hmmm.... physics question for you guys....

[wulfe13]

Re: hmmm.... physics question for you guys....

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LOL, this thread is too much. The plane will not take off. There is no airflow over the wings, plain and simple. You keep confusing enigine thrust with airspeed, not the same thing. Think of it this way, say you get on a treadmill and you are able to crank it up to 50 mph and run at that speed. All of a sudden is the wind blowing in your face like it would if you stuck your head out of a cars window. No, it's because there is no forward motion. The plane has no "airspeed", thats all that matters. Heres a little example that people always think is kinda cool.. Whn I was doing my commercial pilot traing way back in 92. We were doing slowflight practice Slowflight being 5 knots over the stall speed of the plane, in this case around 35 knots in a cessna 172. The air aloft at our altitude was 40knots. We set up for slowflight and guess what, we were actually tracking backwards over the ground., even though the plane was going 35 knots forward indicated. In this treadmill scenario there is no positive airspeed because the plane actually makes no forward momentum. Since it was never allowed to build up speed through a groundroll.

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Are you kidding me? Seriously.

<u> THE WHEELS MEAN NOTHING! THEY ARE FREE ROLLING! THEY DO NOT AFFECT THE PLANES MOVEMENT IN ANY WAY, SHAPE, OR FORM! THEY ARE ONLY ATTACHED TO THE PLANE BY BALL BEARINGS! THEY CANT AFFECT THE THRUST OR AIRSPEED OF AN AIRPLANE </u>

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Prove it. Set an airplane flat on its belly, or block the wheels completely so they never spin (not with short blocks that it can eventually roll over), then crank the engines up to full force. It ain't going anywhere without breaking free of the restraints.

Engine thrust does not cause air to flow over and under the wings. It pushes air out the back (it doesn't pull air like your arms pulling a rope).

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Actually it is pulling air like the rope...

[zeegler]

Re: hmmm.... physics question for you guys....

I just found this same exact thread on the Mythbusters forum. Funny reading their responses too. Basically the same arguments as here. Cool! [img]/images/graemlins/laugh.gif[/img]

[wulfe13]

Re: hmmm.... physics question for you guys....

Did they have an answer?

[Newc]

Re: hmmm.... physics question for you guys....

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If this treadmill idea worked, I guarantee the military would have devloped and quick install type treadmill device that could be put together rather quickly, so they could have their frontline fighters at the front, instead of spending 100's of millions developing vstol aircraft, i guarantee the treadmill would have been cheaper.

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The treadmill would have to be the full length of a runway, in order for the plane to generate enough lift to take-off, so what good would that do?

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But then why would the conveyor need to be as long as the runway? By that, you're saying the plane has to have forward momentum, to which you alluded before it doesn't need, just engine thrust.

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

Physicists are funny people. They invent these hypothetical situations that we'll never be able to test out, like what happens if we were to go in a black hole, or if we were to travel at the speed of light. [img]/images/graemlins/grin.gif[/img] It's like asking what happens to us when we die... we'll never know until we're there. [img]/images/graemlins/grin.gif[/img]

[buzzsaww]

Re: hmmm.... physics question for you guys....

come on people if this were true every aircraft carrier ever made would have this instead of catapults.

[wulfe13]

Re: hmmm.... physics question for you guys....

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If this treadmill idea worked, I guarantee the military would have devloped and quick install type treadmill device that could be put together rather quickly, so they could have their frontline fighters at the front, instead of spending 100's of millions developing vstol aircraft, i guarantee the treadmill would have been cheaper.

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The treadmill would have to be the full length of a runway, in order for the plane to generate enough lift to take-off, so what good would that do?

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But then why would the conveyor need to be as long as the runway? By that, you're saying the plane has to have forward momentum, to which you alluded before it doesn't need, just engine thrust.

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Nobody said we wouldn't need forward momentum! Thrust would cause forward momentum!

[RobRR]

Re: hmmm.... physics question for you guys....

I guess that 4 years of Aerospace Science in high school was a waste for me then right? Politics it is! [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

[VinceV]

Re: hmmm.... physics question for you guys....

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They are there to support the air plane while it builds up speed. Thats it, they are only there to hold up UP.

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Yes build up speed through forward motion, on this treadmill there is no forward motion. You can only build airspeed through forward motion through the relative air. Remember in this scenario, there is no other variables besides, plane and treadmill. Explain how there is airflow over the wings, through the engine yes, because they are sucking in air. but because there is no forward motion no airflow over the wings. Plain and simple.

[RobRR]

Re: hmmm.... physics question for you guys....

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They are there to support the air plane while it builds up speed. Thats it, they are only there to hold up UP.

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Yes build up speed through forward motion, on this treadmill there is no forward motion. You can only build airspeed through forward motion through the relative air. Remember in this scenario, there is no other variables besides, plane and treadmill. Explain how there is airflow over the wings, through the engine yes, because they are sucking in air. but because there is no forward motion no airflow over the wings. Plain and simple.

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The plane doesent get its forward motion from the wheels or the treadmill, thats what your missing. It gets that from the thrusters, the wheels just support the plane while the thrusters build up the planes AIR speed.

[VinceV]

Re: hmmm.... physics question for you guys....

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If this treadmill idea worked, I guarantee the military would have devloped and quick install type treadmill device that could be put together rather quickly, so they could have their frontline fighters at the front, instead of spending 100's of millions developing vstol aircraft, i guarantee the treadmill would have been cheaper.

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The treadmill would have to be the full length of a runway, in order for the plane to generate enough lift to take-off, so what good would that do?

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But then why would the conveyor need to be as long as the runway? By that, you're saying the plane has to have forward momentum, to which you alluded before it doesn't need, just engine thrust.

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Exactly, you guys keep stating that in this treadmill scenario, all you need is a machine equal to the wheelbase of the plane, and somehow the plane will just rise. Isn't going to happen. If this was the case it would have been built. It hasn't because it doesnt work that way.

[zeegler]

Re: hmmm.... physics question for you guys....

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Again LOL, if wheels made did not affect a planes airspeed in any way , then why are they there. They allow the plane to build up airspeed buy rolling forward thus creating lift on the wings. read my post, and if you can say that for certain if you could run 50 mph on a treadmill and there would be wind blowing at you, then I'll agree with you, but thats not what happens.

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By that logic, one would have to assume that seaplanes work under the same wacky rules of physics. So floats, like wheels somehow assist an aircraft to take off. Well, I argue, that other than keeping the aircraft fuselage away from the ground, wheels or floats serve only to create drag, thus impeding the aircraft's take-off. Wheels are a necessary evil for aircraft. It's all about reducing friction. In other words, they do exactly the opposite of the wheels in a car. You want wheels on a car to create as much friction as possible (traction), but in an airplane, the oposite is true. Some experimental planes were launched from linear motors (magnetically powered monorail system), and magnetically supported monorails.

[Newc]

Re: hmmm.... physics question for you guys....

Engines do NOT pull air. Air is an intangible material that cannot be anchored like a rope to a wall.
Engines/props/fan blades PUSH air out the back based on their rotational speed and the angle of the blades. They GENERATE wind force - thrust - out the back, they do not pull.

While they do generate a vacuuous force in the front and semi-solid objects can be pulled into the engine, those objects have to be under a certain weight relative to the vacuum force and have to be relatively solid objects (gas, liquid, plasma, or solid), and they have to be within a certain proximity based on the vacuum force.
However, of those only gasses may pass safely through a turbine/prop, so as not to retard the rotational speed of the blades, and gasses are not solid enough to get a physical grip on in relation to a rope.

[RobRR]

Re: hmmm.... physics question for you guys....

Ok to elaborate on a rope theory yet AGAIN. An airplanes engines create thrust by pulling itself through the air. The air, in essence, isnt moving, the plane is pulling itself through the air. So lets replace the air with a rope, and the engines with a super-high-speed winch with a centrifual clutch. Start up the winch, and it will start to pull the plane. As the plane picks up speed the clutch engages more. Once fully engaged, the plane is at full speed. Regardless of the treadmill speed. Same principle as air, just different coefficients obviously.

[VinceV]

Re: hmmm.... physics question for you guys....

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They are there to support the air plane while it builds up speed. Thats it, they are only there to hold up UP.

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Yes build up speed through forward motion, on this treadmill there is no forward motion. You can only build airspeed through forward motion through the relative air. Remember in this scenario, there is no other variables besides, plane and treadmill. Explain how there is airflow over the wings, through the engine yes, because they are sucking in air. but because there is no forward motion no airflow over the wings. Plain and simple.

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The plane doesent get its forward motion from the wheels or the treadmill, thats what your missing. It gets that from the thrusters, the wheels just support the plane while the thrusters build up the planes AIR speed.

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OMG LOL, there is no forward motion so therfore no airspeed/airflow over the wings. Stop being fixated on the wheels no being powered, doesn't matter. You keep wanting to prove your point, but the fact is your point is just plain wrong. Like I have posted twice already when you get a treadmill and run is there wind blowing in youjr face? Answer that and you have your answer. No airflow OVER WINGS NOT JET INTAKE, WINGS no flight.