Comments on: Airplane-Treadmill Problem Solution - Nihilist http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/ Tue, 06 Jan 2009 03:26:49 +0000 http://wordpress.org/?v=2.0.1 by: David http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-268 Wed, 13 Dec 2006 19:42:54 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-268 Hopefully everyone got a look at Cecil Adams take on this at the Straight Dope website. Just for closure. :-) Hopefully everyone got a look at Cecil Adams take on this at the Straight Dope website. Just for closure. :-)

]]> by: curious bystander http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-267 Wed, 13 Dec 2006 03:34:14 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-267 Reduction in wheel friction and frictional losses, sure. These are all important and potential opportunities in modern day flight. How do they apply to a conveyor belt or etc.? Forward air speed over and under the wings of an aircraft provide lift. Not a moving surface below. Am I missing something? If there is no friction between the ground and an aircraft, we still need air moving over and under a wing surface to provide lift. Helicopter for example! Someone please enlighten me here... Reduction in wheel friction and frictional losses, sure. These are all important and potential opportunities in modern day flight. How do they apply to a conveyor belt or etc.? Forward air speed over and under the wings of an aircraft provide lift. Not a moving surface below. Am I missing something? If there is no friction between the ground and an aircraft, we still need air moving over and under a wing surface to provide lift. Helicopter for example!

Someone please enlighten me here…

]]> by: bill http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-266 Tue, 12 Dec 2006 19:56:59 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-266 Gareth, now I'm confused. Let's just say that friction exists everywhere, because it would have to. Therefore the whole thing is kind of dumb, as has been said by a few (you included) before. What's going to happen is that either the treadmill will be able to get to a speed where the backwards force will be equal to the thrust provided by the engines (the plane remains Earth-bound) or the friction of the bearings in the treadmill will cause the treadmill to be unable to keep up with the plane's forward momentum (the plane takes off). Either way, we are (at least in my view) debating the most minute of minutia... Thanks for keeping me on my toes. Jason:  I saw it as a powered treadmill, otherwise it really isn't capable of even really slowing down the plane significantly as it would adjust physical plane displacement more than wheel speed. Gareth, now I’m confused. Let’s just say that friction exists everywhere, because it would have to. Therefore the whole thing is kind of dumb, as has been said by a few (you included) before. What’s going to happen is that either the treadmill will be able to get to a speed where the backwards force will be equal to the thrust provided by the engines (the plane remains Earth-bound) or the friction of the bearings in the treadmill will cause the treadmill to be unable to keep up with the plane’s forward momentum (the plane takes off).

Either way, we are (at least in my view) debating the most minute of minutia… Thanks for keeping me on my toes.

Jason:  I saw it as a powered treadmill, otherwise it really isn’t capable of even really slowing down the plane significantly as it would adjust physical plane displacement more than wheel speed.

]]> by: Jason S. B. http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-265 Tue, 12 Dec 2006 19:54:50 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-265 Bill, please state the experiment as you understand it. Is it a free turning conveyor belt, or is it a powered treadmill that runs in the reverse direction of the direction the plane would travel to take off under normal circumstances? Bill, please state the experiment as you understand it. Is it a free turning conveyor belt, or is it a powered treadmill that runs in the reverse direction of the direction the plane would travel to take off under normal circumstances?

]]> by: Gareth http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-264 Tue, 12 Dec 2006 19:40:59 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-264 Bill: I meant the inner-mechanics of the treadmill were frictionless, not the surface itself. Bill: I meant the inner-mechanics of the treadmill were frictionless, not the surface itself.

]]> by: Gareth http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-263 Tue, 12 Dec 2006 19:38:42 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-263 Bill: Sorry, I meant the inner-workings of the treadmill were frictionless, not the surface Bill: Sorry, I meant the inner-workings of the treadmill were frictionless, not the surface

]]> by: bill http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-262 Tue, 12 Dec 2006 19:35:02 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-262 Gareth: If the treadmill was frictionless, it wouldn't be a treadmill. It would be a slippery surface. Jason: In reality, the plane would take off if some one actually tried to implement this. However, that is only because it would be practically impossible to get a treadmill to go as fast as it needed to get. By the limits stated in the original problem, it would reach balance and not fly away. Gareth: If the treadmill was frictionless, it wouldn’t be a treadmill. It would be a slippery surface.

Jason: In reality, the plane would take off if some one actually tried to implement this. However, that is only because it would be practically impossible to get a treadmill to go as fast as it needed to get. By the limits stated in the original problem, it would reach balance and not fly away.

]]> by: bill http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-261 Tue, 12 Dec 2006 19:23:16 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-261 Russ: Ok, you bring an interesting point to the table. Let's say the plane does move forward but at an infinitely small amount. It's not going to take off because the treadmill effect kicks well before it has enough velocity to lift off. Russ: Ok, you bring an interesting point to the table. Let’s say the plane does move forward but at an infinitely small amount. It’s not going to take off because the treadmill effect kicks well before it has enough velocity to lift off.

]]> by: Gareth http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-260 Tue, 12 Dec 2006 19:22:17 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-260 But if the plane is on a big, frictionless treadmill, then it can move forward without the wheels turning at all - that's my point. But if the plane is on a big, frictionless treadmill, then it can move forward without the wheels turning at all - that’s my point.

]]> by: Jason S. B. http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-259 Tue, 12 Dec 2006 19:01:41 +0000 http://billoday.net/2006/12/12/airplane-treadmill-problem-solution-nihilist/#comment-259 The other thing I think people aren't grasping (or maybe it's just a matter of the definition of the terms of the experiment) is that the "conveyor belt" is more of a treadmill in that it is powered and moving the opposite direction of the plane. Just think of it this way: You stand on a treadmill while wearing a pair of roller blades. You're holding onto a rope tied to the front of the treadmill. You turn the treadmill on and crank it up to super high speed. Eventually when you're balanced and everything has evened out, the force on the rope you're holding onto isn't all that great. If we picture an airplane in place of the person on rollerblades, the forward force that the airplane engines can produce will be far greater than the force on the rope. Therefore the plane will move forward with ease. And then do you know what it will do? Take off, hoser. The other thing I think people aren’t grasping (or maybe it’s just a matter of the definition of the terms of the experiment) is that the “conveyor belt” is more of a treadmill in that it is powered and moving the opposite direction of the plane.

Just think of it this way: You stand on a treadmill while wearing a pair of roller blades. You’re holding onto a rope tied to the front of the treadmill. You turn the treadmill on and crank it up to super high speed. Eventually when you’re balanced and everything has evened out, the force on the rope you’re holding onto isn’t all that great. If we picture an airplane in place of the person on rollerblades, the forward force that the airplane engines can produce will be far greater than the force on the rope. Therefore the plane will move forward with ease. And then do you know what it will do?

Take off, hoser.

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