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Topic: Anser me this

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

Not many people know this, but I own the first radio in Springfield. Not much on the air then, just Edison reciting the alphabet over and over. "A" he'd say; then "B." "C" would usually follow...

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Re: Anser me this

No it cannot, this is due to lack of drag on the wings

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Re: Anser me this

I was hoping for some stupid answers first X(

Not many people know this, but I own the first radio in Springfield. Not much on the air then, just Edison reciting the alphabet over and over. "A" he'd say; then "B." "C" would usually follow...

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Re: Anser me this

Isn't the belt meant to keep your pants from falling off?!

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Re: Anser me this

I have no idea but wouldn't it be funny if the conveyor belt suddenly stopped? big_smile

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6 Reply by [RPA] Arocalex (edited by [RPA] Arocalex 07-Mar-2009 18:24:57)

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Re: Anser me this

The plane would just lift off then

or possible be torn to shreds

Not many people know this, but I own the first radio in Springfield. Not much on the air then, just Edison reciting the alphabet over and over. "A" he'd say; then "B." "C" would usually follow...

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7 Reply by avogadro (edited by avogadro 07-Mar-2009 18:29:13)

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Re: Anser me this

> Einstein wrote:

> No it cannot, this is due to lack of drag on the wings


wouldnt it be do to the lack of lift on the wings? i thought drag is one of the things that airplanes try to minimize because too much drag and the plane cant fly.

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Re: Anser me this

drag on the wings = lift with the wings.

Air resistance pushes against the wing structure (drag) and the shape of the wings makes the wind push it upwards.

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Re: Anser me this

wtf are you talking about einstein?

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10 Reply by Ps

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Re: Anser me this

Yes it would take off. 747's engine move air. They don't turn wheels. The engines force air over the wings while the wheels are just free spinning. You'd still get lift.

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Re: Anser me this

An engine produces thrust A10 - nothing to do with creating an airflow over the wings.

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Re: Anser me this

Airplane on a Conveyor Belt

A plane cannot take off while sitting on a conveyor belt moving in the opposite direction.

Busted

The MythBusters first performed a small scale test with a model airplane and a small conveyor belt and were able to get the model plane to take off from the belt. They then upgraded to full scale using an actual manned plane and a runway-sized tarp as a makeshift conveyor belt. Like the small scale test, the plane was able to take off from the conveyor belt. The MythBusters explained that this was possible because unlike cars, the plane's main source of propulsion is through its propeller, not its wheels; a car's engine mechanically moves its wheels, which use their contact with the road and the traction it provides to generate forward movement, while the plane's wheels are free-moving, and independent of the propeller, which uses air displacement for forward thrust. Therefore, the conveyor belt has no bearing on the forward momentum of the plane.

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Re: Anser me this

747's dont use propellers tongue

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14 Reply by Ps

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Re: Anser me this

They still move independent of their wheels.

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15 Reply by avogadro (edited by avogadro 07-Mar-2009 20:04:16)

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Re: Anser me this

either the plane is moving forward or it isnt.  if it is moving forward fast enough regardless of whether its by wheels or prop or jet engine, then it will fly. only exception, i guess if the wind is blowing fast enough, the plane wouldnt have to be moving forward to take off.

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Re: Anser me this

About 6 months ago I saw a large jetstream type aircraft get blown onto its tail and two rear wheels (nose in the air) because it was parked into a very strong headwind. People had to go out and use their body weight to bring the nose down tongue.

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Re: Anser me this

The problem is, the plane is staying in the same place, the only part/s that is moving are the wheels.

There isnt enough fast wind blowing over the wings to generate the lift it requires to take off (using jet engine) if it is staying in one spot.

And SAY it did manage to to lift margianally, its doing 100km/h(dont know actual speeds) on the belt, once its in the air it will need to go from 0 to 100km/h as fast as it can or it will drop back down straight away. But i highly doubt it would lift off anyway.

Anyhoo its 5am and i barely know what i am talking about, so someone prove me wrong big_smile

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Re: Anser me this

Yah so the belt would have toi move itself and the plane atop it faster than the plane's jet engines moved the plane. And even then if the plane "tacked" a few degrees, say the belt runs N-S and the pilot steers NNE then the belt is not fully countering the drag on the plane.

I call on the EU to build such a belt in Switzerland and run it once a month for a few seconds.

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19 Reply by Ps

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Re: Anser me this

http://www.youtube.com/watch?v=4owlyCOzDiE

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Re: Anser me this

Lol they even made a movie from it! Amen to that A10!

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21 Reply by avogadro (edited by avogadro 07-Mar-2009 21:37:41)

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Re: Anser me this

the video shows him have the wheels able to go faster then the treadmill. if the wheels arent going faster then the treadmill, then the plane is stationary. the only thing that the video shows is that its easy for the wheels to go faster then the treadmill. it doesnt show if a plane can take off when the wheels arent going faster then the treadmill, which would mean the airplane is stationary. the treadmill isnt matching the speed of the wheels when plane is moving forward ont he conveyor belt.

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Re: Anser me this

http://www.youtube.com/watch?v=jZ3Hhdr8EjI&feature=related smile

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23 Reply by Ps

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Re: Anser me this

>if the wheels arent going faster then the treadmill, then the plane is stationary

The planes wheels are free. Their friction is close to fixed. Once the thrust overcomes that friction the plane takes off regardless of the conveyor's speed.


And that boom is awesome!

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Re: Anser me this

"The planes wheels are free. Their friction is close to fixed. Once the thrust overcomes that friction the plane takes off regardless of the conveyor's speed."

once the plane overcomes the friction, then the treadmill is no longer able to match the wheel's speed and the experiment becomes void.

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Re: Anser me this

the question is if it can be airborne while stationary, not if an airplane's engine is powerful enough to overcome the friction of the wheels.

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