A jet plane on a large treadmill

[Captain Anal]

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

Okay, fine. I'm out.

[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.

[beaterdit]

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.

Bwahahhahahaha! GOLD!


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

[Mustonen]

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.

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.

[flyandski365]

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.

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?

[stuckathuntermtn]

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

[Ted Striker]

!!

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.

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

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.

[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!

[Captain Anal]

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.

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.

[flyandski365]

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

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

[Mustonen]

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

Fucking crazy, right?

[mcsquared]

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.

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

[Ted Striker]

Hook, line, and sinker!

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

[Mustonen]

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!

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.

[flyandski365]

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

[From_the_NEK]

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

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

[beaterdit]

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.

[Art Shirk]

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.

Amen. . . . .

[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.

[DJSapp]

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

[jfost]

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

[GeezerSteve]

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

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.

[f2f]

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.

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!

[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. Does it just fucking levitate?

Sent from my DROID2

[Captain Anal]

If Nicolas Cage were on a treadmill...