[S4B]

On the other hand, S4B when did you say the same thing? I thought you'd not seen it before.

I meant I said the same as Foots that it was a bad idea to start the argument!

[Sunny So Cal]

To be fair, I'm pretty certain TIAL didn't intend to start an argument and had no idea that Foots would be rabid over the combination of "aeroplanes and conveyor belts." Quirky!

[Chris]

I just want to UNDERSTAND................not necessarily in total depth and detail, but just enough so I know what to think.

Conveyor speed = 0
Plane speed = 0

Conveyor speed = -20
Plane speed = -20 (but only if the brakes were on and the wheels were stuck to the conveyor)

Conveyor speed = 20
Engine speed = 20
Plane speed = 20 (it moves forward '20' because that's what speed the engines are sucking/pushing the plane forward at - the wheels aren't connected to anything that gives drive, therefore are nothing to do with the physics of the jet engine moving the plane against the air ... air which is stationary no matter no fast the wheels are moving)
Wheel speed = 40 (because the 'ground' is moving backwards at 20)

If the plane was placed in a wind tunnel, that's a whole different story. Move the air at -20 and the plane goes nowhere if the engines are at 20. Plane+Engines+Air=Car+Wheels+Ground

I think you are getting confused because you think the plane is stationary with the engines running forward as that was the impression the question gave - which is wrong. A standard plane that doesn't move forwards, doesn't take off (VTOL picture above excepted).

[Sunny So Cal]

Chris, you and Console are brilliant. Thank you.

[foot-loose]

I've previously explained like so:

Imagine that you are standing beside one of those automated moving walkway things at the airport. Now, imagine you put a shopping trolley ON the walkway, but you stand still (holding said trolley) OFF the walkway. The trolley also stands still with minimal effort from you (the wheels would be turning but the trolley would remain stationary relative to you).

Now imagine you start walking in the opposite direction to the way the walkway is running, pushing the trolley along with you. You wouldn't need to push much harder with it on the walkway than you would if it was just on the normal ground in front of you. This is because the force to move it forward is coming from you rather than the wheels. The wheels are insignificant.

Now replace the trolley for an aeroplane, replace you with a big sod off thrust engine, the walkway thingy for a conveyor belt and watch as your plane soars off into the distance.

[Andy B]

Actually that's somewhat a dodgy analogy. You would have to be on the side of the walkway on a solid bit of ground. If you were on the walkway behind the trolley you WPULF have to do twice as much work as your feet are pushing against the conveyor.

On the side it would work. I suggest people watch the videos.

[missscotia]

Hasn't this thread gone just a little bit mental as I was only asking how Dom got over to LA with his fear of flying and now it going on about planes taken off on conveyor belts, bloody hell

[MK Chris]

Ah, you'll get used to it if you stick around..

Not that we regularly talk about planes on conveyor belts; actually, the fact that five pages on, this bears some resemblance to the original topic is quite an achievement.

[Yudster]

RIGHT! Thank you very much Chris - I think pretty much everything you said has been mentioned in other bits on here, but I needed to see it all in one place to be able to make sense of it. I won't pretend to understand the physics of flight in any detail, but at least I now get the idea for this scenario, which is all I wanted. Console and foots also thanks for your helpful posts.

I'm going to lie down now.

[foot-loose]

Actually that's somewhat a dodgy analogy. You would have to be on the side of the walkway on a solid bit of ground. If you were on the walkway behind the trolley you WPULF have to do twice as much work as your feet are pushing against the conveyor

imagine you put a shopping trolley ON the walkway, but you stand still (holding said trolley) OFF the walkway.

I'ts been bolded, capitalised and quoted. Is that any clearer?

[Boboff]

If I was catapulted out of a james bond seat whilst doing a big turd, would I go up, and the shit go down, or would the shit shoot straight back up my arse again?

TiAl please, your answer is awaited.

[foot-loose]

Arses are designed to prevent things shooting back up them. Don't ask me how I know this.

[Yudster]

Arses are designed to prevent things shooting back up them. Don't ask me how I know this.

I heard that there are some people who have found a way to get around that particular design feature.

[DannyBoy]

Hasn't this thread gone just a little bit mental as I was only asking how Dom got over to LA with his fear of flying and now it going on about planes taken off on conveyor belts, bloody hell

[foot-loose]

[Munki Bhoy]

Can planes fly upside down?

[DannyBoy]

Can planes fly upside down?

[Munki Bhoy]

I meant passenger airlines.

[Console]

http://www.foot-loose.me.uk/pictures/upsidedownpost.gif

Why have people started top-posting all of a sudden?

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is one of the most annoying things on a forum?

[S4B]

It's only the newbie who seems to like to do things in a complicated fashion!

Foots you make me laugh! thank you xx

[DannyBoy]

awwww shucks, thanks for calling me a "Top Poster" i didn't think i was that good.

http://www.foot-loose.me.uk/pictures/upsidedownpost.gif

Why have people started top-posting all of a sudden?

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is one of the most annoying things on a forum?

[TIAL]

If I was catapulted out of a james bond seat whilst doing a big turd, would I go up, and the shit go down, or would the shit shoot straight back up my arse again?

TiAl please, your answer is awaited.

The shit would fly out of your arse at the same speed relative to yourself as it would have if you'd have been stationary. Due to air resistance, this may be exaggerated a bit more, but otherwise it'd be the same as normal.
NEXT!

[Yudster]

awwww shucks, thanks for calling me a "Top Poster" i didn't think i was that good.

You really, really aren't. I'm less bothered by your ridiculous compulsion to post upside down than I am by your apparent inability to say anything interesting. Which is disappointing, because you don't seem like an idiot at all.

[Boboff]

ooooooh! Get you.

[foot-loose]

Your mother too?