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Physics Vol 2

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By *ralbisw OP   Man  over a year ago

Exeter

Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

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By (user no longer on site)  over a year ago

No, obviously not.

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By (user no longer on site)  over a year ago

Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight.

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By (user no longer on site)  over a year ago


"Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight."

I have passed exams on this stuff. Just to clarify..

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By *oncupiscentTonyMan  over a year ago

Kent


"Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight."

Airflow is generated by prop not the frames relationship to the ground

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk

Yes.

And I cannot believe this is still running.

The Mythbusters link was posted at least 3 times. Did nobody watch it?

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By (user no longer on site)  over a year ago

I want to say yes. It's like if a car was driving at the speed of light (impossible I know) would the lights work if turned on, I think the answer is yes as it is relative

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By *ackDMissMorganCouple  over a year ago

Halifax


"Yes.

And I cannot believe this is still running.

The Mythbusters link was posted at least 3 times. Did nobody watch it?"

Yep. Sort of ended the debate I thought lol. Jack

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By *ackett1962Man  over a year ago

harrow

In short...yes it can.. planes on aircraft carriers are launched this way via catapults

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By *oodmessMan  over a year ago

yumsville

Yep. The conveyor would generate air flow and the necessary lift by passing underneath the plane in such close proximity. The Russian Caspian Sea Monster used Ground Effect to the same ends.

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By *mmmMaybeCouple  over a year ago

West Wales

No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

"

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

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By *obwithkiltMan  over a year ago

Belton

Is it a Ryanair or easyjet plane... Because the only thing to say is that the conveyor runway will be bloody miles away from where you need to be

https://youtu.be/l6pj3Fdbwng

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By *mmmMaybeCouple  over a year ago

West Wales


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal."

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S

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By (user no longer on site)  over a year ago

From what I've read into this whatever the treadmill is doing is pretty much completely irrelevant.

That's why the answer seems to be obviously no. Yet it will actually take off

The way a jet engine works is completely different to how you perceive running on a treadmill to try and go forward.

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By *mmmMaybeCouple  over a year ago

West Wales

So you are saying a plane that to all intents and purposes has no relative forward movement on a conveyor belt that will turn at the same speed as the wheels, could be sitting in front of me and in effect take of vertically, because that's what it would be doing?

Really?

S

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S"

There will be forward motion.

The belt will not stop the 'plane moving forward.

The movement of the wheels will be affected by the belt. The wheels don't control the movement of the 'plane though. They don't connect to any part of any drive system.

Fogetting the belt completely for the moment, if the wheels didn't rotate but were fixed and the engines were started and accelerated as normal, what do you think would happen?

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk


"So you are saying a plane that to all intents and purposes has no relative forward movement on a conveyor belt that will turn at the same speed as the wheels, could be sitting in front of me and in effect take of vertically, because that's what it would be doing?

Really?

S"

It will move forwards normally. It will have forward motion.

Aircraft are not driven by their wheels.

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk

There's a good reason this debate is banned on xkcd

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By *mmmMaybeCouple  over a year ago

West Wales


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S

There will be forward motion.

The belt will not stop the 'plane moving forward.

The movement of the wheels will be affected by the belt. The wheels don't control the movement of the 'plane though. They don't connect to any part of any drive system.

Fogetting the belt completely for the moment, if the wheels didn't rotate but were fixed and the engines were started and accelerated as normal, what do you think would happen?"

The plane would destroy itself or at least the engines or wheels/tyres because its trying to move?

But the conveyor is matched perfectly to the "supposed" forward movement, but the plane does not move relative to the air around it, it you were standing next to it the plane would not be moving, the wheels & engines might be saying "I'm doing take off speed guys" but the wings waiting for their airflow to provide lift will be saying "fuck off are you"..

S

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By (user no longer on site)  over a year ago

Well I'm an idiot n even I know the answer is no!

It's the airflow beneath the wings that governs lift,not how fast the plane is traveling,relatively or otherwise.

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S

There will be forward motion.

The belt will not stop the 'plane moving forward.

The movement of the wheels will be affected by the belt. The wheels don't control the movement of the 'plane though. They don't connect to any part of any drive system.

Fogetting the belt completely for the moment, if the wheels didn't rotate but were fixed and the engines were started and accelerated as normal, what do you think would happen?

The plane would destroy itself or at least the engines or wheels/tyres because its trying to move?

But the conveyor is matched perfectly to the "supposed" forward movement, but the plane does not move relative to the air around it, it you were standing next to it the plane would not be moving, the wheels & engines might be saying "I'm doing take off speed guys" but the wings waiting for their airflow to provide lift will be saying "fuck off are you"..

S"

Ok, you're missing my point.

Go and watch the Mythbusters video.

(Or read The Goddamn Airplane on the Goddamn Treadmill on XKCD which explains why this is actually a completely bullshit question)

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By (user no longer on site)  over a year ago

Its the same as..if you jump up in a plane why dont you move backwards or if you weigh a wagon full of chickens and log it,would it be the same weight if the chickens flapped their wings and were all in the air.....iv had a couple of beers sorry

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By *mmmMaybeCouple  over a year ago

West Wales


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S

There will be forward motion.

The belt will not stop the 'plane moving forward.

The movement of the wheels will be affected by the belt. The wheels don't control the movement of the 'plane though. They don't connect to any part of any drive system.

Fogetting the belt completely for the moment, if the wheels didn't rotate but were fixed and the engines were started and accelerated as normal, what do you think would happen?

The plane would destroy itself or at least the engines or wheels/tyres because its trying to move?

But the conveyor is matched perfectly to the "supposed" forward movement, but the plane does not move relative to the air around it, it you were standing next to it the plane would not be moving, the wheels & engines might be saying "I'm doing take off speed guys" but the wings waiting for their airflow to provide lift will be saying "fuck off are you"..

S

Ok, you're missing my point.

Go and watch the Mythbusters video.

(Or read The Goddamn Airplane on the Goddamn Treadmill on XKCD which explains why this is actually a completely bullshit question)"

OK, I'll do it in the morning

S

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By *oncupiscentTonyMan  over a year ago

Kent


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S

There will be forward motion.

The belt will not stop the 'plane moving forward.

The movement of the wheels will be affected by the belt. The wheels don't control the movement of the 'plane though. They don't connect to any part of any drive system.

Fogetting the belt completely for the moment, if the wheels didn't rotate but were fixed and the engines were started and accelerated as normal, what do you think would happen?

The plane would destroy itself or at least the engines or wheels/tyres because its trying to move?

But the conveyor is matched perfectly to the "supposed" forward movement, but the plane does not move relative to the air around it, it you were standing next to it the plane would not be moving, the wheels & engines might be saying "I'm doing take off speed guys" but the wings waiting for their airflow to provide lift will be saying "fuck off are you"..

S"

Sigh, you're mistaking groundspeed for true airspeed. This has become so fucking tiresome now.

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk


"No it can't, engines surely provide forward momentum not lift, the forward motion does not provide "lift" in the normal sense, on the wing it provides negative air pressure on the top side of the wing and positive air pressure under, this effect gives the lift. No movement = no lift..

S

That's what I believed anyway.

S

But there will be movement.

The wheels rotate freely, whatever they do won't stop the aircraft from moving. It will be propelled forwards as normal.

But there is no relative forward motion to the air around the plane, it is this relative movement that provides the lift..

S

There will be forward motion.

The belt will not stop the 'plane moving forward.

The movement of the wheels will be affected by the belt. The wheels don't control the movement of the 'plane though. They don't connect to any part of any drive system.

Fogetting the belt completely for the moment, if the wheels didn't rotate but were fixed and the engines were started and accelerated as normal, what do you think would happen?

The plane would destroy itself or at least the engines or wheels/tyres because its trying to move?

But the conveyor is matched perfectly to the "supposed" forward movement, but the plane does not move relative to the air around it, it you were standing next to it the plane would not be moving, the wheels & engines might be saying "I'm doing take off speed guys" but the wings waiting for their airflow to provide lift will be saying "fuck off are you"..

S

Ok, you're missing my point.

Go and watch the Mythbusters video.

(Or read The Goddamn Airplane on the Goddamn Treadmill on XKCD which explains why this is actually a completely bullshit question)

OK, I'll do it in the morning

S"

The XKCD one is worth a read. It has pictures and stuff. It explains there are three different ways to look at it, which is why opinions tend to be polarised, with each side patiently trying to explain physics to the other . Oh, and one of those ways is actually physically impossible, just to make matters clearer!

This question has been banned there for ages due to near outbreak of war over it!

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By (user no longer on site)  over a year ago

will we ever need this information?

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By (user no longer on site)  over a year ago

Fuck me this should be down in the politics section!

Two sides arguing and not listening to each other and both think they're right

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By (user no longer on site)  over a year ago

Since Death Valley is below sea level could we dig a hole to the ocean and fill it up with water?..ooops

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By *ait88Man  over a year ago

Plymouth

Aircraft take off and sustain flight by creating a “wind” around the very precisely shaped wings.

Engines do not make such a wind. The old VC10s had them at the back. Some old biplanes had “pusher” propellers behind the wings. Your car doesn’t take off at high speed.

The conveyor is too small to generate the required wind, or the aircraft stalls when it leaves the volume of any wind that a huge conveyor could cause.

Aircraft catapults fire the aircraft forward at enormous rates of acceleration so that they have reached take-off speed by the time they run out of deck. The airflow around the wings generates sufficient lift to stop the aircraft crashing into the sea (often!). The catapults don’t make wind.

The Russian Caspian Sea Monster Ground Effect craft was not an aircraft, any more than a Saunders Roe Hovercraft was an aircraft. The GEC did not have wings that were capable of lifting the craft using airflow around them. The GEC “wings” were stubs that were shaped to use the air trapped between their bottom surfaces and the sea to lift the craft. It “flew” on a cushion of trapped air, just like the Hovercraft.

Aircraft can only fly if their wings are experiencing an APPARANT wind of sufficient velocity. Suppose an aircraft can take-off when it reaches a speed of 80 mph in STILL AIR. At take off the wings are experiencing an apparent wind of 80 mph. Suppose the wind is blowing at 80 mph. If you face the aircraft into the wind, the wings will “see” an APPARANT wind of 80 mph, and lift the stationary aircraft off the ground. It you run the aircraft downwind at 80 mph, it will stay firmly on the ground because the wings aren’t “seeing” any wind at all. When launching aircraft, carriers steam into the wind. If the ship’s speed is 20 mph and the wind speed is also 20 mph, the wings of an aircraft ready for take off will be already be seeing a apparent wind of 40 mph, even though it is stationary in relation to the deck. If it’s take off speed is 140 mph, it will only need to be accelerated to 100 mph along the deck to take off.

The aircraft on the conveyor stays put!

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk


"Fuck me this should be down in the politics section!

Two sides arguing and not listening to each other and both think they're right "

Great ain't it?

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By *ait88Man  over a year ago

Plymouth

[Removed by poster at 18/11/16 01:19:22]

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By *aucy tiggerWoman  over a year ago

Back where I belong

I'm getting a déjà vu feeling xx

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By (user no longer on site)  over a year ago


"The aircraft on the conveyor stays put!

"

No. It does not stay still. grab a toy car, hold it by the roof in your right hand and run your left hand under neath it,

what happens?

right the car is held in place and the wheels spin...

Now while running your left hand under the wheels backwards push the car forwards with your right hand.

What happened?

the car moved forwards despite your left hand moving backwards, But the wheels span faster while the car moved forwards.

But it still moved forwards... just as the plane would, spinning the wheels faster made no difference to the speed your right hand moved the car.

The only way a conveyor could make any difference is if the airplane was powered by its wheels. If it was it would be a bus!

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By (user no longer on site)  over a year ago

P. s. don't try to fly in a bus, they are really not very good at it.

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By *enard ArgenteMan  over a year ago

London and France

Great thread to see how incredibly badly educated and stupid people are.

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By (user no longer on site)  over a year ago

Pisser, is this one still running

Nobody googled conveyor vs plane to see the mythbusters clip? It's only been mentioned about 10 times across the threads

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By *ralbisw OP   Man  over a year ago

Exeter

It is a shame we cannot set up a poll to gauge answers!!

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By *aucy tiggerWoman  over a year ago

Back where I belong


"Pisser, is this one still running

Nobody googled conveyor vs plane to see the mythbusters clip? It's only been mentioned about 10 times across the threads "

Pmsl I think this one will go on and on xx

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By *alandNitaCouple  over a year ago

Scunthorpe

The thing is, that once the engines kicked in, the conveyor would have no effect other than spinning the wheels much quicker. the plane would still move forward relative to the air around it and the conveyor would be unable to keep the plane in the same spot. So... the plane would respond in exactly the same way as it would on a proper runway.

With this in mind, the conveyor is actually a massive waste of energy and probably the reason that air-fares are soo expensive.

Cal

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By *ait88Man  over a year ago

Plymouth

Next Question.

This one’s for the ladies:

If 1 + 1 – x = 3, what is x?

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By *alandNitaCouple  over a year ago

Scunthorpe


"The thing is, that once the engines kicked in, the conveyor would have no effect other than spinning the wheels much quicker. the plane would still move forward relative to the air around it and the conveyor would be unable to keep the plane in the same spot. So... the plane would respond in exactly the same way as it would on a proper runway.

With this in mind, the conveyor is actually a massive waste of energy and probably the reason that air-fares are soo expensive.

Cal"

I was laying in bed last night thinking about this (sad I know) and was thinking along the lines of the toy car analogy above but with me on roller skates

Anyway, having lost sleep over this I also have to concede I was wrong last night

Why is Cal always right?

Nits

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By *alandNitaCouple  over a year ago

Scunthorpe

I can't even get my name right ...

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By *ust RachelTV/TS  over a year ago

Horsham


"Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight.

I have passed exams on this stuff. Just to clarify.."

I didn't, I watched mythbusters

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By (user no longer on site)  over a year ago

So are people saying that if the engines were turned off the plane would remain stationary on the moving belt because the wheels are free moving?.......interesting....

And the jet engine does not draw air over the wing, it sucks air in the front, burns it and the exhaust produces thrust

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By *unandbuckCouple  over a year ago

Sheffield

People getting frustrated explaining that a stationary aircraft cannot take off - we know that!

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By *unandbuckCouple  over a year ago

Sheffield

For a minute forget the engines.

A large aircraft with 'perfect' wheels is sitting on the conveyor belt.

If the belt begins to turn, the aircraft would just remain stationary due the laws of momentum.

The wheels would spin due to the rubber gripping the belt. The wheel bearings allow the wheels to spin.

But there would be no reverse force on the aircraft to move it backwards. It therefore would stay stationary.

Then when the engines are switched on they produce forward thrust on the aircraft frame and it begins to accelerate. The acceleration would be the same as if it was sat on tarmac. Its speed would increase relative to the air around it. It would move forwards relative to a bystander stood on the grass.

It would keep doing so til it took off.

.

.

In the practical world the wheel bearings arent perfect so it would actually move backwards with the engines off. The engines would just have to work the tiniest bit harder than normal to defeat that bit of friction, but thats all.

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By *ackett1962Man  over a year ago

harrow

Has no one on here ever heard of V.T.O.L Planes. They are vertical take off lif jets. They have been in use for over 40 years by both the USA and UK. More commonly known as Jump jets. Most common one being the Harrier Jump jet.

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By *ralbisw OP   Man  over a year ago

Exeter


"Has no one on here ever heard of V.T.O.L Planes. They are vertical take off lif jets. They have been in use for over 40 years by both the USA and UK. More commonly known as Jump jets. Most common one being the Harrier Jump jet."

You forgot to add "and has nothing to do with this problem"

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By (user no longer on site)  over a year ago


"Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight.

Airflow is generated by prop not the frames relationship to the ground"

No. Airflow over the wings is from forward motion. As it's on a roller there is no effective forward motion.

Engines provide thrust (negated in this case by rolling road) wings provide lift. The two are separate.

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By *icentiousCouple  over a year ago

Up on them there hills

Well some Newton guy's 3 law would say it in a state of equilibrium.

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By *avrick15Man  over a year ago

glasgow

Fucking hell this is still going pmsl

Saying nowt

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By *unandbuckCouple  over a year ago

Sheffield


"Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight.

Airflow is generated by prop not the frames relationship to the ground

No. Airflow over the wings is from forward motion. As it's on a roller there is no effective forward motion.

Engines provide thrust (negated in this case by rolling road) wings provide lift. The two are separate. "

Nobody is saying a stationary aircraft can fly!

The plane will move forwards, the treadmill has no effect on the plane apart from making its wheels spin.

Read my post a bit above and see what you think.

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By *unandbuckCouple  over a year ago

Sheffield


"

Fucking hell this is still going pmsl

Saying nowt "

Maybe , 'oops, I see what you mean, it will move forwards and fly?'

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By *ensualtouch15Man  over a year ago

ashby de la zouch

I genuinely can't believe this is a two thread problem , and after some perfect explanations some still don't get it , no wonder some think paranormal activity and spirits exist

The belt is a pure red herring and has zero to do with the flight of the plane

Unless the belt had an effect upon the air above it meaning a vast air mass was moving over the plane , it matters not what speed or direction the belt goes

Even if we say the belt affects the entire air mass around the plane , the air would be moving relative to the wing and cause lift

If the plane had its brakes on and was going backwards at speed, first there would be air over wing and unstable lift would occur , but as soon as the engines fire up the plane would travel forward regardless of belt until it's speed relative to air was correct for lift

Now far more interesting and difficult would be if the plane was on the infinite runway tread mill going sideways at 100 kph how would that affect take off

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By (user no longer on site)  over a year ago

Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift

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By *unandbuckCouple  over a year ago

Sheffield


"Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift"

how much the wheels turn is irrelevant, they are just free spinning, not like car drive wheels.

Think if you were at the gym on a flat treadmill wearing a pair of roller skates standing motionless. You switch the treadmill on, you could hold yourself stationary with a piece of cotton. It wouldn't matter if the belt was going 100mph forwards or back, you would stay still.

The plane is the same. The belt just spins the aircraft wheels, not move it back.

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By (user no longer on site)  over a year ago


"Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift"

Really trying to get my head around this argument...

It sounds as if you think that the engines drive the plane along by turning the wheels - like in a car...

Is that right...?

Um - er.... wot...?

OK, just take the wheels off, and fit skids instead... now explain it to me again please....

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By *unandbuckCouple  over a year ago

Sheffield

Remember, this is supposed to be a confusing question.

The belt is thrown in, because it is counter-intuitive.

If you get my gym rollerskate post above, it will help see why it will move and fly.

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By (user no longer on site)  over a year ago

The plane has to travel along the ground until lift is greater than its weight.

So, no the engines dont directly drive the wheels, they push the plane....along the ground...if the ground is moving backwards at the same rate as the plane is being pushed forwards (either on wheels or skids) the plane isn't moving

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift"

Tell me you are trolling and this is not your thought process , please tell me this ?

The distance traveled is relative to the air when propelled by a fucking jet engine , the number of wheel rotations is totally irrelevant. In your example the wheels would rotate once to match the belt speed and then again to match the forward through air speed

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"The plane has to travel along the ground until lift is greater than its weight.

So, no the engines dont directly drive the wheels, they push the plane....along the ground...if the ground is moving backwards at the same rate as the plane is being pushed forwards (either on wheels or skids) the plane isn't moving"

They push the plane forward , the ground has no relation to this other than upward support

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By (user no longer on site)  over a year ago


"Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift

how much the wheels turn is irrelevant, they are just free spinning, not like car drive wheels.

Think if you were at the gym on a flat treadmill wearing a pair of roller skates standing motionless. You switch the treadmill on, you could hold yourself stationary with a piece of cotton. It wouldn't matter if the belt was going 100mph forwards or back, you would stay still.

The plane is the same. The belt just spins the aircraft wheels, not move it back."

But to move forward the wheels would need to move faster than the belt.

The origional post states that as the speed of the wheels increases so does the speed of the belt (the distinguishing factor between the given question and the mythbusters test).

This means that the plane wont move forwards and so can't generate lift

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By *unandbuckCouple  over a year ago

Sheffield

Lincs white van man,

please read what i've written about standing on a treadmill on roller skates.

That is the crux of why it makes no difference.

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By (user no longer on site)  over a year ago


"The plane has to travel along the ground until lift is greater than its weight.

So, no the engines dont directly drive the wheels, they push the plane....along the ground...if the ground is moving backwards at the same rate as the plane is being pushed forwards (either on wheels or skids) the plane isn't moving

They push the plane forward , the ground has no relation to this other than upward support "

Forward is relative to the ground? As in a distance....unless we are talking geostationary orbit...which we aren't.

I challange anyone to move forward whilst staying on the same piece of ground

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By (user no longer on site)  over a year ago


"Lincs white van man,

please read what i've written about standing on a treadmill on roller skates.

That is the crux of why it makes no difference."

I have, and in that situation you are right, you remain stationary.

The issue is to create lift the plane has to move forwards, not remain stationary

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By (user no longer on site)  over a year ago


"Simple answer is no. If the plane is technically not moving there is no air flow around the wings so no lift is generated.

Simple theory of flight.

I have passed exams on this stuff. Just to clarify.."

So how come you're so wrong?

Ex aircraft engineer here.

It'll take off. Engines give it thrust to take off. How fast the wheels freewheel is nothing to do with it.

Simple.

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By (user no longer on site)  over a year ago

No

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By *ait88Man  over a year ago

Plymouth

The wheels are a red herring. There’s no need to get involved in explanations of “gravity”. So lets get rid of them.

Replace the aircraft’s wheels with floats.

Replace the conveyer belt with a very long straight channel of water – a canal. At one end is a massive dam, which can be used to make the canal water move at any speed through the canal.

The float plane floats on the canal facing the dam

If the water carries the float plane backwards through the air at the same speed as its engines are driving it forwards through the air, the wings can experience no air flow and can not lift the aircraft up. An observer will see the aircraft stationary.

If the water is moving the aircraft backwards through the air at take-off speed, and the engines are driving it forward through the air at the same, the aircraft can not take off, and appears to be stationery to an observer. Stop the water flow, and zoom. Away she goes. Virtually instant take-off – VTOL!

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By (user no longer on site)  over a year ago


"Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift

Tell me you are trolling and this is not your thought process , please tell me this ?

The distance traveled is relative to the air when propelled by a fucking jet engine , the number of wheel rotations is totally irrelevant. In your example the wheels would rotate once to match the belt speed and then again to match the forward through air speed

"

Only once the plane is airborne...untill then it travels along the ground...on its wheels.

If the plane was travelling along the ground faster than its wheels rotate theyd leave dirty great marks on the runway and blow out

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Of course the belt impacts the flight of the plane.

Take away the belt for the moment.

Engines fire up and push the plane along...on its wheels.

If the wheels have a 1m circumference then for every rotatio of the wheel the plane moves forward 1meter.

Plane moves forward fast enough the shape of the wings means that the air travelling over the top has further to travel than tbe air passing under the wing in the same time producing lift.

Reintroduce the belt.

Engines fire up, wheels rotate once...plane hasn't moved forward 1meter because the ground (the belt) moved backwards one meter...plane not moving forward = no air travling over the wings so no lift

how much the wheels turn is irrelevant, they are just free spinning, not like car drive wheels.

Think if you were at the gym on a flat treadmill wearing a pair of roller skates standing motionless. You switch the treadmill on, you could hold yourself stationary with a piece of cotton. It wouldn't matter if the belt was going 100mph forwards or back, you would stay still.

The plane is the same. The belt just spins the aircraft wheels, not move it back.

But to move forward the wheels would need to move faster than the belt.

The origional post states that as the speed of the wheels increases so does the speed of the belt (the distinguishing factor between the given question and the mythbusters test).

This means that the plane wont move forwards and so can't generate lift

"

Actually is says the belt matches the planes speed. The planes speed is not measured relative to belt but relative to the non moving ground or even the air . Thus as the huge jet engine pushes the plane forward through space the belt would travel at same speed backwards but this motion has no effect upon the plane as the plane is not tethered to the belt

Only a big chain with a strength more than the thrust would keep the plane from moving forward

I sense trolling !

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By (user no longer on site)  over a year ago

It's Friday so I'm not giving this question all my attention but only the wheels would go round. The conveyor is relative to the forward thrust therefore cancelling each other out.

No air flow would be created to lift the plane.

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Lincs white van man,

please read what i've written about standing on a treadmill on roller skates.

That is the crux of why it makes no difference.

I have, and in that situation you are right, you remain stationary.

Ok then just give the man a slight push he will move forward on the treadmill

The issue is to create lift the plane has to move forwards, not remain stationary"

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By *unandbuckCouple  over a year ago

Sheffield


"Lincs white van man,

please read what i've written about standing on a treadmill on roller skates.

That is the crux of why it makes no difference.

I have, and in that situation you are right, you remain stationary.

The issue is to create lift the plane has to move forwards, not remain stationary"

OK good. So lets step through:

I can stay stationary on a treadmill, using no force.

The aircraft on the giant treadmill would also stay stationary ,using no force.

When its engines applied forward force to the air, it would move forward as normal.

The treadmill has no method of applying any rearward force to the aircraft.

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By (user no longer on site)  over a year ago

*off to build wall to bang head against

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By *enard ArgenteMan  over a year ago

London and France

Dear god are people still answering this one?

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By (user no longer on site)  over a year ago


"Lincs white van man,

please read what i've written about standing on a treadmill on roller skates.

That is the crux of why it makes no difference.

I have, and in that situation you are right, you remain stationary.

The issue is to create lift the plane has to move forwards, not remain stationary

OK good. So lets step through:

I can stay stationary on a treadmill, using no force.

The aircraft on the giant treadmill would also stay stationary ,using no force.

When its engines applied forward force to the air, it would move forward as normal.

The treadmill has no method of applying any rearward force to the aircraft."

To move forward, how does the plane travel along the ground?

On its wheels?

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By (user no longer on site)  over a year ago

Too late.

It took off.

You missed it

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By (user no longer on site)  over a year ago

No....take off depends on lift overcoming the gross mass of the aircraft. Lift is generated by airflow over the wings reaching a critical speed depending on the mass of the aircraft. As the conveyer belt does not speed up the airflow over the wings the aircraft will not take off....

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By (user no longer on site)  over a year ago


"The wheels are a red herring. There’s no need to get involved in explanations of “gravity”. So lets get rid of them.

Replace the aircraft’s wheels with floats.

Replace the conveyer belt with a very long straight channel of water – a canal. At one end is a massive dam, which can be used to make the canal water move at any speed through the canal.

The float plane floats on the canal facing the dam

If the water carries the float plane backwards through the air at the same speed as its engines are driving it forwards through the air, the wings can experience no air flow and can not lift the aircraft up. An observer will see the aircraft stationary.

If the water is moving the aircraft backwards through the air at take-off speed, and the engines are driving it forward through the air at the same, the aircraft can not take off, and appears to be stationery to an observer. Stop the water flow, and zoom. Away she goes. Virtually instant take-off – VTOL!

"

not VTOL

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By *unandbuckCouple  over a year ago

Sheffield


"

The treadmill has no method of applying any rearward force to the aircraft.

To move forward, how does the plane travel along the ground?

On its wheels?"

Yes, an aircraft wheels just free turn, allowing the aircraft do what it wants.

The belt has no way to push the aircraft back.

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By (user no longer on site)  over a year ago

Clearly not. Planes can only take off when the uplift provided by the wings is greater than the weight of the plane. The uplift is provided by air moving over the wings. Since the plane is stationary relative to the air around it...there is zero uplift. It's going nowhere!

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By *unandbuckCouple  over a year ago

Sheffield


"No....take off depends on lift overcoming the gross mass of the aircraft. Lift is generated by airflow over the wings reaching a critical speed depending on the mass of the aircraft. As the conveyer belt does not speed up the airflow over the wings the aircraft will not take off...."

Nobodys saying that. We are saying the aircraft just goes forward as normal as if it was on tarmac.

the treadmill belt moving below has no influence on anything at all.

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By *enard ArgenteMan  over a year ago

London and France


"Clearly not. Planes can only take off when the uplift provided by the wings is greater than the weight of the plane. The uplift is provided by air moving over the wings. Since the plane is stationary relative to the air around it...there is zero uplift. It's going nowhere!"

So explain how you think that the plane is stationary......

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By (user no longer on site)  over a year ago

People need to read the question again.

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By (user no longer on site)  over a year ago

Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?

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By (user no longer on site)  over a year ago


"Clearly not. Planes can only take off when the uplift provided by the wings is greater than the weight of the plane. The uplift is provided by air moving over the wings. Since the plane is stationary relative to the air around it...there is zero uplift. It's going nowhere!"

On about VTOL...a Harrier for example does not need any airflow over its wings to take of vertically...Only needs those for moving forward. Shall we talk about vectored thrust now

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By (user no longer on site)  over a year ago


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?"

It doesn't. Same as a jogger on a treadmill.

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By (user no longer on site)  over a year ago

Please keep this going to part 3, it's turned into comedy gold.

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By (user no longer on site)  over a year ago

I'm changing my answer to yes now...plane moving forward speed 0...treadmill speed 0...vectored thrust, plane takes off vertically ...Do I win?

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By *unandbuckCouple  over a year ago

Sheffield

Right, lets forget the plane for a minute.

Back to the gym.

Stand on the treadmill wearing roller skates.

There is a rope tied to the wall in front of you.

You hold the rope gently.

you switch the treadmill on.

You stay motionless.

You speed the treadmill up.

You stay motionless.

You speed the treadmill up to 200mph.

You stay motionless.

You pull on the rope gently.

you move forwards, same as on the floor.

You are the plane.

roller skates are its wheels.

engines are the rope.

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By *orwegian BlueMan  over a year ago

Iceland, but Aldi is closer..

In theory it should take off as the thrust from the engine will push the plane forward irrelevant of what the ground and wheels are doing..

But....

It cannot because the way the question was posed created the following environment..

The assumption is that the belt can travel at an infinite speed and the engines can produce infinite forward motion.

The wheels cause drag and the airpressure cause resistance to the forward motion, therefore the plane is unable to overcome the resistance posed by the entire system and will Remain totally static...

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By (user no longer on site)  over a year ago

And you don't fly!

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?"

OK you keep repeating the same none truth

What effect do you think the jet engines have upon the plane and how exactly does the movment of the treadmill affect this

The wheels only support the plane the have zero influence upon the forward or backward motion

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By *enard ArgenteMan  over a year ago

London and France


"Right, lets forget the plane for a minute.

Back to the gym.

Stand on the treadmill wearing roller skates.

There is a rope tied to the wall in front of you.

You hold the rope gently.

you switch the treadmill on.

You stay motionless.

You speed the treadmill up.

You stay motionless.

You speed the treadmill up to 200mph.

You stay motionless.

You pull on the rope gently.

you move forwards, same as on the floor.

You are the plane.

roller skates are its wheels.

engines are the rope."

You are wasting your time;

They ;

A. can't understand the question.

B. don't know how a plane works, especially how it takes off, and can't get it out of their heads that the wheels do nothing except support the plane and provide minimal rolling resistance while it's taking off.

C. Or that the " conveyor belt" is irrelevant

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”"

No this is the question

And in this above question it even gives the answer

"The plane moves "

It says nothing about holding the plane still , that has been wrongly assumed and repeated

In fact the wheels on the plane would be rotating at double the planes forward speed through space

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By *ralbisw OP   Man  over a year ago

Exeter


"Please keep this going to part 3, it's turned into comedy gold. "

Oh I hope so..... or it will be banned before it gets there!!

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By (user no longer on site)  over a year ago

Do I get cashew nuts or olives with my champagne up here in First Class??

Oh and when do we arrive at our destination?

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By *enard ArgenteMan  over a year ago

London and France

You can see why science and engineering is so fucked up in the UK .

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By (user no longer on site)  over a year ago


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?

OK you keep repeating the same none truth

What effect do you think the jet engines have upon the plane and how exactly does the movment of the treadmill affect this

The wheels only support the plane the have zero influence upon the forward or backward motion "

as they are carrying or supporting the plane they need to move forwards for the plane to move forwards.

Wheels do this by rolling...if they are rolling forwards at the same rate as the ground is moving bacwards they arent moving....so the plane isnt moving.

If you are on rollerskates and i push you its my push that is the force moving you forwards.

The rollerskates are only supporting you...but I'm pretty sure that the speed and distance you travel will be directly related to the rotations of the wheels

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By (user no longer on site)  over a year ago

[Removed by poster at 18/11/16 14:05:30]

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By (user no longer on site)  over a year ago


"Do I get cashew nuts or olives with my champagne up here in First Class??

Oh and when do we arrive at our destination? "

Never, at the rate of some

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?

OK you keep repeating the same none truth

What effect do you think the jet engines have upon the plane and how exactly does the movment of the treadmill affect this

The wheels only support the plane the have zero influence upon the forward or backward motion as they are carrying or supporting the plane they need to move forwards for the plane to move forwards.

Wheels do this by rolling...if they are rolling forwards at the same rate as the ground is moving bacwards they arent moving....so the plane isnt moving.

If you are on rollerskates and i push you its my push that is the force moving you forwards.

The rollerskates are only supporting you...but I'm pretty sure that the speed and distance you travel will be directly related to the rotations of the wheels

"

You are just trolling now

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By (user no longer on site)  over a year ago


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?

OK you keep repeating the same none truth

What effect do you think the jet engines have upon the plane and how exactly does the movment of the treadmill affect this

The wheels only support the plane the have zero influence upon the forward or backward motion as they are carrying or supporting the plane they need to move forwards for the plane to move forwards.

Wheels do this by rolling...if they are rolling forwards at the same rate as the ground is moving bacwards they arent moving....so the plane isnt moving.

If you are on rollerskates and i push you its my push that is the force moving you forwards.

The rollerskates are only supporting you...but I'm pretty sure that the speed and distance you travel will be directly related to the rotations of the wheels

You are just trolling now "

Is that translated as "i finally see your point?"

If not then I suggest that there may well ba a troll.

I'm still open to reasoned discussion...and if that discussion has me see that I'm wrong then i will comment as such, not call that person a troll...

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By *enard ArgenteMan  over a year ago

London and France


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?

OK you keep repeating the same none truth

What effect do you think the jet engines have upon the plane and how exactly does the movment of the treadmill affect this

The wheels only support the plane the have zero influence upon the forward or backward motion as they are carrying or supporting the plane they need to move forwards for the plane to move forwards.

Wheels do this by rolling...if they are rolling forwards at the same rate as the ground is moving bacwards they arent moving....so the plane isnt moving.

If you are on rollerskates and i push you its my push that is the force moving you forwards.

The rollerskates are only supporting you...but I'm pretty sure that the speed and distance you travel will be directly related to the rotations of the wheels

You are just trolling now

Is that translated as "i finally see your point?"

If not then I suggest that there may well ba a troll.

I'm still open to reasoned discussion...and if that discussion has me see that I'm wrong then i will comment as such, not call that person a troll..."

Well for a start you still are not reading the question ( FUCKING big clue posted just now by the OP). It didn't say " wheels", it said "the plane."

Anyway, its irrelevant.

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By (user no longer on site)  over a year ago

I haven't read all the posts so apologies if this has been said before.

If the forward momentum was provided by the wheels, then the plane would standstill. However, as the plane uses its jets/propellor to provide the thrust, the plane will still move forward as normal and take off.

The wheels effectively do nothing other than hold the plane up and allow it to move over the ground until it reaches enough speed to take off.

The only difference the conveyor belt would make is that at any point in the take off the wheels are turning twice as fast as they would be on a normal takeoff.

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Ok so until take off it travels on its wheels.

On you analogy, to move forwards on the running machine your rollerskate wheels need to be moving forwards faster than the tredmill is turning backwards?

The origional question says the experiment is set up so the speed of tbe treadmill matches the speed of your rollerskate wheels.

How can you move forwards?

OK you keep repeating the same none truth

What effect do you think the jet engines have upon the plane and how exactly does the movment of the treadmill affect this

The wheels only support the plane the have zero influence upon the forward or backward motion as they are carrying or supporting the plane they need to move forwards for the plane to move forwards.

Wheels do this by rolling...if they are rolling forwards at the same rate as the ground is moving bacwards they arent moving....so the plane isnt moving.

If you are on rollerskates and i push you its my push that is the force moving you forwards.

The rollerskates are only supporting you...but I'm pretty sure that the speed and distance you travel will be directly related to the rotations of the wheels

You are just trolling now

Is that translated as "i finally see your point?"

If not then I suggest that there may well ba a troll.

I'm still open to reasoned discussion...and if that discussion has me see that I'm wrong then i will comment as such, not call that person a troll..."

That's the point reasoned discussion has been exceeded. The explanation cannot be made more clear . There is a word called obtuse, arguing not because one has a point but just to wind up

You know full well free wheeling wheels have no relevance in this case and exceptionally clear explanations why not have been eloquently explained from a number of people in a variety of ways , deliberately missing the point for argument is trolling. Xx

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By (user no longer on site)  over a year ago

So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

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By (user no longer on site)  over a year ago


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?"

Yes

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By *unandbuckCouple  over a year ago

Sheffield


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?"

It makes no difference either way.

I don't want this to sound snotty, I just want to try to explain why it moves. Do you know the wheels aren't driving the plane during takeoff and taxiing?

If you think they are drive wheels it's going to screw the whole thing up.

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By (user no longer on site)  over a year ago


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

Yes

"

Ohhhh!

In that case, of course it'll take off...

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By *unandbuckCouple  over a year ago

Sheffield


"I haven't read all the posts so apologies if this has been said before.

If the forward momentum was provided by the wheels, then the plane would standstill. However, as the plane uses its jets/propellor to provide the thrust, the plane will still move forward as normal and take off.

The wheels effectively do nothing other than hold the plane up and allow it to move over the ground until it reaches enough speed to take off.

The only difference the conveyor belt would make is that at any point in the take off the wheels are turning twice as fast as they would be on a normal takeoff. "

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By (user no longer on site)  over a year ago


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?"

Another way of looking at it is the speed of the wheels is proportional to the speed of the plane and the speed of the belt.

If you like, the turning of the wheels is a function of plane speed and conveyor speed.

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By (user no longer on site)  over a year ago


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

"

It actually does.

It makes the difference between flight or no flight

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By *ee VianteWoman  over a year ago

Somewhere in North Norfolk

Nobody read the XKCD page then?

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By *unandbuckCouple  over a year ago

Sheffield


"In theory it should take off as the thrust from the engine will push the plane forward irrelevant of what the ground and wheels are doing..

But....

It cannot because the way the question was posed created the following environment..

The assumption is that the belt can travel at an infinite speed and the engines can produce infinite forward motion.

The wheels cause drag and the airpressure cause resistance to the forward motion, therefore the plane is unable to overcome the resistance posed by the entire system and will Remain totally static...

"

no. even on my imaginary gym treadmill, if the treadmill was connected to a 1000 bhp engine and could spin at 500 mph, if it stand on it on my roller skates, I can still pull myself forward as normal with a piece of rope.

The belt has no method to produce any rearward force, due to the wheels being in-between.

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By *unandbuckCouple  over a year ago

Sheffield


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight"

the belt can turn at a million miles an hour if it wants. The wheels spin backwards at a million miles an hour , the plane will accelerate forward as normal.

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By (user no longer on site)  over a year ago


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight

the belt can turn at a million miles an hour if it wants. The wheels spin backwards at a million miles an hour , the plane will accelerate forward as normal."

Well actually,,, there is slight resistance in the wheels at some point the belt will he going fast enough that the resistance is high enough to actually push the plane back... I suspect the wheels will have burst way before that point is reached though!

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By (user no longer on site)  over a year ago


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight

the belt can turn at a million miles an hour if it wants. The wheels spin backwards at a million miles an hour , the plane will accelerate forward as normal."

No the wheels would need to be spinning at a million and one miles an hour to move forwards

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By (user no longer on site)  over a year ago

This should resolve the debate https://m.youtube.com/watch?v=YORCk1BN7QY

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By *unandbuckCouple  over a year ago

Sheffield


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight

the belt can turn at a million miles an hour if it wants. The wheels spin backwards at a million miles an hour , the plane will accelerate forward as normal.

Well actually,,, there is slight resistance in the wheels at some point the belt will he going fast enough that the resistance is high enough to actually push the plane back... I suspect the wheels will have burst way before that point is reached though!"

Yes, in the practical real world, the belt can push back on the plane a tiny bit because of the friction in the bearings. The engines just need to work a tiny bit harder to counteract that friction. But its already too complicated.

The basic physics is that the moving belt can't slow or stop the plane moving forward.

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By *ralbisw OP   Man  over a year ago

Exeter

Shall we assume friction is negligible and the brakes on the plane main wheels are unserviceable and don't work?

Does that change anyone's thought process??

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By *unandbuckCouple  over a year ago

Sheffield


"This should resolve the debate https://m.youtube.com/watch?v=YORCk1BN7QY"

yayyy 1

Also, my mates Isaac Newton, and prof Brian Cox have profiles on here. Just PM them and ask what they say:

I_Suck_Newton

Big_Cock_Cox

they'll confirm it will fly.

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By *unandbuckCouple  over a year ago

Sheffield


"Shall we assume friction is negligible and the brakes on the plane main wheels are unserviceable and don't work?

Does that change anyone's thought process??"

Yes, it can't have it brakes on. If its brakes were on, the belt would move it backwards.

But its trying to take off, the brakes are off

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight

the belt can turn at a million miles an hour if it wants. The wheels spin backwards at a million miles an hour , the plane will accelerate forward as normal.

No the wheels would need to be spinning at a million and one miles an hour to move forwards"

Actually wheels spin in rpm not mph a spinning thing can move as a vector in any direction regardless of its spin

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By *unandbuckCouple  over a year ago

Sheffield


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight

the belt can turn at a million miles an hour if it wants. The wheels spin backwards at a million miles an hour , the plane will accelerate forward as normal.

No the wheels would need to be spinning at a million and one miles an hour to move forwards

Actually wheels spin in rpm not mph a spinning thing can move as a vector in any direction regardless of its spin"

That doesn't help people who think it can't fly. I'm trying to bring something useful to the table.

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By *omez42Man  over a year ago

gloucester

The belt is irrelevant, as is movement, or engines.

The only thing that gives lift is airflow over the wing. If there were a wind blowing onto the wing at above the stall speed of that wing, lift would occur.

The Antonio AN2 biplane has such a low stall speed that it can hold itself in the hover, or even fly backwards in a strong wind.

Take a small aircraft, like an Icarus C42 up into the stronger winds at altitude, drop the engine rpm and hold it in the incipient stall, about 35mph. If you are pointed into a wind higher than the stall speed, look at the ground or gps, you will be going backwards, yet the airspeed will be be showing a positive number.

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By *omez42Man  over a year ago

gloucester

I meant Antonov!

Bloody autocorrect

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By *unandbuckCouple  over a year ago

Sheffield


"The belt is irrelevant, as is movement, or engines.

"

This about any regular size jet. People don't get that it can move forwards on the belt and therefore fly.

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By (user no longer on site)  over a year ago

OK - different example...

An aeroplane takes off from a runway in a westerly direction. There is no conveyor belt at all, the runway is stuck on the ground. OK, is that simple enough?

But due to the Earth's rotation, the ground surface, and hence the runway, are moving at about 1000 miles per hour in an easterly direction - opposite to the aeroplane's motion....

Can the aeroplane still take off????

Go to any sodding airport - watch the damn thing, and find out!!!

Waaaaaa - I give in....

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By (user no longer on site)  over a year ago


"OK - different example...

An aeroplane takes off from a runway in a westerly direction. There is no conveyor belt at all, the runway is stuck on the ground. OK, is that simple enough?

But due to the Earth's rotation, the ground surface, and hence the runway, are moving at about 1000 miles per hour in an easterly direction - opposite to the aeroplane's motion....

Can the aeroplane still take off????

Go to any sodding airport - watch the damn thing, and find out!!!

Waaaaaa - I give in....

"

Yep. Simply because the aircraft, runway, earth are moving relative to each other.

It's simply Einsteins man on a train.

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By *imiUKMan  over a year ago

Hereford

Head, meet desk...

Why is it that people cannot accept that a theoretical pemise is incorrect when it is posed in the form of a question, ergo the answer to the question is counter-intuitive?

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By *ralbisw OP   Man  over a year ago

Exeter

This problem is exacerbated a lot by it being difficult to get across succinctly what you actually really mean!

Does anyone still think it won't take off?

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By (user no longer on site)  over a year ago


"This problem is exacerbated a lot by it being difficult to get across succinctly what you actually really mean!

Does anyone still think it won't take off? "

Plenty of people will.

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By *orwegian BlueMan  over a year ago

Iceland, but Aldi is closer..


"In theory it should take off as the thrust from the engine will push the plane forward irrelevant of what the ground and wheels are doing..

But....

It cannot because the way the question was posed created the following environment..

The assumption is that the belt can travel at an infinite speed and the engines can produce infinite forward motion.

The wheels cause drag and the airpressure cause resistance to the forward motion, therefore the plane is unable to overcome the resistance posed by the entire system and will Remain totally static...

no. even on my imaginary gym treadmill, if the treadmill was connected to a 1000 bhp engine and could spin at 500 mph, if it stand on it on my roller skates, I can still pull myself forward as normal with a piece of rope.

The belt has no method to produce any rearward force, due to the wheels being in-between."

I toyed with both notions, but based upon the original description, and checked with people that know how, it was confirmed that flight would be practicable impossible..

If full thrust was instantaneous and the belt started slowly, then forward motion would be possible but because they are equal, it can never overcome the external influence of resistance.

He then went on to explain the science behind the facts and at which point i dozed off..

It still doesn't make sense to me, as far as I can see, it should be able to take off, but I seem to be missing the importance of the text in the original post...

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”"

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that?

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By (user no longer on site)  over a year ago

Seems a pointless question but the answer is probably not. If the aircrafts thrust is being directly negated by the conveyer belt runway, the thrust is equal to the drag. Therefore no lift is possible. Only when thrust outweighs drag can lift be possible. Basic aerodynamics. The only caveat is that if there is sufficient windspeed, eg. 240mph windspeeds against the direction of the aircrafts thrust, then takeoff would potentially be feasible if the aircraft remains effectively stationery. But the airflow would have to be consistent at that speed for a safe takeoff and that's hardly likely!

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"In theory it should take off as the thrust from the engine will push the plane forward irrelevant of what the ground and wheels are doing..

But....

It cannot because the way the question was posed created the following environment..

The assumption is that the belt can travel at an infinite speed and the engines can produce infinite forward motion.

The wheels cause drag and the airpressure cause resistance to the forward motion, therefore the plane is unable to overcome the resistance posed by the entire system and will Remain totally static...

no. even on my imaginary gym treadmill, if the treadmill was connected to a 1000 bhp engine and could spin at 500 mph, if it stand on it on my roller skates, I can still pull myself forward as normal with a piece of rope.

The belt has no method to produce any rearward force, due to the wheels being in-between.

I toyed with both notions, but based upon the original description, and checked with people that know how, it was confirmed that flight would be practicable impossible..

If full thrust was instantaneous and the belt started slowly, then forward motion would be possible but because they are equal, it can never overcome the external influence of resistance.

He then went on to explain the science behind the facts and at which point i dozed off..

It still doesn't make sense to me, as far as I can see, it should be able to take off, but I seem to be missing the importance of the text in the original post...

"

The person you spoke to had no idea !

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? "

wrong

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Seems a pointless question but the answer is probably not. If the aircrafts thrust is being directly negated by the conveyer belt runway, the thrust is equal to the drag. Therefore no lift is possible. Only when thrust outweighs drag can lift be possible. Basic aerodynamics. The only caveat is that if there is sufficient windspeed, eg. 240mph windspeeds against the direction of the aircrafts thrust, then takeoff would potentially be feasible if the aircraft remains effectively stationery. But the airflow would have to be consistent at that speed for a safe takeoff and that's hardly likely! "

Just explain how a conveyer belt pushing upon free spinning wheels can overcome 40 000 pounds of thrust ?

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By *enard ArgenteMan  over a year ago

London and France


"So the speed of the belt is set to match the speed of the plane, not the speed of its wheels?

It makes no difference either way.

It actually does.

It makes the difference between flight or no flight"

You are either terminally stupid, or just winding everyone up;

I shall assume the latter.

The wheels , the belt, are completely irrelevant; the only thing that is relevant is that the propeller(s) or the jet(s) are providing thrust to the aircraft body. As soon as that thrust has accelerated the aircraft forward sufficiently for the airflow to create lift which is greater than the aircraft weight, it will take off.

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”"

You say the plane is standing.. therefore no wind passing the wing at speed so no lift can be generated

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? wrong"

Ok, how so?

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

You say the plane is standing.. therefore no wind passing the wing at speed so no lift can be generated "

If the pilot powers up I'd say it could take off tho.. the power is not transferred through the wheels like on a car

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

You say the plane is standing.. therefore no wind passing the wing at speed so no lift can be generated "

You read that but missed the plane MOVES in one direction

That movement occurs from engine thrust which is then matched by the conveyer in the opposite direction but has NO EFFECT upon the movement of the plane

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? wrong

Ok, how so? "

Seriously ?

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? wrong

Ok, how so?

Seriously ?"

Yes, you're disagreeing with my reasoning but not giving reasoning of your own, hence my asking

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By *ensualtouch15Man  over a year ago

ashby de la zouch


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? wrong

Ok, how so?

Seriously ?

Yes, you're disagreeing with my reasoning but not giving reasoning of your own, hence my asking "

You

read that but missed the plane MOVES in one direction

That movement occurs from engine thrust which is then matched by the conveyer in the opposite direction but has NO EFFECT upon the movement of the plane

Which bit of the conveyer has no effect upon the motion of the plane do you seriously not understand

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? wrong

Ok, how so?

Seriously ?

Yes, you're disagreeing with my reasoning but not giving reasoning of your own, hence my asking

You

read that but missed the plane MOVES in one direction

That movement occurs from engine thrust which is then matched by the conveyer in the opposite direction but has NO EFFECT upon the movement of the plane

Which bit of the conveyer has no effect upon the motion of the plane do you seriously not understand

"

The motion of the plane has an effect on the wheels, it'll make them go faster, my point is that if the belt then matches this it will stop the plane taking off because the plane will still be effectively at a standstill, if it dosent it won't because the plane will then beat the belt, how did u not understand that??

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By (user no longer on site)  over a year ago


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

You say the plane is standing.. therefore no wind passing the wing at speed so no lift can be generated

You read that but missed the plane MOVES in one direction

That movement occurs from engine thrust which is then matched by the conveyer in the opposite direction but has NO EFFECT upon the movement of the plane "

I think the plane would still move, power is not transferred through the ground like it would be in a car, the wheels might turn twice as fast as they would normally tho

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By *ophieslutTV/TS  over a year ago

Central

I am fairly certain that under some circumstances then this plane could definitely take off. The definition of 'take off' may mean something different to the first element of a succesful transatlantic flight of course, so it's also worthwhile taking note of that.

If there were more elements controlling the potential uplift of the plane, then it would be more difficult. With the major limitation being the conveyor belt and its control system, then a couple of things spring immediately to mind:

firstly that the monitoring gets the conveyor belt to respond in arrears to what the plane has achieved. As it's in arrears, then it's playing catchup: thus the plane could achieve actual take-off, before the delayed response from the belt. In essence, there only needs to be one nano second of delay and that may well be the nano second that the plane takes off.

I sense that there could be so many extraneous factors that could influence positively the achievement of take-off, with just a delayed response from the actual belt itself that the odds are highly in favour of the plane getting there. The amount of energy, its availability, gradients etc, as well as the physical conditions in situ, will all influence the potential for the plane to take off.

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By (user no longer on site)  over a year ago


"Seems a pointless question but the answer is probably not. If the aircrafts thrust is being directly negated by the conveyer belt runway, the thrust is equal to the drag. Therefore no lift is possible. Only when thrust outweighs drag can lift be possible. Basic aerodynamics. The only caveat is that if there is sufficient windspeed, eg. 240mph windspeeds against the direction of the aircrafts thrust, then takeoff would potentially be feasible if the aircraft remains effectively stationery. But the airflow would have to be consistent at that speed for a safe takeoff and that's hardly likely!

Just explain how a conveyer belt pushing upon free spinning wheels can overcome 40 000 pounds of thrust ?

"

By creating 40000 pounds of drag! Wheels against any surface produces drag. If you have enough drag to counteract the thrust, what do you suppose the result is? Basics of aviaton!

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By (user no longer on site)  over a year ago

If you are arguing that the belt going at the same speed as the plane in the opposite direction does NOT create an equilibrium of drag against thrust then of course we must assume the outcome would be different. Perhaps some of us are confusing tge question of speed counteracting speed rather than tge effect of drag counteracting thrust. Technically, all the time thrust is significantly greater than drag, the aircraft will have the potential for lift.

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By *eesideMan  over a year ago

margate sumwear by the sea


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”"

If the plane dus,not moove from its start poshishoun then regardlis how mutch thrust the engines make if the plan dus not moove fallwood throw the air then Thar will be no air flow under and over the wings thear for it can not take off. But if the convayer belt wos to stop sudnley with the engines at fall thrust it wood be a short take off.

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By *enard ArgenteMan  over a year ago

London and France


"Great thread - lets keep the discussion going.

Does it fly or not?

“A plane is standing on a runway that can move (some sort of band conveyer belt). 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?”

I've had a think about this and seen the vids and I think it depends, say the wheels and belt are both going at 50 mph, then the engines are turned on and start to drag in air this will then push the plane to go faster, for arguments sake let's say to 100 mph, so the plane is now being pushed to twice what the belt was originally going, if the belt speed increases to match then no the plane won't take off, if the belt stays the same then yes it will

How's that? wrong

Ok, how so?

Seriously ?

Yes, you're disagreeing with my reasoning but not giving reasoning of your own, hence my asking

You

read that but missed the plane MOVES in one direction

That movement occurs from engine thrust which is then matched by the conveyer in the opposite direction but has NO EFFECT upon the movement of the plane

Which bit of the conveyer has no effect upon the motion of the plane do you seriously not understand

The motion of the plane has an effect on the wheels, it'll make them go faster, my point is that if the belt then matches this it will stop the plane taking off because the plane will still be effectively at a standstill, if it dosent it won't because the plane will then beat the belt, how did u not understand that?? "

how on earth can you come to that conclusion?

The conveyor belt and the wheels are totally, utterly irrelevant.

All that matters is that the jets or propellers provide forward thrust to the aircraft, which moves forward, irrespective of what the wheels or the conveyor belt is doing. Once the wings are moving forward fast enough to provide lift, the aircraft takes off.

The conveyor belt and the wheels have nothing to do with the engines and the thrust on the aircraft;

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By (user no longer on site)  over a year ago

Stewardess.. please may I have some more champagne?

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By *oncupiscentTonyMan  over a year ago

Kent


"I am fairly certain that under some circumstances then this plane could definitely take off. The definition of 'take off' may mean something different to the first element of a succesful transatlantic flight of course, so it's also worthwhile taking note of that.

If there were more elements controlling the potential uplift of the plane, then it would be more difficult. With the major limitation being the conveyor belt and its control system, then a couple of things spring immediately to mind:

firstly that the monitoring gets the conveyor belt to respond in arrears to what the plane has achieved. As it's in arrears, then it's playing catchup: thus the plane could achieve actual take-off, before the delayed response from the belt. In essence, there only needs to be one nano second of delay and that may well be the nano second that the plane takes off.

I sense that there could be so many extraneous factors that could influence positively the achievement of take-off, with just a delayed response from the actual belt itself that the odds are highly in favour of the plane getting there. The amount of energy, its availability, gradients etc, as well as the physical conditions in situ, will all influence the potential for the plane to take off. "

The belt is irrelevant, there is no force from the belt transferred to the plane...it (the rearward force created by the belt) cannot travel any further than the wheels.

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By *unandbuckCouple  over a year ago

Sheffield

I'll repost:

Right, lets forget the plane for a minute.

Back to the gym.

Stand on the treadmill wearing roller skates.

There is a rope tied to the wall in front of you.

You hold the rope gently.

you switch the treadmill on.

You stay motionless.

You speed the treadmill up.

You stay motionless.

You speed the treadmill up to 200mph.

You stay motionless.

You pull on the rope gently.

you move forwards, same as on the floor.

.

.

You are the plane.

roller skates are its wheels.

engines are the rope

The plane moves forward exactly as normal. It gets up to full speed as normal and takes off as normal

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By *avrick15Man  over a year ago

glasgow

Ok let's come at this in the spirit of the hypothetical as it was posed

Plane and belt move in opposite directions in perfect synchronicity

The landing gear, i.e. Wheels do not provide drive they support the mass (weight) of the plane whilst stationary

Therefore if the belt and plane move simultaneously the airflow does not provide lift and therefore weight is still transferring down to the wheels keeping it on the ground

The only way to break the cycle is if the plane accelerates past the force in reverse of the belt and creates forward motion thus airflow, cancelling weight and allowing lift

Everyone have a drink and chill the fuck out

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By *unandbuckCouple  over a year ago

Sheffield


"

Ok let's come at this in the spirit of the hypothetical as it was posed

Plane and belt move in opposite directions in perfect synchronicity

The landing gear, i.e. Wheels do not provide drive they support the mass (weight) of the plane whilst stationary

Therefore if the belt and plane move simultaneously the airflow does not provide lift and therefore weight is still transferring down to the wheels keeping it on the ground

The only way to break the cycle is if the plane accelerates past the force in reverse of the belt and creates forward motion thus airflow, cancelling weight and allowing lift

Everyone have a drink and chill the fuck out "

But in this you are agreeing the plane is moving forward.

If the plane is moving forward it has airflow over the wings.

It then takes off.

The belt has no effect on anything.

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By *avrick15Man  over a year ago

glasgow


"

Ok let's come at this in the spirit of the hypothetical as it was posed

Plane and belt move in opposite directions in perfect synchronicity

The landing gear, i.e. Wheels do not provide drive they support the mass (weight) of the plane whilst stationary

Therefore if the belt and plane move simultaneously the airflow does not provide lift and therefore weight is still transferring down to the wheels keeping it on the ground

The only way to break the cycle is if the plane accelerates past the force in reverse of the belt and creates forward motion thus airflow, cancelling weight and allowing lift

Everyone have a drink and chill the fuck out

But in this you are agreeing the plane is moving forward.

If the plane is moving forward it has airflow over the wings.

It then takes off.

The belt has no effect on anything."

No, the plane is accelerating but forward motion is cancelled due to the belt matching the acceleration. The weight cannot be transferred into velocity creating airflow so no lift.

The planes position is exactly the same. If you had a gps point it would not move in this case.

Remember the treadmill? You stay in the same overall position.

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By (user no longer on site)  over a year ago


"I'll repost:

Right, lets forget the plane for a minute.

Back to the gym.

Stand on the treadmill wearing roller skates.

There is a rope tied to the wall in front of you.

You hold the rope gently.

you switch the treadmill on.

You stay motionless.

You speed the treadmill up.

You stay motionless.

You speed the treadmill up to 200mph.

You stay motionless.

You pull on the rope gently.

you move forwards, same as on the floor.

.

.

You are the plane.

roller skates are its wheels.

engines are the rope

The plane moves forward exactly as normal. It gets up to full speed as normal and takes off as normal"

Gets my vote

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By *avrick15Man  over a year ago

glasgow

Fuck me... ok then simple logic question then

Why haven't all the huge spaces of runways been replaced by fucking belts??

Thank you.... I'm out

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By *avrick15Man  over a year ago

glasgow


"

Fuck me... ok then simple logic question then

Why haven't all the huge spaces of runways been replaced by fucking belts??

Thank you.... I'm out "

Clearly these engineers are fuckwits and fab swingers have the answers pmsl

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By *oncupiscentTonyMan  over a year ago

Kent


"

Ok let's come at this in the spirit of the hypothetical as it was posed

Plane and belt move in opposite directions in perfect synchronicity

The landing gear, i.e. Wheels do not provide drive they support the mass (weight) of the plane whilst stationary

Therefore if the belt and plane move simultaneously the airflow does not provide lift and therefore weight is still transferring down to the wheels keeping it on the ground

The only way to break the cycle is if the plane accelerates past the force in reverse of the belt and creates forward motion thus airflow, cancelling weight and allowing lift

Everyone have a drink and chill the fuck out

But in this you are agreeing the plane is moving forward.

If the plane is moving forward it has airflow over the wings.

It then takes off.

The belt has no effect on anything.

No, the plane is accelerating but forward motion is cancelled due to the belt matching the acceleration. The weight cannot be transferred into velocity creating airflow so no lift.

The planes position is exactly the same. If you had a gps point it would not move in this case.

Remember the treadmill? You stay in the same overall position."

For crying out loud how does the belt match the acceleration of the air!!!!?, THE BELT US IRRELEVANT BECAUSE THE WHEELS BREAK THE CHAIN BETWEEN THE BELT AND THE PLANE THE BELT CANNOT INFLUENCE THE PLANE IN ANY WAY WHATSOEVER!!

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By *avrick15Man  over a year ago

glasgow


"

Ok let's come at this in the spirit of the hypothetical as it was posed

Plane and belt move in opposite directions in perfect synchronicity

The landing gear, i.e. Wheels do not provide drive they support the mass (weight) of the plane whilst stationary

Therefore if the belt and plane move simultaneously the airflow does not provide lift and therefore weight is still transferring down to the wheels keeping it on the ground

The only way to break the cycle is if the plane accelerates past the force in reverse of the belt and creates forward motion thus airflow, cancelling weight and allowing lift

Everyone have a drink and chill the fuck out

But in this you are agreeing the plane is moving forward.

If the plane is moving forward it has airflow over the wings.

It then takes off.

The belt has no effect on anything.

No, the plane is accelerating but forward motion is cancelled due to the belt matching the acceleration. The weight cannot be transferred into velocity creating airflow so no lift.

The planes position is exactly the same. If you had a gps point it would not move in this case.

Remember the treadmill? You stay in the same overall position.

For crying out loud how does the belt match the acceleration of the air!!!!?, THE BELT US IRRELEVANT BECAUSE THE WHEELS BREAK THE CHAIN BETWEEN THE BELT AND THE PLANE THE BELT CANNOT INFLUENCE THE PLANE IN ANY WAY WHATSOEVER!!"

What are you talking about acceleration of the air???

The belt is pulling the weight of the plane backwards and only being cancelled out by the acceleration of the planes engines in the opposite direction.. so... it just trundles... however fast you want! along in the SAME overall position

No airflow over the wings because position wise it's NOT FUCKING MOVING

The air is doing fuck all except going through the thrust ports of the engine.

Forget all the technical aruguments.. I refer you to the above... why are all these silly airports wasting land space? Shortage of rubber maybe.. fuck me

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By *inky-MinxWoman  over a year ago

Grantham

[Removed by poster at 18/11/16 21:25:05]

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By *oncupiscentTonyMan  over a year ago

Kent


"

Ok let's come at this in the spirit of the hypothetical as it was posed

Plane and belt move in opposite directions in perfect synchronicity

The landing gear, i.e. Wheels do not provide drive they support the mass (weight) of the plane whilst stationary

Therefore if the belt and plane move simultaneously the airflow does not provide lift and therefore weight is still transferring down to the wheels keeping it on the ground

The only way to break the cycle is if the plane accelerates past the force in reverse of the belt and creates forward motion thus airflow, cancelling weight and allowing lift

Everyone have a drink and chill the fuck out

But in this you are agreeing the plane is moving forward.

If the plane is moving forward it has airflow over the wings.

It then takes off.

The belt has no effect on anything.

No, the plane is accelerating but forward motion is cancelled due to the belt matching the acceleration. The weight cannot be transferred into velocity creating airflow so no lift.

The planes position is exactly the same. If you had a gps point it would not move in this case.

Remember the treadmill? You stay in the same overall position.

For crying out loud how does the belt match the acceleration of the air!!!!?, THE BELT US IRRELEVANT BECAUSE THE WHEELS BREAK THE CHAIN BETWEEN THE BELT AND THE PLANE THE BELT CANNOT INFLUENCE THE PLANE IN ANY WAY WHATSOEVER!!

What are you talking about acceleration of the air???

The belt is pulling the weight of the plane backwards and only being cancelled out by the acceleration of the planes engines in the opposite direction.. so... it just trundles... however fast you want! along in the SAME overall position

No airflow over the wings because position wise it's NOT FUCKING MOVING

The air is doing fuck all except going through the thrust ports of the engine.

Forget all the technical aruguments.. I refer you to the above... why are all these silly airports wasting land space? Shortage of rubber maybe.. fuck me "

FFS the belt is NOT pulling the weight of the plane backwards!!!

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By *inky-MinxWoman  over a year ago

Grantham


"What are you talking about acceleration of the air???

The belt is pulling the weight of the plane backwards and only being cancelled out by the acceleration of the planes engines in the opposite direction.. so... it just trundles... however fast you want! along in the SAME overall position

No airflow over the wings because position wise it's NOT FUCKING MOVING

The air is doing fuck all except going through the thrust ports of the engine.

Forget all the technical aruguments.. I refer you to the above... why are all these silly airports wasting land space? Shortage of rubber maybe.. fuck me "

You're still trying?

Anyone who cannot see that two equal and opposite motions will cancel each other out does not deserve your help

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By *avrick15Man  over a year ago

glasgow


"What are you talking about acceleration of the air???

The belt is pulling the weight of the plane backwards and only being cancelled out by the acceleration of the planes engines in the opposite direction.. so... it just trundles... however fast you want! along in the SAME overall position

No airflow over the wings because position wise it's NOT FUCKING MOVING

The air is doing fuck all except going through the thrust ports of the engine.

Forget all the technical aruguments.. I refer you to the above... why are all these silly airports wasting land space? Shortage of rubber maybe.. fuck me

You're still trying?

Anyone who cannot see that two equal and opposite motions will cancel each other out does not deserve your help"

Ha ha true.. fuck it it's Friday hot sex and cocktails for everyone!! Forget all this technical mind bending and go bend someone over for a good un!

Ps I will be looking out for all these people flying out of gym windows on their treadmills and expect delays at Glasgow airport as they install all the belts to save land space

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By *unandbuckCouple  over a year ago

Sheffield

Mavrik

Nobody is saying the plane stand still and suddenly floats up.

It moves forward exactly as normal for the mile or whatever. It doesnt matter if underneath it is tarmac or a belt.

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By *avrick15Man  over a year ago

glasgow


"Mavrik

Nobody is saying the plane stand still and suddenly floats up.

It moves forward exactly as normal for the mile or whatever. It doesnt matter if underneath it is tarmac or a belt."

Hey Bun

I no longer care... I'm now focusing on more lovely Friday things... such as your lovely tooshy bent over that bed

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By *ralbisw OP   Man  over a year ago

Exeter

Lol

Are we nearly ready for a Vol 3???

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By *avrick15Man  over a year ago

glasgow


"Lol

Are we nearly ready for a Vol 3???"

Don't you fucking dare!!! Lol driving me nuts

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By (user no longer on site)  over a year ago

I can't read all this thread. Can someone make me an audio book, preferably read by Stephen Fry......!!

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By *avrick15Man  over a year ago

glasgow


"I can't read all this thread. Can someone make me an audio book, preferably read by Stephen Fry......!!"

You'd be better with Stephen hawking to convince some folk on here!

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By *riskynriskyCouple  over a year ago

Essex.

The plane is pushed forwards by the thrust of the engines.

Say the thrust pushes the plane forward at 100 mph, the belt is rolling back at 100 mph.

All this means is the wheels are doing 200mph...

The plane is still travelling forward at a fast enough speed to take off...

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By *ensualtouch15Man  over a year ago

ashby de la zouch

I am amazed

Seems we need to draw a picture

First level is ground . For this we shall say not moving

Second level is moving surface moving backwards let's say at 100 kph

Third level is a wheel attached to an under carriage and the brakes are off , it can spin freely touching the moving surface . The wheel has a circumference of 1 meter

The undercarriage is tethered to the ground

The wheel is now rotating at 1666 rpm however it's speed relative to the ground is 0 kph

The drag on the undercarriage from the moving surface is about 100 pounds

Attached to the undercarriage is a jet engine that can push at 100 000 pounds

Set the engine to produce 100 pounds thrust

The carriage stays still

Reduce the thrust the undercarriage follows the direction of the moving surface

Increase the thrust to 50 000 pounds and the carriage accelerates forward bringing it's wheels forwards relative to the ground , the moving surface and most importantly the air mass

The only equation that is relevant here is

Acceleration equals mass divided by force

Thus as long as the force on the undercarriage is less than that of the engine the plane accelerates

As wheels are attached to bearings and designed to reduce drag and no where is it suggested the brake would be applied

It seems many are thinking that with the moving runway it is being suggested the plane does not need to move forward but can stand still and fly , some one mentioned why have long run ways if a conveyer would work lol lol

This is a misunderstanding the plane still needs to move forwards relative to both ground and air mass , it's just the moving runway has no influence upon this action it just rolls forward , it's wheels move forward at the planes speed, BUT rotate at twice the rpm

Gosh simple physics

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By *ait88Man  over a year ago

Plymouth

OK, GRAVITY

Put the aircraft on the conveyor, engine not running, facing against the direction that the belt will move in.

The aircraft’s wheels are pressed very tightly to the belt by its weight. The wheels are designed to have maximum friction against the tarmac / belt so that they can help to steer and brake the aircraft.

Fire up the conveyor so that it runs a 1 mph. If this happens instantaneously, the aircraft will jerk forwards against the belt’s direction of motion, and then stop, and move with the belt. If the belt takes time to get up to speed, the aircraft will sit motionless on the belt – the wheels will not go around – they are held firmly to the belt by their friction (stickiness), and the weight of the aircraft. It’s called “inertia. The whole contraption moves at 1 mph. The air is passing around the wings at 1 mph from astern.

Try pushing a car. It is relatively difficult to get it rolling, but relatively easy to keep it rolling. Stop pushing the car and it stops rolling. Gravity and tyre friction try to ram it down into the ground.

Put a sheet of paper flat on a table. Put a toy car on the paper and move it around. The car stays motionless on the paper unless you jerk it in the right direction. The car stops moving on the paper after the jerk.

Once the belt speed settles at 1 mph, there is no sufficiently large force available to overcome the aircraft’s inertia – the force of gravity pressing it hard against the conveyor belt’s surface. It stays put on the belt.

Increase the belt speed to 2 mph. Whether accelerated quickly or slowly, the aircraft will end up stationary on the belt, which moves it backwards through the air a 2 mph. The air is passing around the wings at 2 mph from astern.

Increase the belt speed to 10 mph. Whether accelerated quickly or slowly, the aircraft will end up stationary on the belt, which moves it backwards through the air a 10 mph. The air is passing around the wings at 10 mph from astern.

Fire up the aircraft’s engine and accelerate it to 10 mph THROUGH THE AIR in the opposite direction to the conveyor belt’s motion. It isn’t flying, gravity is still holding it down on the belt, but the wheels go around. The wings are still experiencing a 10 mph wind from astern generated by the belt. But now they are also feeling a 10 mph wind from ahead generated by the engine. The two winds cancel each other – the wings experience a net dead calm. No lift, no fly. The belt and aircraft’s speeds are the same, but in opposite directions.

Increase the belt speed to 100 mph and the aircraft’s speed through the air to 100 mph. Same result. The wings experience no airflow from ahead, the aircraft can’t fly, regardless of the fact that it’s wheels are going round because they are being moved at 100 mph along the belt.

The source of confusion is the aircraft’s inertia. It wants to stay put on the belt, and has to be forced to move. If the belt moves, the aircraft is rammed down on it by gravity, and has to move too. The aircraft can only move along the belt if a force is applied from ahead or astern. That force has to be very substantial to overcome the “pressure” of the aircraft’s gravity. The force moving the belt at a constant speed is way too small. It only becomes big enough if the belt is accelerated very, very quickly. This would cause the aircraft to fly momentarily! This doesn’t happen in the postulated circumstances. The belt only accelerates at the same rate as the aircraft, not at take-off speed.

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