FabSwingers.com forum: Physics Vol 2

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..

That's what I believed anyway.

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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..

That's what I believed anyway.

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

That's what I believed anyway.

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..

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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?

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By *ee VianteWoman
over a year ago

Somewhere in North Norfolk

That's what I believed anyway.

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..

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?

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

That's what I believed anyway.

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..

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"..

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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

That's what I believed anyway.

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..

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?

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

That's what I believed anyway.

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..

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?

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

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By *oncupiscentTonyMan
over a year ago

Kent

That's what I believed anyway.

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..

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?

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

That's what I believed anyway.

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..

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?

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

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.

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.

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.

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

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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 ?

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.

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

"
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

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?

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.

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.

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...

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?

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!