# will the plane take off?



## marshhunter (Mar 20, 2008)

A plane is standing on a movable runway (something like a conveyor) As the plane moves, the conveyor moves but in the opposite direction. The conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction.

The question is, will the plane take off or not and why, or why not


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## MarkU (Jun 3, 2013)

I'm going to say no. Not enough wind flowing to create lift.


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## Jolly Roger (May 21, 2004)

The plane will still take off, Mythbusters tested it.


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## Super Dave (May 26, 2004)

marshhunter said:


> A plane is standing on a movable runway (something like a conveyor) As the plane moves, the conveyor moves but in the opposite direction. The conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction.
> 
> The question is, will the plane take off or not and why, or why not


the old play on words trick. define speeds as air speed, ground speed etc and then re-ask the question. the devil is in the details.


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## Jerry-rigged (May 21, 2004)

The problem assumes the conveyor movement means the airplane will never move. If we accept this assumption, the plane will never take off. However-

Airplane propulsion is not depended on ground speed. Airplane wheels are "freewheeling", so conveyor movement cannot prevent the plane from moving forward. So if the conveyor is long enough, the plane will eventually reach flight air-speed, and take off.


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## StinkBait (May 31, 2004)

The plane will take off. The moving wheels have no effect on the ability of the prop to pull the plane forward generating lift on the wings. And this thread has been done here already. About 30 pages worth, lol.

http://2coolfishing.com/ttmbforum/showthread.php?t=416541&highlight=treadmill+plane

http://2coolfishing.com/ttmbforum/showthread.php?t=150212&highlight=treadmill+plane

http://2coolfishing.com/ttmbforum/showthread.php?t=98703&highlight=treadmill+plane


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## EndTuition (May 24, 2004)

Of course it will, how fast the tires spin, or how fast the ground (converyor) is moving under it has nothng to do with "lift".


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## Tankfxr (Dec 26, 2007)

Yes the plane will take off.


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## 98aggie77566 (Jul 7, 2009)

Nope.

Flight is based on the Bernoulli Principle which requires air speed.... Ground speed is irrelevant.

Similar question: if a plane is flying 100 mph (air speed) into a 100 mph head wind, it will have a ground speed of 0 mph. Will it continue in flight? Absolutely! Air speed remains 100 mph...they just aren't going anywhere.

This is why planes take off into a headwind, and land that way as well. It reduces the ground speed (and length of runway required as a result). If a plane try's to take off with the wind, then the ground speed at landing increases for each mph of wind (roughly assuming its a direct tail wind).

For those that think the prop or jet provides the air flow for lift...that is completely wrong...otherwise how would a glider remain or take flight. Lift is provided by the air moving over/under the wing at different speeds as a result of moving "forward". The prop/jet is what moves the plane forward....but the air movement from the jet does not provide any measurable lift. Think about jets...the engine is below/behind the wing.


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## StinkBait (May 31, 2004)

98aggie77566 said:


> Nope.


I hope you are just stirring the pot to make this Monday go by faster.:rotfl:


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## 4 Ever-Fish N (Jun 10, 2006)

This is interesting. I'm not a pilot or engineer but I do not believe the plane will ever leave the ground. If the conveyor is matching the speed of the plane, it doesn't seem like there will be any forward motion of the plane. If there is no forward motion, there will be no lift.


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## JamesAggie (Jun 28, 2012)

Interesting, but I also do not think it will leave the ground. Where does the "lift" come from? The wheels are turning but the plane is not moving, therefore no lift. I think you would have to add in wind speed.


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## 98aggie77566 (Jul 7, 2009)

StinkBait said:


> I hope you are just stirring the pot to make this Monday go by faster.:rotfl:


Stirring in what way? The "nope" was in response the previous folks indicating the airplane would take flight.

Believe it or not....the plane in this situation ain't going no where.


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## ReelWork (May 21, 2004)

*Yes, it will take off and fly normally... *

The conveyor is not affecting windspeed going over the wings or into the prop/jet which is what creates the lift or propulsion to actually fly. The wheels also provide no thrust to take off, only braking... Or to put it another way, engines and wings don't care about wheels or ground speed so long as it has enough lift and/or engine thrust to fly.

If the wheels were providing the thrust, then sure it wouldn't go anywhere. Take away the conveyor and it ain't gonna fly either because once it leaves the ground your thrust from the wheels is gone...


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## Jerry-rigged (May 21, 2004)

98aggie77566 said:


> Nope.
> 
> Flight is based on the Bernoulli Principle which requires air speed.... Ground speed is irrelevant.
> 
> ...


Thrust, drag, lift weight. The motors (prop or jet) provide Thrust, not lift. The conveyor adds drag... as long as the motors have enough thrust to overcome the added drag of the tires spinning faster than normal, the plane will fly.

The problem assumes that when the plane is on the ground, it moves like a car, with the wheels providing thrust. Not true, so the conveyor CANNOT prevent the plane from moving.


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## donf (Aug 8, 2005)

98aggie77566 said:


> Nope.
> 
> Flight is based on the Bernoulli Principle which requires air speed.... Ground speed is irrelevant.
> 
> ...


Totally correct sir, as a student pilot, I flew a Cessna 150 to Dallas . Clear weather, hard north wind. Cars driving on I45 below me were passing me up.


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## heli.clay (Sep 1, 2011)

It'll fly.


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## surf_ox (Jul 8, 2008)

yes as the wheels arent propelling the plane (like a car) the thurst from the jets are.

conveyor has no effect on thrust


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## Oyster Dog (May 21, 2005)

If it's a Delta flight, it won't take off.


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## Waymore (Jul 6, 2011)

The wheels are just freewheeling so the conveyor will not keep the plane from moving, so when it reaches liftoff speed it will fly.


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## POC Troutman (Jul 13, 2009)

surf_ox said:


> yes as the wheels arent propelling the plane (like a car) the thurst from the jets are.
> 
> conveyor has no effect on thrust


does the conveyor not work to offset the trust? Think in regards of vectors here. Two opposing vectors of equal magnitude will completely offset each other.

The way i read the question the first time was that the wheels are in contact with the conveyor. In order for the thrust provided by the airplane's engine to be transferred into forward motion, the wheels must rotate. The wheels being on the conveyor belt that is set to directly offset that movement means that the wheels turn, but no forward motion is achieved and thus there is no lift created under the wing by the varying pressure the wings are designed to create as air flows above and below them (Bernoulli principle).

i read it again and i think it's just a play on words here. i can see where someone might say "the plane is moving 100 mph due west and the conveyor is moving 100 mph due east. The wheels would be turning at a rate of speed that would otherwise constitute 200 MPH without the conveyor belt being there. so i get where you guys are coming from...i say she will fly


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## Bozo (Jun 16, 2004)

You are forgetting the fact that speed is taking place for the conveyor to move. It clearly states that forward motion must be occurring for the conveyor to move. If that equated to zero progress then there isn't a speed for the conveyor to move. The mere fact that the conveyor is moving means that the plane is making forward progress.

Don't confuse wheel speed with the speed of the plane as whole.

So, if forward progress is obtainable then it is possible for the plane to take off.


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## Ruthless53 (Jul 6, 2007)

In the point of your post no! If the conveyor is moving fast enough that the plane does not move forward then there's no way for the plane to create lift by moving wind under the wing.


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## goatchze (Aug 1, 2006)

No it will not take off because it's an impossible question.

For the plane to take off, it must be moving forward WRT the air around it.

For it to move forward, the wheels must necessarily move faster than the conveyor.

If we state that the wheels will not move faster than the conveyor, then the plane cannot move forward.

Ergo, the plane cannot take off.


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## ReelWork (May 21, 2004)

Wow.... I can see how this gets "discussed" amongst the brain trust. :slimer:

Here's another question: So when a plane lands and the wheels are not turning,. i.e. zero MPH does the plane come to an immediate stop or is the plane speed immediately cut in half as the wheels spin up? Please, don't answer this... :sarcasm


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## grayson (Oct 21, 2011)

I have a similar type question - you are driving at 60 mph in your car. Inside your car there is a fly and he flies from the back of the car to the front of the car. Is the fly going 60 mph or is he going the actual speed he is flying?


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## POC Troutman (Jul 13, 2009)

goatchze said:


> No it will not take off because it's an impossible question.
> 
> For the plane to take off, it must be moving forward WRT the air around it.
> 
> ...


that's the play on words here. The question doesn't say anything about the rate of rotation of the tires. just that the plane and conveyor go the same speed in the opposite direction. The plane has it's forward speed, the conveyor has it's "backwards" speed, and the wheels spin at a rate that would combine the two.

i did the same thing the first time i read it, but the plane could potentially take off i would say. BUT the necessary thrust for the plane to take off, all else constant, is increased.


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## StinkBait (May 31, 2004)

grayson said:


> I have a similar type question - you are driving at 60 mph in your car. Inside your car there is a fly and he flies from the back of the car to the front of the car. Is the fly going 60 mph or is he going the actual speed he is flying?


actual speed he is flying, the air in the car is 0mph, now if the windows are down or the AC is on high then it is a total different answer


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## V-Bottom (Jun 16, 2007)

No
...........no wind..no low pressure area...no lift


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## osobrujo (Jan 13, 2005)

Anyone ever notice that every time his post is reposted, it's always the youngsters that think that the plane can't take off? LOL


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## Bozo (Jun 16, 2004)

Although the fly is flying his normal speed in relation to the encapsulated environment of the car, the cars speed would be included in it's actual rate of travel in the whole environment of Earth. Then if you want to include the environment of the solar system you would factor in the Earths speed traveling around the Sun. Then factor in the speed of the solar system in the galaxy...galaxy in universe..and then....

speed is always relative to environment. How finite you want to describe the environment as is variable. So the answer is, depends.


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## CHARLIE (Jun 2, 2004)

If you are traveling faster than the speed of light and you turn on a flashlight towards the direction you are heading will be beam of light ever leave the flashlight ?


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## bill (May 21, 2004)

I have changed my mind over the years and now understand the logic, the plane will fly


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## Lagunaroy (Dec 30, 2013)

It is all just L/D


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## BonesNTX (Aug 14, 2006)

I say until the entire conveyor assembly with the plane on it get to approximately 100 MPH or so it will not fly.

Pretty sure part of this scenario states however fast the plane goes the conveyor matches. No advantage is achieved, no lift.

The source of the motion is irrelevant be it jets, driven wheels,etc.... What is important is the lack of motion/velocity and none can be achieved with this criteria. No air is going to flow over the wing to satisfy that old French guy.

Like I said, until it all gets moving nothing is going anywhere.


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## JamesAggie (Jun 28, 2012)

The plane is not moving relative to the environment, the conveyor is just offsetting forward velocity. So if the plane takes off, does it shoot off like a rocket or just hover there? I just don't see any way the plane takes off without any forward motion. Someone said mythbusters proved it, have a link?


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## Jolly Roger (May 21, 2004)

JamesAggie said:


> The plane is not moving relative to the environment, the conveyor is just offsetting forward velocity. So if the plane takes off, does it shoot off like a rocket or just hover there? I just don't see any way the plane takes off without any forward motion. Someone said mythbusters proved it, have a link?


here you go, they did several different ways with model planes on tread mills to full scale. In all cases the plane always take off. As long as the propeller can move air, the plane will take off. In very basic math, all it does is make a stationary runway. The prop will pull hard enough and move enough air to lift the plane.


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## Bozo (Jun 16, 2004)

JamesAggie said:


> The plane is not moving relative to the environment, the conveyor is just offsetting forward velocity. So if the plane takes off, does it shoot off like a rocket or just hover there? I just don't see any way the plane takes off without any forward motion. Someone said mythbusters proved it, have a link?


Where are you getting the idea that the plane isn't moving? Thinking that wheel speed negates forward motion was never included in the question.

To think so is identical to thinking that peeeling out in your car with the tired spewing smoke while you inch along at 10 mph means your going 90 because that is how fast the forfeiture says you are going.

Think of the conveyor as a roller bearing race and the plane wheel as a bearing roller, all that masters is how fast the porter race I'd going vs the spindle speed.


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## captnickm (Feb 16, 2011)

I don't like to get involved in questions like this. But, here it goes.
Everyone who says no is thinking of it like a car on the conveyor. The planes wheels spin freely. So if the plane is going 100mph in one direction and the conveyor is going 100mph in the opposite direction they the wheels on the plane will be spinning at 200mph and the plane will still be going 100 MPH actual speed. The way they word it is a tricky one. Yes, the plane will take off.


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## INTOTHEBLUE (Jun 21, 2011)

That plane still had forward motion though. If it wasn't outrunning the conveyor it would have stayed between a couple cones. If you watch the video the plane is passing cones because it is moving forward. All they proved was the plane outran the conveyor and it took off.


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## JamesAggie (Jun 28, 2012)

Bozo said:


> Where are you getting the idea that the plane isn't moving? Thinking that wheel speed negates forward motion was never included in the question.
> 
> To think so is identical to thinking that peeeling out in your car with the tired spewing smoke while you inch along at 10 mph means your going 90 because that is how fast the forfeiture says you are going.
> 
> Think of the conveyor as a roller bearing race and the plane wheel as a bearing roller, all that masters is how fast the porter race I'd going vs the spindle speed.


"The conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction."

So my understanding of this statement is that if the plane is moving forward 100mph, the conveyor is going opposite direction 100 mph, thus the plane would not be physically moving, although the wheels are spinning.


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## Jolly Roger (May 21, 2004)

JamesAggie said:


> "The conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction."
> 
> So my understanding of this statement is that if the plane is moving forward 100mph, the conveyor is going opposite direction 100 mph, thus the plane would not be physically moving, although the wheels are spinning.


Prop on the plane is still going to pull the plane forward. Does not matter what the wheels are doing.


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## ReelWork (May 21, 2004)

JamesAggie said:


> The plane is not moving relative to the environment, the conveyor is just offsetting forward velocity. So if the plane takes off, does it shoot off like a rocket or just hover there? I just don't see any way the plane takes off without any forward motion. Someone said mythbusters proved it, have a link?


Acording to your logic, when the plane is airborne what would keep it flying since the wheels aren't on the ground. Conversely, if the wheels provided thrust (rotated with power), it would stall out as soon as it got airborne... :headknock


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## JamesAggie (Jun 28, 2012)

I'm guess I'm just too dense (my wife says so all the time). I just don't get it. Guess it's a good thing I'm not an aerospace engineer.


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## Jolly Roger (May 21, 2004)

JamesAggie said:


> I'm guess I'm just too dense (my wife says so all the time). I just don't get it. Guess it's a good thing I'm not an aerospace engineer.


You can not make the plane sit still using the wheels. This is not where the plane's propulsion comes from. The wheels could be spinning 200mph in the wrong direction, yet the prop would still pull the plane forward and fly. The wheel speed has no effect on the plane taking off. It is the prop that does all the work and the prop that moves the plane forward.


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## BonesNTX (Aug 14, 2006)

Jolly Roger said:


> You can not make the plane sit still using the wheels. This is not where it's propulsion comes from. The wheels could be spinning 200mph in the wrong direction, yet the prop would still pull the plane forward and fly. The wheel speed has no effect on the plane taking off. It is the prop that does all the work and the prop that moves the plane forward.


The wheels are in contact with the moving conveyor belt so the plane moves with the belt til the belt speed is overcome. Then it needs another 100 mph or so for lift off.

Then what about when it lifts off. It's going to go kind of like James said..."a rocket" because it will have instantly overcome the conveyor belt resistance + whatever speed it achieved to get flying.


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## POC Troutman (Jul 13, 2009)

Jolly Roger said:


> You can not make the plane sit still using the wheels. This is not where the plane's propulsion comes from. The wheels could be spinning 200mph in the wrong direction, yet the prop would still pull the plane forward and fly. The wheel speed has no effect on the plane taking off. It is the prop that does all the work and the prop that moves the plane forward.


now that is not entirely true. the wheels making contact with the ground create a resistant force, friction, that acts on the plane. The motion of the prop creates thrust to over come the force of friction and propel the plane forward. The conveyor belt moving opposite the direction of the thrust creates additional force required to counteract both the force of friction and the force of the conveyor belt acting in the opposite direction. Think about when a plane starts up and the prop starts to turn. The plane doesn't instantly start moving right? even if there are no breaks set and the wheels aren't chalked, the plane still would not instantly move.


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## JamesAggie (Jun 28, 2012)

"
A plane is standing on a movable runway (something like a conveyor) As the plane moves, the conveyor moves but in the opposite direction. *The conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction*.

The question is, will the plane take off or not and why, or why not "

This comment to means the plane is not moving at all, just wheels and conveyor belt. The plane in the video is still clearly moving forward.


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## Jolly Roger (May 21, 2004)

BonesNTX said:


> The wheels are in contact with the moving conveyor belt so the plane moves with the belt til the belt speed is overcome. Then it needs another 100 mph or so for lift off.
> 
> .


no, prop moves air for population. Does not matter what the belt under it is doing the plane is going to move forward unless you stop the prop from moving air.

Wheels spin freely. Does not effect forward motion of a plane.


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## poppadawg (Aug 10, 2007)

The plane needs speed to get enough friction against the air for lift off. No forward speed, no air friction, no lift off


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## Jolly Roger (May 21, 2004)

POC Troutman said:


> now that is not entirely true. the wheels making contact with the ground create a resistant force, friction, that acts on the plane. The motion of the prop creates thrust to over come the force of friction and propel the plane forward. The conveyor belt moving opposite the direction of the thrust creates additional force required to counteract both the force of friction and the force of the conveyor belt acting in the opposite direction. Think about when a plane starts up and the prop starts to turn. The plane doesn't instantly start moving right? even if there are no breaks set and the wheels aren't chalked, the plane still would not instantly move.


Very little friction, wheels are bearings. They spin freely separate from the plane's prop. In this case speed of the conveyor will greatly reduce the amount of friction, in turn making it easier for the plane to take off.


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## Jolly Roger (May 21, 2004)

poppadawg said:


> The plane needs speed to get enough friction against the air for lift off. No forward speed, no air friction, no lift off


prop pulls plane forward using AIR. Nothing the converoy belt can do to stop this. The plane will move forward because it is using the AIR to move, not it's wheels.


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## boom! (Jul 10, 2004)

Just how would you keep a plane from moving forward on anything without tying it down?


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## POC Troutman (Jul 13, 2009)

Jolly Roger said:


> no, prop moves air for population. Does not matter what the belt under it is doing the plane is going to move forward unless you stop the prop from moving air.
> 
> Wheels spin freely. Does not effect forward motion of a plane.


the wheels do effect the forward motion of the plane though. also, what if the plane is a jet instead of a prop plane. no prop to force air under the wing. Also, the prop itself on an airplane is meant to move the plane through the air and use the air to lift the plane with pressure difference, not designed to force air under the wings for lift. If that was the case, why would you need a runway at all. just chalk up the wheel, get the prop going and boom, up you go.


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## Jolly Roger (May 21, 2004)

POC Troutman said:


> the wheels do effect the forward motion of the plane though. also, what if the plane is a jet instead of a prop plane. no prop to force air under the wing. Also, the prop itself on an airplane is meant to move the plane through the air and use the air to lift the plane with pressure difference, not designed to force air under the wings for lift. If that was the case, why would you need a runway at all. just chalk up the wheel, get the prop going and boom, up you go.


The prop is going to use AIR to pull the plane fast enough to get lift. Does not matter what the wheels are doing. If it was a jet, be the same. Jet would push it fast enough to get lift using air. Would not matter what the wheels were doing.

The belt under the wheels can not stop a plane from moving forward as it does not effect a plane's propulsion.


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## 24Buds (Dec 5, 2008)

this is funny. You need air over the wings. airspeed=lift. regardless of the wheels. Yes the wheels will cause friction, but not enough to stop the plane from moving forward, in turn air speed, and then lift.


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## boom! (Jul 10, 2004)

Jolly Roger said:


> The prop is going to use AIR to pull the plane fast enough to get lift. Does not matter what the wheels are doing. If it was a jet, be the same. Jet would push it fast enough to get lift using air. Would not matter what the wheels were doing.
> 
> *The belt under the wheels can not stop a plane from moving forward* as it does not effect a plane's propulsion.


Bingo.


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## goatchze (Aug 1, 2006)

POC Troutman said:


> that's the play on words here. The question doesn't say anything about the rate of rotation of the tires. just that the plane and conveyor go the same speed in the opposite direction. The plane has it's forward speed, the conveyor has it's "backwards" speed, and the wheels spin at a rate that would combine the two.
> 
> i did the same thing the first time i read it, but the plane could potentially take off i would say. BUT the necessary thrust for the plane to take off, all else constant, is increased.





Jolly Roger said:


> Prop on the plane is still going to pull the plane forward. Does not matter what the wheels are doing.


Ya'll made me bust out paint! The only way that the plane takes off is if the wheels are moving faster than the conveyor i.e. the surface of the wheel is moving at a greater velocity than the surface of the conveyor, or the wheels are slipping (such as peeling out in your car). See illustration below.

There is no doubt that an airplane can take off from a conveyor belt. All that matters is that the wheels support the weight of the plane and that the planes propulsion can overcome whatever resistance they might provide. Their rotational speed has no bearing on whether the plane can take off; only the speed of the airplane WRT to the air around it will determine whether the plane can take off.

But, assuming the conveyor system itself is stationary, then it is impossible for the airplane to move initially without violating the problem statement. The moment the airplane begins to move due to any kind of propulsion, the conveyor belt is no longer going to be matching the speed of the wheels. The wheels will be moving faster than the conveyor or they will be skidding.



CHARLIE said:


> If you are traveling faster than the speed of light and you turn on a flashlight towards the direction you are heading will be beam of light ever leave the flashlight ?


I'm not sure, but if you pass someone traveling the speed of light int he other direction, it's probably best not to make eye contact.


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## POC Troutman (Jul 13, 2009)

24Buds said:


> this is funny. You need air over the wings. airspeed=lift. regardless of the wheels. Yes the wheels will cause friction, but not enough to stop the plane from moving forward, in turn air speed, and then lift.


so the question does not stipulate speed of the conveyor right... so let me ask you this... do you think there is a speed at which the belt could move to keep the plane from taking off?


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## DA REEL DADDY (Jun 7, 2005)

Sorry, for the interruption, but I say yes, if the engine is running.


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## StinkBait (May 31, 2004)

POC Troutman said:


> so the question does not stipulate speed of the conveyor right... so let me ask you this... do you think there is a speed at which the belt could move to keep the plane from taking off?


lol, let it go man, you might as well go argue with a fence post. and no, the conveyor belt could spin at a trillion rpm's and the plane still takes off.


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## 24Buds (Dec 5, 2008)

POC Troutman said:


> so the question does not stipulate speed of the conveyor right... so let me ask you this... do you think there is a speed at which the belt could move to keep the plane from taking off?


I don't think so. your thoughts?


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## poppadawg (Aug 10, 2007)

POC Troutman said:


> so the question does not stipulate speed of the conveyor right... so let me ask you this... do you think there is a speed at which the belt could move to keep the plane from taking off?


At exactly the same speed or faster than the planes thrust.


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## POC Troutman (Jul 13, 2009)

edit: i changed my mind!

the wording of the question always allows the plane to take off.


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## MikeS2942 (Mar 5, 2010)

nope!


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## BonesNTX (Aug 14, 2006)

Jolly Roger said:


> no, prop moves air for population. Does not matter what the belt under it is doing the plane is going to move forward unless you stop the prop from moving air.
> 
> Wheels spin freely. Does not effect forward motion of a plane.


It is stated in initial query that it does matter what the belt does.

Example: Imagine the plane on the moving belt with no thrust...Where's it going to be? Same place you and I end up if we are on a treadmill and stop walking. All the way to the end of the belt.

You may be thinking someone/something is holding the plane stationary? I didn't think that the case as stated.


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## 24Buds (Dec 5, 2008)

POC Troutman said:


> i think there would be a speed of the conveyor belt that would keep the plane from taking off. if you don't limit the amount of thrust available to the plane, then the plane always takes off.
> 
> basically the question i asked could be stated "if the airplane under normal conditions has a maximum attainable ground speed of 500 mph, what would be the speed of the conveyor belt to keep the plane from taking off" the friction force overcomes or limits the forward movement that the plane can't generate enough lift to take off at some point.


I see what you are saying. If the conveyor belt could run fast enough to create enough friction in the wheels then yes, it would not work. My guess is that the tires would come apart way before that friction was up to the required amount to drag the plane from accelerating.

I need a beer.:cheers:


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## T_rout (Jul 25, 2013)

There has to be some form of vertical motion. The thrusters are providing horizontal energy so it doesn't matter how fast the wheels spin or how fast the plane is moving. No upward energy no take off!! The only way it could take off is if the wind was blowing really hard! Really really hard!


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## surf_ox (Jul 8, 2008)

ok googled it

http://www.airplaneonatreadmill.com/

I hope those two scenarios clearly illustrate the difference in motive force between cars and planes. Cars create their forward movement from torque applied to the wheels, which push against the ground and create forward motion from friction. Planes create their forward movement from thrust applied to the air, which pushes the plane forward regardless of the surface it is on.

Imagine a plane without wheels. The fuselage would sit on the runway, and as you fired up the engines, it would skid spectacularly along the runway, possibly spewing sparks in its wake and doing quite a number on the body of the aircraft. No matter how fast it was going, the frictional force against the airplane would be _constant_; friction does not depend on speed! If the engines were strong enough to get the plane up to the critical take-off speed, then it would still take off. The _only_ reason planes have wheels is to reduce this sliding friction. The wheels roll along the runway instead of sliding, and the only friction that the plane feels is in the bearings of the wheels. This is substantially less than the friction that a sliding fuselage would create, and it's a much smoother ride for the passengers as well.

Good example

If you don't believe me, imagine this (or even try it at home): you're standing on a skateboard on a treadmill. You hold onto the handrails of the treadmill and turn it on. Of course, you'll remain stationary (relative to the ground). In fact, you only need to use a very light touch to stay stationary - perhaps a few fingers pressed against the handrails. Crank up the treadmill speed as high as you like. You'll still only need the same light touch to remain stationary. At any time you like, you can move forward - closer to the treadmill console - by simple pulling on the handrails. If you had a jet engine, or super-strong hairdryer, you could use this to propel yourself forward instead of holding onto the handrails. In fact, if you're really careful, you might be able to do this at home with a skateboard and a leafbower, but I doubt you'll have a sensitive enough control of your leafblower thrust to get yourself to remain stationary.


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## boom! (Jul 10, 2004)




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## Jerry-rigged (May 21, 2004)

The problem with the problem is the solution as nothing to do with the facts stated in the problem.

Similar problem:

You plan a fish fry for all your friends. The number pf people you plan on inviting depends on how many fish you catch. You catch no fish. Can you still buy a half gallon of Bluebell on the way home?


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## 24Buds (Dec 5, 2008)

good show of short takeoffs and landings!


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## poppadawg (Aug 10, 2007)

this is some smart stuff right here. where are the nasa folks when you need them


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## boom! (Jul 10, 2004)

By the way, if you get a 65mph wind to the front of a cessna 152 it will take off with the brakes on. (zero wheel speed)


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## goatchze (Aug 1, 2006)

Jerry-rigged said:


> The problem with the problem is the solution as nothing to do with the facts stated in the problem.
> 
> Similar problem:
> 
> You plan a fish fry for all your friends. The number pf people you plan on inviting depends on how many fish you catch. You catch no fish. Can you still buy a half gallon of Bluebell on the way home?


Is it on sale?


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## coachlaw (Oct 26, 2005)

Seems to me that this is a very good intelligence test. Lots of people here seem to be lacking. Guys, if there is no air speed, there is no lift. Engines do not create lift, they create thrust, which unimpeded should create airspeed. If you have the plane on a treadmill, the thrust is negated and once again, with no airspeed, you have no lift. Thrust can only create airspeed if the engines are vertical such as in a rocket or if the exhaust can be diverted downward such as in a VTOL aircraft (Harrier, Osprey, etc.). This overpowers the force of gravity creating lift. With engines horizontal, as in the proposed problem, no lift = no takeoff. Anyone who thinks otherwise isn't thinking or does not have the capacity to think. Sorry if I hurt any feelings.


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## surf_ox (Jul 8, 2008)

coachlaw said:


> Seems to me that this is a very good intelligence test. Lots of people here seem to be lacking. Guys, if there is no air speed, there is no lift. Engines do not create lift, they create thrust, which unimpeded should create airspeed. If you have the plane on a treadmill, the thrust is negated and once again, with no airspeed, you have no lift. Thrust can only create airspeed if the engines are vertical such as in a rocket or if the exhaust can be diverted downward such as in a VTOL aircraft (Harrier, Osprey, etc.). This overpowers the force of gravity creating lift. With engines horizontal, as in the proposed problem, no lift = no takeoff. Anyone who thinks otherwise isn't thinking or does not have the capacity to think. Sorry if I hurt any feelings.


thrust from jets is pushing against the air...nothing to do with treadmill


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## Hotrod (Oct 11, 2006)

Nothing to add but some funnies from Fed Ex Aircraft mechanics

http://www.quickmeme.com/p/3vqlfy

,


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## boom! (Jul 10, 2004)

coachlaw said:


> Seems to me that this is a very good intelligence test. Lots of people here seem to be lacking. Guys, if there is no air speed, there is no lift. Engines do not create lift, they create thrust, which unimpeded should create airspeed. If you have the plane on a treadmill, the thrust is negated and once again, with no airspeed, you have no lift. Thrust can only create airspeed if the engines are vertical such as in a rocket or if the exhaust can be diverted downward such as in a VTOL aircraft (Harrier, Osprey, etc.). This overpowers the force of gravity creating lift. With engines horizontal, as in the proposed problem, no lift = no takeoff. Anyone who thinks otherwise isn't thinking or does not have the capacity to think. Sorry if I hurt any feelings.


Ok oh wise one, explain to me how you keep a plane from moving forward without brakes or tying it down. lol


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## StinkBait (May 31, 2004)

coachlaw said:


> Seems to me that this is a very good intelligence test. Lots of people here seem to be lacking. Guys, if there is no air speed, there is no lift. Engines do not create lift, they create thrust, which unimpeded should create airspeed. If you have the plane on a treadmill, the thrust is negated and once again, with no airspeed, you have no lift. Thrust can only create airspeed if the engines are vertical such as in a rocket or if the exhaust can be diverted downward such as in a VTOL aircraft (Harrier, Osprey, etc.). This overpowers the force of gravity creating lift. With engines horizontal, as in the proposed problem, no lift = no takeoff. Anyone who thinks otherwise isn't thinking or does not have the capacity to think. Sorry if I hurt any feelings.


Quite a bold statement there, lol. Think of it this way. The props/jets are working in air that is not moving (and this air speed has nothing to do with the speed of the treadmill) The prop WILL pull the plane thru this air, yes the wheels will spin faster but it does not matter. The prop will continue pulling the plane forward in the dead air until it gains enough forward speed to form lift on the wings.


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## MilkBucket (Oct 22, 2012)

Your wheel speed will be twice the speed of the plane, and the plane will fly.


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## Jerry-rigged (May 21, 2004)

coachlaw said:


> Seems to me that this is a very good intelligence test. Lots of people here seem to be lacking. Guys, if there is no air speed, there is no lift. Engines do not create lift, they create thrust, which unimpeded should create airspeed. If you have the plane on a treadmill, the thrust is negated and once again, with no airspeed, you have no lift. Thrust can only create airspeed if the engines are vertical such as in a rocket or if the exhaust can be diverted downward such as in a VTOL aircraft (Harrier, Osprey, etc.). This overpowers the force of gravity creating lift. With engines horizontal, as in the proposed problem, no lift = no takeoff. Anyone who thinks otherwise isn't thinking or does not have the capacity to think. Sorry if I hurt any feelings.


You are getting sucked into the invalid argument. A moving treadmill will not prevent an airplane under power from moving. The wheel friction is too low. The treadmill argument works fine for a car, train, boat, horse, person, or anything else that relies on pushing against the ground to move. Airplane don't push against the ground to move. They push against the air, which is not effected by the treadmill.


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## blaze 'em (Jun 4, 2012)

coachlaw said:


> Seems to me that this is a very good intelligence test. Lots of people here seem to be lacking. Guys, if there is no air speed, there is no lift. Engines do not create lift, they create thrust, which unimpeded should create airspeed. If you have the plane on a treadmill, the thrust is negated and once again, with no airspeed, you have no lift. Thrust can only create airspeed if the engines are vertical such as in a rocket or if the exhaust can be diverted downward such as in a VTOL aircraft (Harrier, Osprey, etc.). This overpowers the force of gravity creating lift. With engines horizontal, as in the proposed problem, no lift = no takeoff. Anyone who thinks otherwise isn't thinking or does not have the capacity to think. Sorry if I hurt any feelings.


Wrong... the thrust would not be negated unless you had a tailWIND similar to the thrust of the plane. A tailwind may be what your mistaking the reverse direction of the belt for. If that was the case then your right, the airspeed is negated. But the free moving (minus the friction of the bearings in the wheel) wheels don't have any effect because the thrust is what moves the plane. "AIR" as someone mentioned earlier.

Sent from my SAMSUNG-SGH-I747 using Tapatalk 2


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## Category6 (Nov 21, 2007)

If a plane full of dummies crashes in the forest, and no thinking people are around to hear it, did it really make a sound?


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## BonesNTX (Aug 14, 2006)

Category5 said:


> If a plane full of dummies crashes in the forest, and no thinking people are around to hear it, did it really make a sound?


Depends on wind speed and direction.


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## poppadawg (Aug 10, 2007)

The plane has to have the air pass over its wings to fly. So the plane has to be moving thru air to get lift off. The thrust allows the plane to move through the air. If the thrust and conveyor belt are perfectly matched the plane isnt moving. there has to be forward movement to create the air friction required for
flight


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## StinkBait (May 31, 2004)

poppadawg said:


> The plane has to have the air pass over its wings to fly. So the plane has to be moving thru air to get lift off. The thrust allows the plane to move through the air. If the thrust and conveyor belt are perfectly matched the plane isnt moving. there has to be forward movement to have flight


Yes it will, the jets/prop will be working in air that has no speed, the props will pull the plane forward and the jets would push the plane forward.
hahahahahaha you guys kill me.:brew2::brew2:


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## boom! (Jul 10, 2004)

poppadawg said:


> The plane has to have the air pass over its wings to fly. So the plane has to be moving thru air to get lift off. The thrust allows the plane to move through the air. If the thrust and conveyor belt are perfectly matched the plane isnt moving. there has to be forward movement to create the air friction required for
> flight


What keeps the thrust from moving the plane forward on the conveyor belt?


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## Mont (Nov 17, 1998)

BonesNTX said:


> Depends on wind speed and direction.


and angle of impact


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## poppadawg (Aug 10, 2007)

If the plane moves forward there can be flight. The premise as I understand it is that the thrust and conveyor belt are perfectly synchronized so that the plane doesnt move forward


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## goatchze (Aug 1, 2006)

boom! said:


> What keeps the thrust from moving the plane forward on the conveyor belt?


The problem statement.


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## Shallow_Minded (Sep 21, 2004)

All of you are wrong. It's obvious the conveyor would be sucked into the engine inlets causing the engines to compressor stall and eventually FOD out. Therefore the conveyor wouldn't move, the jet wouldn't move, the escape slides would be deployed, the emergency crews would arrive, and everyone on board would escape with their lives. The captain would be hailed a hero and the aircraft certainly would not have flown, however I'm sure heads would roll....


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## Bozo (Jun 16, 2004)

Some of you keep focusing on a belief that the conveyors speed will negate the forward movement of the plane. You are forgetting the rule of the question that states the conveyor only moves as fast as the plane in the opposite direction. The plane must be moving forward for the conveyor to turn at all. If the forward motion was negated, then the conveyor is not moving. At no time that the conveyor is moving is the plane not making forward motion.


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## JamesAggie (Jun 28, 2012)

http://www.airplaneonatreadmill.com/

This website was very helpful. The question is very poorly written. The way I initially understood the question implied the plane does not move so of course it would not take off. The website cleared it up though, the plane will continue to accelerate forward where it will obtain enough velocity to obtain lift.

Very interesting debate.


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## Jerry-rigged (May 21, 2004)

Seems like this should fit here:



Ron White said:


> I flew all the way from Flagstaff, Arizona to Phoenix, Arizona because my manager doesn't own a globe. We flew on a plane that big, like a pack of gum with eight people in it, just (imitates sound of a tiny airplane). We took off from the Flagstaff Airport, Hair Care and Tire Center there. We were going half the speed of smell. We got passed by a kite. There was a goose behind us, the pilot was screaming, "Go around! Go around!" On the way there, we lost some oil pressure in one of the engines, so we had to turn around. It's a 9-minute flight...can't pull it off with this equipment. And they told us about it over the speaker system of the plane, which was stupid because they coulda just went [looks backward] "Hey, we lost some oil pressure." [gives a thumbs-up] Heard ya! Sure did. Everybody else was panicking, but I'd been drinking since lunch, so I was like, "Take it down, I don't care." Ever have one of those days? "Hit somethin' hard, I don't wanna limp away from this piece of ****." The guy sitting next to me is losing his mind; apparently, he had a lot to live for. He turns to me, he says "Hey man! [gasps for air] Hey, man! Hey, man! [gasps for air] If one of these engines fails, [gasps for air] how far will the other one take us?" [As himself]"All the way to the scene of the crash! Which is pretty handy, 'cause that's where we're headed. I bet we beat the paramedics there by a half-hour! We're haulin' ***!"


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## boom! (Jul 10, 2004)

goatchze said:


> The problem statement.


"The problem statement" says that the plane is tied back?


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## T_rout (Jul 25, 2013)

There has to be some form of vertical motion. The thrusters are providing horizontal energy so it doesn't matter how fast the wheels spin or how fast the plane is moving. No upward energy no take off!! The only way it could take off is if the wind was blowing really hard! Really really hard!


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## goatchze (Aug 1, 2006)

boom! said:


> "The problem statement" says that the plane is tied back?


The only way for the plane to move forward is for the wheels to be moving faster than the conveyor. This has nothing to do with thrust, propulsion, the air-speed velocity of an unladen swallow, or anything else.

If the two are moving at the same speed (that is the wheel surface and the treadmill surface), regardless of what that speed is, the plane cannot be moving forward WRT to the air around it.

The problem statement therefore says the plane cannot move forward.


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## Waymore (Jul 6, 2011)

The plane will move forward the same speed as if it was on a runway, only the wheels would be turning at twice the speed. It will fly at the point of lift on either. You just have to see the wheels don't drive anything>>>


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## Rack Ranch (May 25, 2004)

WOW!!!


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## boom! (Jul 10, 2004)

goatchze said:


> The only way for the plane to move forward is for the wheels to be moving faster than the conveyor. This has nothing to do with thrust, propulsion, the air-speed velocity of an unladen swallow, or anything else.
> 
> If the two are moving at the same speed (that is the wheel surface and the treadmill surface), regardless of what that speed is, the plane cannot be moving forward WRT to the air around it.
> 
> The problem statement therefore says the plane cannot move forward.


I'd better see about getting a wheel speed indicator installed then. :rotfl:


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## T_rout (Jul 25, 2013)

Jerry-rigged said:


> You are getting sucked into the invalid argument. A moving treadmill will not prevent an airplane under power from moving. The wheel friction is too low. The treadmill argument works fine for a car, train, boat, horse, person, or anything else that relies on pushing against the ground to move. Airplane don't push against the ground to move. They push against the air, which is not effected by the treadmill.


The friction may be low but the plane is pushing against the ground. Weight in relation to gravity makes the plane push against the ground. The amount of energy created from the engines has to be greater than the amount of force being applied to the ground, via the tires, in order for the plane to move. Then there has to be some sort of positive vertical energy to get the plane off the ground, hence the wings and air speed. Since the plane is not actually moving, only the wheels are spinning on a belt or conveyor, there will not be any air speed besides the wind.


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## Rack Ranch (May 25, 2004)

9.8m/sec2


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## Jerry-rigged (May 21, 2004)

T_rout said:


> The friction may be low but the plane is pushing against the ground. Weight in relation to gravity makes the plane push against the ground. The amount of energy created from the engines has to be greater than the amount of force being applied to the ground, via the tires, in order for the plane to move. Then there has to be some sort of positive vertical energy to get the plane off the ground, hence the wings and air speed. Since the plane is not actually moving, only the wheels are spinning on a belt or conveyor, there will not be any air speed besides the wind.


Wrong.

Per Physics, the ground is providing LIFT. The ground is preventing the plane from going DOWN, not forward. Drag prevents the plane from going forward, and unless you forgot to release the brakes, Airplane wheels provide very little drag, compared to the thrust the motor provides.

Thrust Lift Drag Weight. Learn what they do, and what is causing them.


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## MilkBucket (Oct 22, 2012)




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## StinkBait (May 31, 2004)

boom! said:


> I'd better see about getting a wheel speed indicator installed then. :rotfl:


Boom! Most won't get it. lol


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## CHARLIE (Jun 2, 2004)

Op says conveyer is traveling at the exact same speed of the airplane.


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## ChuChu (Jan 23, 2010)

If it would fly, the Navy would have such a system on every ship. Ever thought of why the Navy uses Harriers?


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## Category6 (Nov 21, 2007)

let me clear this up for yall what aint gettin it. If a plane were to LAND at 175 mph on a conveyor runway moving in the opposite direction and able to match the wheel speed of the plane, would it immediately stop from 175 mph to 0 mph in 0 seconds? I think not! The wheels spin however fast they need to in order to keep up with the plane.


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## ralph7 (Apr 28, 2009)

boom! said:


> Ok oh wise one, explain to me how you keep a plane from moving forward without brakes or tying it down. lol


By matching the speed exactly backwards from where the plane wants to go?
Isn't that the same as placing a car on a free-wheeling conveyer? Wouldn't it just sit there?
And if a plane is just sitting there, it ain't getting any airflow around the wings.


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## The Salty Raider (Sep 25, 2012)

Everyone read this and move on with life

http://www.airplaneonatreadmill.com/2008/01/airplane-on-treadmill.html

I dont care how you spin it or what you say...the plane will in fact take off


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## boom! (Jul 10, 2004)

ralph7 said:


> And if a plane is just sitting there, it ain't getting any airflow around the wings.


My point is that the plane will not just "sit there" unless it is tied back. I don't care how fast you spin the wheels in the opposite direction. Exercise in futility I guess. I must not have been paying attention in gym class.


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## Category6 (Nov 21, 2007)

ralph7 said:


> By matching the speed exactly backwards from where the plane wants to go?
> Isn't that the same as placing a car on a free-wheeling conveyer? Wouldn't it just sit there?
> And if a plane is just sitting there, it ain't getting any airflow around the wings.


What about the fact that a car transmits its power directly to the wheels, and a plane transmits its power by moving air? The plane doesn't care how fast the wheels are spinning, the stupid wheels can either come with or not, the plane is still going however fast the horsepower moving the air will allow. This is very similar to the speed over ground vs. speed over water thing on a boat.


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## Bozo (Jun 16, 2004)

For those of you that think the plane won't take off, if the plane was coming in for a landing and the conveyor was moving in the same direction and speed a the plane, could it stop with it's reverse thrusters o yr would it never stop and be in perpetual motion?


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## ralph7 (Apr 28, 2009)

The Salty Raider said:


> Everyone read this and move on with life
> 
> http://www.airplaneonatreadmill.com/2008/01/airplane-on-treadmill.html
> 
> I dont care how you spin it or what you say...the plane will in fact take off


I just read this and now I get it. The person on the treadmill, on the skateboard comparison made me see it. I'm a bit stubborn ya see.


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## Bozo (Jun 16, 2004)

ralph7 said:


> By matching the speed exactly backwards from where the plane wants to go?
> Isn't that the same as placing a car on a free-wheeling conveyer? Wouldn't it just sit there?
> And if a plane is just sitting there, it ain't getting any airflow around the wings.


Simple answer is no, it is not the same.


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## 98aggie77566 (Jul 7, 2009)

The only way the plane will take off is if the pilot uses the "hold my beer and watch this" intro to the stunt.


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## indaskinny (May 25, 2009)

Airplane wheels provide no energy....


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## CoastalOutfitters (Aug 20, 2004)

no it will not, TSA found finger nail clippers in a handbag search and one passenger had 4oz. of toothpaste. the plane is grounded for 2 hours


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## speckle-catcher (May 20, 2004)

12 more pages of people that suck at math.

I sure hope they don't require you to answer "what is 2+2?" in order to shut down those operating units many of ya'll work in.

:slimer:


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## blaze 'em (Jun 4, 2012)

speckle-catcher said:


> 12 more pages of people that suck at math.
> 
> I sure hope they don't require you to answer "what is 2+2?" in order to shut down those operating units many of ya'll work in.
> 
> :slimer:


Nope, all you gotta do is push a button to shut them down. No math involved...

Sent from my SAMSUNG-SGH-I747 using Tapatalk 2


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## mrau (Mar 17, 2010)

Oyster Dog said:


> If it's a Delta flight, it won't take off.


Hah. DELTA = Don't Ever Leave The Airport.

Setting the conveyor aside, an airplane in the air can hover or actually fly backwards. Take up a Piper Cub after a brisk winter norther blows threw and if you turn it into a 40 Knot headwind once you slow to just below that you will begin to fly backwards.

Your wing still develops lift, and you will still have an indicated airspeed on the gauge, but your ground speed will be negative ... You'll be flying in reverse. The low and slow planes are some of the funniest.


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## goatchze (Aug 1, 2006)

boom! said:


> I'd better see about getting a wheel speed indicator installed then. :rotfl:





StinkBait said:


> Boom! Most won't get it. lol


You're the one not getting it stink. It doesn't matter whether we're talking about a plane, a car, or a unicycle. For anything to move forward on a conveyor/treadmill, the surface of the wheel must be traveling faster than the surface of the conveyor/treadmill (assuming no slip). That is 100%, absolute fact.

If Boom's wheel speed indicator states that the speed of the airplane is that of the conveyor (the problem statement), then his airplane is not moving WRT to the ground or air around him. If his indicator says that the speed is less than he conveyor speed, he's moving backwards. If it says his speed is greater, he is moving forward.


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## Category6 (Nov 21, 2007)

goatchze said:


> You're the one not getting it stink. It doesn't matter whether we're talking about a plane, a car, or a unicycle. For anything to move forward on a conveyor/treadmill, the surface of the wheel must be traveling faster than the surface of the conveyor/treadmill (assuming no slip). That is 100%, absolute fact.
> 
> If Boom's wheel speed indicator states that the speed of the airplane is that of the conveyor (the problem statement), then his airplane is not moving WRT to the ground or air around him. If his indicator says that the speed is less than he conveyor speed, he's moving backwards. If it says his speed is greater, he is moving forward.


Oh he got it! He was being sarcastic about the fact that wheel speed is completely irrelevant, whether the plane is on the runway, in the air, on a treadmill, in Oklahoma, in Canada, or on mars.


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## StinkBait (May 31, 2004)

Category5 said:


> Oh he got it! He was being sarcastic about the fact that wheel speed is completely irrelevant, whether the plane is on the runway, in the air, on a treadmill, in Oklahoma, in Canada, or on mars.


lol, thank you.


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## MilkBucket (Oct 22, 2012)

goatchze said:


> You're the one not getting it stink. It doesn't matter whether we're talking about a plane, a car, or a unicycle. For anything to move forward on a conveyor/treadmill, the surface of the wheel must be traveling faster than the surface of the conveyor/treadmill (assuming no slip). That is 100%, absolute fact.
> 
> If Boom's wheel speed indicator states that the speed of the airplane is that of the conveyor (the problem statement), then his airplane is not moving WRT to the ground or air around him. If his indicator says that the speed is less than he conveyor speed, he's moving backwards. If it says his speed is greater, he is moving forward.


An airplanes speed is not based on its wheel speed, if a plane is going 30 mph and the conveyor is 30 mph in reverse the wheels are turning at 60 mph.


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## Jolly Roger (May 21, 2004)

goatchze said:


> You're the one not getting it stink. It doesn't matter whether we're talking about a plane, a car, or a unicycle. For anything to move forward on a conveyor/treadmill, the surface of the wheel must be traveling faster than the surface of the conveyor/treadmill (assuming no slip). That is 100%, absolute fact.
> 
> If Boom's wheel speed indicator states that the speed of the airplane is that of the conveyor (the problem statement), then his airplane is not moving WRT to the ground or air around him. If his indicator says that the speed is less than he conveyor speed, he's moving backwards. If it says his speed is greater, he is moving forward.


Think the skate board example is a good one for reference.

Put it this way, if you were standing on a skate board and the wheels of the skate board were on a treadmill going 20mph. The wheel speed and the tread mill match each other exact. You could still pull yourself forward using your arms. Even with the wheels of the skate board and the tread mill speed exactly the same.

The plane would still have forward motion on the tread mill because the prop will use the air to pull the plane forward. It would take off. Does not matter what the wheels are doing.


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## tentcotter (Oct 23, 2009)

Here's how it works. Prop pulls against air just like man pulls rope. When man pulls rope, he advances forward. If treadmill speeds up to match his speed, the wheels on his skates turn faster (irelevant to problem) but he still advances faster as he pulls rope faster. 

Plane takes off. No math.


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## BonesNTX (Aug 14, 2006)

Wheel speed doesn't have a @!#$# thing to do with this. Friction is not a factor either.
Wheels are only there for vertical support. Keeps plane off it's belly.

This latest "pull the rope" diagram is kind of right.
Pull the rope about 100 mph and you get enough velocity for adequate lift= flying.


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## poppadawg (Aug 10, 2007)

BonesNTX said:


> This latest "pull the rope" diagram is kind of right.
> Pull the rope about 100 mph and you get enough velocity for adequate lift= flying.


Bingo. unless the prop is spinning fast enough to move the palne forward no flight. But that was not the premise. The premise is the propeller is only spinning fast enough to keep the plane stationary on the conveyor. If the plane doesnt move relative to the ground -no flight


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## goatchze (Aug 1, 2006)

Jolly Roger said:


> *Think the skate board example is a good one for reference.
> *
> 
> OK!
> ...


:doowapsta


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## Jolly Roger (May 21, 2004)

goatchze said:


> :doowapsta


all the treamill can do is match the speed of the wheels, it can not stop the plan from advancing forward with it's prop. The speed of the plane forward is gained from the prop and air. There is nothing the wheels or the tread mill can do to stop the plane from moving air. No speed or forward movement comes from the plane's wheels. The plane speed will be different from it's wheel speed. The plane will move forward at an increasing pace from 0 to whatever it needs to lift off. At the same time the wheel speed will increase and the belt will match the wheel speed.

Unless the air or the prop of the plane are changed, the plane will move forward no matter what the wheels are doing. The effects on the wheels and the plane are effected by two separate forces that are not bound to each other.

The air is not moving above the treadmill. So to the plane, it is exactly like taking off the ground starting at 0 mph no matter how fast it's wheels are spinning. Plane uses AIR to move, not it's wheels.


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## BonesNTX (Aug 14, 2006)

When the plane is "on the belt" via it's wheels, when the belt moves the plane will move with it. If there is no propulsion such as by jets (NOT wheels) to counteract the belt motion, the plane will be taken away by the belt.
That is not what the problem presents. Have a look see back at original question.
It is stated that the belt and plane speed are matched.

As long as they are matched, essentially there is no velocity achieved by the stationary plane and no lift.

Wheel speed is not a factor.


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## boom! (Jul 10, 2004)

Six year olds get it. lol


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## Jolly Roger (May 21, 2004)

BonesNTX said:


> When the plane is "on the belt" via it's wheels, when the belt moves the plane will move with it. If there is no propulsion such as by jets (NOT wheels) to counteract the belt motion, the plane will be taken away by the belt.
> That is not what the problem presents. Have a look see back at original question.
> It is stated that the belt and plane speed are matched.
> 
> As long as they are matched, essentially there is no velocity achieved by the stationary plane and no lift.


The question asked if the plane could take off. The answer is yes, it would take off.

The wheel speed has no effect on air speed.

the red part is false, when the belt moves the wheels of the plane spin. The belt has no effect on the plane or the air the plane uses to move.


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## Jerry-rigged (May 21, 2004)

poppadawg said:


> Bingo. unless the prop is spinning fast enough to move the palne forward no flight. But that was not the premise. *The premise is the propeller is only spinning fast enough to keep the plane stationary on the conveyor. *If the plane doesnt move relative to the ground -no flight


no, the premise is that as the plane speeds up, so does the belt. Not the other way around. The plane is controlling the belt speed. The belt can only react, and can't keep the plane from moving.


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## bleacher_bum (Jan 31, 2010)

Jolly Roger said:


> The plane will still take off, Mythbusters tested it.


This. Mythbusters knows...


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## Category6 (Nov 21, 2007)

BonesNTX said:


> When the plane is "on the belt" via it's wheels, when the belt moves the plane will move with it. If there is no propulsion such as by jets (NOT wheels) to counteract the belt motion, the plane will be taken away by the belt.
> That is not what the problem presents. Have a look see back at original question.
> It is stated that the belt and plane speed are matched.
> 
> ...


the wheels on the plane go round and round, round and round, round and round...,


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## goatchze (Aug 1, 2006)

Jolly Roger said:


> all the treamill can do is match the speed of the wheels, it can not stop the plan from advancing forward with it's prop. The speed of the plane forward is gained from the prop and air. There is nothing the wheels or the tread mill can do to stop the plane from moving air. No speed or forward movement comes from the plane's wheels. The plane speed will be different from it's wheel speed. The plane will move forward at an increasing pace from 0 to whatever it needs to lift off. *At the same time the wheel speed will increase and the belt will match the wheel speed.*
> 
> Unless the air or the prop of the plane are changed, the plane will move forward no matter what the wheels are doing. The effects on the wheels and the plane are effected by two separate forces that are not bound to each other.
> 
> The air is not moving above the treadmill. So to the plane, it is exactly like taking off the ground starting at 0 mph no matter how fast it's wheels are spinning. Plane uses AIR to move, not it's wheels.


Everything you said is true, except the bold statement. If the plane is moving forward WRT to the ground (or air around it assuming no wind), the belt cannot be matching the speed of the wheels.

:mpd:


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## bill (May 21, 2004)

Can a seaplane still take off IF it's going against the tide? Planes don't even need wheels, so just remove them from the equation.


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## Shallow_Minded (Sep 21, 2004)

Just view #37, most of us knew the answer already.


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## Finn Maccumhail (Feb 16, 2009)

I'm no engineer and intuitatively I would argue that no, the plane cannot take off.

However, I've seen demonstrations where people with far more scientific credentials than I possess have done experiments and proven that in fact, yes the plan will take off.

I forget the physics behind it but the plane takes off.


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## Billphish (Apr 17, 2006)

it will take off. but...

what if the plane had a tub of water in it and the conveyor had a scale. if you dropped a ten pound fish is the tub of water in the plane how much extra weight would the scale indicate?


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## goatchze (Aug 1, 2006)

Billphish said:


> it will take off. but...
> 
> what if the plane had a tub of water in it and the conveyor had a scale. if you dropped a ten pound fish is the tub of water in the plane how much extra weight would the scale indicate?


Depends. What kind of fish is it?


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## BonesNTX (Aug 14, 2006)

goatchze said:


> Depends. What kind of fish is it?


Which way is the fish swimming after he lands in the water?
Tires flatten with that extra weight added?


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## Billphish (Apr 17, 2006)

goatchze said:


> Depends. What kind of fish is it?


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## Jerry-rigged (May 21, 2004)

marshhunter said:


> A plane is standing on a movable runway (something like a conveyor) *As the plane moves, the conveyor moves* but in the opposite direction. The conveyor has a system that tracks the speed of the plane and matches it exactly in the opposite direction.
> 
> The question is, will the plane take off or not and why, or why not


I thought it would be worth a re-post of the original question, as some people didn't read it, apparently. Also note the bold bit, as it is the really important bit. And let's break it down it down a bit-

Plane is stopped, treadmill is stopped, wheels are stopped.
Plane is moving 1mph, Treadmill is moving 1mph, wheels are moving/tracking 2mph
plane is moving 10 mph, treadmill is moving 10 mph, wheels are moving/tracking 20mph.

Plane is moving 100mph, Treadmill is moving 100mph, wheels are moving/tracking 200mph

Plane Flys.

Please note, that if any time the plane STOPS MOVING, so does the treadmill. So if your argument is based on that the plane will never move, you are wrong. Wheel speed is ALWAYS 2x the planes speed, till it flys...

Any Questions?


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## BonesNTX (Aug 14, 2006)

Jerry-rigged said:


> I thought it would be worth a re-post of the original question, as some people didn't read it, apparently. Also note the bold bit, as it is the really important bit. And let's break it down it down a bit-
> 
> Plane is stopped, treadmill is stopped, wheels are stopped.
> Plane is moving 1mph, Treadmill is moving 1mph, wheels are moving/tracking 2mph
> ...


Yeh,
Why are we so worried about the @#!%$ wheels? (By the way your wheel speed calculations are correct)
Yes, 100 mph or so will get it flying...agreed.


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## goatchze (Aug 1, 2006)

It's a slow day at the office, so here's the math.

Vt is the velocity of the treadmill.
Vw is the velocity of the surface of the wheel.
Vairplane is the velocity of the airplane.
10 is just an arbitrary "take off" speed. Who cares about the units.
Omega is the RPM or rate that the wheels are turning.

We're assuming that the wheels are not slipping WRT to the conveyor surface. That's where the Va=Vw-Vt comes from. If Va=Vw-Vt isn't true, then the wheels are either skidding or peeling out. Since we're neither applying brakes or power to the wheels, they should not be slipping.

When Vt=0, that's just like the airplane sitting on the ground. The conveyor is not moving.

When Vairplane = 0, that means the airplane is just chilling on the conveyor, not moving WRT to the air around it.

When Vairplane = 10, the plane is taking off, regardless of what Vt is.

As you would expect, if the plane is on the treadmill moving at 10, and the conveyor is moving at 10, the wheels are turning twice as fast as compared to when the conveyor is not moving.

BUT! Notice that, in both cases where the plane is moving forward, Vw > Vt. Only in the case where the plane is stationary does Vw=Vt.

The problem statement says that Vw=Vt, so if this is true, the plane is necessarily stationary. Therefore:

*The Plane Cannot Take Off*

Hope you guys have a Happy New Years!

EDIT: Jerry, you have a point. I'm working off of the old discussion where we went down the rat hole of saying the conveyor was matching the speed the wheels were rotating at (i.e. was matching Vw). If the statement is that Vt=-Vairplane, then the graphic proves your point as well, mainly that Vw= 2*Vairplane and Vw<>Vt.


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## BonesNTX (Aug 14, 2006)

The Wheels????
Do you work down the hall from me or what.
Thanks for your explanation /depiction. 
My post #35 in this thread agrees with you.

We can agree to agree?


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## goatchze (Aug 1, 2006)

BonesNTX said:


> The Wheels????
> Do you work down the hall from me or what.
> Thanks for your explanation /depiction.
> My post #35 in this thread agrees with you.
> ...


I dunno, but if I'm your boss, get back to work!

Yeah. I was harkening back about seven years:
http://2coolfishing.com/ttmbforum/showthread.php?t=98703&highlight=plane


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## Tennif Shoe (Aug 11, 2011)

Why did we go through 3 pages of this when there is not 1, but 2 videos of an airpane taking off while going down a convaer going in the opposite way?


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## BonesNTX (Aug 14, 2006)

Tennif Shoe said:


> Why did we go through 3 pages of this when there is not 1, but 2 videos of an airpane taking off while going down a convaer going in the opposite way?


You can fake anything on video...and then it's on the internet as well.

Nah, truly the video does not represent the question as the plane exceeds the speed of the conveyor belt.
It was a nice try though.


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## tentcotter (Oct 23, 2009)

Wow. This is still being debated? Oh yeah, BTW, Happy new year. 

The math genius determines that Pi r round and still comes to the wrong conclusion and someone else suggests that the video proof must have been faked. In what universe do common sense, visual proof and logic not amount to s***? Oh yeah, the 2 cool universe. My bad.


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## DA REEL DADDY (Jun 7, 2005)

*Get A jET*

Better yet get a balloon. Lol


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## surf_ox (Jul 8, 2008)

Thought I'd dig an old one up. 




--------------

We never become who God created us to be trying to be like everybody else.


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## THA (Jan 5, 2016)

*New thought*

If when an airplane takes off, it breaks ground... What does it do when it lands, break wind?


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