Aircraft and conveyor belt (again)

[megawatt]

You're rambling ... What point are you trying to make other than we will probably consider what you are posting as nonsense?

 

[blondini]

You're rambling ... What point are you trying to make other than we will probably consider what you are posting as nonsense?

The point is that the real world has a bit of give even when it may not be obvious, and a bit of give is all that is required to allow the OP 'wheels' to set in motion.

 

[Softus]

It is impossible, at the same time, for the plane to be moving, and the conveyor to match the speed of the wheels.

The forward speed of the plane must be equal to the forward speed of the wheels minus the backward speed of the conveyor.

The rules in the question cannot be met unless the plane is stationary.

Again with the paradox. This is completely correct. Nobody is arguing about that.
___________________

Every action has an equal and opposite reaction. e.g. You push against a soild wall and it pushes back with equal force. The wall behaves as if it is tuned to match the force you apply. Although the wall doesn't appear to move, it must do so in order to react. The runway surface is pushing upwards to support the aircraft and it is also pushing back against the lateral force trying to move the aircraft. Even before the aircraft begins to move, it is applying a lateral force to the runway and the runway is pushing back. Most people would consider all of this paragraph to be nonsense.

Nobody who understands the principles of Newtonian physics would find it to be anything other than [mostly] correct. The idea of the wall actually moving is, however, incorrect.

A tyre rolling along a surface will experience a minute amount of slippage in the direction it is travelling. If the tyre is being pushed by the vehicle it will rotate slightly slower than the speed of the vehicle. If it were propelling the vehicle it would travel slightly faster. There is a bit of give here, although again, most people would consider this to be nonsense.

This is leading nowhere, because the people who might need to allow such a thing as "give" are the very same ones who aren't capable of understanding your point.

And you can't play the "give" card with anyone who tends towards pedantry, because they'll point out that slippage, whilst difficult to calculate predictively. with any precision, is both observable and, indirectly, measurable.

 

[blondini]

I'm just kicking some ideas around Softus.

The runway surface is pushing upwards to support the aircraft and it is also pushing back against the lateral force trying to move the aircraft. Even before the aircraft begins to move, it is applying a lateral force to the runway and the runway is pushing back. Most people would consider all of this paragraph to be nonsense.

Thinking about this one a little further. The opposing lateral force of the runway, static or stationary conveyor, is applied to the plane only through the rolling resistance of the wheels. With only a small force from the engines, the plane will not move. As the force applied by the engines increases it will reach a point where it exceeds the rolling resistance of the wheels and at this point the wheels would start to turn. Now consider that the conveyor is actively pushing back without moving, without needing to move, until the point where the rolling resistance of the wheels is overcome. What happens at this point? I think the runway will begin to move backwards.

 

[Softus]

I'm just kicking some ideas around Softus.

That's cool. I'm just hoofing a couple of them back towards you. Jumpers for goalposts, etc.

Thinking about this one a little further. The opposing lateral force of the runway, static or stationary conveyor, is applied to the plane only through the rolling resistance of the wheels. With only a small force from the engines, the plane will not move. As the force applied by the engines increases it will reach a point where it exceeds the rolling resistance of the wheels and at this point the wheels would start to turn.

That seems completely correct to me.

Now consider that the conveyor is actively pushing back without moving, without needing to move, until the point where the rolling resistance of the wheels is overcome. What happens at this point? I think the runway will begin to move backwards.

I think so too, but I think it's just restating the original premise.

 

[AtoZ]

it is amazing to me that some obviously clever people cannot see how this would work.

i certainly dont mean to be rude in anyway, to anyone.

we have been set a question that has tried to close off the loopholes but it is still seen as open by some.

look at it differently and you will see it will work.
ice, water, a powered conveyor that drives the wheels backwards and forwards. any of these must alter your thinking.

i know that to look outside will not answer what we were asked but it will help you 'see'.

 

[Softus]

it is amazing to me that some obviously clever people cannot see how this would work.

Could you be more specific? Who do you think it is who cannot see it?

 

[blondini]

I look outside and...

Those two bags of sand are going to have to go back in the boot before I go anywhere.

i certainly dont mean to be rude in anyway, to anyone.

Me neither. It's been an interesting exchange of views and ideas.

 

[blondini]

Now consider that the conveyor is actively pushing back without moving, without needing to move, until the point where the rolling resistance of the wheels is overcome. What happens at this point? I think the runway will begin to move backwards.

I think so too, but I think it's just restating the original premise.

I'm trying to escape from the paradox that the plane would have to move forward and rotate it's wheels in order to set the conveyor in motion. Therefore making the wheel speed unequal to the conveyor speed.
I'm exploring the possibility that the wheels could be set in motion by the conveyor at the point just before the plane would begin to move.

 

[AtoZ]

it is amazing to me that some obviously clever people cannot see how this would work.

Could you be more specific? Who do you think it is who cannot see it?

i could be, but i would rather not

i have the need for people to 'see' it rather than prove them wrong.

i should have been a teacher, teach rugby... but i would have squeezed too many necks and got the sack..

sad but true..

 

[RF Lighting]

http://www.youtube.com/watch?v=0ul_5DtMLhc

 

[blondini]

http://www.youtube.com/watch?v=0ul_5DtMLhc

Another good find, but I think we would all agree that the aircraft in the vid would take off. Our OP is

different.

 

[joe-90]

No it's not, you heard the pilot - "took off as normal".

Give up - it's sorted.

 

[tim west]

Does anyone remember the original question in its entirety to the letter? Its been so long ago i'm beginning to wonder if the wheel itself let alone aircraft tyres had been invented then.

 

[blondini]

No it's not, you heard the pilot - "took off as normal".

Give up - it's sorted.

It is different. You haven't been paying attention.