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747 on a treadmill conundrum..
September 5, 2014 at 5:19 pm
Surely you guys have seen this before?
"Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?"
This is a forum norm, and I'm still not convinced either way !
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RE: 747 on a treadmill conundrum..
September 5, 2014 at 5:22 pm
Yes. The wheel speed is unimportant as the plane derives thrust from essentially blowing air backwards. It may add a slight bit of extra drag, but that's it.
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RE: 747 on a treadmill conundrum..
September 5, 2014 at 5:30 pm
I saw this on another forum and it went to 20 pages and resulted in several homicides. It will not end well.
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RE: 747 on a treadmill conundrum..
September 5, 2014 at 5:34 pm
If the treadmill can exactly match the speed of the wheels, then I don't think it will take off, since there will be no air passing over the wings, so no pressure difference between above the wing and below it, hence no lift force. The problem is that in the real world, no such treadmill would be able to be made.
If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. - J.R.R Tolkien
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RE: 747 on a treadmill conundrum..
September 5, 2014 at 5:35 pm
The engine thrust is against the air, and for me the conveyor would need to go faster and faster in order to prevent the plane from moving forward... a bit like ice... but ice on acid !
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RE: 747 on a treadmill conundrum..
September 5, 2014 at 5:38 pm
(September 5, 2014 at 5:35 pm)lifesagift Wrote: The engine thrust is against the air, and for me the conveyor would need to go faster and faster in order to prevent the plane from moving forward... a bit like ice... but ice on acid !
The benefits of a thought experiment like this is that you don't have to give a shit about real world problems.
If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. - J.R.R Tolkien
