A jet plane on a large treadmill

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Originally Posted by Captain Anal

Okay okay. So the OP is stupid/poorly worded/not enough information or something. What is the plane moving in relation to? The air? The treadmill? GSA?

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Really? I didn't think so. I mean, you can turn it into some metaphysical discussion about reality ("We're all MOVING, maaannnn") but the OP is pretty clear. What I think is remarkable is how people add their own crap to it and try to defend it to the death.

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Originally Posted by Mustonen

Really? I didn't think so. I mean, you can turn it into some metaphysical discussion about reality ("We're all MOVING, maaannnn") but the OP is pretty clear. What I think is remarkable is how people add their own crap to it and try to defend it to the death.

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I'm not adding anything to it. If the plane is only being propelled by the wheels how can the fucking thing MOVE if the conveyor is moving in the opposite direction? It would sit still with only the wheels spinning beneath it. Since there is really no movement in relation to the air, then there is no air moving over the airfoil and so there is no lift. But if you turn on the jets, then the plane will actually 'move' and air will flow over the airfoil creating lift and allowing the plane to take off.

http://www.forgingelitesarcasm.com/w...12/01/jeez.jpg

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Originally Posted by Mustonen

Ah. See. You're wrong there. Go read the OP again. Treadmill moves when the plane moves. If the plane doesn't move the treadmill doesn't move. For the treadmill to move, the plane must also be moving. If the plane is moving, air will move over the airfoil. It doesn't matter what's propelling it. For goddamn christ's sake.

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I'm pretty sure you're wrong here man. How does the plane move forward if it is being propelled by the wheels and the treadmill is matching speed in the other direction? It doesn't. As far as I understand it, the treadmill is basically being used to mimic a frictionless surface. Something driven by wheels uses torque and friction to propel the object forward. No friction = no forward motion.

All of that really doesn't matter though does it? Planes don't use wheels for propulsion.

I've got to be at the office for 2.5 more hours, I've got no work left to do, this day was going slow as shit already, checking the spare at 5:30.

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Originally Posted by Captain Anal

I'm not adding anything to it.

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Bullshit. OP says the plane moves in a direction. You started talking about friggin wheelspin. Who brought up wheelspin? You did. The treadmill doesn't give a shit about wheelspin, it cares about the plane moving in a direction. It doesn't counter it, it just moves at the same speed in the opposite direction.

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Originally Posted by Captain Anal

If the plane is only being propelled by the wheels how can the fucking thing MOVE if the conveyor is moving in the opposite direction? It would sit still with only the wheels spinning beneath it.

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Incorrect. Plane moves forward at X, conveyor moves backward at -X, wheels spin at 2X.

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Originally Posted by flyandski365

How does the plane move forward if it is being propelled by the wheels and the treadmill is matching speed in the other direction?

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Because the treadmill is matching airplane speed, not wheel speed. The two are not inseperable.

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All of that really doesn't matter though does it? Planes don't use wheels for propulsion.

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None of this actually matters. Shit dood, it's Friday afternoon over here. It is sort of fundamental, though, to understanding the scenario as presented.

Heh, always amusing to see this pop up. This was the thread that brought me to TGR way back in '05 from a link on [cough]tele-tips[cough]. After reading that drivel for a couple years I thought the innernets were dead until I found this place. I remember LOLing constantly at some of the stuff here. What ever happened to that? Did I kill teh TGRs?

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Originally Posted by stuckathuntermtn

No. There is no airflow over the lifting surface.
0 Knots True Airspeed.
It's Ground Speed could be 400KTA relative to the tread mill, but as long as there is 0KTA over the airfoil, it can't take off.
That's why planes take-off and land into the wind. While the plane may be fighting a head wind and have a lower ground speed, its airspeed is higher by however many knots the headwind is.
for example: at 200kts ground speed in a 10kt headwind, the kta is 210kts. and off into the wild blue yonder you go.


Morans.
http://en.wikipedia.org/wiki/Airfoil

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Originally Posted by Garbanzo

It would depend on the size of the treadmill. If it was miles long and wide enough, then it would affect the air above it and result in a big headwind. The jet might lift off without moving forward but only for a second before encountering normal air and falling. At which point it would fly up as it encounters the fast airstream ... and then fall again.

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Quality trolling here guys. Bravo!

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Originally Posted by pisteoff

This is exactly what I was talking about. Correct answer to a different question; wrong answer to this one.



No.

What force moves the airplane forward? What force holds it back?

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Hook, line, and sinker!

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Originally Posted by Mustonen

Bullshit. OP says the plane moves in a direction. You started talking about friggin wheelspin. Who brought up wheelspin? You did. The treadmill doesn't give a shit about wheelspin, it cares about the plane moving in a direction. It doesn't counter it, it just moves at the same speed in the opposite direction.

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Okay, so what I am gathering from your argument is that in your interpretation of the question, the treadmill actually does not even play a factor in this whatsoever. So if we go with your interpretation, the plane might as well be sitting on pavement, a herd of cattle, or boiled hot dogs and it wouldn't make any difference.

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Originally Posted by Dantheman

Incorrect. Plane moves forward at X, conveyor moves backward at -X, wheels spin at 2X.

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Okay, fine. I'm out.

Holy fuck. Some of you should be embarrassed. Except Stuckatthuntermtn, par for the course there. The plane takes off. The harder you argue against it the stupider you get.

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Originally Posted by mcsquared

Holy fuck. Some of you should be embarrassed. Except Stuckatthuntermtn, par for the course there. The plane takes off. The harder you argue against it the stupider you get.

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Bwahahhahahaha! GOLD!


And BTW YetiMan answers the question correctly in the very first response.

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Originally Posted by Captain Anal

Okay, so what I am gathering from your argument is that in your interpretation of the question, the treadmill actually does not even play a factor in this whatsoever. So if we go with your interpretation, the plane might as well be sitting on pavement, a herd of cattle, or boiled hot dogs and it wouldn't make any difference.

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Uh... sure it does. Those wheels spin twice as fast as a result of the whole hoary mess.

My assumptions in my "interpretation": When it says airplane it means the airplane. When it says move it means change position relative to its environment (not spin the wheels). I guess my interpretations could be opened up for debate - but I don't really fucking think so, man.

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Originally Posted by Mustonen

Bullshit. OP says the plane moves in a direction. You started talking about friggin wheelspin. Who brought up wheelspin? You did. The treadmill doesn't give a shit about wheelspin, it cares about the plane moving in a direction. It doesn't counter it, it just moves at the same speed in the opposite direction.

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In a direction relative to what? That isn't stated in the OP, and seems to be causing some consternation here. If we assume that the plane is able to move relative to the ground independent of the treadmill, then like Dantheman said the wheels have to spin twice as fast as the aircraft is moving. I think though that a lot of people interpret the question to mean that the plane is moving relative to the surface of the treadmill, which given the conditions of the question would make it impossible for the plane driven by wheels to move.

If we make the first assumption, how is this even a question?

Jets, propellers, or unicorn farts. It doesn't matter. If the airfoil is not moving relative to the air, there is no lift. It could be a fucking nuclear submarine. There is no airflow over the lifting surface. The kta is 0.
I guess if it was an osprey, it could tilt its rotors up and take off. But that still only works because of airflow over the proprotors, which are lifting bodies. And the thrust is directed downward.

Ok, here's another similar analogy:
If you were running on a treadmill and you had one of those little drag chutes attached to you, would it inflate/deploy?

Of course not. As long as you move at the same speed that the treadmill moves, you could have a fucking rocket pack on your back. Your kta is 0.



Sent from my DROID2

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Originally Posted by Mustonen

!!

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Well, it was 6 years ago.

I didn't bother going back and reading the OP because this isn't the only place this was discussed. It was beaten to death IRL at my job, and on other forums that I was on at the time. The first time it was put to me, it was phrased that the motion of the conveyor belt exactly and instantaneously matched the rotation of the plane's wheels. That wording implied that the plane cannot move. Yet the plane's engines would push it forward, hence the paradox. I admit that the OP didn't say that. In the OP's version, there is absolutely nothing preventing the airplane from taking off.

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Originally Posted by Mustonen

Water is obviously not frictionless - but if water speed is equal to the max speed of the airplane (and not the airplane's actual speed), the force of the river (even just that force being applied to the airplane) is far greater than that of the props. I'm guessing that a combination of plane+lift from the wings are necessary for a plane to actually get out of the water - though I suppose I don't know that for a certainty. Either way, bad analogy, and even if it wasn't bad it bears little relation to either the OP scenario

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I only said max speed because I knew someone would say that the float plane is capable of going faster than the speed required to lift off, so I nipped that argument in the bud. The way it pertains to the OP's scenario is that it's the opposite - and it illustrates what people are thinking when they say it doesn't take off.

I love how on the first couple pages it is mainly civil discourse, now it is all "OF FUCKING COURSE IT TAKES OFF YOU CUMGUZZLING IDIOTS"...

heh, classic!

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Originally Posted by Mustonen

Uh... sure it does. Those wheels spin twice as fast as a result of the whole hoary mess.

My assumptions in my "interpretation": When it says airplane it means the airplane. When it says move it means change position relative to its environment (not spin the wheels). I guess my interpretations could be opened up for debate - but I don't really fucking think so, man.

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The problem here is that I made certain assumptions about what the OP actually meant (what flyandsky is saying) and you did not make those assumptions and are just answering the question.

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Originally Posted by Mustonen

Because the treadmill is matching airplane speed, not wheel speed. The two are not inseperable.

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I realize that, but see my above post.

I think we can all agree though that the whole thing is retarded and that the plane takes off

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Originally Posted by Captain Anal

and you did not make those assumptions and are just answering the question.

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Fucking crazy, right?

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Originally Posted by stuckathuntermtn

Of course not. As long as you move at the same speed that the treadmill moves, you could have a fucking rocket pack on your back. Your kta is 0.

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This is a brilliant analogy. However, it proves the exact opposite of what you think it does. But carry on.

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Originally Posted by beaterdit

Hook, line, and sinker!

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It would be if they were trolling, but they aren't.

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Originally Posted by jfost

I love how on the first couple pages it is mainly civil discourse, now it is all "OF FUCKING COURSE IT TAKES OFF YOU CUMGUZZLING IDIOTS"...

heh, classic!

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Better than saying something similar to my coworkers on a friday afternoon at the end of a shitty week -- all too likely a scenario. I've found that kind of thing goes over much better here on TGR.

Heh, there's definitely a correlation between Friday afternoon and when these types of threads heat up.

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Originally Posted by mcsquared

This is a brilliant analogy. However, it proves the exact opposite of what you think it does. But carry on.

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I was going to write a long reply to his post but saw yours and it sums up what I was going to say nicely :)

Also, the answer is built right into the question. If the plane doesn't move neither does the treadmill. THE PLANE HAS TO MOVE IN ORDER FOR THE TREADMILL TO MOVE. If the plane moves, it takes off.

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Originally Posted by mcsquared

Holy fuck. Some of you should be embarrassed. Except Stuckatthuntermtn, par for the course there. The plane takes off. The harder you argue against it the stupider you get.

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Amen. . . . .

If I read the OP correctly the plane is not moving forward. If the plane isn't moving forward air isn't rushing over/under the wings and it won't take off.

Hey stuckathunter--have you seen the youtube video where the plane was trying to take off on the runway, and it dropped it's driveshaft to the starboard wheels and flipped? It's fucking crazy. Check it out.

www.youtube.com/watch?v=dQw4w9WgXcQ

I've DEFINITELY got $20 towards a drag chute, a treadmill and a rocket pack to film stuck's proposed experiment... we should probably do it outside though ;)

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Originally Posted by Todds

If I read the OP correctly the plane is not moving forward.

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You misread the OP. It said that the plane was on a conveyor belt. It does not say that the plane was not moving forward.

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Originally Posted by Todds

If I read the OP correctly the plane is not moving forward. If the plane isn't moving forward air isn't rushing over/under the wings and it won't take off.

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if i hear one more of this sort of argument I swear i'm going to start slapping people over standard TCP/IP.

some jets can do vertical takeoff. your argument is invalid.

sweet jesus tapdancing on a cracker!

Explain to me how the plane takes of or the drag chute inflates if the treadmill is moving backwards at the same speed you are moving forwards. Does it just fucking levitate?

Sent from my DROID2

Attachment 114310
If Nicolas Cage were on a treadmill...

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Originally Posted by stuckathuntermtn

Explain to me how the plane takes of or the drag chute inflates if the treadmill is moving backwards at the same speed you are moving forwards.

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Explanation:

1. wheels spin

2. airplanes are propelled by jets or propellers, not by wheels, i.e., an airplane is not a car

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Originally Posted by stuckathuntermtn

Does it just fucking levitate?

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yes. that is the correct term. a vertical takeoff plane levitates. as does a helicopter.

goddamn this thread makes me so mad. off to drink beer.

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Originally Posted by f2f

if i hear one more of this sort of argument I swear i'm going to start slapping people over standard TCP/IP.

some jets can do vertical takeoff. your argument is invalid.

sweet jesus tapdancing on a cracker!

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Originally Posted by f2f

yes. that is the correct term. a vertical takeoff plane levitates. as does a helicopter.

goddamn this thread makes me so mad. off to drink beer.

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The Harrier Jet (and I assume you mean a harrier because an osprey/helicopter uses rotating blades that are their own airfoils and do have air rushing over them to generate lift) generates lift by vectoring the thrust produced by it's engines downwards. When this thrust opposes the downward weight force of the aircraft, the aircraft will lift of. This is entirely different than a jet accelerating down a runway and generating lift from the air rushing over it's wings. A 747 is not a vertical lift aircraft with vectored thrust engines.

Read this.

http://www.aerospaceweb.org/question...s/q0102a.shtml

Fucking airplanes how do they work. A mystery like magnets

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Originally Posted by OverTurn

A 747 is not a vertical lift aircraft with vectored thrust engines.

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Yes, of course, but a 747 has wheels that spin freely and is powered by jet thrust. The conveyor belt makes the wheels spin faster but does not inhibit the 747 from moving forward. An airplane on a conveyor belt is not like a car on a conveyor belt.