15

THE PLANE WILL NOT TAKE OFF

2/1/2008 7:11:12 PM

the treadmill takes off from underneath the plane.

2/1/2008 8:01:18 PM

Quote :

"Not really a problem at all. The friction force is always a reaction force and at worst case the assumption gives the static friction forces to be a fraction of the weight of the plane. Also, remember that a lot of that static-friction force on the wheels is going into accelerating the wheels, not the plane anyways. Yeah the no slip condition isn't exactly perfect and you will get some slipping at higher speeds, but it still doesn't change the relative magnitudes of forces you're dealing with or any of the conceptual stuff. Why exactly do you think it's a problem though? No-slip just establishes that the movement of the wheels is purely rolling as opposed to skipping along the ground. It doesn't mean they're not turning. Besides, when exactly that slipping occurs isn't relevent to the end conclusion that the plane would move forward. Complete no slip for the wheels is the best someone could hope for in terms of total force applied to the plane from the treadmill- and even that ends up being fairly small. When you consider slipping then that just makes the treadmill even that more laughable as far as stopping the plane from taking off."

I don't even know what you're arguing. Your first paragraph is a restatement of what I said in previous posts. I already said why the no-slip condition is a problem. For some planes, no matter how fast the treadmill goes or how fast it accelerates, the wheels will slip and the plane will slide forward.

Quote :

"When you consider slipping then that just makes the treadmill even that more laughable as far as stopping the plane from taking off."

That's exactly the argument I was making.

2/1/2008 8:56:38 PM

You're the one who said the no-slip condition was a "big problem." It simplifies the the solution to the physics but you still get the same basic qualitative answer. How is that a problem?

[Edited on February 2, 2008 at 12:22 AM. Reason : ]

2/2/2008 12:18:19 AM

y'all need to build a conveyor belt.

I'll take an airplane off from it when i get back to NC in a few months for $1000

and I'll also bet anyone who wants to bet it can't be done.

I'll put my own ass and money on the line

then take your money

[Edited on February 2, 2008 at 12:48 AM. Reason : i'll do it with a radio controlled airplane for $100 OR enough bets to win that it'll be worthwhile]

2/2/2008 12:47:42 AM

i bet nobody would question this shit if a harrier were involved.

2/2/2008 2:00:15 AM

nope

but i'll do it in a Cessna

or with a radio controlled airplane

2/2/2008 2:34:54 AM

^^^^I meant it's a big problem for the treadmill-prevents-forward-motion-of-the-airplane individuals.

2/2/2008 4:07:32 PM

Quote :

"i bet nobody would question this shit if a harrier were involved."

haha yea.

2/2/2008 4:10:59 PM

ok, new twist to the problem

what if one wheel is on a treadmill going backward and one wheel is on a treadmill going forward and the tail wheel is on the ground between the treadmills?

2/2/2008 5:16:44 PM

I believe it is quite obvious the plane will spin in circles while ripping a whole in space. A black hole will spawn from this tear and we'll all be sucked in

Except for the plane which will fly like a helicopter

2/2/2008 5:30:51 PM

yep, after making some unrealistic assumptions about friction and other sciencey stuff, i calculated the exact same thing!1!!!

2/2/2008 5:37:58 PM

2/7/2008 2:38:45 PM

haha that pic is priceless

2/7/2008 2:44:41 PM

Quote :

"y'all need to build a conveyor belt. I'll take an airplane off from it when i get back to NC in a few months for $1000"

god damn. both sides keep clinging to this stupid shit. what the fuck is wrong with you people.

2/7/2008 4:38:52 PM

ahhh ha ha what a good mama hippo

2/7/2008 4:49:55 PM

Quote :

"WON'T TAKE OFF"

2/11/2008 3:03:15 PM

and again

4/12/2009 8:41:11 PM

This topic makes me rofl

4/12/2009 9:21:44 PM

Quality bttt.

I forgot I'd posted in this one.

Brought the lol.

4/12/2009 11:29:08 PM

somebody may have brought this up before, but is there a difference between a stationary plane on a treadmill and a plane with it's wheels locked so it's also stationary?


why the need to build a conveyor belt, why not just lock the wheels and see if the plane can take off when it's not moving at all?

then again, if that were the case, then why do we need runways?

4/12/2009 11:42:49 PM

^I might be getting trolled, but...

The point of the myth is not to test if a stationary plane could take off. (Especially since with the engine/propeller turned on at normal takeoff speeds, the treadmill couldn't possibly stop the plane's forward motion anyway and still remain within the constraints of the myth)

The point of the myth is to fool people into thinking that a plane's forward motion is generated by the wheels acting against the ground (like a car does) instead of by the engine/propeller acting against the air, with the wheels freely spinning (like a plane does).

[Edited on April 12, 2009 at 11:47 PM. Reason : .]

4/12/2009 11:46:40 PM

you watch mythbusters on a totally different level than me.

4/12/2009 11:50:44 PM

I didn't even watch the episode, I've just seen enough of the laughable internet debate over it.

4/12/2009 11:52:16 PM

Quote :

"god damn. both sides keep clinging to this stupid shit. what the fuck is wrong with you people. "

Are you serious? You have a degree in civil engineering and think the airplane won't take off?

4/13/2009 8:39:20 AM

http://www.youtube.com/watch?v=YORCk1BN7QY

the mythbusters video for this page

4/13/2009 8:46:04 AM

^Problem solved end of discussion

4/13/2009 9:26:34 AM

lulz, trolls and fools argue that it won't take off

4/13/2009 10:25:43 AM

I could never understand why the pilot thought it wouldn't work.

of all the people who would get it you'd think he would.

4/13/2009 11:19:07 AM

whoa wait a minute. He wasn't stationary, he was going right past those fucking cones.


I call bullshit.


get a bigger plane. One data point is not a fucking science experiment

4/13/2009 11:26:22 AM

^ they performed the same experiment at a much smaller scare with a remote control plan and smaller conveyor belt. It still worked.

And by it still worked I mean the plane took off.

[Edited on April 13, 2009 at 11:29 AM. Reason : df]

4/13/2009 11:29:04 AM

Quote :

"whoa wait a minute. He wasn't stationary, he was going right past those fucking cones."

that's the entire fucking point of why the myth is based on a false premise.

No matter how fast the truck/treadmill is moving, as soon as the plane exerts thrust with its propeller, it will begin to move forward relative to the ground and cones. The treadmill could be moving 1000mph backwards, and with just a wee bit of thrust, the plane would move right on ahead with no problem, assuming the wheel bearings don't burn up from spinning so fast on the treadmill.

Quote :

"get a bigger plane. One data point is not a fucking science experiment"

an experiment is not even needed in this case. The whole problem can be solved definitively using only theory and known principles. Mythbusters could have just gotten a chalkboard and a professor to explain how the myth works, but that's just not how their show works

[Edited on April 13, 2009 at 11:34 AM. Reason : . ]

4/13/2009 11:32:19 AM

the myth is a plane taking off on a treadmill not a stationary plane taking off... for the 100x in this thread.

lol at the harrier comment, i bet people thinking a plane would not take off would say, only a harrier could take off on a treadmill like it is some magic plane

4/13/2009 11:32:24 AM

pfffth...lies

4/13/2009 11:39:53 AM

it doesnt take an engineering degree to understand that the plane will take off. all it takes is common sense. the plane will move forward, the plane will take off. the engine/props dont care what the wheels or conveyor belt are doing. they are going to push the plane through the air at ground level until lift is acheived and the plane takes off. the plan WILL NOT sit still; it will always move forward.

4/13/2009 12:24:22 PM

how would you know what a plane cares about

4/13/2009 2:47:37 PM

I know what a plane cares about.

4/13/2009 3:07:45 PM

EXACTLY: Best friends, homework and saing no to drugs

planes are essentially hard working people but they get confused and start experimenting in college.

4/13/2009 3:16:24 PM

^This man speaks the truth.

4/13/2009 3:19:08 PM

i am racist against planes

4/13/2009 3:20:08 PM

What about a plane on a giant turntable?

Not just a turntable big enough to fit a helicopter, I mean one HUGE FUCKING TURNTABLE. Like a turntable the size of a small town.

4/13/2009 3:20:26 PM

shit, how about a sphere?

Not just a sphere big enough to fit a plane, I mean one HUGE FUCKING SPHERE.

Like a sphere the size of the whole planet.*






* yes, i realize the earth is not quite spherical

4/13/2009 3:24:14 PM

Shit, put the plane on the north and/or south pole and they'd be the same experiment.

Though the earth doesn't quite spin fast enough for my purposes.

4/13/2009 3:29:28 PM

you're a dick, marko.

4/13/2009 4:05:09 PM

if a plane is on a treadmill going the same direction will it take off 2x as fast?

4/13/2009 4:10:59 PM

nope, for the same reason as the solution to the original problem. The plane will go as fast as its engines tell it to go. It does not care what the treadmill is doing, whether it's running forward or backward. (If it was running sideways, then we'd have an interesting result.)


(of course, neglecting the small amount of friction in the bearings. A treadmill running forward will give it a small amount of additional forward motion, but not enough to really worry about, just like the backwards treadmill will pull it back just a little bit.)

[Edited on April 13, 2009 at 4:23 PM. Reason : ]

4/13/2009 4:22:02 PM

well, the treadmill could also move the air in the region near in its direction (actually increasing the airspeed at the wings) which might actually decrease the power required from the engine to take off.

4/13/2009 4:25:11 PM

are you guys assuming that the treadmill will move the wheels of the plane forward, but the plane stays still (if the plane was powered off)...so no friction between wheels and plane?

4/13/2009 4:29:05 PM

the friction is negligible

4/13/2009 4:30:30 PM

more or less, but you don't even really need that assumption. the power of the engine moving the plane through the air is more than enough to get the wheels moving.

4/13/2009 4:30:48 PM