For those that hate the BNP .......

[Dodge]

you are taking it out of context.
the scenario was that what happens if the conveyor provided as much force one way as the jets provided the other way.
the answer is simply the plane would stay at a stationary point when measured with the ground beside it.

That's where you've lost the plot, the conveyor doesn't provide any force. a rope or chains or some other anchor would but the conveyor just moves backwards from under the aircraft and the wheels will just turn quicker than they would on stationary ground when the aircraft moves forward. Anyone who thinks a conveyor will be able to hold an aircraft stationary is clearly lacking in the common sense department.

now get a real plane, and try and setup the above scenario, even if it were an RC plane, that conveyor belt would probably have to rotate backwards at thousands of miles per hour to match the forward force of just a tiny engine. so it just wouldnt happen.

the difference between real life situations and theory.

You've contradicted yourself.

Either it would or it wouldn't, theory and practice have match, if they don't the theory is wrong.

I've no need to set it up, it has been done and there is a link in this thread.

An aircraft on a conveyor travelling at the same speed will take off, the conveyor has no influence over the aircraft's forward motion because it's engines provide thrust that isn't dependant on the ground underneath it.

[dieselboy]

You have countered your own argument. The conveyor doesn't provide any force, directional speed maybe but not force,

there is no such thing. to have directional speed, a force must have acted on it in the first place.
this is why in space, once they are travelling thousand miles an hour, they turn off all engines. they dont slow down because there is no force to slow them down.

the only force or "drag" to speak of is the friction of the wheel bearings. The force created by the engines to get several hundred tons of steel to travel at hundreds of miles an hour requires such force that the fact the there is a little drag from the wheel bearing is negligible in comparison.

you're mistaking real life with the theory and this question.

A leaf blower on a running machine it is no comparison. The belt doesn't provide any force it is gravity and the friction of the wheel bearings, hard to counter these with a leaf blower, but with thousands of pounds of thrust from an aircraft engine only a micro fraction of this force is actually required to counter the rotation of a few bearings . . . if the wheels were jacked up off the grounds, brakes off you could turn them with your hand and maybe even a leaf blower.

yes but thats not the question. the question is if the conveyor provided as much force as the engine. in your scenario, you are saying the conveyor is not providing as much force as the engine.

this is why the leaf blower scenario is more easier understood, as it could be more realistically produced.

[dieselboy]

Here's a question for those who don't think it will fly.

Lets hust say that by some fluke, the plane manages to take off, it circles once and comes in to land on the conveyor belt. Plane is landing at 160mph, belt is spinning in the opposite direction at 160mph. When the plane hits the belt, will it stop dead? If not, why not?

course not. because it would be a combined ground to wheel speed of 320mph. thats all. there is no mention of counter forces, just a wheel speed difference. the plane will definately feel like its landed at a much faster speed

[dieselboy]

The arguement arises because of folk's fixation for driven wheels.

we all know the forward driving force is the jet engines NOT the wheels.
the arguement is the fixation with the conveyor belt.
the question states that the conveyor belt provides as much force as the engines provide. therefore this is an equal force and therefore the plane cannot move.
what you or some other people are saying is that in real life the conveyor wouldnt provide as much force and the almeighty power of the jet engine would cause the plane to roar forward, overcome the tiny reverse force of the conveyor and take off. well, there is the flaw right there, and has broken the boundaries of the scenario the question creates.

[dieselboy]

That's where you've lost the plot,
exqueeze me? the conveyor doesn't provide any force. why not? a rope or chains or some other anchor would well you could involve gravity here instead but the conveyor just moves backwards from under the aircraft and the wheels will just turn quicker than they would on stationary ground when the aircraft moves forward. Anyone who thinks a conveyor will be able to hold an aircraft stationary is clearly lacking in the common sense department. well it could do, if it provided the exact same opposite force as the jet engines

You've contradicted yourself.

Either it would or it wouldn't, theory and practice have match, if they don't the theory is wrong.

I've no need to set it up, it has been done and there is a link in this thread.
okay, in that case i will believe you, but you must show me the link, show me what they did to prove the forces of the conveyor matched that of the jet engine (or whatever engine they used to move the air). i want to see formulas and equasions they used, their theories and their controls (control as in how did they make it a fair experiment) otherwise i will fold my arms and laugh

.

[Albannach]

the question states that the conveyor belt provides as much force as the engines provide. therefore this is an equal force and therefore the plane cannot move.

No it doesn't, it does not mention force anywhere. It merely states that the conveyor belt will mach the 'plane's forward speed, but in reverse.

Mate, you're starting to make yourself look silly. Let it go. The plane will fly, live with it...

[dieselboy]

No it doesn't, it does not mention force anywhere. It merely states that the conveyor belt will mach the 'plane's forward speed, but in reverse.

Mate, you're starting to make yourself look silly. Let it go. The plane will fly, live with it...

cant see how, when there are a minority gripping on to a tiny thread of reality (or unreality) which doesnt equate. if i am making myself look silly then fair enough. if the conveyor matches the planes speed but in reverse then the plane isnt moving is it. this is why i involved forces and theories which had been written years ago

[dieselboy]

post #278 of those that hate the BNP
LOL

[Albannach]

cant see how, when there are a minority gripping on to a tiny thread of reality (or unreality) which doesnt equate. if i am making myself look silly then fair enough. if the conveyor matches the planes speed but in reverse then the plane isnt moving is it. this is why i involved forces and theories which had been written years ago

The plane is moving through the air, not along the ground. Its landing gear is only there to stop the fuselage hitting the ground.

[Dodge]

cant see how, when there are a minority gripping on to a tiny thread of reality (or unreality) which doesnt equate. if i am making myself look silly then fair enough. if the conveyor matches the planes speed but in reverse then the plane isnt moving is it. this is why i involved forces and theories which had been written years ago

You're a mental case. If the aircraft isn't moving then neither is the conveyor if their speeds match.

The conveyor doesn't apply any force.

It moves but there is no force applied to the aircraft as it's wheels turn. The faster the conveyor moves the quicker the wheels rotate, the thrust from the engines will move the aircraft forward.

If there were a brick wall on the conveyor that might stop the aircraft but there isn't. The only thing above the conveyor is air and it is the air that the aircraft's engines push against.

You cannot have a theory and a different real life event without the real life event disproving the theory.

Theory: An egg cannot be broken with a lump hammer.
Real life event: I hit the egg with a lump hammer, the egg breaks.

I have disproved the theory.

Look through this thread, there is a link to the video, Mythbusters filmed and proved it.

[JUDWAK]

is the aircraft black or white?
and is the BNP contorling the conveyor?
this may make a difference in the out come

[BUSHWHACKER]

Aww bless his little cotton socks.

http://uk.news.yahoo.com/21/20090620...y-6323e80.html

[dieselboy]

The plane is moving through the air, not along the ground. Its landing gear is only there to stop the fuselage hitting the ground.

ah ha! the plane IS moving along the ground. even when its stationary - the conveyor is moving the same speed as the plane would be but the opposite direction.

[dieselboy]

You're a mental case. If the aircraft isn't moving then neither is the conveyor if their speeds match.
excuse me? i'm mearly presenting something to you and i am even presenting a theory to back up my statement. there is no need to go along the lines of name calling because your thoughts or opinions differ from mine.
The conveyor doesn't apply any force.
yes it does, for it to NOT apply any force then the plane and the conveyor must NOT be touching. you cannot change this.

It moves but there is no force applied to the aircraft as it's wheels turn. The faster the conveyor moves the quicker the wheels rotate, the thrust from the engines will move the aircraft forward.
blah blah

If there were a brick wall on the conveyor that might stop the aircraft but there isn't. The only thing above the conveyor is air and it is the air that the aircraft's engines push against.
You cannot have a theory and a different real life event without the real life event disproving the theory.
okay then. please try and prove newton and einstein wrong about their theories.

Theory: An egg cannot be broken with a lump hammer.
Real life event: I hit the egg with a lump hammer, the egg breaks.
this one is new to me! who wrote that?

I have disproved the theory.

Look through this thread, there is a link to the video, Mythbusters filmed and proved it.

i have watched said video. it shows a load of people using an RC plane which they could hardly keep in a straight line. the conveyor belt was not matching the engines forward force. the plane moved forward.
why dont you watch the video again, and you will see there is a point in the vid that the plane is going backwards with the conveyor. if you look even closer, you can even see a point when the plane is stationary with the people next to it even though the prop is providing a limited thrust even though its just for a fraction of time.

[Dodge]

excuse me? i'm mearly presenting something to you and i am even presenting a theory to back up my statement. there is no need to go along the lines of name calling because your thoughts or opinions differ from mine.

But you are mental, you are arguing your different opinion even when you've been proved wrong.

yes it does, for it to NOT apply any force then the plane and the conveyor must NOT be touching. you cannot change this.

It applies no force to the aircraft, it mearly moves in the opposite direction. the only force between the conveyor and the aircraft is gravity and the aircraft overcomes gravity every time it takes off.

blah blah

Is this technical evidence to back up your idea?

okay then. please try and prove newton and einstein wrong about their theories.

What? Just because someone has a theory doesn't mean you have to prove it right or wrong. Read what I wrote again . . . "You cannot have a theory and a different real life event without the real life event disproving the theory."

this one is new to me! who wrote that?

I did, just because you have a theory doesn't mean it's correct. I just used that simply as an example of how a theory and an actual event cannot be different without the theory being disproved.

i have watched said video. it shows a load of people using an RC plane which they could hardly keep in a straight line. the conveyor belt was not matching the engines forward force. the plane moved forward.
why dont you watch the video again, and you will see there is a point in the vid that the plane is going backwards with the conveyor. if you look even closer, you can even see a point when the plane is stationary with the people next to it even though the prop is providing a limited thrust even though its just for a fraction of time.

You're watching the wrong video, the one with a real aircaft is the one you should be watching.

http://mythbustersresults.com/episode97

ah ha! the plane IS moving along the ground. even when its stationary - the conveyor is moving the same speed as the plane would be but the opposite direction.

No the conveyor is moving over the ground.

The question asked if the conveyor was moving at the same speed as the aircraft. So if the airspeed indicator on the aircraft was linked to the speed control of the conveyor and the aircraft was stationary the belt wouldn't be moving.

If the conveyor started to move when the aircraft did all that the conveyor would achieve would be to make the aircraft's wheels turn faster.

If the conveyor started to move before the aircraft, the aircraft would still out pace the conveyor because the only force the engines thrust would have to overcome would be the friction of the wheel bearings, the same as if it were to take of from a static runway.