Okay, What The Hell...

[Pashley26]

f**k me sideways, i think one of the New Members has a fan designed specificly for letting planes take off on tredmills......

Jarrod

[Revolver]

f**k me sideways, i think one of the New Members has a fan designed specificly for letting planes take off on tredmills......

in that case, lets do this thang

btw

SHOTGUN

[Fish-Finger-er]

the plane doesn't take off because as it is propelled, the treadmill compensates, meaning the plane essentially goes nowhere.

but the clever bit is, it's nothing to do with that. WINGS need air moving under them to create lift, thus the plane can push as hard as it likes with its jets, if it is not physically moving into the air (e.g if it was on a treadmill) then there will be no lift, and believe it or not, that means no take off

unless its a harrier or another VTOL, in which case, the force goes down, the treadmill doesn't move in that direction and it will fly

however, if there was a PHAT fan blowing at the plane at the same time, maybe it would take off

no, your wrong, it will be physically moving through the air though. as the air isnt on the treadmill.

if the plane was set to fly over a treadmill at 200 mph, with its wheels an inch above the floor, with the treadmill going at 200mph,theres no connection between the 2, so the plane still moves at 200 mph. correct?

now what difference does it make if the planes wheels are on the treadmill, its still got no actual connection between the 200 mph plane and the 200mph treadmill, the wheels just spin freely along the treadmill at 400 mph.

the thing you need to get your head round, is the planes forward propulsion comes through the air, not the wheels.the plane moves in relation to the air at the back of its jets, not in relation to the ground under its wheels.

[Pashley26]

Ha, this is why i just LOVE TF...

You can come out with the most random bullshit XD

But i still hate the fact that it's been a week and were still talking about the same bullshit under differnt topics !!!! Ha...

Believe it or not i've never actually ridden a trials bike on a Plane.....But i was on a plane when we smashed up Madonnas Jet at Lasham Airfield...

And Jordan and Peter Andre (or how ever you spell it) moved into the house next to my local and i met them the other night and got drunk and started staring at her tits really blatently...Got a photo of me and her on my phone

...

See yet more usefull Trials Chat XD

In all serious though, they are the two best stories i've got from my whole life ! the rest is like really boring, excpet for the time i took the bearded lady of guildford out for dinner in TGI fridays and asked her if she would sleep with me after we drunk like 6 manhattens and ate Jack daniels steak....Then we had a big share size Choclate obsession ice cream glass and then we went down the river and she said she had to go home..... Probably worth saying she's got a big beard and she's 60 about now.....

Jarrod

[Simpson]

I cant see the puzzles cos my laptops gay, but as far as i can tell

A number - its 2 values = a multiple of 9

The air speed and floor speed are 2 independant variables

with the friction caused being negligble to the overall speed result???

[Fish-Finger-er]

The air speed and floor speed are 2 independant variables

with the friction caused being negligble to the overall speed result???

exactly,

and jarrod, what in gods name are you chatting about?

i believe the plane and the treadmill is a hugely popular urban myth, and most of the arguments in this topic are based on physics. as opposed to your heat gossip?!?!?

[Pashley26]

Sorry man, i'm just in a funny mood ! Ignore me, i'll even shut up if it helps !

Jarrod

I can see what you mean with the plane though...

Becouse the Jets are providing the forwards thrust not the wheels the engines will push the Plane forwards and the tredmill will push the wheels back faster at the speed the tredmill is moving, but the wheels will also move due to the forwards thrust provided by the engines......

You'd have to be f**king stupid to not understand that, why don't yo post it in new members as a test ?

Edited December 30, 2007 by Pashley26

[Tomm]

I'm sorry, I agree with JT!, but it all depends on the exact wording of the question.

If the plane's speed is matched by the treadmill, it takes off as the two are entirely independent. Obvious.

BUT

If the speed of the plane's wheels is matched by the treadmill, it's more interesting. For the plane to even move forward(regardless of where the power is coming from), the wheels would have to be moving faster than the treadmill, right? Which we have already said is impossible. The plane doesn't take off. Which is what I'm talking about and I'm pretty sure what JT is on about too.

All this talk about friction is totally stupid as it's an entirely theoretical question. There are other much more practical reasons why this couldn't work, but that's not really the point.

[Gavyn.]

aerodynamics don't really matter, wing shape matters obviously.

for example

Thats a eurofighter typhoon and it varies alot aerodynamically from this -

but both of them will take off on a tread mill if it matches the planes speed and not the planes wheel speed..

I don't see it as an urban myth because there is no real myth, it's actually just a basic general knowledge question with a hint of physics much like the first one posted in this thread was a basic maths question yet it still confuses most people the first time they do it.

I'm sorry, I agree with JT!, but it all depends on the exact wording of the question.

If the plane's speed is matched by the treadmill, it takes off as the two are entirely independent. Obvious.

BUT

If the speed of the plane's wheels is matched by the treadmill, it's more interesting. For the plane to even move forward(regardless of where the power is coming from), the wheels would have to be moving faster than the treadmill, right? Which we have already said is impossible. The plane doesn't take off.

All this talk about friction is totally stupid as it's an entirely theoretical question. There are other much more practical reasons why this couldn't work, but that's not really the point.

exactly it's all in the wording the plane may or may not take off depending on those two factors.

Edited December 30, 2007 by G4vyn

[Muel]

OK, I know I havn't been on as much as I normally am these last few days...

But what the f**k is going on with that plane bollocks?

[Mark W]

But it would never move in the first place.

The tyre would blow or something like that befor it got anywhere near take off speed.

Yes, it would move. The plane is totally indifferent to whatever it's wheels are doing. The only thing they are doing is stopping it from rubbing along the floor.

Seriously, read what I wrote about take off speeds. Their tyres have to be rated to take a shitload of force when the plane lands. The tyres go from 0mph to f**king pacing it when the plane touches the floor, and that force on the tyre is greater than the slow, gentle build-up of speed they'd get when the plane accelerated.

but the clever bit is, it's nothing to do with that. WINGS need air moving under them to create lift, thus the plane can push as hard as it likes with its jets, if it is not physically moving into the air (e.g if it was on a treadmill) then there will be no lift, and believe it or not, that means no take off

It would be "physically moving into the air". If the jets are working, the wheels - that freely spin - can do whatever they want, all they're doing is just stopping it from being a plane lying on the floor. The actual body of the plane would move forward as it was powered by the jet - it's not going to be just static, with a f**king roaring jet engine poking out the back/hanging off the wings. It's going to be moving forward through the air, it's just it's going to have it's landing gear down, being spun backwards by a conveyor belt which makes no difference to anything else, at all.

Think about it like this - if you had a little treadmill, and you put a toy car on it, the car - with no power from you - is going to just move backwards on the treadmill (if it's going backwards, obviously). However, if you push the car's body forward by hand, the actual wheels of the car will spin in the other direction, as they're being influenced by the treadmill. However, all it means is that the speed they'll be spinning in the opposite direction in will be proportional to how fast the body of the car moves forwards. However, the body of the car - the important bit - will still be moving forwards. Now, just substitute 'toy car' for 'aeroplane', and 'you pushing the body' to 'hulking great jet engines'.

[Muel]

What if one of the tyres explode due to it stretching off the rim because of the increased gyroscopic effect of the wheels going propoh quick? Would it take off then or would it just crash and burn?

[Tomm]

Think about it like this - if you had a little treadmill, and you put a toy car on it, the car - with no power from you - is going to just move backwards on the treadmill (if it's going backwards, obviously). However, if you push the car's body forward by hand, the actual wheels of the car will spin in the other direction, as they're being influenced by the treadmill. However, all it means is that the speed they'll be spinning in the opposite direction in will be proportional to how fast the body of the car moves forwards. However, the body of the car - the important bit - will still be moving forwards. Now, just substitute 'toy car' for 'aeroplane', and 'you pushing the body' to 'hulking great jet engines'.

I disagree Mark.

• If you hold a toy car on a treadmill which is going at, say, 20mph, the car's wheels would have to be spinning at 20mph. Correct?
• If the car was going forwards at 5mph (because you were pushing it at that speed), the wheels would have to be spinning at 25mph. Correct?
• But 25mph /= 20mph; the speeds are no longer equal. Therefore, we have proven that for the car to move forwards, its wheels MUST be moving faster than the treadmill.

So it doesn't take off

Because of this:

it all depends on the exact wording of the question.

If the plane's speed is matched by the treadmill, it takes off as the two are entirely independent. Obvious.

BUT

If the speed of the plane's wheels is matched by the treadmill, it's more interesting.

[Danny]

Tomm shut up it takes off ok?

[Tomm]

Tomm shut up it takes off ok?

Which question are we talking about?

it all depends on the exact wording of the question.

If the plane's speed is matched by the treadmill, it takes off as the two are entirely independent. Obvious.

If the speed of the plane's wheels is matched by the treadmill, it's more interesting.

[Muel]

The Plane, DOES take off.

The Car, DOES NOT take off, due to the lack of f**king wings.

[Tomm]

OK, I know I havn't been on as much as I normally am these last few days...

But what the f**k is going on with that plane bollocks?

I thought this topic would make approximately no sense to a lot of people reading it. Read this: http://www.trials-forum.co.uk/forum/index....showtopic=71757

[Muel]

Excellent.

Anyway, let's get back to the original post, no?

I think that's pretty clever.

[Tomm]

Anyway, let's get back to the original post, no?

Well I wondered that, but came to the conclusion that we'd answered it so who cares?

[Muel]

Yeh, it was a real let down when I read how it's done. It was like Christmas for a while.

[ManxTrialSpaz]

FFS. The plane takes off! Think about this. You know you've got a sheet of paper or a dvd underneath a pile of something/more dvds. And you whip it out, the pile above doesn't move out with the sheet of paper/dvd. This is because the friction between the paper and the pile is smaller than the air resistance(?).

Applied to the plane. At low speeds, the treadmill would move the plane backwards (providing that the plane doesn't have it's engines on), but at high speeds, the treadmill (and the plane's wheels) would just spin but the plane would go nowhere. Too tired to caryy on but basically, for both scenearios, the plane would take off.

Well. It should do.

Maybe.

[Muel]

We have established that the plane takes off! All you have done is make it more complicated and now I don't know where I live or what my name is!!!

[ManxTrialSpaz]

We have established that the plane takes off! All you have done is make it more complicated and now I don't know where I live or what my name is!!!

Quick! You're called Donkey Boy and you live in Finland. No! Wait....

[JT!]

He's right, sorry jt but like you i was adamant the thing wouldn't take off last time we had this discussion. I've long since seen that it will in fact take off. The above example is as good as you can get. Basically as the wheels are just spinning on axles they can go as fast as they like, so long as the plane has air being pushed it can take off. The wheel speed and the floor travelling backwards is irrelevant.

I know, the first thing poeple say is the plane can't take off becuase there's no air moving over the wings, this is wrong.

Then people say becuase the engines propel the plane, not the wheels, it takes off.

However, ue to the wording of the question...

"A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in the opposite direction). Can the plane take off?"

The tredmill matches the speed of the plane. So when the plane starts to move, the tredmill speeds up, it will have to go very fast to try and keep the plane stationary, to the point where it would destory a wheel, or the friction would be holding the plane back.

no, your wrong, it will be physically moving through the air though. as the air isnt on the treadmill.

if the plane was set to fly over a treadmill at 200 mph, with its wheels an inch above the floor, with the treadmill going at 200mph,theres no connection between the 2, so the plane still moves at 200 mph. correct?

now what difference does it make if the planes wheels are on the treadmill, its still got no actual connection between the 200 mph plane and the 200mph treadmill, the wheels just spin freely along the treadmill at 400 mph.

the thing you need to get your head round, is the planes forward propulsion comes through the air, not the wheels.the plane moves in relation to the air at the back of its jets, not in relation to the ground under its wheels.

I know i have my head around it, i'm just taking it one step further. Wheels have friction, but wheels not touching the ground don't.

I'm sorry, I agree with JT!, but it all depends on the exact wording of the question.

If the plane's speed is matched by the treadmill, it takes off as the two are entirely independent. Obvious.

BUT

If the speed of the plane's wheels is matched by the treadmill, it's more interesting. For the plane to even move forward(regardless of where the power is coming from), the wheels would have to be moving faster than the treadmill, right? Which we have already said is impossible. The plane doesn't take off. Which is what I'm talking about and I'm pretty sure what JT is on about too.

All this talk about friction is totally stupid as it's an entirely theoretical question. There are other much more practical reasons why this couldn't work, but that's not really the point.

But, if the planes speed is matched (relative to the ground of which the tredmil stands) then it still wont take off becuase of what i said up there. The wording of it says that the tredmill macthes the planes speed, if it starts moving at 1mph, the temill will move and 1mph. However, it's a contrediction in terms becuase the plane will now be still and the tremill will be matching the planes speed which is 0.

This is where the earth impoleds.

Yes, it would move. The plane is totally indifferent to whatever it's wheels are doing. The only thing they are doing is stopping it from rubbing along the floor.

Seriously, read what I wrote about take off speeds. Their tyres have to be rated to take a shitload of force when the plane lands. The tyres go from 0mph to f**king pacing it when the plane touches the floor, and that force on the tyre is greater than the slow, gentle build-up of speed they'd get when the plane accelerated.

It would be "physically moving into the air". If the jets are working, the wheels - that freely spin - can do whatever they want, all they're doing is just stopping it from being a plane lying on the floor. The actual body of the plane would move forward as it was powered by the jet - it's not going to be just static, with a f**king roaring jet engine poking out the back/hanging off the wings. It's going to be moving forward through the air, it's just it's going to have it's landing gear down, being spun backwards by a conveyor belt which makes no difference to anything else, at all.

Think about it like this - if you had a little treadmill, and you put a toy car on it, the car - with no power from you - is going to just move backwards on the treadmill (if it's going backwards, obviously). However, if you push the car's body forward by hand, the actual wheels of the car will spin in the other direction, as they're being influenced by the treadmill. However, all it means is that the speed they'll be spinning in the opposite direction in will be proportional to how fast the body of the car moves forwards. However, the body of the car - the important bit - will still be moving forwards. Now, just substitute 'toy car' for 'aeroplane', and 'you pushing the body' to 'hulking great jet engines'.

I disagree Mark.

• If you hold a toy car on a treadmill which is going at, say, 20mph, the car's wheels would have to be spinning at 20mph. Correct?
• If the car was going forwards at 5mph (because you were pushing it at that speed), the wheels would have to be spinning at 25mph. Correct?
• But 25mph /= 20mph; the speeds are no longer equal. Therefore, we have proven that for the car to move forwards, its wheels MUST be moving faster than the treadmill.

... and as you pushed that car forward, the tremill would speed up faster an faster untill the little shitty plastic wheels f**ked up, and it'd be shot off backwards into your new 52" plasma tv your got for chirtsmas.

To sum up, the question is seriously flawed. Hence why no one can come up with a stright answer. Both mine an tomms interpritation of the question is right, and so is OBM.

[Fishy]

So does it take off?