I'd like to see that proof. I've seen one similar to that before, but it divides by zero and only Chuck Norris can do that.
Plane on a Treadmill
- Thread starter Warder60
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I'd like to see that proof. I've seen one similar to that before, but it divides by zero and only Chuck Norris can do that.
Why won't there be forward motion?
I'm sure somebody somewhere could devise an ideal treadmill that could prevent a plane from taking off. I could also devise a static runway that would prevent a plane from taking off. By covering the runway with rocks, dirt, mud, sand, etc., I could develop enough rolling resistance to counteract the thrust of the plane's engines and prevent the plane from reaching takeoff speed.
It seems to me that the question being asked is whether a covnetional airplane on a conventional treadmill/conveyer would take off. Using a model airplane, we certainly have conveyor systems large enough to test the scenario. And the answer is yes, the plane will take off because conventional treadmills are not designed to impart a rolling resistance large enough to oppose the thrust of the planes engines.
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Again, the reason this whole thing causes so much debate is because the whole puzzle is framed with just enough information that arguemnts can be made for either outcome.
We all agree a plane won't fly without air movement across the wings. That part is easy.
The question is, will the plane move forward. To answer that question, we need to further understand the situation. When words like "infinitely" are used in describing the problem, people are going to stray from real world limitations.
In a real world, there is no treadmill that someone could build that could keep plane from moving forward.
We all agree a plane won't fly without air movement across the wings. That part is easy.
The question is, will the plane move forward. To answer that question, we need to further understand the situation. When words like "infinitely" are used in describing the problem, people are going to stray from real world limitations.
In a real world, there is no treadmill that someone could build that could keep plane from moving forward.
When I first started reading this thread, I thought there was no way that a plane could take off on a treadmill. I thought that the plane itself would have problems keeping up with the treadmill, and just with that insufficient wind would be driven across the wings, therefore keeping it on the ground (yes, I'm using layman's speak for this).
Then an interesting thought occurred to me - assume that the engine on the plane is completely turned off and is not exerting any thrust on the plane whatsoever. Could the force of friction that is exerted on the plane by the treadmill even overcome the force of gravity that is being exerted on the plane (i.e., if you pulled backward on the treadmill, with no force other than gravity and friction acting on the plane, would the plane be pulled backward)?
As it just so happens, I was able to test this theory at my work desk as I have a die cast Aston Martin DBS on my desk (what can I say - I was a big fan of Casino Royale, especially the car in the movie, and I bought the movie at Best Buy just to make sure I got the car :wink
. What I did was put this car on top of a sheet of paper and pulled on the sheet of paper. What happened was the car did move back a little bit from its original location (about an inch or so), but in essence the sheet of paper couldn't overcome the force of gravity on the die cast car. This pretty much proves it to me that the plane WILL take off - if the treadmill can't even overcome the force of gravity on the plane, how is it going to overcome the thrust provided by the engines, a much greater force that is exerted on the plane?
Then an interesting thought occurred to me - assume that the engine on the plane is completely turned off and is not exerting any thrust on the plane whatsoever. Could the force of friction that is exerted on the plane by the treadmill even overcome the force of gravity that is being exerted on the plane (i.e., if you pulled backward on the treadmill, with no force other than gravity and friction acting on the plane, would the plane be pulled backward)?
As it just so happens, I was able to test this theory at my work desk as I have a die cast Aston Martin DBS on my desk (what can I say - I was a big fan of Casino Royale, especially the car in the movie, and I bought the movie at Best Buy just to make sure I got the car :wink
. What I did was put this car on top of a sheet of paper and pulled on the sheet of paper. What happened was the car did move back a little bit from its original location (about an inch or so), but in essence the sheet of paper couldn't overcome the force of gravity on the die cast car. This pretty much proves it to me that the plane WILL take off - if the treadmill can't even overcome the force of gravity on the plane, how is it going to overcome the thrust provided by the engines, a much greater force that is exerted on the plane?
If you understand this quote, then you will understand how 1 + 1 = 10:
:wink:
And that is exactly my point. The question is - given (an ideal) treadmill, will a plane takeoff.
I did something similar a couple years ago (younger and dumber) with my rollerblades and a treadmill. Coudn't outrun the mill - mostly ended up behind it and on my face because I suck at blading and it was too hard and narrow to keep pace with the mill.
Alot of you guys are trying to prove that the treadmill is the flaw - and it very well may be. But the question isn't "Can a treadmill stop the forward motion of a plane?"
People are over-thinking this IMO (and good for you cause I sure as heck don't get alot of what's being said) But in doing so, it would seem the initial question is getting lost.
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What is an ideal treadmill? Is it an ideal device for preventing an airplane from taking off? Or is it an ideal device for human exercise? These are different devices, and they would be designed differently. There is no single ideal multipurpose treadmill.
Somehow, I think that when the person first pondered this question, that person probably wasn't thinking about the plane-stopping treadmill, but more likely was thinking about the human exercise treadmill...
Fine - whatever.
I would have to say that it's such a device that would prevent the planes wheels from progressing in a forward manner. Much in the same way that a human treadmill keeps a person in a stationary local.
However, I sincerely doubt they're going to put a 727 on your average YMCA running device. :skeptical:
This is what happens when someone poses a question like this on a forum with a bunch of engineering geeks. :wink:
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