Mythbusters: Airplane on a conveyor belt

[draticus]

I don't know of a more suitable forum to post this so I'm going to start here with a rough draft.

Myth: If an airplane is placed on a conveyor belt that spins in the opposite direction from which the plane is trying to take off and the conveyor belt matches the planes speed, will the plane ever take off?

Authors answer? No, because the plane will not be moving relative to the air and air under the planes wings creates lift, not speed relative to the ground beneath it.

Commonly accepted answer? Yes, because when the plane is going 100mph and the belt is going 100mph the plains wheels will just be going 200mph and the plane will still move down the conveyor belt and take off.

I propose that mythbusters and the commonly accepted answer are wrong. The plane does not take off if you remain true to the authors intent. The fact that the author was knowledgeable enough to create a puzzle that's meant to teach the concepts of aerodynamics and lift tell me that he was smart enough to know that if the conveyor belt is matching the planes speeds relative to the ground around the conveyor belt it would still take off.

Authors intent-
So then why did the author say No, it doesn't take off?: Because his intention was that the conveyor belt was matching the speed of the plane relative to itself. If the plane is going 100mph relative to the ground and the conveyor belt is moving 100mph against the plane then the plane is going 200mph relative to the conveyor belt and the belt is not matching its speed. If we assume that the conveyor belt is capable of matching the planes speed relative to itself, as opposed to the ground, then for every millimeter the plane moves forward the plane is now moving faster than the belt and the belts speed increases. The plane can never truly move forward unless the belt is failing to match its speed. There is no reason why a hypothetical belt that's given one purpose should be assumed to fail that purpose. In order for the wheels to turn they must overcome the friction being created by gravity pushing the plane down. The faster the wheels spin the more friction is created and the more force is required to increase the rate of spin. The amount of friction on the axle is limited only by the belts speed. With enough speed we create enough friction to match the engines ability to pull the plane forward. If the belt reacts fast enough it will accelerate to incredible speeds instantly in order to create enough friction on the wheels. Once again there is no reason to assume that the hypothetical belt is slow and fails to match the planes speed and fulfill its only role in this hypothetical scenario.

Example-
If the plane is sitting on a conveyor belt and the belt starts moving backwards before the plane starts then the plane moves backwards with it. If, as most people state, the wheels are irrelevant, why doesn't the plane remain still while the wheels simply turn? Because of Friction. In order for the plane to remain still the engines would have to create enough force to move the plane forward. Its true that the plane behaves very differently in this situation than a car which is often used as an example in this debate. The car is pushing off of the ground and overcoming friction and air speed. Since a car on a belt that's matching its speed isn't encountering any air speed its only overcoming the friction of the wheels. The wheel speed is practically limited by gearing but theoretically only limited by friction. The plane also has to overcome the friction on the wheels but since its pulling itself forward with its propellers as opposed to pushing off the ground it can overcome that friction much easier than the car. Just because its easier doesn't mean there is no limit. If the belt is moving backwards at 5 mph and the planes engines turn very slowly they could match the friction of the wheels and cause the plane to remain still indefinitely. Now if the belt increases its speed the plane will start moving backwards. It won't move backwards at a speed equal to the increase in speed of the belt but the friction will increase so without an increase in thrust the plane will start moving backwards ever so slightly. The amount of additional force the plane needs to produce to remain stationary or start moving forward is extremely small because the increase in friction on the wheels is almost insignificant but its still there. With a huge increase in belt speed you need a tiny increase in propeller speed to compensate for the friction on the axle. So if the speed of the belt has no upper bound but the force of the engine does then incredible speeds could produce incredible amounts of friction and overcome the power of the engine.

Getting technical-
Some of you will say that no known conveyor belt can move that fast. Remember: the conveyor belt is not the point of the puzzle. The point is whether the plane takes off or not. The belt is just a hypothetical prop with one function: to match the planes speed. If you want to get really technical the belt would increase to such an incredible speed that the tires of the plane would blow out and the rims would make contact with the belt which is traveling over a thousand mph and the plane would flip. This still does not result in a take off. Once again, the tires are not the point though. The point is that if a belt could match the planes speed and never allow it to move forward, would the plane take off?

Conclusion-
The author understood physics enough to try to teach others the lesson that speed relative to the air creates lift, not speed relative to the ground/belt beneath it. If the belt beneath the plane matches its speed relative to itself and prevents the plane from moving forward, will the plane take off? No, because there will be no air flowing under the planes wings. This is obviously the intent of the puzzle. The only way you can reach the conclusion that the plane takes off is if the belt is only supposed to match the planes speed relative to the ground(which obviously wasn't his intent given his answer and would make the entire puzzle pointless) or the belt is designed to match the planes speed relative to itself but it fails to do the one job it is given in the puzzle.

If you stay true to the authors intent and assume that all of the elements of the puzzle do what they're supposed to do the plane does not take off.

[Soyuz]

You know why Mythbusters is so popular? They present science in a fun way. I have learned more from Mythbusters then from 6 months listening to a dusty old teacher explaining everything with numbers.
I already have a short attention span and when things don't interest me I, :SQUIRREL:!!

Your wall of text reminded me of those school books. Though it may be interesting, sadly enough, it doesn't hold my attention.
I like planes though so here is an interesting question..

The backward force produced by the airplane's propeller does cause a minimal amount of lift on the wings. Though hardly even noticeable it could reduce the friction between the plane's wheels and the belt. Therefore the belt is not dragging the plane at the full 100mph backwards.

Disclaimer: I love planes and the wonders of science, but I suck at math. So my assumptions could be wrong.

[Deleted]

So if the speed of the belt has no upper bound but the force of the engine does then incredible speeds could produce incredible amounts of friction and overcome the power of the engine.

Why are you making this assumption? Why does the belt have infinite power, but the plane doesn't? Yes, even in the case where both the conveyor belt and the plane could accelerate indefinitely, the plane would still remain stationary and not take off.

But, in this situation the myth doesn't make any sense from a practical point of view anymore. This thread is called "Mythbusters: Airplane on a conveyor belt". Mythbusters tested the myth correctly. Regardless of what the "author" (Who is this author, anyways?) might've or might've not originally meant, the myth is completely irrelevant if you start considering the belt to have indefinite power.

In the sense of teaching physics, the mythbusters's take on it is more educational. What you're saying is that the original lesson was whether or not the plane will raise into the air when staying stationary. The answer to that is plain and simple common sense. At least the Mythbusters take on the myth was a little more complicated than that.

[draticus]

Why are you making this assumption? Why does the belt have infinite power, but the plane doesn't? Yes, even in the case where both the conveyor belt and the plane could accelerate indefinitely, the plane would still remain stationary and not take off.

But, in this situation the myth doesn't make any sense from a practical point of view anymore. This thread is called "Mythbusters: Airplane on a conveyor belt". Mythbusters tested the myth correctly. Regardless of what the "author" (Who is this author, anyways?) might've or might've not originally meant, the myth is completely irrelevant if you start considering the belt to have indefinite power.

In the sense of teaching physics, the mythbusters's take on it is more educational. What you're saying is that the original lesson was whether or not the plane will raise into the air when staying stationary. The answer to that is plain and simple common sense. At least the Mythbusters take on the myth was a little more complicated than that.

Its like the myth: If you let a monkey type on a keyboard for an infinite amount of time time would he eventually produce the complete works of shakespeare? The answer is yes. The fact that a monkey can't type forever is irrelevant.

Would it make sense for Mytbusters to test this myth by putting a monkey on a keyboard for 1 day and then call it busted because a Monkey could never type for infinity? No, that would be silly. Its a hypothetical situation.

The point of the monkey myth is whether or not an infinite amount of random will produce every possible outcome no matter how unlikely. The answer is yes. Whether a monkey can live forever is irrelevant

The point of the airplane myth is whether or not an air airplane on a belt that matches its speed can take off. The answer is no. Whether or not a belt can accellerate that fast is irrelevant.

Why does the belt accelerate infinitely to match the planes speed while the plane doesn't have an infinitely powerful engine? Because the myth says the belt can match the planes speed. The myth does not presuppose anything about the planes engine. Just like the monkey myth states that the monkey types forever but it doesn't say that the keyboard has an infinite amount of keys(which would break that myth just like an infinitely powerful airplane would break this myth. An infinitely powerful engine wouldn't even need lift under the wings. It could launch like a rocket)

Mythbusters tested this old, famously debated myth the only way they could - by changing it entirely. If I remember correctly they even started wording it differently later in the show, saying "If the belt is going at the planes take off speed." IMO if the myth has a presupposed impossible element that it hinges on then they shouldn't touch the myth or else they end up producing an answer that is untrue to the original myth.

[Deleted]

You keep saying "original myth" and "author". What is this original myth? Where is it from? Where can it be found? Who is this author?

And you cannot compare the monkey myth on this one. The monkey myth is completely hypothetical from the ground up and has absolutely no practical applications, where the plane on a conveyor belt can actually be tested, at least in some form.

And back to the educational and entertaining aspects of the myth and how it was tested - we're talking about Mythbusters here after all. Like I said earlier, you're basically saying that the original myth is whether or not the plane will take off while remaining stationary. You also say this is a famous and highly debated myth, but what is there to debate about that? Of course the plane will not take off while remaining stationary. The only debate here is whether or not you want to make the assumption of indefinitely powerful conveyor belt or not. The only argument here is not about physics, but rather semantics and the intention of the original author.

And that would make a shitty Mythbusters episode. Mythbusters tested it from one point of view - the only one that can be tested in practice - and provided an entertaining episode in the meanwhile and some new info for most of the viewers. I for example hadn't completely understood what would actually happen if you did put a plane on a conveyor belt and was interested to see and understand why it behaves differently than a car.

You, or anyone else, can't really say that Mythbusters tested it "wrong" or shouldn't of touched it at all. The myth isn't the property of the original author. All stories and myth have a life of their own where they twist and turn and change, and isn't that exactly how myth and urban stories are born? I'm not saying you're wrong as you clearly aren't, but you need to understand that what ever the original author might've ment is only one point of view on the matter.

[Fooliecoolie]

You keep saying "original myth" and "author". What is this original myth? Where is it from? Where can it be found? Who is this author?

http://www.straightdope.com/columns/...plane-take-off

[Deleted]

You keep saying "original myth" and "author". What is this original myth? Where is it from? Where can it be found? Who is this author?

http://www.straightdope.com/columns/...plane-take-off

That can't be the original source. With four seconds of googling I was able to find several older sites discussing the same myth. Additionally, even the question states "The discussion has been going on for ages".

[perera]

I think the most important part of all is that a plane's propulsion comes from turbines and not wheels even while it's on the ground, and as such it would not make the conveyor belt move, it would instead behave just like normal ground. The wheels are only there to prevent attrition, and no matter what speed the conveyor belt moved at (even if it had another source for its movement) the plane would speed up normally, unless the wheels were to collapse due to the speed the 'ground' is moving under them.

[Deleted]

How can this be a myth at all? The matter is really quite simple, as it is comparable to a plane without wheels, but mounted fixed on a lever that would only allow vertical movement.

Planes fly because of the air going by the wings. The turbines do provide a certain amount of draft that pulls some air, but that is hardly enough to do anything. The only important thing is air strongly blowing from the front. That can either be provided by speeding the plane up relative to the surrounding air (turbines + horizontal movement), or that could also just be one biiiiiig ass fan in front of the plane - with such, it could start vertically since no relative-to-ground movement is involved in lifting up at all. You just need to make air go by from front to back, be it by movement of the plane through air, or by moving the air itself.

This should be obvious by common sense if one isn't bare of any even slightest education, but no MYTH!

How is that relevant to what was discussed in the topic?

Noone was questioning how planes work, but whether or not it will take off a conveyor belt. And that has nothing to do with any biiiiig ass fans or levers that only allow vertical movement. The myth still only boils down to two options; either the conveyor belt is a regular, conventional conveyor belt and the plane takes off or then it's a hypothetical one that can indefinitely match the planes speed and the plane wont take off.

[draticus]

http://www.straightdope.com/columns/...plane-take-off


That can't be the original source. With four seconds of googling I was able to find several older sites discussing the same myth. Additionally, even the question states "The discussion has been going on for ages".

So why are you asking where the myth came from? Its a very old physics tool. Everyone knows the original answer was "no, it doesn't take off because without forward momentum there is no air flow and no lift." Even mythbusters states that as the answer to the "myth." So since we know that was the original authors intent we know he was intending the belt to match the planes speed perfectly. His name is irrelevant. The monkey myth is a perfect analogy in that they both have hypothetical components that are assumed to fulfill a task which is impossible in the practical world but is necessary to lead to the conditions which are the point of the scenario.

The monkey typing forever isn't possible but also isn't the point of the scenario. The belt matching the planes speed isn't possible but also isn't the point of the scenario. If the monkey types forever he'd produce every book. If the belt matched the planes speed perfectly it would not take off. Both are just assumed hypothetical tools in a larger scenario. Let them do their jobs.

We've established the authors intent. We've established that if you stay true to that intent then the plane doesn't take off either because the tires blow out(If you want to get super technical) or they spin to a point of friction that matches the power of the planes engine(less anal, more true to the simple nature of the scenario in order to teach the lesson of air flow and lift)

[Deleted]

So why are you asking where the myth came from? Its a very old physics tool. Everyone knows the original answer was "no, it doesn't take off because without forward momentum there is no air flow and no lift." Even mythbusters states that as the answer to the "myth." So since we know that was the original authors intent we know he was intending the belt to match the planes speed perfectly. His name is irrelevant. The monkey myth is a perfect analogy in that they both have hypothetical components that are assumed to fulfill a task which is impossible in the practical world but is necessary to lead to the conditions which are the point of the scenario.

The monkey typing forever isn't possible but also isn't the point of the scenario. The belt matching the planes speed isn't possible but also isn't the point of the scenario. If the monkey types forever he'd produce every book. If the belt matched the planes speed perfectly it would not take off. Both are just assumed hypothetical tools in a larger scenario. Let them do their jobs.

We've established the authors intent. We've established that if you stay true to that intent then the plane doesn't take off either because the tires blow out(If you want to get super technical) or they spin to a point of friction that matches the power of the planes engine(less anal, more true to the simple nature of the scenario in order to teach the lesson of air flow and lift)

You keep saying the same things over and over again with no new information.

I still don't understand how can you say "So since we know that was the original authors intent" if we don't know who the original author was or we haven't even been shown the original myth/problem? We don't know the originals authors intent, wording of the problem or anything else until you show it to us. I'm asking because I've never actually seen the said problem before, only debates about it. So either show us the original author and problem or stop saying "since we know the authors intent", please.

And again, you started this thread in reference to Mythbusters. So I'm saying it again, they tested it the only way possible and provided an entertaining and actually an educational episode. What's wrong with that? Furthermore, who are you or anyone else to say that Mythbusters aren't allowed to test the myth from a practical point of view? Like I said earlier, the original problem and author's intent is merely one take on this whole issue. According to you, it used to be merely "a very old physics tool", perhaps a textbook exercise? In that form it's not a myth of any sort. It has been gaining mythical proportions over the years and years (maybe even decades?) of debating.

There is no debating whether or not the plane will take off off a conveyor belt that can match it's speed. It won't, we all agree on that. So the only debate is how you want to interpret the issue. Mythbusters took the side that is testable, and showed in practice how that side of the myth works. They didn't test it wrong. Maybe they could've worded their mythbusting better or perhaps they should've brought up the other side of the myth too, but nevertheless they didn't test anything wrong.

[draticus]

You keep saying the same things over and over again with no new information.

Funny, I was thinking the same thing of you. I accept that since all versions of the myth being debated around the internet for the past 10 years say the plane is not supposed to take off that means the authors intent was for the plane to not take off. Unless you think everyone everywhere accidentally reversed the supposed answer. Even with the authors intent aside a literal interpretation of the myth says the belt matches the planes speed, not that it tries to match the plane speed.

I could twist the monkey myth and say that maybe the author(who is also unkown to me, not that it matters) intended for "eternity" to just mean "until the monkey gets tired and takes a nap." This makes the myth testable. But unfortunately it also makes the myth totally pointless and flawed and goes against the obvious intent which can be assumed from the given answer of "yes." Mythbusters would be stupid to test this version and then say "The" monkey myth is busted.

Likewise, I could twist the airplane myth to say that maybe the author intended for "matches the planes speed" to mean it "tries to match the planes speed" or "matches the planes airspeed." This makes the myth testable. But unfortunately it also makes the myth totally pointless and flawed and goes against the obvious intent which can be assumed from the given answer of "no, it doesn't take off." Mythbusters was stupid for testing this significantly altered version and then saying "The" airplane myth is busted.

I keep repeating myself because this is fairly simple logic to me so I'm rephrasing it in such as way so you'll understand. If you still don't agree and have nothing new to add then I'm cool with saying we agree to disagree. Thanks for the debate.

[draticus]

How is that relevant to what was discussed in the topic?

Noone was questioning how planes work, but whether or not it will take off a conveyor belt. And that has nothing to do with any biiiiig ass fans or levers that only allow vertical movement. The myth still only boils down to two options; either the conveyor belt is a regular, conventional conveyor belt and the plane takes off or then it's a hypothetical one that can indefinitely match the planes speed and the plane wont take off.

He is suggesting more "fool proof" ways of demonstrating the principles that the myth is trying to demonstrate. The conditions of the myth obviously need to be changed since everyone is failing to apply them correctly and are contradicting the results of non-takeoff. People are getting hung up on the belt and trying to make it fail in order to ruin the myth so hes suggesting ways to improve it in order to preserve the physics lesson of ground speed vs air speed and lift.

What he is saying is very relevant to the myth and the physics its trying to teach.

[Deleted]

I accept that since all versions of the myth being debated around the internet for the past 10 years say the plane is not supposed to take off that means the authors intent was for the plane to not take off.

Tell me, what the hell have all the people around the internet debated about for the past 10 years if there are no disputes about how the conveyor belt works?

He is suggesting more "fool proof" ways of demonstrating the principles that the myth is trying to demonstrate. The conditions of the myth obviously need to be changed since everyone is failing to apply them correctly and are contradicting the results of non-takeoff. People are getting hung up on the belt and trying to make it fail in order to ruin the myth so hes suggesting ways to improve it in order to preserve the physics lesson of ground speed vs air speed and lift.

What he is saying is very relevant to the myth and the physics its trying to teach.

I already said this before too, but are you trying to say that the physics the problem is trying to teach is that the plane wont take off while remaining stationary? Is the problem meant for 10 year olds or something?

And of course people are getting hung up on the belt, because the belt is the only part that the problem even slightly interesting. If it had said "The plane is chained to the ground, does it take off?", it would've never been debated over the internet for 10 years.

What ever the original authors intent might've been, it seems to have been a very stupid intent. Why bother with the conveyor belt at all if its only purpose is the same as chaining the plane to the ground? I'm happy the Mythbusters completely and utterly destroyed and butchered it.

[draticus]

Tell me, what the hell have all the people around the internet debated about for the past 10 years if there are no disputes about how the conveyor belt works?

Some of the people on the internet have been stating the myth correctly but then debating whether a plane will take off from a conveyor belt that fails to match its speed. Some people argue that even with a broken belt hte plane won't take off because they dont understand physics. Other people are arguing because they are assuming the belt should be doing its job and actually stopping forward movement. After all thats what the myth actually says, both in the question, and in the answer.Simple physics goes right over people heads. Apparently so does reading comprehension because the people who do understand physics can't understand the intent of the riddle. When I'm saying its obvious I'm not saying everyone agrees, I'm saying everyone SHOULD be agreeing because its so obvious.

I already said this before too, but are you trying to say that the physics the problem is trying to teach is that the plane wont take off while remaining stationary? Is the problem meant for 10 year olds or something?

It should be that obvious but its not. It should also be obvious that the riddle says the belt matches the planes speed so no one over 10 should then assume it doesn't do what the riddle just said it does do, right?

And of course people are getting hung up on the belt, because the belt is the only part that the problem even slightly interesting. If it had said "The plane is chained to the ground, does it take off?", it would've never been debated over the internet for 10 years.

Either it matches the planes speed and it obviously doesn't take off or it doesn't match the planes speed and it obviously does take off. Either way is obvious, boring, and shouldn't have to be explained to educated people. Breaking the belt doesn't make it more interesting, it just breaks the riddle, ruins the basic physics lesson, and turns it into an equally boring and obvious scenario but with an opposite outcome.

What ever the original authors intent might've been, it seems to have been a very stupid intent. Why bother with the conveyor belt at all if its only purpose is the same as chaining the plane to the ground? I'm happy the Mythbusters completely and utterly destroyed and butchered it.

Teaching physics is not stupid. Neither is teaching reading comprehension. You act like the mythbusters version of the myth was interesting... like there should have been doubt in anyone mind whether or not a belt going 100mph would stop a plane from taking off because the wheels can't just simply spin 200 mph as it cruises down the belt. Of course it won't. That should be obvious. That's boring. How can you possibly say that a plane on a belt that matches its speed would be so obvious that its boring but then act like a plane on a belt that doesn't match its speed is an interesting myth that no one should know the answer to until they test it. They're exactly the same. They're both equally obvious to an educated person but only one version is true to the myth. The myth was always "IF a plane is on a belt that matches its speed but in the opposite direction can it take off" and the myth answer was always "No, because you need air speed to create air flow under the wings and give them lift." It was simple. It was obvious. It taught a simple lesson. One would hope only kids need to learn that lesson but we both know thats not the case. No one should have ever argued it but a bunch of people who were good at physics and bad at reading comprehension thought they could disprove the myth and started assuming the belt fails and trying to teach a different physics lesson.

The people who say the plane does take off aren't bad at physics, they're just bad at reading comprehension and aren't staying true to the conditions of the scenario.

[Eurytos]

A few things, #1 it is impossible to answer yes to the Monkey typing the complete works of Shakespeare given an infinite amount of time. Random is random, that doesn't mean that over an infinite amount of time every possible scenario would be covered. The monkey could just as easily press the same button over and over for infinity, thus I would say no. But I can't say that either, since that is also an assumption. I would make far fewer and more believable assumptions to prove my "No" answer than you would have to make to prove a "Yes." But as I initially said, it's not possible to know whether a monkey typing randomly on a keyboard for eternity would indeed make the works of Shakespeare.

On to the main point. Planes fly because lift is created from the air around them, not the speed of the ground beneath them. Air travels faster over the airfoil, or wing, than it does underneath, therefore creating lift. Speed of the ground is irrelevant. Argument over. There is nothing else to even talk about. When air travels faster over the wing than under the wing you will get lift. Get the right amount of upward force for your object, and it will fly, regardless of what type of foundation it is resting on top of.

[Saverem]

That was TLDR, but if a plane is put on a conveyor belt, nothing will change. The plane will still move forward and take off because the propellers use the air to pull the plane, the wheels on the conveyor belt are irrelevent. If they put the plane in a wind tunnel large enough, then yes, the plane could take off and stay in place assuming the wind is strong enough.

100 MPH wind going S and plane facing N with propellers doing 100MPH will have the plane "hover" on that spot.

[belshamaroth]

what if the conveyor belt caused the air speed above it to increase due to air resistance? :O lol

[jonfauscett]

ok, the reason that the plane would not take off is because it's wings are staying in the same spot. do you feel any wind blowing when you run on a treadmill? The wind is the cause of the lift and if the wings are not catching any gusts the plane will just sit there, well technically roll there, but it amounts to the same thing... no lift.

[draticus]

A few things, #1 it is impossible to answer yes to the Monkey typing the complete works of Shakespeare given an infinite amount of time. Random is random, that doesn't mean that over an infinite amount of time every possible scenario would be covered. The monkey could just as easily press the same button over and over for infinity, thus I would say no. But I can't say that either, since that is also an assumption. I would make far fewer and more believable assumptions to prove my "No" answer than you would have to make to prove a "Yes." But as I initially said, it's not possible to know whether a monkey typing randomly on a keyboard for eternity would indeed make the works of Shakespeare.

Actually it is a mathematical fact that they would. You're underestimating infinity. If something has a 1 in 100,000,000,000,000,000,000,000,000,000,000,000,000 chance of occurring then if you tried 100,000,000,000,000,000,000,000,000,000,000,000,000 times then odds are it would occur. If you tried an infinite amount of times then it has an infinite chance of occurring. The chances that monkeys would produce the works of Shakespeare if they typed for the life of the universe are very slim. But infinity guarantees that every possible outcome will occur.

On to the main point. Planes fly because lift is created from the air around them, not the speed of the ground beneath them. Air travels faster over the airfoil, or wing, than it does underneath, therefore creating lift. Speed of the ground is irrelevant. Argument over. There is nothing else to even talk about. When air travels faster over the wing than under the wing you will get lift. Get the right amount of upward force for your object, and it will fly, regardless of what type of foundation it is resting on top of.

Exactly, and this is the lesson that the riddle teaches us. The reason most people disagree is because they picture the belt having a limited speed which would allow the plane to simply go faster than the belt and gain forward momentum /air speed and achieve lift. I was showing that this is wrong because they are assuming that a part of the puzzle which is assumed to perform a given task fails to perform that task.

---------- Post added 2010-07-02 at 04:30 PM ----------

That was TLDR, but if a plane is put on a conveyor belt, nothing will change. The plane will still move forward and take off because the propellers use the air to pull the plane, the wheels on the conveyor belt are irrelevent. If they put the plane in a wind tunnel large enough, then yes, the plane could take off and stay in place assuming the wind is strong enough.

100 MPH wind going S and plane facing N with propellers doing 100MPH will have the plane "hover" on that spot.

I explained exactly why you are wrong but you couldn't be bothered to read it in the first place so please dont bother responding.