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imamartian
There are so many new people on here, and so many of the old crowd not, is it worth digging up this little treasure? I still don't think we ever got a definitive answer? 
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imamartian
i'm still not convinced either way...
the story is this... you have a plane on a runway. However, the runway is a conveyor belt which will run at the same speed at the wheels of the plane. Will the plane actually take off?
the story is this... you have a plane on a runway. However, the runway is a conveyor belt which will run at the same speed at the wheels of the plane. Will the plane actually take off?
Depends on which way it's running, with the plane or against it.
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joinerjohn
Nah, planes take off because of the speed of the air over the wing surfaces. It can only achieve this by moving through the air. Putting a conveyor belt under an aircraft, won't make it move through the air any faster. So this is a myth that a plane could take off from a moving conveyor belt. It would still have to move forwards through the air.
Exactly , so if the conveyor is running in the same direction as the plane it will take off with less effort or distance just like a plane catapult on an aircraft carrier.
My guess is no!
If the plane is moving forward and the belt is also moving which results in the plane remaining in the same place then how will it achieve its LIFT, the flow of AIR under its wings is not there!!!!
If the plane is moving forward and the belt is also moving which results in the plane remaining in the same place then how will it achieve its LIFT, the flow of AIR under its wings is not there!!!!
Not a very good explanation from you. The wheels on a plane are pulled along by the engines and turn when in contact with the elevator which ever way the elevator is moving. The direction and speed of the wheels has nothing to do with the how the wing speed increases to provide lift. Its the planes wing moving through the air that provides lift solely from the engines. So long as the planes engine has enough power to pull it over what friction is caused by the wheel to elevator friction then forward motion will provide lift.
Does that satisfy you!
Does that satisfy you!
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joinerjohn
I think the mythbusters proved that the plane wouldn't travel as far to take off, but the plane still had to move forward through the air.
Bernoulli's theorum proves this. Without air travelling over the wing surfaces, no lift is generated.
Put simply, if a planes take off speed is 120mph and it takes off into a headwind of 30mph, it will theoretically attain lift at 90mph ground speed. However if it takes off into a tailwind, lift won't be achieved until the plane is travelling at 150mph groundspeed.
Bernoulli's theorum proves this. Without air travelling over the wing surfaces, no lift is generated.
Put simply, if a planes take off speed is 120mph and it takes off into a headwind of 30mph, it will theoretically attain lift at 90mph ground speed. However if it takes off into a tailwind, lift won't be achieved until the plane is travelling at 150mph groundspeed.
And of couse the original poser of this question hasn't said if the engines are running.
So with a conveyor running at 120 or 150mph the plane would be carried trough the air at 120 or 150mph but may take off but won't fly.
So with a conveyor running at 120 or 150mph the plane would be carried trough the air at 120 or 150mph but may take off but won't fly.
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imamartian
i don't know who the original poser of the question is... but if you mean me... i put to you that the engines were running, pushing the plane forwards, but the runway ran back as quick as the wheels..
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imamartian
i think this problem challenges certain scientific principles... e.g. the conveyor belt versus the wheels is designed to introducce ultimate friction free...
There are so many new people on here, and so many of the old crowd not, is it worth digging up this little treasure? I still don't think we ever got a definitive answer?
Oh God what have you started!
Ok practicalities aside such as the lenght of conveyor needed for example.
I'll assume the plane is taking off northwards and has a take off speed of 120mph.
The runway (or conveyor in our case) is running from north to south at 120mph.
The plane taxis onto the runway(again ignoring the practical issues here) pointing north and is to all intents and purposes now travelling backwards at 120mph relative to the air.
It now powers up its engines.
At a speed produced by the engines of 120mph the plane will be standing still relative to the air surrounding it so won't lift up.
Now about the hovering bird in a moving transit when the driver hits the brakes
I'll assume the plane is taking off northwards and has a take off speed of 120mph.
The runway (or conveyor in our case) is running from north to south at 120mph.
The plane taxis onto the runway(again ignoring the practical issues here) pointing north and is to all intents and purposes now travelling backwards at 120mph relative to the air.
It now powers up its engines.
At a speed produced by the engines of 120mph the plane will be standing still relative to the air surrounding it so won't lift up.
Now about the hovering bird in a moving transit when the driver hits the brakes
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