Rack your brain...

[imstock]

I am going to create chaos before I goto work...

A jet airplane sits atop a tread-mill style conveyor belt with it's nose cone facing your right. As the turbine spools up the belt begins to rotate counter clockwise in sync with the turbines output. Will the airplane take off or stay grounded due to the counter rotation of the treadmill?

Toil over the problem, and when I get back tonight at 10pm I will post the solution. I can almost guarantee this will be utter chaos in the mean time...

[zippo855]

we debated this in high scool. the obvious answer is wrong, the plane will take off. without having to type it out heres a link talking about it.
http://www.straightdope.com/columns/...plane-take-off

[Lucky7]

They did it on Myth Busters.

of course it will take off, its sucking the same ammount of air threw it, its just gonna be sitting still while its doing that, when it has what it needs its just gonna lift up and go.

[65mustangrock]

it will take off because even though there is a force pushing against the plane on the wheels the plane still takes off because the propeller pulls the plane and if the belt matches the plane than it will get the speed needed to fly some time

[KITT222]

mythbusters did this. in fact see for yourself!

http://video.google.com/videosearch?...busters+plane#

[texan_idiot25]

Engines create enough thrust to create lift.

[BART]

It does not matter how fast the turbine spins nor how fast the conveyor goes, the speed of the plane compared to the conveyor is irrelevant. The speed of the plane in relation to the ground (and therefore the air) never changes and the plane will never lift off. No increased airflow across the wings...no flight.

Edit; now wheres my cookie!

[theoriganalRiD3R1967]

Originally Posted by ZX9RBART

The speed of the plane in relation to the ground (and therefore the air) never changes and the plane will never lift off. No increased airflow across the wings...no flight.
Edit; now wheres my cookie!

i agree, there is no vacume force helping it...fly...

also the plane would have to incline its allerons/flaps and the air that its supposed to be heading into would anlge it up (supposing there was air(but there is not)), with no air to help angle it nose up it, the plane would not get off the ground.

[KITT222]

Originally Posted by theoriganalRiD3R1967

i agree, there is no vacume force helping it...fly...

you see, planes arent like cars. cars are propeled by their wheels, so they wouldnt move. but planes have freespinning wheels, and are powered by their motors which push/pull it along. the wheels dont matter.

[BART]

Originally Posted by KITT222

you see, planes arent like cars. cars are propeled by their wheels, so they wouldnt move. but planes have freespinning wheels, and are powered by their motors which push/pull it along. the wheels dont matter.

Hmmmmm, I stand corrected. I could just edit my post but that wouldn't be very fair. The plane would accelerate forward regardless of ground speed and take off. (saw it on mythbusters once but forgot the outcome so I just used (incorrect) logic.

[Donziikid]

In my opinion this all depends on the type of plane used on the "conveyor belt" runway. A propeller powered airplane (take a Cessna 172 for instance) where the propeller is positioned on the front of the plane creates enough wind force to flow over and under the wings to create lift causing this to be possible (as proven by MythBusters). However, in most typical jets (take a Boeing 747 for instance) the propulsion system is located beneath, and often behind, the wing. Since the propulsion system is located beneath, and often behind the wing, no air is moving over and under the wing to create lift causing the plane to remain grounded and motionless.

Truthfully this is just my theory. I've heard this story time and time again out at the field but never has it been discussed in such a manner where it seems logical for any plane to take off from a, for lack of a better term, "reversible," tarmac; nor can any one of our members prove or disprove anyone else's opinion/theory.

[BulletsRain]

I don't know about that mythbuster's test. I would think the weight of the plane would cause the wheels to still have some contact with the ground, even though the conveyor is being pulled. I don't know, but this does have me wondering....
I can understand that the engine will cause lift, and allow the plane to take off, but I am just not so sure. Even after I watched the Mythbuster's thing. I think you would need one big conveyor, that is off the ground, to test this right.

[BART]

Originally Posted by Donziikid

In my opinion this all depends on the type of plane used on the "conveyor belt" runway. A propeller powered airplane (take a Cessna 172 for instance) where the propeller is positioned on the front of the plane creates enough wind force to flow over and under the wings to create lift causing this to be possible (as proven by MythBusters). However, in most typical jets (take a Boeing 747 for instance) the propulsion system is located beneath, and often behind, the wing. Since the propulsion system is located beneath, and often behind the wing, no air is moving over and under the wing to create lift causing the plane to remain grounded and motionless.

Truthfully this is just my theory. I've heard this story time and time again out at the field but never has it been discussed in such a manner where it seems logical for any plane to take off from a, for lack of a better term, "reversible," tarmac; nor can any one of our members prove or disprove anyone else's opinion/theory.

It's kind of a trick question. the plane moves by thrust (regardless of its position) forward through the air creating the needed lift, the trick part is that the conveyor is irrelevant... all it is doing is turning the wheels and has no impact on flight. When I first thought of it I imagined the plane sitting still when in fact it would move forward on the treadmill until proper flight speed is reached, the treadmill could go 5000 mph in reverse and it wouldnt matter.The fact is that the plane is in no way stationary and free to move forward.

[zippo855]

copied from the link i posted

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.

[BART]

To me it's more fun to use your brain than to just copy and paste though.

[zippo855]

yeah like i said we debated this back in highschool so i used my brain alot to come up with the same conclusion. had to find several sources that would back up what we were saying and drawings and all that. so i just copied and pasted this instead of typing it all out.

[BART]

Gotcha

[KITT222]

just for you sceptics, im going to make a video with my RC plane on my treadmill, and a rc car on the treadmill. it should be posted on youtube very soon.

[texan_idiot25]

Originally Posted by KITT222

just for you sceptics, im going to make a video with my RC plane on my treadmill, and a rc car on the treadmill. it should be posted on youtube very soon.

Not the same concept, because in practice eventually the thrust of the real plane can make the the plane pull off the treadmill. In the question above the treadmill spins in sync with the speeds of the plane's engines. In otherwords, faster the engine, faster the treadmill