*light blue touch paper*

Will the plane take off?

  • Yes

    Votes: 52 49.1%

  • No

    Votes: 54 50.9%
  • Total voters
    106
  • Poll closed .
Status
Not open for further replies.
Steve said:
Mecha. I'm disappointed in you.
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I wouldn't be. This is a riddle, you're supposed to get it wrong. I got it way more wrong than that, at least Mecha's makes some sort of sense :P

The only difference is that once you get it wrong, you admit that you got it wrong...

And kirov, isn't that basically what everybody in this thread has agreed upon already, save one or two?
 
Erestheux said:
I wouldn't be. This is a riddle, you're supposed to get it wrong. I got it way more wrong than that, at least Mecha's makes some sort of sense :P

The only difference is that once you get it wrong, you admit that you got it wrong...

And kirov, isn't that basically what everybody in this thread has agreed upon already, save one or two?
Click to expand...
But Mecha...he...I...penis...awwww

I suck.
 
kirovman said:
I think I've got the explaination which should satisfy everyone. If anyone else has already mentioned it, this should reinforce that.

The engines produce a thrust (Force) and hence and acceleration. The only significant thing that stops these engines from accelerating the aircraft is the drag force, from air resistance, that occurs usually once an aircraft is already airbourne. This only matches the thrust once the aircraft reaches some terminal directionwards velocity.
Therefore the aircraft will continue to accelerated by the engines until it reaches lets say 200 mph airspeed. The wheels will be freerolling at 400 mph, but the aircraft will still take off.

The thrust will constantly accelerate the aircraft until the air resistance can match it.
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Ok, lets try and close this discussion. Some of you people seem to believe that this airplane has infinite thrust, and will beable to overcome to friction and speed of the conveyer. That is not the case.

What is happening here is a simulation of ground speed. The conveyer is going the exactly same speed as the plane only in the opposite direction. And when I mean speed, I mean the speed of the wheels because that's what is in contact with the conveyer, not the body of the aircraft. You have to see that, no matter how much thrust the engines can produce, the conveyer will compesate for the ground speed of the plane (Which the wheels coming in contact with the ground.)

So what is going on is a simulation meaning that the plane's avionics are saying it's going a certain speed, but its really not moving at all. So there is no way the plane could takeoff, without the amount of lift from the air going across and under the wings. You people are right that the wheels are not what's accelerating the plane but the wheels are what touching the conveyer. It doesn't matter how powerful the engine is, the conveyer will always tune to the planes ground speed.

Parrot of doom said:
I think perhaps PoS (no pun intended) should study the question, maybe he doesn't realise that all the conveyor does is move at an equal speed to the aircraft, in the opposite direction. The conveyor doesn't 'counter' the aircraft speed.

Theres a subtle and important difference.
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What do you mean doesn't counter the speed of the aircraft? You said in your question that the conveyor adjusts itself to the plane's speed (which is the GROUND SPEED and not AIR SPEED) Of course it counters the plane's speed, because the wheels are touching the ground. As long as the wheels are on the ground and the conveyor is adjusting to the ground speed of the aircraft, the aircraft is going absolutly Nowhere.

And to make this question as simple as possible forget about the friction or the maximum thrust of the engine or the maximum speed of the conveyor and treat this as a high school physics question.
 
Okay, seriously. Look.

The ONLY time the wheels would truly matter is if the wheels were what pulled the vehicle along the ground. But they aren't. They only lubricate the plane's travel along the ground.

The plane's engines are not countered by the conveyor belt, because they're not pushing against the conveyor belt. They're pushing against they air.
 
dream431ca said:
It doesn't matter how powerful the engine is, the conveyer will always tune to the planes ground speed.
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Right, this is what I thought (before anyone bothered to be clear :shh: ). But the conveyor is only spinning the wheels. The thrust of the plane is coming from the props, or the jet, which is completely independant to the conveyor belt. They are going to move the plane forward anyway. See Steve's roller-skates-on-a-treadmill analogy.

You're on a treadmill with rollerskates and a rope attached to you. Someone is pulling the rope. The treadmill is tracking the speed of your rollerskates and compensating - but it doesn't matter, because the wheels are free-spinning and the rope, the thing pulling you forward, is completely unaffected by the treadmill. If you were running on the treadmill you wouldn't get anywhere but the rollerskates mean a vast decrease in friction, allowing you to be pulled forward at the expense of spinning a lot faster.

The plane would take longer to take off but it would take off.

Unless you're saying that the plane will go fast, and the wheels will spin twice as fast, so the conveyor will go twice as fast, so the wheels will spin four times as fast, so the conveyor will go twice as fast. But if you've got indestructable wheels (and we're assuming you have) that's not going to matter as far as I can see.
 
Sulkdodds said:
Right, this is what I thought (before anyone bothered to be clear :shh: ). But the conveyor is only spinning the wheels. The thrust of the plane is coming from the props, or the jet, which is completely independant to the conveyor belt. They are going to move the plane forward anyway. See Steve's roller-skates-on-a-treadmill analogy.

You're on a treadmill with rollerskates and a rope attached to you. Someone is pulling the rope. The treadmill is tracking the speed of your rollerskates and compensating - but it doesn't matter, because the wheels are free-spinning and the rope, the thing pulling you forward, is completely unaffected by the treadmill. If you were running on the treadmill you wouldn't get anywhere but the rollerskates mean a vast decrease in friction, allowing you to be pulled forward at the expense of spinning a lot faster.

The plane would take longer to take off but it would take off.

Unless you're saying that the plane will go fast, and the wheels will spin twice as fast, so the conveyor will go twice as fast, so the wheels will spin four times as fast, so the conveyor will go twice as fast. But if you've got indestructable wheels (and we're assuming you have) that's not going to matter as far as I can see.
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Great post...great idea too. I know that the engines are competely seperate from the wheels, but that doesn't matter. What does matter is the speed of the wheels has to be effecient enough to move the aircraft forward, not the engines. The engines are there to get the wheels rolling as some people would say. I've read some other people's ideas about this and from what I can tell is that, the the plane is moving 200 MPH and the wheels are moving at 400 MPH...if that could happen then you would sheer the wheels completely from the aircraft. Now I could be wrong about this, but it's a good debate. The only thing that is making the aircraft move across the ground is the wheels, not the engines (in this case only, as the runway is moving the exactly same speed but in the opposite direction of travel). I'll have to do some math for this but I'll try to prove to you that the plane will not takeoff.
 
dream431ca said:
Great post...great idea too. I know that the engines are competely seperate from the wheels, but that doesn't matter. What does matter is the speed of the wheels has to be effecient enough to move the aircraft forward, not the engines.
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No, no, no. You think this is a car, apparently. The engines don't power the wheels! The engine is not there to get the wheels rolling! The wheels are there to allow the plane to move along the ground without tearing off the foliage! The plane would move along the ground whether it had wheels or not!

The speed of the wheels matters? No, it doesn't. Because the wheels aren't pushing against anything. They're not generating any force. They are not what moves the plane.
 
I did some number crunching and here's what the math says:

If the conveyor is always adjusting to the planes speed then the engines will overcome it after a while.

Lets say the runway is around 4000 feet (1.23 KM)

Now after the conveyor has reached a certain speed the engines will start to push the aircraft along, but at a very slow pace which is about 0.23 m/s (meters per second). A 737 needs to be going at around 290 Km/h to takeoff. So doing some more math, with the runway being only 4000 feet long, the plane will only reach a speed of 280 Km/h, which is not enough for takeoff. So in this case the plane will not takeoff. This would only work if the plane was on a longer runway, but most runways are about 4000 feet, so...you happy now!? Definitive evidence that the plane will not takeoff. Now you can close this thread.

Steve said:
No, no, no. You think this is a car, apparently. The engines don't power the wheels! The engine is not there to get the wheels rolling! The wheels are there to allow the plane to move along the ground without tearing off the foliage! The plane would move along the ground whether it had wheels or not!

The speed of the wheels matters? No, it doesn't. Because the wheels aren't pushing against anything. They're not generating any force. They are not what moves the plane.
Click to expand...


I must ask you to think your answer over again. Clearly, there is something that you don't understand. I do understand that the engines are not powering the wheels...what's the difference? And if the plane did not have wheels, it would be sitting on the ground and going nowhere, even at full thrust, believe me, I've seen it. After all I do work in the aviation field. What you must understand is that the wheels are there to transfer the energy of the engines to the ground so you can get the plane to be moving across the ground, otherwise it would be going nowhere.
 
Must I quote myself again?

Please people.....why do you insist it won't take off! It took me 3 minutes to firgure out on my own that it will take off. Why why why why why why!

Bah, eff it. I'm going to stop posting in this thread. It gets me angry.

EDIT: Just read your post above.... It does take off as you stated. Sure most runways are 4000 feet but most runways aren't conveyor belts either. So given a little more room to speed up and it WILL take off. You sir, just owned yourself.
 
Dumb Dude said:
Must I quote myself again?

Please people.....why do you insist it won't take off! It took me 3 minutes to firgure out on my own that it will take off. Why why why why why why!

Bah, eff it. I'm going to stop posting in this thread. It gets me angry.

EDIT: just read your post above.... It does take off as you stated. Sure most runways are 4000 feet, but most runways aren't conveyor belts either. So, given a little more room to speed up and it WILL take off.
Click to expand...

Your going out of the bounds of the question. There is no such thing as a "little more feet" only 4000. And this question does have a conveyor belt in it, so I'm using it in my answer. Mind you, if the plane went off the conveyor belt with the wheels going more than 3 times as fast as the aircraft itself, the wheels would sheer of the aircraft and the aircraft will crash. That's what you get with a "little more feet". And, also the wheels would have been completely destroyed right before takeoff anyway, so the plane would crash..more evidence.

Plane at 279Km/h

Wheels speed at 837Km/h.

Aircraft wheels are good up until 580 Km/h (unless your talking about fighter jet wheels), so the plane would go boom and it would not takeoff.
 
dream431ca said:
Your going out of the bounds of the question. There is no such thing as a "little more feet" only 4000. And this question does have a conveyor belt in it, so I'm using it in my answer. Mind you, if the plane went off the conveyor belt with the wheels going more than 3 times as fast as the aircraft itself, the wheels would sheer of the aircraft and the aircraft will crash. That's what you get with a "little more feet".
Click to expand...
The question never states 4000 feet and it doesn't state its a 737 either. You sir just fixed these numbers just to get to your answer, so that you aren't wrong.
 
dream431ca said:
I did some number crunching and here's what the math says:

If the conveyor is always adjusting to the planes speed then the engines will overcome it after a while.

Lets say the runway is around 4000 feet (1.23 KM)

Now after the conveyor has reached a certain speed the engines will start to push the aircraft along, but at a very slow pace which is about 0.23 m/s (meters per second). A 737 needs to be going at around 290 Km/h to takeoff. So doing some more math, with the runway being only 4000 feet long, the plane will only reach a speed of 280 Km/h, which is not enough for takeoff. So in this case the plane will not takeoff. This would only work if the plane was on a longer runway, but most runways are about 4000 feet, so...you happy now!? Definitive evidence that the plane will not takeoff. Now you can close this thread.
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There is no statement of how long the runway is.

There is no statement as to what kind of plane it is.

The question is, WILL IT TAKE OFF.

IF you're saying the plane will accelerate, then, given a long enough runway, the plane WILL take off.
dream431ca said:
After all I do work in the aviation field. What you must understand is that the wheels are there to transfer the energy of the engines to the ground so you can get the plane to be moving across the ground, otherwise it would be going nowhere.
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Okay, I'm now going to ask you to read what you're typing.

You're saying that the wheels exist as a conduit of energy between the engines and the ground.

So you're saying that the engines push against the ground for thrust.

They don't.
 
Steve said:
Okay, I'm now going to ask you to read what you're typing.

You're saying that the wheels exist as a conduit of energy between the engines and the ground.

So you're saying that the engines push against the ground for thrust.

They don't.
Click to expand...

IF the plane is on the ground, Gravity pushes down on the aircraft, and because gravity is keeping the wheels on the ground, the engines transfer the thrust to the wheels thus making the aircraft move forward. So in a way, the engines are pushing against the ground. Remeber, it's not the engines that lift the plane, it's the air pressure under the wings. You must remeber, the only part of that aircraft that is touching the ground is the wheels. If the aircraft were not touching the ground, then it would be the wings that would be lifting the aircraft due to the air pressure underneath the wings. The engines must transfer energy somewhere or the aircraft goes nowhere.
 
Would a plane move along a (non-conveyor belt) runway if it had no wheels?
The wheels are just the contact point between the plane and the ground. In this case, the wheels would spin freely due to the movement of the conveyor belt. The plane would continue to move forwards. There would be a small amount of negative velocity applied to the plane due to friction from the wheels (hubs and contact patches) but that is all.

Or, to put it another way:

Take a treadmill. Take a skateboard. Place the skateboard on the treadmill. Hold the skateboard in place while you speed the treadmill up. See how it freewheels? Now give it a shove against the direction of the treadmill. What happens?
 
Pi Mu Rho said:
Would a plane move along a (non-conveyor belt) runway if it had no wheels?
The wheels are just the contact point between the plane and the ground. In this case, the wheels would spin freely due to the movement of the conveyor belt. The plane would continue to move forwards. There would be a small amount of negative velocity applied to the plane due to friction from the wheels (hubs and contact patches) but that is all.
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yes correct, but spin freely according to the speed of the aircraft with the conveyor belt going the opposite direction means destruction of aircraft, the wheels would not take that much friction...you would basically see blue smoke for a while then the plane would crash due to loss of wheels.

But if the aircraft had no wheels and the belly of the aircraft was on the ground, it would move, but it would be ripped to shreads before it got to a respectable speed.

Basically there are two answers to the main question of the thread:

1. If you had a million feet of runway, had no friction, nothing to interefere with anything, the aircraft would takeoff.

2. If you had any feet of runway, with real world effects such as friction, airspeed, weight and gravity, the plane would not takeoff, due to destruction of the wheels. It's the forum members choice to choose which one they want to choose.

EDIT: I'm starting to really enjoy this thread. Never had a debate like this in a while :thumbs:
 
Realistically the wheels would break because of the exponential increase in speed.
 
Sulkdodds said:
Realistically the wheels would break because of the exponential increase in speed.
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exactly...the wheels would basically fall apart. Then your riding on the wheel struts, which would break and the plane would go boom.
 
dream431ca said:
yes correct, but spin freely according to the speed of the aircraft with the conveyor belt going the opposite direction means destruction of aircraft, the wheels would not take that much friction...you would basically see blue smoke for a while then the plane would crash due to loss of wheels.

But if the aircraft had no wheels and the belly of the aircraft was on the ground, it would move, but it would be ripped to shreads before it got to a respectable speed.

Basically there are two answers to the main question of the thread:

1. If you had a million feet of runway, had no friction, nothing to interefere with anything, the aircraft would takeoff.

2. If you had any feet of runway, with real world effects such as friction, airspeed, weight and gravity, the plane would not takeoff, due to destruction of the wheels. It's the forum members choice to choose which one they want to choose.

EDIT: I'm starting to really enjoy this thread. Never had a debate like this in a while :thumbs:
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I just want to say that it's good to finally have the words of an avionics expert in the thread.

Well, I think we can all agree that the wheels would be destroyed, but if you'd read the whole thread carefully, we've started to assume indestructible wheels, the ideal situation, etc.
 
Steve said:
I just want to say that it's good to finally have the words of an avionics expert in the thread.

Well, I think we can all agree that the wheels would be destroyed, but if you'd read the whole thread carefully, we've started to assume indestructible wheels, the ideal situation, etc.
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So basically a high school physics problem..those are pretty fun :cheers:

In those questions you always assume the ideal, almost never the real...sometimes you do include gravity or friction but not all the parts of the real world.

EDIT: I must say I enjoy these debates, gets me thinking a lot. It's fun to see what other people are thinking. great stuff.
 
Sulkdodds said:
Realistically the wheels would break because of the exponential increase in speed.
Click to expand...

...and the plane would be thrown off the back 'o the conveyor due to the axle friction!

TAEK THAT STEEVEN!!!

Mathematical physics is my only weakness. It is like kryptonite! :P
 
Who here is awesomely rich and has an airplane? You need to check this out for us. :P
 
The correct answer would depend on the circumstances behind it, there would be some situations where the plane wouldn't fly and then there are others where it would.

Given the general overview of the original question though, it would fly. The reason being that the wheels would have no bearing on aircraft movement across the conveyer belt as it's not the wheelsthat power the aircraft, but the engines. When the engines reach full power and are forcing the plane forward, the wheels would start skidding on the conveyer belt as it's moving in the opposite direction, the plane would carry on getting faster and faster until the plane takes off.
 
If it's a little itty bitty cessna then I doubt the wheels would spin so fast as to be destroyed.

And give it 4000 feet of runway and it'd take off.
 
Dumb Dude said:
The plane takes off! CLOSE THE THREAD!
Click to expand...

QFMFT!!

Holy cr@p!!! How the hell is this thread still going?!?!?! Unless someone comes up with some maths to prove the theory one way or the other (i would but i don't think i remember enough of my Aeronautical Engineering degree to be able to.........that and i can't be arsed), i say close the thread and lets get back to discussing more trivial / less interesting stuff.

Also Dream431ca, can you please give your thoughts to Pi's analogy on page 23 (which is basically the same as mine on page 7).
 
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