation that is possible and move on.

Relax your ego there for a moment and realize that I'm not the first person to bring up the alternate scenario. I wish I was, but it has been discussed before.

Furthermore, I don't give a ballsack as how to how it was posted 'all around the internet'. I posted a question that you yourself agree makes sense, so there's no reason for this.

See post in other thread

We are all cool, lets just discuss the OP where it was all about linear speed. :thumbsup:

Well ok then 🙂. But the OP has already been discussed to death. The plane takes off, everyone lived happily ever after, nothing new there.

The curious piece of the puzzle now is what happens if the belt moves at twice the speed it would in the original scenario. My argument here is that the plane will not advance forward, and as such I believe the plane will take off in the original scenario but with much greater difficulty.

 

[PurdueRy]

Originally posted by: NanoStuff

Well ok then 🙂. But the OP has already been discussed to death. The plane takes off, everyone lived happily ever after, nothing new there.

The curious piece of the puzzle now is what happens if the belt moves at twice the speed it would in the original scenario. My argument here is that the plane will not advance forward, and as such I believe the plane will take off in the original scenario but with much greater difficulty.

While I agree that is an interesting question there is a problem with introducing that. Once you do that, the minor details that could be ignored in the first problem can no longer be ignored. Questions come up such as has been raised by Mugs. What is the delay in the electronics/mechanics of the treadmill system...is it a second?...two?...this is very important.

I think with that stipulation thrown in...the entire scenario comes down to semantics that would have to be stipulated. Since we don't have those...I think the OP will have to do 😉

 

[Fox5]

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed. It will take longer to take off, but it will still take off, but it seems like a very pointless what-if question.

There are only 3 possibilities for a plane (or anything) on a treadmill.
1. It moves foward, thus eventually taking off.
2. It stays in place, doing nothing.
3. It goes backwards.
And if the treadmill isn't powered, it can't go backward, and only maybe in an extreme theoretical case would it stay in place, so the plane would take off eventually.

 

[ta8689]

Really, its like this. All the belt does is add a little friction. Think of it as taking off on a grass runway as opposed to a paved runway. it still works. Im not going to read this anymore because im tired of getting mad at the idiots who are telling everyone it wont move

 

[NanoStuff]

Originally posted by: Fox5

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed.

The point of the question is to examine how many people believe it will not take off. 🙂

And yes... there are a lot of those people.

 

[PurdueRy]

Originally posted by: Fox5

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed. It will take longer to take off, but it will still take off, but it seems like a very pointless what-if question.

There are only 3 possibilities for a plane (or anything) on a treadmill.
1. It moves foward, thus eventually taking off.
2. It stays in place, doing nothing.
3. It goes backwards.
And if the treadmill isn't powered, it can't go backward, and only maybe in an extreme theoretical case would it stay in place, so the plane would take off eventually.

because if you had the same situation with a car...it would stay in place. Thats the whole point of the question. A car on a treadmill traveling 1 MPH forward...treadmill going 1 MPH backwards...wheels going 2 MPH rotationally...would stay in the same place.

 

[NanoStuff]

Originally posted by: ta8689
Really, its like this. All the belt does is add a little friction. Think of it as taking off on a grass runway as opposed to a paved runway. it still works. Im not going to read this anymore because im tired of getting mad at the idiots who are telling everyone it wont move

How much friction the belt adds depends on how fast it's moving. How fast it's moving depends on how fast the plane is moving. The conclusion is that the plane will take off, but the friction is not all that insignificant.

 

[NanoStuff]

Originally posted by: PurdueRy

Originally posted by: Fox5

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed. It will take longer to take off, but it will still take off, but it seems like a very pointless what-if question.

There are only 3 possibilities for a plane (or anything) on a treadmill.
1. It moves foward, thus eventually taking off.
2. It stays in place, doing nothing.
3. It goes backwards.
And if the treadmill isn't powered, it can't go backward, and only maybe in an extreme theoretical case would it stay in place, so the plane would take off eventually.

because if you had the same situation with a car...it would stay in place. Thats the whole point of the question. A car on a treadmill traveling 1 MPH forward...treadmill going 1 MPH backwards...wheels going 2 MPH rotationally...would stay in the same place.

Here, like I said before, I believe a car would react the same way 🙂.

Reason being is that the belt only 'tracks' the forward movement, regardless of what propels the object forward. A plane moving forward at 50k would have the same angular velocity on the wheels as a car moving at that same speed.

 

[PurdueRy]

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: Fox5

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed. It will take longer to take off, but it will still take off, but it seems like a very pointless what-if question.

There are only 3 possibilities for a plane (or anything) on a treadmill.
1. It moves foward, thus eventually taking off.
2. It stays in place, doing nothing.
3. It goes backwards.
And if the treadmill isn't powered, it can't go backward, and only maybe in an extreme theoretical case would it stay in place, so the plane would take off eventually.

because if you had the same situation with a car...it would stay in place. Thats the whole point of the question. A car on a treadmill traveling 1 MPH forward...treadmill going 1 MPH backwards...wheels going 2 MPH rotationally...would stay in the same place.

Here, like I said before, I believe a car would react the same way 🙂.

Reason being is that the belt only 'tracks' the forward movement, regardless of what propels the object forward. A plane moving forward at 50k would have the same angular velocity on the wheels as a car moving at that same speed.

The difference is the treadmill can pull the car backwards...unlike the aircraft(neglecting serious amounts of friction). So a car in this case, again going back to the FBD, has a force applied to the wheels that directly affect the car since they are in the same "system". This force cancels with the engines speed forwards causing the car to stay in place.

 

[NanoStuff]

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: Fox5

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed. It will take longer to take off, but it will still take off, but it seems like a very pointless what-if question.

There are only 3 possibilities for a plane (or anything) on a treadmill.
1. It moves foward, thus eventually taking off.
2. It stays in place, doing nothing.
3. It goes backwards.
And if the treadmill isn't powered, it can't go backward, and only maybe in an extreme theoretical case would it stay in place, so the plane would take off eventually.

because if you had the same situation with a car...it would stay in place. Thats the whole point of the question. A car on a treadmill traveling 1 MPH forward...treadmill going 1 MPH backwards...wheels going 2 MPH rotationally...would stay in the same place.

Here, like I said before, I believe a car would react the same way 🙂.

Reason being is that the belt only 'tracks' the forward movement, regardless of what propels the object forward. A plane moving forward at 50k would have the same angular velocity on the wheels as a car moving at that same speed.

The difference is the treadmill can pull the car backwards...unlike the aircraft(neglecting serious amounts of friction). So a car in this case, again going back to the FBD, has a force applied to the wheels that directly affect the car since they are in the same "system". This force cancels with the engines speed forwards causing the car to stay in place.

Well... again, if the wheel is rotating at TWICE the speed of the conveyor belt, would whatever is attached to those wheels not move forward?

 

[PurdueRy]

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: NanoStuff

Originally posted by: PurdueRy

Originally posted by: Fox5

Originally posted by: PurdueRy

Originally posted by: ThePresence
I didn't read the whole thread, but if it would take off why wouldn't they use this method on aircraft carriers instead of the catapults? It would take up less room, probably be alot more cost-effecient and be a whole lot less dangerous.

because you don't get it. It would move FORWARD on the treadmill. We are not saying that the plane would accelerate to speed in place and magically takeoff.

What's the point of that question then? If we're assuming that the plane is moving foward on the treadmill, the only effect of that is that its wheel speed will be higher than its actual speed. It will take longer to take off, but it will still take off, but it seems like a very pointless what-if question.

There are only 3 possibilities for a plane (or anything) on a treadmill.
1. It moves foward, thus eventually taking off.
2. It stays in place, doing nothing.
3. It goes backwards.
And if the treadmill isn't powered, it can't go backward, and only maybe in an extreme theoretical case would it stay in place, so the plane would take off eventually.

because if you had the same situation with a car...it would stay in place. Thats the whole point of the question. A car on a treadmill traveling 1 MPH forward...treadmill going 1 MPH backwards...wheels going 2 MPH rotationally...would stay in the same place.

Here, like I said before, I believe a car would react the same way 🙂.

Reason being is that the belt only 'tracks' the forward movement, regardless of what propels the object forward. A plane moving forward at 50k would have the same angular velocity on the wheels as a car moving at that same speed.

The difference is the treadmill can pull the car backwards...unlike the aircraft(neglecting serious amounts of friction). So a car in this case, again going back to the FBD, has a force applied to the wheels that directly affect the car since they are in the same "system". This force cancels with the engines speed forwards causing the car to stay in place.

Well... again, if the wheel is rotating at TWICE the speed of the conveyor belt, would whatever is attached to those wheels not move forward?

can't compare angular speeds to linear. Only the linear speeds matter in this case. The linear speed forward of the car is 1 MPH...the linear speed of the treadmill is 1 MPH...so no its not going anywhere