A Puzzler

[Doc]

they're not thickies, they're right

Imagine if you turned the plane upside down - spinning the wheels wouldn't cause it to move would it?

The purpose of the wheels on a car is to provide traction - that is generate friction between the wheels and the ground, so that when you spin the wheels (using the engine) the car moves forward because of the friction.
The purpose of the wheels on the airplane is the opposite - reduce the friction, bacause they're not driven. They're like casters on a piece of furniture

[Seen]

I've changed my mind, it WOULD take off.

Who the hell has voted "no"?

[slick]

I'd take ODM's side here as the plane depends on lift to take off which it gets from the air passing over its wings.

I could actually test this out tell the truth as i work in aeronautical engineering and am currently updating a wind tunnel with a rolling road, but as the rolling road is in a wind tunnel i think thats answers the question.

I know fcuk all about the technicalities of it as i just do the control systems but i know a bloke that does.

[slick]

by the way the plane wouldent move in any direction as its on a rolling rd, unless its propelled forward so i can't see it taking off unles the fcukers a harrier.

[ONEDUNME]

Exactly slick. That's what I'm trying to explain to the thick fuckers (including Seen)

that is generate friction between the wheels and the ground, so that when you spin the wheels (using the engine) the car moves forward because of the friction.
The purpose of the wheels on the airplane is the opposite - reduce the friction, bacause they're not driven. They're like casters on a piece of furniture

That's the key. Are you telling us that an upside down airoplane could take off Doc?

[Quandram]

An upside down plane on an upside down runway would indeed take off. It's called gravity. This is distinctly less impressive than the similar theory that a F1 car upside down on an upside down track would not take off due to the down draft created from its wings.

If either of these upside down tracks were rolling roads then both would take off due to our old friend gravity again.

On a non-upside down rolling road the plane would not take off because it isn't moving.

For the record and to complete the possibilities in this post the F1 car would not take off on a rolling road, it would be held down, but that's by gravity again and not drag generated as their isn't any as it isn't moving either.

How anyone can think anything can move on a rolling road is beyond me.

[ONEDUNME]

Go Quandram

[Seen]

The issue at hand is not if the plane will take off. The issue is whether or not a jet engine can move a wheeled object on a conveyer belt.

The problem with this question is in the wording. The conveyor belts speed matches the speed of the WHEELS and NOT the speed of the plane, the force of the engines will push the plane forward faster than its wheels are turning, and therefore 'beating' the conveyor belt. So the plane is NOT stationary, which is what is confusing most people.

I can't believe some people have voted 'no'

[ONEDUNME]

Thicko

[traeth]

A VTOL aircrfaft can create enough thrust to lift the aircraft off the ground , so I expect most aircraft can . All you need to do it have the aircraft in a vertical orientation like a rocket and it would take off.

p.s. the rolling road need not move as the aircraft's not moving

p.p.s. i've done a seen and changed my mind

[ONEDUNME]

A VTOL aircraft works by thrusting against the ground though Traeth. We are assuming that this is a normal airoplane and there's no mention of dodgy dealings like repositioning the plane in a vertical position to enable it to take off.

If it was that easy don't you think they'd be doing it at all airports now It would save queuing up to use the runway.

[Doc]

you have to make some assumptions in any problem like this.

The obvious ones are that there is no friction in the wheels and that the road and wheels can move at any speed

Think of a car trying to drive up an icy hill to get an idea - the friction between the wheels and the road is reduced - eventually you can get to a stage where you can spin the wheels as fast as you like but the car is still going to slide down the hill. Now imagine you had a rocket engine on top of the car and you flicked a switch to engage that - it wouldn't matter about the wheels and whether they spun or not. You could flick the car into reverse, but the rocket thrust would overcome both gravity and any traction you might get from the wheels spinning.

[ONEDUNME]

We must all agree that the first stage of takeoff is getting the plane to move forward. Initially, this is done by moving forward on its wheels. Then at a later stage the acceleration is increased so that eventually the wheels aren't needed as there is enough SPEED through the air to drive the plane forward fast enough for the aerodynamics to kick in and lift the plane.

The obvious ones are that there is no friction in the wheels and that the road and wheels can move at any speed

If this happens then you can never get past the initial stage and move the plane forward. If you can't move forward then you can't get enough speed to take off.

The craft that Traeth is talking about is no longer a plane, it's a rocket taking off from a standing start.

[Quandram]

Originally Posted by Doc

you have to make some assumptions in any problem like this.

The obvious ones are that there is no friction in the wheels and that the road and wheels can move at any speed

Think of a car trying to drive up an icy hill to get an idea - the friction between the wheels and the road is reduced - eventually you can get to a stage where you can spin the wheels as fast as you like but the car is still going to slide down the hill. Now imagine you had a rocket engine on top of the car and you flicked a switch to engage that - it wouldn't matter about the wheels and whether they spun or not. You could flick the car into reverse, but the rocket thrust would overcome both gravity and any traction you might get from the wheels spinning.

But in that example the road isn't moving to counteract the wheels, it's stationary and you are sliding.

In this question the road is moving. There is no possibility of forward momentum because as fast as the plane is propelled by the engines, the wheels turn and the road adjusts thus the plane remains stationary.

If this ends up in one of us writing equations i fucking hope whoever it is is drunk by that point.

[Seen]

In this question the road is moving. There is no possibility of forward momentum because as fast as the plane is propelled by the engines, the wheels turn and the road adjusts thus the plane remains stationary.

But the turning of the wheels would have NO effect on the planes movement as they don't drive the plane - they are like spinning castors.

I think

Fuck it, I've changed my mind again...there's NO FUCKING WAY it would take off