Airplane: Does it take off?

[craigwatanabe]

Re: Airplane: Does it take off?

No Kimo, RC Cola has disappeared from the face of the earth

The whole point of a conveyor belt is to spin the wheels of the plane right? Why don't you just motorize the wheels and suspend the whole plane with a string.

If your theory proves true the plane should fly around in circles tethered by the string...like Buzz Lightyear.

But that's all you'll be doing...spinning your wheels. It won't fly...literally! You don't have to be a Rocket Scientist to figure that one out.

You want a really perplexing science/physics project, try running East to West then West to East and see if your time is faster going East to West because you're running against the rotation of the earth so you'll cover more ground because the Earth's rotation is acting like a conveyor belt.

Or here's another one for Myth Busters...set yourself afloat in a hot air balloon and use the stars to geo sync your balloon with the stars so you stay in one spot relative to the stars and outside of the rotation of the Earth. Technically speaking if you could do this, the world would revolve beneath you and you'd circumnavigate the Earth in 23 Hours and 56 minutes with no propulsion system.

Theoretically speaking of course. Reality begs that in order to stay in one spot while the earth precesses, you'd have to fight the mass of the earth's rotational speed of around 1000 MPH to keep up with it. So to save gas when you drive, always drive East to West.

[cezanne]

Re: Airplane: Does it take off?

The "problem" is being discussed at an RC Flight board that I go to and got a laugh out of this response:

"Why, just the other day I was running full speed on my treadmill, held out my arms, and could just feel myself slowly levitating......(and that blast of air sure felt good on my face)"

[pzarquon]

Re: Airplane: Does it take off?

Mythbusters this ain't.

All right, look, if you're going to "test" this, guess what? You don't need a treadmill, or a model plane with a working motor. Why? The "theory" is, the plane can be stationary and still take off. So here's your test:

Take one toy plane. Working wheels, or moving parts of any kind, not required. Place plane on ground. Observe.

Does it lift off? Be sure to report your results to Mr. Wizard's Fun Hotline, kids!

[Paul Ogata]

Re: Airplane: Does it take off?

Well what if the pilot leans forward?

No?

What if he leans forward and farts?

...

I'll be over here, <points to corner and walks sheepishly away>

[zztype]

Re: Airplane: Does it take off?

What if he leans forward and farts?

Whoa. Whatever he ate, I ain't having! That's gotta be one hella fart to make the plane take off. Did he light a match at the same time??? Yow.

---

I'll go stand in the OTHER corner now...OK?

[1stwahine]

Re: Airplane: Does it take off?

hahahahahaha! I neva laugh all day!

hahahahahaha!

Thank you.

Auntie Lynn

[tutusue]

Re: Airplane: Does it take off?

Well what if the pilot leans forward?

No?

What if he leans forward and farts?

Finally...someone who put this thread in understandable, non-technical terms!

I'll be over here, <points to corner and walks sheepishly away>

Hey...watch where you're goin'. That's MY corner.

[craigwatanabe]

Re: Airplane: Does it take off?

Of course he lit the match how do you think he lit the afterburners

[Lei K]

Re: Airplane: Does it take off?

Oh man, I part Portagee, this stay too complicated for me until we started talking about farts.

[cezanne]

Re: Airplane: Does it take off?

Whoa. Whatever he ate, I ain't having! That's gotta be one hella fart to make the plane take off. Did he light a match at the same time??? Yow.

Ahhh the memories...the BLUE FLAME! BLUE FLAME! BLUE FLAME! chant in the background.

[tutusue]

Re: Airplane: Does it take off?

Oh man, I part Portagee, this stay too complicated for me until we started talking about farts.

Oh yah! Me too! Well, not the Portagee part. We of the Blarney relate much easier to farts than to jet propulsion!

[pzarquon]

Re: Airplane: Does it take off?

It's amazing when familiar topics will flare up elsewhere. The "airplane-treadmill" question is suddenly burning up pixels all over the blogosphere. The latest flare-up seems to have been prompted by New York Timestechnology writer David Pogue's blog, where he posted the conundrum on Monday. To date, over 600 people have commented with mostly well-argued but completely different answers to the question.

The Boing Boing blog gave the question a shot, too, and similarly netted many, many well-argued responses. And it turned up in Kottke.org some months ago, with 300 comments before the discussion was closed.

Most, though, seem to cite The Straight Dope's Cecil Adams and his answer to the "airplane-treadmill" question as the definitive, and correct one. The plane takes off. But I'm still not convinced.

[Composite 2992]

Re: Airplane: Does it take off?

Well, here's what happened in real life.

When there were some very stiff winds a Honolulu flight instructor (Chacy Eveland, now retired) and his student landed a Cessna 152 on Molokai. Winds were coming straight down the runway and they did a full-flap approach.

On touchdown airspeed matched windspeed and the plane's wheels settled with almost no forward movement. The instructor had to open up the throttle to taxi forward.

With airplanes groundspeed doesn't matter. What matters is airspeed. How fast the air goes under and over the wings is what counts. And that is determined by how the aircraft's propulsion system interacts with the surrounding air. Doesn't matter if the ground is dead stil or moving. The only problems that might be encountered is a blow-out if the tires overheat on roll-out or if the plane has to deal with a up-slope or down-slope.

Turn the situation sideways and think of it this way: If someone were to move the dock as you paddled a canoe, would it affect how fast your canoe moved through the water?

[Kungpao]

Re: Airplane: Does it take off?

It's amazing when familiar topics...

Most, though, seem to cite The Straight Dope's Cecil Adams and his answer to the "airplane-treadmill" question as the definitive, and correct one. The plane takes off. But I'm still not convinced.

Nor should you be convinced.

Once the pilot fires up the engines, the plane moves forward at pretty much the usual speed relative to the ground--and more importantly the air--regardless of how fast the conveyor belt is moving backward.

Ok.. The jets push the plane. If the situation was normal, the rubber on the wheels would push against the ground and the air at the equivalent force of the jet engine's force on the plane. Makes sense. A force of action creates an equal yet opposite force of reaction. (My phisics teacher would kill me for not remembering the law exactly lol) So two scenarios occur the jets push the plane and thanks to gravity, the plane's weight pushes the wheels to the ground. Let's picture the plane so that if you're looking at it, the plane's nose is to your left and the rear is on the right. The jets push the plane to the left. The reason that the plane moves is because the ground is solid and does not move therefore the force translates to the plane.

In the proposed argument, the ground moves. The ground provides the opposite reaction to the force being applied by the jets. The Jets CANNOT apply more force than the conveyor moves in the opposite direction. If they did, the plane would take a nose dive into the pavement. Ground speed is directionally proportional to the force that the jets provide.

You were right the first time IMHO The plane does not move. It has no air movement to apply another force to the wings.




something i just thought of. Do lumberjacks doing a log rolling competition go anywhere? If you strap wings to them while they run on the log will THEY take off?

[craigwatanabe]

Re: Airplane: Does it take off?

If you read my post (post #11) it explains it. It's the mass of the air flowing over and under the wings of the plane that determines whether the plane will lift not the speed of the conveyor belt.

With the plane stationary and no head wind, there is no air flow around the wings so no lift occurs.

This isn't rocket science, this is high school physics! This scenerio just plain doesn't work.