Will it fly??

[Bullrush]

this was posted on my WRX forum and brought up some good discussions...

A plane is standing on a runway that can move like a giant conveyor belt. The plane applys full forward power and attempts to take off. This conveyer has a control system that tracks the plane's wheel speed and tunes the speed of the conveyer to be exactly the same but in the opposite direction, similar to a treadmill.

The question is:

Will the plane take off or not?

[stunsjoo]

No because the plane is not moving at all. The wheels are just turning and will not provide the lift needed. Kinda like you said on a treadmill when you run on a treadmill do you feel the wind in your face? No because there is not forward advancement being made.

[Doula Doom]

Old meme is old. Of course the plane will fly, its propelled by jet turbines not by wheels. It'll simply move off the edge of the conveyor once the engines apply thrust. That this question brought about 'good discussion' is sad, to say the least.

This is a 4chan meme.

[stunsjoo]

Wrong doula, yes the engine propels the plane but it has to roll on the wheels to gain the speed and the wind velocity it needs to lift. But if the conveyor moves the same speed as the wheels the plane will not move at all and there will not be enough lift because there is no wind moving around the wings because the plane is stationary.

[Doula Doom]

OK yea if you dont actually start the engines, its not going to fly.

[brekken]

yes it will take off, yall ever played with a remote control airplane? you can hold the brakes on it so it doesnt move and crank the propeller speed to max, release the brakes and and it will take off with no runway time. while i know full sized planes do not have the same thrust to weight ratio of model planes, in theory i would think it should still work. perhaps someone with more knowlege of physics could tell me why im wrong

[Axiom]

Yes it will fly

[stunsjoo]

if the plane is stationary on a treadmill then how is it going to get the necisary lift needed to get off the ground? The engines propel the plane forward which it gains speed and thus giving the lift needed.

[Sporty]

Here, I solve the problem for you. No the plane will not fly if it has jet engines. That is because, like stuns mentioned, a jet relies upon lift generated from air movement over the wings. So a jet on a treadmill will simply stay on the treadmill. Think about it like this. Picture the plane doing this in water, or picture yourself on a treadmill in water. If you are running in place (not actually moving) the water has no counter-current force (remember newtons 3rd law here? =P) to generate lift.

The same occurs in the air. A plane that sits in place (despite how much thrust its engines generate) will remain in place.

Now, Brekken you bring up a good point, though I sincearly doubt you realize it. A prop plan, would indeed take off. Why? The prop, if you have ever observed one up close, is slightly angled. It works on the same principle your fan does. The fan remains in place, but generates wind (a current force). The fan however, lacks the RPMs and angle-ing ability to generate lift (though you can make some cool flying machines from fan parts).

The prop plane generates its own lift because of the angle of the prop, wind from movement is not needed, in theory. If the prop can accelerate to high enough speeds and is angled correctly it could, in theory take off.

I say in theory because that is an idealization of a prop plane. The prop generates air current and forward thrust, the forward thrust is translated to speed (through the wheels) and is eventually transfered to lift (when the 'wind' from the forward thrust passes over the wings). I sincearly doubt most prop planes would be able to generate enough thrust from angle and prop alone to take off in this circumstance.

Helicopters (a prop plane with top mounted-downward thrust prop), however would have no problem with this. And of course this is baring jets like the joint-strike fighter and harrier jet or osprey (a prop plane with the ability to rotate props to a vertical position)http://www.defenselink.mil/transformation/images/photos/2005-04/Hi-Res/Osprey1.jpg

[Bullrush]

im sorry to say this cam but pretty much everything you said above is wrong... and doula said this was a worthless attempt at discussion

[brekken]

ya see, i was an infantryman. the only times i had to think about jests or hellicopters was when i was in such deep shit my thoughts had nothing to do with their takeoffs lol. i understand the point i raised sporty, my only uncertanty was weather prop planes had the necesary thrust to do what model planes can, i dont know anything about aviation mechanics so was hopeing you could inform as you usually do

[Bullrush]

http://www.zenithair.com/stolch701/pic06/floats931a.jpg

[Sporty]

http://www.zenithair.com/stolch701/pic06/floats931a.jpg


Meh, cant be right all the time I suppose. I take solace in the facts that A) Tim you could not have come up with this explanation on your own and B) I am now right over you 99.8% of the time as opposed to 99.9% of the time.

[stunsjoo]

Doula is right. Everyone is too thick skulled to even listen to reason sometimes

[Sporty]

ya see, i was an infantryman. the only times i had to think about jests or hellicopters was when i was in such deep shit my thoughts had nothing to do with their takeoffs lol. i understand the point i raised sporty, my only uncertanty was weather prop planes had the necesary thrust to do what model planes can, i dont know anything about aviation mechanics so was hopeing you could inform as you usually do


Actually BR is correct, my statement was incorrect. The plane on water should give you the clue, does it mater if the plane takes off upstream or downstream?

If that doesnt help draw a free body diagram and youll see it.


Edit: Although, I would venture the wheels (which would move 2x the speed relative to the plane) would likely melt and wreck the plane onto the treadmill long before it ever actually gets off the ground.

[stunsjoo]

The picture of the plane on water is not anywhere near accurate to this situation. If the plane was going downstream and the water was moving the same speed. Yes it would fly but it is not stationary like it would be on a treadmill. If the water current was really fast and the plane was going up stream it would not be able to lift off because it would be pushed backwardes and not able to create the lift needed. I still say it will not fly because there is no forward progress being made by the plane to create the lift needed.

[brekken]

but prop planes work by creating their own wind and forceing it over their wings, so even if the plane isnt moveing the propellers are pushing air around the wings, thus creating lift

[stunsjoo]

they propellers are there to propel the plane hence the name Propellers. There are all kinds of proplanes that that have the propellers in the back and what not. A plane can not be stationary and take off. Unless its a VTOL like the osprey which use pure thrust to lift it off the ground. The wheels have nothing to do with the take off in relativity to the engines. They simply provide a more simple way for the plane to move. BUT!!!!! The wheels allow the plane to move forward thus forcing wind over the wings which in turn create the lift needed to push the plane in the air. Look at aircraft carriers they use catapults to push the plane forward acheving the lift and drag around the wings pushing it up in the air. If a plane could take off on a conveyor belt then why do we need such long run ways?

[brekken]

makes sence

[Doula Doom]

The treadmill cant prevent the plane from moving forwards, dont you see? The treadmill isnt a part of the equation. As for the planes taking off by slingshot, i dont know but my guess is that its not very good for the plane, and very expensive.

[stunsjoo]

no but as the pale speeds up it causes the wheels to move so the pane can advance. But as as those wheels accelerate so does the treadmill which impeed the movement of the plane causing it to stay stationary. When have you know the us goverment to care about cost of anything? No I can not see how tread mill is going to allow the plane to move forward if the reverse speed of the treadmill matches the forward speed of the planes wheels. Although the planes wheels do not propel it they allow it to move forward.


If a car is on a treadmill that moves in the oposite direction and it automaticly adjust its speed to match that of the car and the cars spedometer reads 100mph. Is the car moving 100mph or is that the speed of the wheels? And if you stuck your head out the car window would you feel the wind in your face at 100mph?

[brekken]

doula, catapults on aircraft carriers project the jet (not planes) to the necesary speed for them to take off of a 300 foot aircraft carrier runway, they are designed this way and it does no damage to them, with out the catapult a jet could never take off a aircraft carrier.

stuns thanks for answering this topic

[Doula Doom]

OK think about it this way then... say you've got a huge rope ok? and you're strong enough to pull this treadmill plane. So you're pulling the plane forwards OFF the treadmill. Do you think the treadmill is going to inhibit your pulling of the plane forwards? You're still standing on solid ground, and the plane is on wheels which reduce the planes frictional relationship with the ground/treadmill. No, the treadmill is NOT going to stop you from pulling the plane forward since it is not adding any resistance, in the same way the propeller turning or the jet engine applying thrust is still going to force the plane forwards.

[Doula Doom]

and here is someone with more time on their hands who can explain it more verbosely.
Dear Cecil:

Please, please, please settle this question. The discussion has been going on for ages, and any time someone mentions the words "airplane" or "conveyor belt" everyone starts right back up. Here's the original problem essentially as it was posed to us: "A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

There are some difficulties with the wording of the problem, specifically regarding how we define speed, but the spirit of the situation is clear. The solution is also clear to me (and many others), but a staunch group of unbelievers won't accept it. My conclusion is that the plane does take off. Planes, whether jet or propeller, work by pulling themselves through the air. The rotation of their tires results from this forward movement, and has no bearing on the behavior of a plane during takeoff. I claim the only difference between a regular plane and one on a conveyor belt is that the conveyor belt plane's wheels will spin twice as fast during takeoff. Please, Cecil, show us that it's not only theoretically possible (with frictionless wheels) but it's actually possible too. --Berj A. Doudian, via e-mail

Cecil replies:

Excuse me--did I hear somebody say Monty Hall?

On first encounter this question, which has been showing up all over the Net, seems inane because the answer seems so obvious. However, as with the infamous Monty-Hall-three-doors-and-one-prize-problem (see The Straight Dope: "On Let's Make a Deal" you pick Door #1, 02-Nov-1990), the obvious answer is wrong, and you, Berj, are right--the plane takes off normally, with no need to specify frictionless wheels or any other such foolishness. You're also right that the question is often worded badly, leading to confusion, arguments, etc. In short, we've got a topic screaming for the Straight Dope.

First the obvious-but-wrong answer. The unwary tend to reason by analogy to a car on a conveyor belt--if the conveyor moves backward at the same rate that the car's wheels rotate forward, the net result is that the car remains stationary. An aircraft in the same situation, they figure, would stay planted on the ground, since there'd be no air rushing over the wings to give it lift. But of course cars and planes don't work the same way. A car's wheels are its means of propulsion--they push the road backwards (relatively speaking), and the car moves forward. In contrast, a plane's wheels aren't motorized; their purpose is to reduce friction during takeoff (and add it, by braking, when landing). What gets a plane moving are its propellers or jet turbines, which shove the air backward and thereby impel the plane forward. What the wheels, conveyor belt, etc, are up to is largely irrelevant. Let me repeat: 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. This generates lift on the wings, and the plane takes off. All the conveyor belt does is, as you correctly conclude, make the plane's wheels spin madly.

A thought experiment commonly cited in discussions of this question is to imagine you're standing on a health-club treadmill in rollerblades while holding a rope attached to the wall in front of you. The treadmill starts; simultaneously you begin to haul in the rope. Although you'll have to overcome some initial friction tugging you backward, in short order you'll be able to pull yourself forward easily.

As you point out, one problem here is the wording of the question. Your version straightforwardly states that the conveyor moves backward at the same rate that the plane moves forward. If the plane's forward speed is 100 miles per hour, the conveyor rolls 100 MPH backward, and the wheels rotate at 200 MPH. Assuming you've got Indy-car-quality tires and wheel bearings, no problem. However, some versions put matters this way: "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation." This language leads to a paradox: If the plane moves forward at 5 MPH, then its wheels will do likewise, and the treadmill will go 5 MPH backward. But if the treadmill is going 5 MPH backward, then the wheels are really turning 10 MPH forward. But if the wheels are going 10 MPH forward . . . Soon the foolish have persuaded themselves that the treadmill must operate at infinite speed. Nonsense. The question thus stated asks the impossible -- simply put, that A = A + 5 -- and so cannot be framed in this way. Everything clear now? Maybe not. But believe this: The plane takes off.

--CECIL ADAMS

[stunsjoo]

Who is Cecil Adams?

[Axiom]

Who is Cecil Adams?


Cecil Adams is a name, generally assumed to be a pseudonym, which designates the unknown author or authors of The Straight Dope, a popular question and answer column published in The Chicago Reader since 1973. The column has since been syndicated in thirty newspapers in the United States and Canada and is also available online. Billed as the "World's Smartest Human Being", Adams responds to often unusual inquiries with abrasive humor (often directed against the questioner), and at times exhaustive research into obscure and arcane issues, urban legends, and the like. On more than one occasion, Cecil has been forced to retract an answer or at least modify it substantially when confronted by "the teeming millions", which he does in a gentlemanly and good-humored manner, often claiming overwork and staff shortages. On rare occasions, Adams has made appearances on the Straight Dope's Message Board.


google ftw!

[stunsjoo]

so a nobody.

[Doula Doom]

He might not be anyone, but his explanation of why the plane WILL fly is exactly correct.

[stunsjoo]

I wrote mythbusters about this one! They will find the truth.

[Levitacus]

Jan 30, 9:00 pm EST
(60 minutes)

MythBusters
Airplane on a Conveyor Belt
TV-PG

In this three-myth blockbuster the team takes a crash-course in remote controlled airplane flying, bug-out by testing the "cockroach survival" theory, then return to fraternity pranks with exploding cans of shaving cream.

[Sporty]

The air plane will fly. Because a treadmill will not keep the plane from moving forward and taking off. As I said draw the free body diagram to see this. Since I dont know if you guys know what a free body diagram is, I drew one in paint for you. Excuse my 5 minute paint skills.

http://img181.imageshack.us/img181/2025/airplanego0.jpg

So allow me to explain. The only thing of the plane touching the ground are the wheels and the only interaction between the ground and the wheels are the force of friction (f) created from the bearings.


The Normal force is the upward pointing force that counteracts the force of gravity (Fw) or the weight of the plane.
This force is incredibly small with good bearings. So the plan has to apply the most minimal thrust (Ft1) to negate the force of friction. NO MATTER HOW MUCH FASTER THE TREADMILL SPINS THE ONLY FORCE THE PLANE NEED OVERCOME TO STAY STATIONARY IS THE FORCE OF FRICTION FROM THE WHEELS BEARINGS.


Lets use some arbitrary numbers to make it easier to understand. Lets say the planes mass is 1000 kg. Its weight would be 9800 Newtons, directed down. The normal force (since the plane is not falling) is equal and opposite of this, so 9800 N upward.

Lets say we were using some crazy good wheel bearings with a coefficient of friction (U) as .0001.

To calculate the force of friction (f) on the plane it is given by,

f=FnU=(9800)(.0001)=.98N in a West direction (according to the picture). Now the plane's engines are easily capable of producing .98 N of forward thrust. So lets say the plane applies this thrust in the forward direction.

The sum (E) of forces on the plane are

EF=f-Ft1=0, meaning the plane remains stationary.

What if we increase the velocity of the treadmill?

Nothing happens, the plane gets to apply the same amount of thrust and maintain the exact same position. Because the force of friction (the only force trying to pull the plane off the treadmill) remains unchanged (in an ideal system) by speeding up the treadmill.

So if plane applies the smallest amount of more thrust, it will easily take off from the treadmill, because the wheels are free spinning.

[Doula Doom]

CO2 is a greenhouse gas.

[brekken]

and playing left fielf is doula lol but seriously thanks for the cecil adams response

[Axiom]

The air plane will fly. Because a treadmill will not keep the plane from moving forward and taking off. As I said draw the free body diagram to see this. Since I dont know if you guys know what a free body diagram is, I drew one in paint for you. Excuse my 5 minute paint skills.

http://img181.imageshack.us/img181/2025/airplanego0.jpg

So allow me to explain. The only thing of the plane touching the ground are the wheels and the only interaction between the ground and the wheels are the force of friction (f) created from the bearings.


The Normal force is the upward pointing force that counteracts the force of gravity (Fw) or the weight of the plane.
This force is incredibly small with good bearings. So the plan has to apply the most minimal thrust (Ft1) to negate the force of friction. NO MATTER HOW MUCH FASTER THE TREADMILL SPINS THE ONLY FORCE THE PLANE NEED OVERCOME TO STAY STATIONARY IS THE FORCE OF FRICTION FROM THE WHEELS BEARINGS.


Lets use some arbitrary numbers to make it easier to understand. Lets say the planes mass is 1000 kg. Its weight would be 9800 Newtons, directed down. The normal force (since the plane is not falling) is equal and opposite of this, so 9800 N upward.

Lets say we were using some crazy good wheel bearings with a coefficient of friction (U) as .0001.

To calculate the force of friction (f) on the plane it is given by,

f=FnU=(9800)(.0001)=.98N in a West direction (according to the picture). Now the plane's engines are easily capable of producing .98 N of forward thrust. So lets say the plane applies this thrust in the forward direction.

The sum (E) of forces on the plane are

EF=f-Ft1=0, meaning the plane remains stationary.

What if we increase the velocity of the treadmill?

Nothing happens, the plane gets to apply the same amount of thrust and maintain the exact same position. Because the force of friction (the only force trying to pull the plane off the treadmill) remains unchanged (in an ideal system) by speeding up the treadmill.

So if plane applies the smallest amount of more thrust, it will easily take off from the treadmill, because the wheels are free spinning.

God Damnit Sporty! Don't you know that you need to purchase carbon offsets before you can actually fly a plane!

God damn global warming

[brekken]

lmao

[Arson]

It's called the POAT problem. (Plane On A Treadmill)
the answer
(http://dsc.discovery.com/video/?playerId=203711706&categoryId=210013704&lineupId=1283221956&titleId=1347908538) is coming sometime

[Queq]

So what is the final outcome on this will the fucker fly or not? I still agree with Slo "kinda hard to believe I know" but without foward momentium(?sp) I do not see how the correct amount of lift could be obtained.. Lets look at it like this, an aircraft carrieres deck would only need to be about 200ft long if this would actually work, runways would need to be only as long as the plains themselves. So I say it would'nt work or it would be the norm now.

[Sporty]

CO2 is a greenhouse gas.


Yep, it most certainly is.

[Doula Doom]

So what is the final outcome on this will the fucker fly or not? I still agree with Slo "kinda hard to believe I know" but without foward momentium(?sp) I do not see how the correct amount of lift could be obtained.. Lets look at it like this, an aircraft carrieres deck would only need to be about 200ft long if this would actually work, runways would need to be only as long as the plains themselves. So I say it would'nt work or it would be the norm now.

See all of my previous posts in this thread, plz.

[stunsjoo]

Please explain where the air that goes under the wings that pushes theplane up comes from?

My final stand is It will not fly it will be proven tonight.

[brekken]

it gonna be on mythbusters?

[stunsjoo]

Tonightat 9

[Sporty]

Btw Doula,


so heres the 2007 predictions for you doula, so you can come back to this thread at the end of the year and sulk.

Named Storms (NS) (9.6)=17
Named Storm Days (NSD) (49.1)=85
Hurricanes (H) (5.9)=9
Hurricane Days (HD) (24.5)=40
Intense Hurricanes (IH) (2.3)=5
Intense Hurricane Days (IHD) (5.0)=11
Accumulated Cyclone Energy (ACE) (96.2)=170
Net Tropical Cyclone Activity (NTC) (100%)=185

The number of named storms? 14. (It would also be good to remember that we now name many more storms than we did during the second half the 20th century). Also bare in mind that 8 storms where named in September (conspiracy to affirm eco-terrorists fears? who knows).
Named Storm days? 33.5
The total number of hurricanes? 6.
Major Hurricanes (intense hurricanes)? 2
Hurricane Days? 11.2
Intense Hurricane Days? 5
ACE? 68
NTC? 94.5


So, in case you are unfamiliar with the two important hurricane statistics I went ahead and bolded them for you.

Btw some fun math to apply

% error for ACE predictions.
{|68-170)|/170}*100=60% error

% error for NTC predictions.
{|94.5-185|/185}*100=48.9%

THIS IS NOT SCIENCE, THIS IS CALLED GUESSING AND IS WHAT WE DO IN RELIGION/SEX/SPORTS/etc.

60% fucking error, give me a break, that is so outside the norms of acceptable deviations its ridiculous.

And you want to listen to this shit about weather and climate predictions 25, 50 or 100 years in the future. Hopefully Doula, you take away from this that climate science is still in its infancy and there is currently no way to predict what future climate has in store. Mind you too, we are coming out of an ice age.

This is chicken-little-dom. If you wish to live your life in fear of global warming Doula, go ahead. At this point though, I would think you maybe willing to concede some ground that climate scientists are simply throwing darts at the dart board. Especially when we have instances like this where the best climate science institutions in the world say things like:


Experts at the NOAA Climate Prediction Center are projecting a 75 percent chance that the Atlantic Hurricane Season will be above normal this year


Global warming and Dramatic climate change, what a gd silly ass political tool. The sad part is, it is something that should be getting unbiased research (as the climate on this planet is never static and will change provided we survive long enough), tho is clouded with political chicken-littler's.


Anyway, see you on the thread about the 08 season doula. Would you care to loose some money this year?

[Sporty]

Let's remember where we live Douladoom. We live on an small planet circling an average star, in the backwoods of our quaint little galaxy. We have a 5 billion year history where change, is the norm. We are now on our third atmosphere. The first, He and H was violently ejected into space because the planet was so hot and active. As the Earth cooled, volcanic activity produced the second, Carbon Dioxide. The more it cooled, the more water vapor condensed, forming the oceans we see today.

Around 3 billion years ago, some simple cells evolved that consumed CO2 and excreted the most poisonous substance known, Oxygen. Another type of bacteria released nitrogen. These little microscopic fellas dominated the landscape for the next 1.5 billion years. Our atmosphere changed again, and those that could not adapt, died out.

All during this time, the Earth's lands were floating on raging tectonic plates which eventually crashed together, interrupting the oceanic flows. It got cold, real cold, so cold the entire earth was markedly similar to a giant snowball. The first ice showed up a mere 2 billion years ago.

For the last seven hundred thousand years we have been in a geological ice age. Dominated by advancing and retreating glaciers. For reasons unbeknown to geologists a major ice advance (as in planet covering) occurs every 200,000 years. Smaller advances occur every 20,000 years, with the last one occurring 20,000 years ago. We're due....

Even after 5 billion years, our planet is active. We have a volcanic eruption every 2 weeks. Earthquakes are continuous, an average of a million and a half per year; With a moderate (5.0) every 6 hours. Scary earth quakes (7+) happen every 10 days. Tsunamis cross the pacific at least once every 3 months.

Our atmosphere is no less violent, at any given moment there are 1500 electrical storms. 11 lightning bolts hit the Earth per second. A tornado wreaks havoc every 6 hours. And every 4 days a giant cyclonic storm, hundreds of miles in diameter, releasing more energy than our nuclear arsenal, spins up from no mans land.

And we insignificant little beings, the most recent line of descendants of apes, can do nothing but run and hide. And these nasty little apes pretend they could stabilize our plant? How arrogant of them. The reality is, we run from the storms, from the climate. The status quo, is change, a peaceful atmosphere/planet is the illusions of a little ape monster with a knack for abstract thought (thanks evolution!).

[Sporty]

Please explain where the air that goes under the wings that pushes theplane up comes from?

My final stand is It will not fly it will be proven tonight.


Stuns,

Maybe I wasn't that clear in my example (though I thought it was). A treadmill under the plane, matching the planes wheel's speed, can not stop a plane from accelerating forward. Because the plane's wheels are not what give it forward motion, so The plane need only exert a little thrust to offset the frictional force from the wheels. Any thrust exerted after that will accelerate the plane forward.

Tim (and the original) question is worded poorly. The plane would not necessarily remain in place, because as I am sure you will see tonight, a tiny bit of thrust is all that is necessary to offset the treadmill. The rest would be applied normally.

[Doula Doom]

I may concede that global climate change is unpredictable and so the overwhelming suggestion that the planet is heating up AND human activity is accellerating that warming MAY be incorrect, but I believe that it IS correct and logically, it stands to reason that if we are putting greenhouse gasses into the environment in ever increasing and substantial amounts, it will increase the greenhouse effect on Earth. Is this actually going to be a bad thing? I think overall yes, but I'm sure there will be benefits.

I dont know what it is about your posts Sporty, but after about 10 words my eyes glaze over and I just start skimming, hoping that some piece of regurgitated data makes a point.

[stunsjoo]

I understand what you are saying sporty. Let me put it the way I am thinking. If the plane stays on the treadmill it will not take off. If the engines are able to thrust the plane completely off the treadmill of courseit will fly. The reason why I say it will not fly is if the belt impeeds the forward movement of the plane it is impossible it will fly. The planes need long runways some longer then others to gain the speed and lift needed. You are correct the plane uses the wheels to offset the friction but they are also the vehicle for forward movement with the help of the thrust from the engines.

[Doula Doom]

AIOLFDHUQWEOC I(QE( PWEHPQ(WHD P(QHC_P(HQ(HDC_(WERG!#@EP: LNP !@PHEP!@HE _(@!H(H!@E _PH@H H@EEHPH@!EP IU@!EY@E_{ @EH H@ EH@E P@!EHP@(EH P@!EH P!@E@!PIEHE@!PHE OPI!@ P@!P E(P @!EH)(@!EHD _FHD(_ HWQEF_*HQF +QWH_@!E(P!@EHP(!HU@E( _(QW D_(WHQ D(_H@!W _H D D!)(H H D!@( HD!(PH D@(_H W_DH!P{#@HE P{)!@HE _(WD D Q(@!H PDPH@!D _(!D_WD_!HJ W DN

[Axiom]

I understand what you are saying sporty. Let me put it the way I am thinking. If the plane stays on the treadmill it will not take off. If the engines are able to thrust the plane completely off the treadmill of courseit will fly. The reason why I say it will not fly is if the belt impeeds the forward movement of the plane it is impossible it will fly. The planes need long runways some longer then others to gain the speed and lift needed. You are correct the plane uses the wheels to offset the friction but they are also the vehicle for forward movement with the help of the thrust from the engines.

The thing is Slo, the tredmill will not stop the plane from moving forward becuase the thrust is not generated from the wheels. The only force the propellers or the engines have to overcome is the friction between the wheels and the tredmill. Since this is the case, the propellers and/or engine only have to overcome the same amount of frictions (wheels on pavement or wheels on treadmill) to take off.

I maybe completely wrong, but it sounds right =)

[brekken]

from what i gather, since the wheels are free spinning, the tredmil wont be able to hold the plane from moveing forward. the wheels will spin infanitly faster in order to allow the plane body to advance. so since nothing is dependant on the wheels other then to smoth the forward movement while on the ground, a tredmill cant stop the plane from upward movement

[Sporty]

Well as you all could see on mythbusters, the plane could not have been stopped from flying. Because as the treadmill only negates GROUND SPEED, which in the end is irrelevant to a plane flying. AIR SPEED (yes even when the plane is touching the ground) is what matters.

[stunsjoo]

looks like it will fly. At least last night on myth busters it flew. The only diffrence in their "myth" than this one is the speed compensation of the treadmill.