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

[Newc]

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

[ QUOTE ]
The plane only needs to overcome the conveyor belt by just a tiny little bit in order to start moving forward, unless the belt operator jacked up the belt speed. The plane CAN theoretically take off if it actually starts moving (akin to Zeegs' analogy of pulling yourself forward faster and faster on an infinite treadmill whilst perched atop rollerskates).

[/ QUOTE ]

But that infers that the plane CAN travel forward faster than the belt travels in reverse, which is not an option stated in the original post.

The rope is a grounded solid stationary object. The air is not. Air is intangible. WIND FORCE is tangible, as is the thrust coming from an airplane's engines, but if wheels were unneccessary for takeoff, then a plane could be launched from a stationary platform lying on a bed of rollers with the landing gear fully retracted, and achieve the required air speed the instant it leaves the platform.

The arms pulling the rope is an incorrect analogy to the thrust of the engines pushing against the air, because you're introducing 2 solid, physically-anchored elements (arms and ropes) that are not available to the plane.

[zeegler]

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

[ QUOTE ]
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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You either didn't read, or didn't understand my posts.

[Newc]

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

Zeegs, are you an engineer, or a pilot?

[wulfe13]

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

Wow! This thread exploded! I am glad I gave you all something to think about. I actually got this question from one of the car forums I frequent.

My brother and I disagree on this. I can see why people might think it wouldn't move but, I think the thrust against the air would move the plane. You have to think about which is a greater force. Gravity holding the plane to the conveyor or thrust pulling the plane thru the air. And I am saying air! I know thrust won't make a plane fly but it causes movement which then creates the lift needed. The plane is pulling (like the rope) air, so I don't believe the conveyor matters. Now if you don't have enough thrust to move the plane thru the air (I mean just standing air) then NO it wouldn't move. But with enough thrust I think you overcome the resistance of gravity on the plane which is what is holding it to the conveyor.

[RobRR]

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

[ QUOTE ]
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.

[/ QUOTE ]

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>

Running on a treadmil is different because your getting your power directly from the treadmil, not the stationary air above it! What airline do you fly for? Just so I know never to fly on that one... For I pilot, I would have expected more common sense and technicality on this issue.

The problem is, YOU are confusing a treadmil with a wind tunnel.

[Number Of The Priest]

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

[ QUOTE ]
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,

[/ QUOTE ]

Yeah, but how would these aircraft land? On these portable treadmill runways too? [img]/images/graemlins/grin.gif[/img]

[zeegler]

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

[ QUOTE ]
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.

[/ QUOTE ]

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?

[VinceV]

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

I read all the post, sorry but your just wrong. Like was just stated your rope theory isnt valid here. When you pull on the rope your are actually adding more forward momentum by using a solid object, hence the forward momentum. Thats not gonna happen with the plane because the plane has ZERO AIRSPEED, you keep thinking thrust if airspeed., not the same. Airspeed comes from forward motion through the relative air. Because the plane was not allowed to build up airspeed through a groundroll, there will be no lift. It isnt a rocket or a 1 to 1 thrust vehicle.

[wulfe13]

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

[ QUOTE ]
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.

[/ QUOTE ]

We're not confusing thrust and airspeed or lift.

Think of it this way... If you had a plane with no engines but somehow it was moving at exactly the same speed as the conveyor, then yes....no airflow, no lift. But when you add a jet engine to the equasion (sp?) then you have an "outside" force working against the air, moving the plane and finally creating lift.

[Jack Napalm]

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

[ QUOTE ]

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>

[/ QUOTE ]

I think you all need to go back to talking about politics. Someone is going to get hurt in this thread.

[Number Of The Priest]

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

[ QUOTE ]


I think you all need to go back to talking about politics. Someone is going to get hurt in this thread.

[/ QUOTE ]

LOL [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]

[Newc]

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

[ QUOTE ]
[ QUOTE ]
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.

[/ QUOTE ]

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>

[/ QUOTE ]

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).

[RobRR]

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

Ive figured out why people cant understand this: They are somehow confusing a treadmil with a wind tunnel.

[VinceV]

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

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.

[RobRR]

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

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