Author Topic: Plane on a Treadmill (Read 19827 times)

The D · « **on:** Feb 23, 2006, 04:55:25 PM »

This has stumped people on other boards and even started an argument on 4chan's IRC channel.

Imagine a jet plane (although it could probably be any sort of plane), and a runway that's a giant treadmill. When the plane's on the treadmill, the treadmill matches the plane's airspeed (relative to the ground) but in the opposite direction. So when the plane's at the end of the runway/treadmill going 0mph, the treadmill's going 0mph. When the plane's traveling at 80 knots facing north, the treadmill's going 80 knots southward.

Does the plane take off? This answer doesn't require complex math, just common sense.

I believe it can take off. I'll say why after a while, to see if someone else can explain it.

tomduo · « **Reply #1 on:** Feb 23, 2006, 05:00:17 PM »

If there's opposing motion, there's no drag.

The D · « **Reply #2 on:** Feb 23, 2006, 05:07:09 PM »

Wrong.

And no mention of planes is complete without this:

tomduo · « **Reply #3 on:** Feb 23, 2006, 05:18:05 PM »

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Wrong.

No, not wrong. If the plane is stationary, there is nothing moving through the air, which means there's no drag, which means the plane couldn't make lift.

Rama · « **Reply #4 on:** Feb 23, 2006, 11:21:22 PM »

He's right. As much as I hate to admit it. If the plane isn't moving forward, Lift can't build up under the wing and therefore it can't rise off the ground. The way a plane wing works, is that the bottom is flat and the top is curved. When it cuts though the air, it takes longer for the air to travel over the wing then he does under the wing and this causes lift. If there is no forward movement, then this won't happen.The people at those other boards are just dumb.

B E C K · « **Reply #5 on:** Feb 23, 2006, 11:39:28 PM »

The plane should just try vomiting for a few weeks. Then it'll fit into that prom dress, no problem.

tomduo · « **Reply #6 on:** Feb 23, 2006, 11:51:34 PM »

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He's right. As much as I hate to admit it. If the plane isn't moving forward, Lift can't build up under the wing and therefore it can't rise off the ground. The way a plane wing works, is that the bottom is flat and the top is curved. When it cuts though the air, it takes longer for the air to travel over the wing then he does under the wing and this causes lift. If there is no forward movement, then this won't happen.The people at those other boards are just dumb.

Aren't you glad I wasn't aborted?

Chopper Face 69 · « **Reply #7 on:** Feb 24, 2006, 12:04:34 AM »

Yeah. Plane won't take off. This is my opinion as an engineer and, briefly, air cadet as well as non idiot.

The reason is stated above. Plane uses it's movement relative to the air around it, not the ground, to take off.

Extra Zero · « **Reply #8 on:** Feb 24, 2006, 12:05:27 AM »

I hate 4Chan...so very much...

Rama · « **Reply #9 on:** Feb 24, 2006, 12:07:46 AM »

Quote

Quote
He's right. As much as I hate to admit it. If the plane isn't moving forward, Lift can't build up under the wing and therefore it can't rise off the ground. The way a plane wing works, is that the bottom is flat and the top is curved. When it cuts though the air, it takes longer for the air to travel over the wing then he does under the wing and this causes lift. If there is no forward movement, then this won't happen.The people at those other boards are just dumb.
Aren't you glad I wasn't aborted?

Eh....I could go either way.

Extra Zero · « **Reply #10 on:** Feb 24, 2006, 12:10:42 AM »

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Eh....I could go either way.

I LOL'D.

Rama · « **Reply #11 on:** Feb 24, 2006, 12:15:24 AM »

I just want someone to love me!

tomduo · « **Reply #12 on:** Feb 24, 2006, 03:05:38 AM »

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I could go either way.

I just want someone to love me!

...are you hitting on me? :huh:

IDE · « **Reply #13 on:** Feb 24, 2006, 06:24:20 AM »

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I hate 4Chan...so very much...

4chan loves me

Faye Valentine · « **Reply #14 on:** Feb 24, 2006, 07:39:14 AM »

Rama almost answered correctly, but he didn't.

Now,here's the real answer. And it's real cause my dad being a pilot, I probably know more about airplanes than most of you B)
Wait, oh shit I was gonna talk about the big airplanes, i don't know about little jets. forget it.

Wickedly Yours E · « **Reply #15 on:** Feb 24, 2006, 09:37:12 AM »

Damn you Faye, getting my hopes up like that.

Rama · « **Reply #16 on:** Feb 24, 2006, 11:09:55 AM »

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Rama almost answered correctly, but he didn't.

Now,here's the real answer. And it's real cause my dad being a pilot, I probably know more about airplanes than most of you B)
Wait, oh shit I was gonna talk about the big airplanes, i don't know about little jets. forget it.

The basic princple is the same for all winged aircraft. Large or small...The only difference is the amount of powet it takes to reach lift off speed. IE: the larger the plane the more powet you need.

Now if you had an Anti-gravity driven aircraft then that's different...but those arn't suppose to exist. :unsure:

tomduo · « **Reply #17 on:** Feb 24, 2006, 12:21:34 PM »

How did Faye give us an answer when she didn't..?

WORST EPISODE EVER!

Rodent of Unusual Size · « **Reply #18 on:** Feb 24, 2006, 01:41:30 PM »

You can have a nuclear-powered rocket engine with the ability to reverse the Earth's rotation, and it wouldn't matter. If there's an equal and opposite force holding the plane in it's fixed position (the treadmill matching velocity), there is no relative airspeed; i.e., no air is passing under the wing and thus no lift.

Saying it can is idiotic.

tomduo · « **Reply #19 on:** Feb 24, 2006, 02:53:57 PM »

*already said that* <.<

Why does anyone go to 4chan aside for looking for pr0n?

B E C K · « **Reply #20 on:** Feb 24, 2006, 08:33:23 PM »

"6 Firefox"? FTW? Are you telling me you're not using the tabs and actually have six windows open? Why?

IDE · « **Reply #21 on:** Feb 24, 2006, 08:37:11 PM »

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*already said that* <.<

Why does anyone go to 4chan aside for looking for pr0n?

There's this guy that posts there that's really funny.

B E C K · « **Reply #22 on:** Feb 24, 2006, 08:39:20 PM »

...and incidentally has manga-boobies.

IDE · « **Reply #23 on:** Feb 24, 2006, 08:52:04 PM »

oh you know anonymous.

The D · « **Reply #24 on:** Feb 25, 2006, 02:57:10 PM »

You're wrong, and you make the assumption that everyone makes, which is incorrect.

First off, you're comparing your thinking to that of a car on a treadmill. Since the car propells itself forward by friction from the ground, if it's driving on a treadmill going the same speed, the speed of the treadmill cancels out the speed of the car.

However, an airplane has wheels that freely turn. And the plane gets it's thrust from the engines, not the wheels. As the plane starts to accelerate from zero, the conveyor belt would match it's speed. The wheels would spin along with the belt, but the plane itself would be mostly unaffected by the backwards movement of the treadmill. Thus, the plane WOULD be moving forward and would have air traveling under the wings and would take off.

I have websites to prove it, too!
http://experts.about.com/q/Physics-1358/Ai...ving-runway.htm
http://www.straightdope.com/columns/060203.html

Also, you guys failed to take into account the plane might be a VTOL or be flying into a really STRONG wind.

tomduo · « **Reply #25 on:** Feb 25, 2006, 03:06:00 PM »

And the wind is blowing in the exact direction of the airplane, and I mean exact without crosswinds?

And most of the stuff found online is crap, and this smells of it. Even with the engines providing the movement, the plane is still remanining stationary.

If this was a viable option, we wouldn't still build aircraft carriers.

Chopper Face 69 · « **Reply #26 on:** Feb 25, 2006, 03:12:49 PM »

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VTOL

A VTOL doesn't have to use a runway to take off. Why would it even have wheels? By your analogy the treadmill would be completely immobile.

As for the other stuff... it's crap. If like "you" say the plane is moving faster than it's wheels then it's already flying and it can't get to that speed to fly just a little if it's not actually moving relative to it's outside environment because of the conveyor belt. What you're saying is like... if you tied a plane up and put it on blocks and then cut the cord as you removed the blocks then the plane would just start from a stationary position.. well yeah I don't believe that. The plane would go down, at least a bit, before getting speed and raising itself and unless the initial momentem takes it go up right off before going forward then the treadmill thing is crap.

As for wind it would have to be so strong that it would make an immobile plane just take off... which is retarded. Planes parked on a runway don't generally just take off when it's a bit windy.

B E C K · « **Reply #27 on:** Feb 26, 2006, 12:53:42 PM »

Mind did, but then again it was made out of paper.

The D · « **Reply #28 on:** Feb 26, 2006, 09:58:44 PM »

I'm still right, fools!

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It was an interesting argument, but as things progressed, more rational heads prevailed, pointing out that the airplanes do not apply their thrust via their wheels, so the conveyor belt is irrelevant to whether the airplane will takeoff. One guy even got one of those rubber band powered wood and plastic airplane that sell for about a buck, put it on the treadmill someone foolishly donated to the Lounge years ago, thinking that pilots might actually exercise. He wound up the rubber band, set the treadmill to be level, and at its highest speed. Then he simultaneously set the airplane on the treadmill and let the prop start to turn. It took off without moving the slightest bit backwards.

They even did the experiment and it worked!

I also like the comparison to the hovercraft. Stick a hovercraft on this conveyor belt runway, and no matter how fast the conveyor belt rotates, the hovercraft will still travel forward... there's little friction with the ground.

tomduo · « **Reply #29 on:** Feb 26, 2006, 10:40:11 PM »

Who the fuck is Rick Durden, and if he was so smart, why does he blog instead of fuck supermodels in the Turks and Caicos Islands like Bill Gates, Lockheed and Martin.

You fail, and so does Rick Durden.