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Current time: March 29, 2024, 8:53 am

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Airplane & the conveyer belt
#1
Airplane & the conveyer belt
As they say: this question is as old as the internet and needles to say that it has been discussed, and even MythBusters made an episode about it (it can not take off).

But what bothers me is why is this question even a thing, let alone so popular because in this situation the airplane is standing still. So even if you don't know the physics behind it, it is obvious that the airplane needs to move on the ground to take off, therefore this conveyer belt does absolutely nothing to the airplane except that it turns its wheels fast.

[Image: upU5PLza_o.jpeg]
teachings of the Bible are so muddled and self-contradictory that it was possible for Christians to happily burn heretics alive for five long centuries. It was even possible for the most venerated patriarchs of the Church, like St. Augustine and St. Thomas Aquinas, to conclude that heretics should be tortured (Augustine) or killed outright (Aquinas). Martin Luther and John Calvin advocated the wholesale murder of heretics, apostates, Jews, and witches. - Sam Harris, "Letter To A Christian Nation"
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#2
RE: Airplane & the conveyer belt
I'll wait until other people weigh in, first. It's sort of a trick question.
If you get to thinking you’re a person of some influence, try ordering somebody else’s dog around.
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#3
RE: Airplane & the conveyer belt
Yeah, after I wrote this I figured it was more complicated than I realized.

I guess you could also ask: If a giant hand was holding an airplane in the air even after it started to run its engines to the full maximum and then the hand would let it free, would the airplane fall on the ground or would it fly? If you go by Bernoulli it would fall, but if you go by air suction it would fly.
teachings of the Bible are so muddled and self-contradictory that it was possible for Christians to happily burn heretics alive for five long centuries. It was even possible for the most venerated patriarchs of the Church, like St. Augustine and St. Thomas Aquinas, to conclude that heretics should be tortured (Augustine) or killed outright (Aquinas). Martin Luther and John Calvin advocated the wholesale murder of heretics, apostates, Jews, and witches. - Sam Harris, "Letter To A Christian Nation"
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#4
RE: Airplane & the conveyer belt
Lift is created by air flowing over the airfoil wing, creating a higher pressur zone under the wing, and a lower pressure zone above the wing. Without that airflow, no lift, no takeoff. The aircraft my be moving relative to the belt, but it's not moving relative to the air any more than it would be if it were motionless on the ground.
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#5
RE: Airplane & the conveyer belt
Aircraft test stands in WWII actually tested this. The speed of the air over and under the wing, there's no hurricane blowing, is not significant.
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#6
RE: Airplane & the conveyer belt
OK. The conveyer belt isn't moving, and it's long enough for the plane to take off. How fast do you think that the tires are going at any point on the runway, when in contact with it? I'll tell you- it's zero pick-your-own-units. The tires are in non-skidding contact, so even though they are spinning relative to the ground at a given point, they are "stationary" at the point of contact. If someone arbitrarily starts the conveyer, then no, it won't take off. By the same token, the top of the tire is at the greatest speed, rotationally.
If you get to thinking you’re a person of some influence, try ordering somebody else’s dog around.
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#7
RE: Airplane & the conveyer belt
Never mind

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#8
RE: Airplane & the conveyer belt
No, they'd be neutralizing the belt.
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#9
RE: Airplane & the conveyer belt
Some of the wind goes over the wing in flight. Some goes under. In this example the wind isn't going anywhere.
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#10
RE: Airplane & the conveyer belt
the plane can take off by running its engines as if it was taking off from the stationary runway.    The engine thrust would move the plane forward on the conveyor belt at a normal relative velocity to the still air over the conveyor, the wheels will just spin much faster to accommodate the backward motion of the conveyor.


When a plane is accelerating down the runway to take off, the air resistance of the wings, fuselage abs empennage vastly exceed the rolling resistance of the landing gear, almost all of the engine thrust is devoted to overcoming air drag and accelerating the mass of the plane against inertia.   The fact that the wheels are creating more rolling resistance when rolling twice as fast as normal will have little material impact on the plane’s ability to achieve take off speed relative to still air.

The effort will, however, probably overheat and destroy the tires and bearings of the landing gear wheels that’s not been designed to roll twice as fast as normal take off speed while under the load of the aircraft’s weight

so i guess whether or not the plane can take off depends on whether the landing gear will be damaged enough by rolling twice as fast as intended to actually seize up, causing it to be ripped off and the plane collapse onto its belly before it can actually take off.
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