Is it just me or are people fucking thick?

[Jedburgh]

You see, this is why I gave up physics after O-level.

[skweek]

Does the magical conveyer belt perfectly match the aircraft's landspeed or airspeed?

The question is flawed. Mnnng.

I agree.

There's no real way of keeping the plane still by driving it's wheels in the other direction is there?

If the plane stays at a fixed point on the ground it will never take off, that's why they put chocks under the wheels right?

If the plane is moving along the conveyor at sufficient speed then it can take off.

It really depends on how the conveyor works.

[WiredWorm]

Unless i'm on the plane and going somewhere really nice then I really don't give a toss if it'll take off or not.

Agree with kalmar though - question needs more detail to give a definitive answer.

[kalmar]

Yes, there would be some rolling resistance, probably insignificant. Especially since the plane would have moved forwards off the treadmill in a the first few seconds.

But it's a 'magical' treadmill, so I think we can assume it will perfectly match the plane's wheel rotation at every stage of the process?

It's even more nonsensical when you add the word "magical"
The wheels still aren't anything to do with propelling the plane.

[stealthbanana]

Erm, yes it would take off.

Airflow across the wings.

Think of an aircraft carrier, they have a catapult to move aircraft at a sufficient speed for take off.

The conveyor would save fuel on take off, but would not stop the plane taking off.

If the 'magical' conveyer were also in a bloody huge wind tunnel cancelling out the airflow, no.

[kalmar]

It really depends on how the conveyor works.

If they mean "it works like a giant wind tunnel" then I'd buy it, since this is obviously possible (the plane would take off while remaining stationary).

But in that case the whole treadmill analogy is a red herring. Which is probably the point.

[TDM]

No i don't think people are 'fucking thick', but i think often people talk about stuff they have no real clue about.

Will the plane take off?

I have no fucking idea, let's try it and see.

[zip accident]

poster on another forum wrote:

The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.

That bit is impossible, it can only be true if the plane and it's wheels are stationary. The conveyer belt matches the speed of rotation of the wheels? but that makes some of the speed of rotation of the wheels depend upon the speed of the belt, so the converyer belt is always playing catch up with the speed of rotation that it itself is causing, so it is impossible that it could succeed. The conveyer belt would be exceeding mach one while the plane was barely making 10 mph, and the wheels of the plane would of course catch fire from the friction.

[aureole]

The question really is - if you put a plane on a conveyor belt, then fire up the engines, will it move relative to the ground (not the belt). Think about planes on ice etc.

This has set a little bit of my head going off though, I saw or heard a nice bit of comedy that compounded all the three-doorways and a goat, walking on the south pole, doctor operation on her son-type brainteasers into a monologue. But I can't remember where/when I heard it. I *think* it was on the Mitchell and Webb show, or Peep Show, but now I just don't know.

[gilesgoat]

I think we could try to see it this way (I can be wrong):

let's imagine the airplane is like pulling itself on an horizontal rope, you
are on the airplane and you are pulling this rope .. the "rope" is the air
flux, the "pulling act" are the turbines.

The wheels are just the keep you in equilibrium while you get enough
speed by pulling on the rope, if they have friction or zero friction that
won't change a thing.

The fact is, no matter what mat you'll have under you are still pulling that
rope and MOVING forward, even if the mat would make your wheels spins
reverse I think it would make no difference, the weels would spin on their
axe at some speed yet the airplane would be moving forward in the air.

I don't think there's any way you could make the airplane stary steady
in a point.

A bit like if I'd tie a rope to your car and I'd be pulling it, yes I could
put something under your weels to make them "spin reverse" or stop
but no way the car would be pulled away anyway because it's not the
weels keeping it in place.

Does it make any sense ?

[WiredWorm]

Think of an aircraft carrier, they have a catapult to move aircraft at a sufficient speed for take off.

Yeah, but an aircraft carrier doesn't travel in the same direction as the aircraft taking off - nor does it move at a similar speed.

I guess it does illustrate though that the wheels are f*ck all to do with the planes increase in velocity. Not sure about the airflow argument though - if you think about running on a treadmill - do you feel any breeze or anything when running like you would if you were running and actually moving? (erm, if you see what I mean).

Edit: Anyone fancy giving Boeing a ring to see if they can lend us an aircraft to test this out?

[Baggypants]

You're all missing the point

theres a Magical Treadmill!

why are we discussing a plane when we can blatantly fly on the treadmill becase its magic!

fools

[Flabio]

The catapult on an aircraft carrier has nothing to do with the relative speed of the plane and the carrier. The only factor that affects an aircrafts lift is the absolute speed of the air past it's wings.

The catapult is there cause the runway is too short to accelerate to the speed required for takeoff unassisted.

If by some miracle the conveyor is able to cancel the forward thrust of the planes engines, there'd be no airflow and no lift. But such a thing would not be possible, so it's a completely pointless thought experiment.

[phattslagg]

Yes, there would be some rolling resistance, probably insignificant. Especially since the plane would have moved forwards off the treadmill in a the first few seconds.

But it's a 'magical' treadmill, so I think we can assume it will perfectly match the plane's wheel rotation at every stage of the process?

It's even more nonsensical when you add the word "magical"
The wheels still aren't anything to do with propelling the plane.

No, but they are to do with allowing the plane to be propelled. If the plane just had metal spikes which scraped across the tarmac, then takeoff would be a little more..interesting, wouldn't you say?

[kalmar]

poster on another forum wrote:

The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.

That bit is impossible, it can only be true if the plane and it's wheels are stationary. The conveyer belt matches the speed of rotation of the wheels?

Yeah, exactly. Does not compute.

The only way it could "cancel out" the the rotation of the wheels is by the surface moving in the *same* direction as the plane, at the same speed. So the plane would still move forwards as normal and take off, but without the wheels having turned.

But again that doesn't fit the treadmill analogy, since the surface there goes in the opposite way that you are trying to.