12/12/2007 - the Conveyor Belt myth will be busted

So, to me, the only thing that would hamper flight would be the fact the tires would be destroyed. I think someone else also made that observation.
 
wbarnhill said:
Secondly, a number of us have gotten caught up on the question and it's usually worded in a specific vague way to trick you. Is the conveyor moving fast enough to cancel the forward motion or is the conveyor only matching the forward motion speed? As you can see, the answer to the question is different for each of those premises.
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No it is not. Tell me how the conveyor can manipulate the forward motion of the plane. When you really understand the question you will see that the conveyor will NEVER do anything to the plane no matter what it does. Plus the tires will never explode or catch on fire. The plane, once moving will remove most of the weight off the tires. Have you ever pulled a cloth from under a glass on a table? Do it slow and it does not work do it fast and it comes right out. Same principle applies, the faster the belt goes the the less contact you get with the tire at some point it will just hydroplane right on by.

Dan
 
AWACSEng said:
So, to me, the only thing that would hamper flight would be the fact the tires would be destroyed. I think someone else also made that observation.
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I have never timed it but I don't think it takes me over 10 sec to get airborne. You will never generate enough heat to start anything on fire in 10 sec. I bet you could not even do it with a torch.

Dan
 
stingray said:
I have never timed it but I don't think it takes me over 10 sec to get airborne. You will never generate enough heat to start anything on fire in 10 sec. I bet you could not even do it with a torch.

Dan
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Torch, meet gasoline ... or tinder ... or gunpowder ... or ...

10, 9, boom ! :D
 
But tires are designed with a certain max speed. May not be a factor for a light single, but definately an issue for machines that rotate in the 120kts+ range. 120kts of foward speed plus lets say 100kts of opposing conveyor movement = exceeding tire limit speed.
 
Exceeding tire speed limit != Guaranteed tire explosion, particularly on a takeoff roll.

In any case in re: the Bernoulli comment above. We are all clear on the fact that Bernoulli has at most a cursory bearing on aircraft flight? right?

~ Christopher

P.S. I cannot believe that we are on page 7 of this.
 
You're right. Mods, how about locking this one up before folks start jumping out of windows over this.
 
smigaldi said:
Shoot at least you are home from being out. I am awake because the wind is howling so loud that I can't sleep. You are having more of a life than me. :yes:
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Yeah, that wind was enough that the plane would have taken off no matter what the treadmill was doing! No motion relative to the ground required!:yes: We were showing 43MPH, gusting to 48.
 
What's awesome, is that if we keep posting how much we can't believe how long the thread is, it will always continue.

I'm doing my part:

Wow - this thread is REALLY long!!
 
LOCK IT...please? Seriously, nothing good is coming from this. Just cut the losses and let's move on.
 
Maybe we should start another thread. You know, to finally put this to rest.

;)
 
I think we should put into effect a policy I've seen on other boards...Start a new thread that has already been talked about and receive a 48hr posting ban. Do it again and it's a week. One more time and permanent. Would cut down on some of this silliness. One thread about a topic is enough. Feel free to add to that ONE thread all you want, just don't make us read the same thing stated 4 different ways. OK, rant over...sorry
 
AWACSEng said:
I think we should put into effect a policy I've seen on other boards...Start a new thread that has already been talked about and receive a 48hr posting ban. Do it again and it's a week. One more time and permanent. Would cut down on some of this silliness. One thread about a topic is enough. Feel free to add to that ONE thread all you want, just don't make us read the same thing stated 4 different ways. OK, rant over...sorry
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I see what you're saying, but I have a much simpler solution. If you see a thread on a topic that you're sick of...don't open the thread.
 
FlyNE said:
I see what you're saying, but I have a much simpler solution. If you see a thread on a topic that you're sick of...don't open the thread.
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Excellent idea, but...

I suppose one would never imagine another causing controversy then making a rapid departure... for the mere purpose of entertainment.
 
KennyFlys said:
Excellent idea, but...

I suppose one would never imagine another causing controversy then making a rapid departure... for the mere purpose of entertainment.
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One could imagine that, but one would also have to consider the fact that controversy can only be caused in such a situation if one allows themselves to get worked up by the miscreants.
 
FlyNE said:
One could imagine that, but one would also have to consider the fact that controversy can only be caused in such a situation if one allows themselves to get worked up by the miscreants.
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But, some did.

I went back and placed my previous posts with the truth. That set off a couple even more. I don't care.

Even so, you'll never convince me I'm wrong in my own theory. So der!

Circling_Smiley_Group.gif
 
KennyFlys said:
But, some did.

I went back and placed my previous posts with the truth. That set off a couple even more. I don't care.

Even so, you'll never convince me I'm wrong in my own theory. So der!
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The only thing that you accomplished was to show everybody that you felt it less important to learn than to try to save face when confronted with the unthinkable possibility that you might not know everything. I never once attacked you and I didn't make a "rapid departure". I simply wasn't going to dignify your hissy fit with a response. Frankly, I didn't care enough to let it bother me and it wasn't worth getting the thread locked.
 
FlyNE said:
The only thing that you accomplished was to show everybody that you felt it less important to learn than to try to save face when confronted with the unthinkable possibility that you might not know everything. I never once attacked you and I didn't make a "rapid departure". I simply wasn't going to dignify your hissy fit with a response. Frankly, I didn't care enough to let it bother me and it wasn't worth getting the thread locked.
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People keep changing the terms. There is only ONE way it would work and it does not fall under the premise of the original question.

If it's so dang important to you to be right about it, contact GT, MIT or some other tech school with a significant aerospace department to back you up with an actual experiment.

I really don't care. Either way, until someone lays out the exact terms right down to the last detail then establishes WHY it will or will not become airborne, I might be willing to listen. Thus far, this has not happen.

Is it possible I'm wrong? A slight possibility. Based on what has been presented thus far, I don't believe I'm wrong.

But, I'm sure as hell getting a kick how upset everyone is because I won't concede. I grew up in Missouri, dude. Get over it.
 
KennyFlys said:
People keep changing the terms.
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So... if the plane on the treadmill gets busted, as the title of this thread suggests, does the pilot of the plane have to consent to a search of the aircraft by the arresting officer?

Later!

Joe
 
KennyFlys said:
People keep changing the terms. There is only ONE way it would work and it does not fall under the premise of the original question.
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Care to explain your reasoning on that? And by the way, if I understand the original question, and what its premise IS, I submit the premise is wrong.

I really don't care. Either way, until someone lays out the exact terms right down to the last detail then establishes WHY it will or will not become airborne, I might be willing to listen. Thus far, this has not happen.
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Oh I think it has. Many times over.

Is it possible I'm wrong? A slight possibility. Based on what has been presented thus far, I don't believe I'm wrong.
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Ken, you are going to have to lay down in specific detail what premise you are operating under. Maybe then we can understand where you are coming from. Until then, in the real world with real, not theoretical physics, the airplane WILL fly.

But, I'm sure as hell getting a kick how upset everyone is because I won't concede. I grew up in Missouri, dude. Get over it.
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So am I and so was I. Show me. LOL:rofl:
 
KennyFlys said:
People keep changing the terms. There is only ONE way it would work and it does not fall under the premise of the original question.

If it's so dang important to you to be right about it, contact GT, MIT or some other tech school with a significant aerospace department to back you up with an actual experiment.

I really don't care. Either way, until someone lays out the exact terms right down to the last detail then establishes WHY it will or will not become airborne, I might be willing to listen. Thus far, this has not happen.

Is it possible I'm wrong? A slight possibility. Based on what has been presented thus far, I don't believe I'm wrong.

But, I'm sure as hell getting a kick how upset everyone is because I won't concede. I grew up in Missouri, dude. Get over it.
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Here you go Ken,

Original question: A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?

The question is very simple no controversy, It says the plane MOVES in one direction. Only going that far all you have to do is stop that plane from moving to prove that it will not take off. If you can use the conveyor belt to stop the planes forward movement I will jump on the "will not fly band wagon with you". It also says that the belt tracks the plane speed (not wheel speed) and matches it in the opposite direction. So even with a normal 172 the fastest the belt will move is 120 kts.

There is nothing hidden and nothing left out. There is nothing to interpret.

Even if you want to track the wheel speed you still have to stop the plane, you need some explanation that the belt can stop the forward movement of the plane and do it in less than 10 sec (Time to liftoff).

Dan
 
how can the belt stop the plane from moving (unless the brakes are locked?) All tha happens is that the wheels spin faster due to the relative motion of the belt. But (besides miniscule losses do to bearing friction) no extra energy is needed, the plane moves forward at normal speed, the wheels spinning at (plane speed+belt speed).
 
TMetzinger said:
how can the belt stop the plane from moving (unless the brakes are locked?) All tha happens is that the wheels spin faster due to the relative motion of the belt. But (besides miniscule losses do to bearing friction) no extra energy is needed, the plane moves forward at normal speed, the wheels spinning at (plane speed+belt speed).
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Apparently there are 11 pilots that think it can.

Dan
 
What it comes down to is your definition of "The plane moves".

If your view is that the airplane's movement is relative to the moving belt beneath the wheels, then the answer is "NO!".

If your view is that the airplane's movement is relative to the ground under the moving belt, then the answer is "Yes, if you can get enough thrust to overcome the backward pull of the moving belt and attain rotation speed (relative to the ground beneath the belt)."

And, as many have noted, it is relative wind that provides lift.
 
"e pur si muove" (and yet it moves)
Attributed to Galileo Galilei

and I got #200 on this thread!
 
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