John
Member
Registered: 30th Jun 03
User status: Offline
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Are you kidding SVM?
You are showing yourself up here.
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DarrenGSi
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Registered: 11th Jul 05
Location: East Ayrshire Drives: Civic Jordan 381
User status: Offline
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quote:
Originally posted by John
Even if the conveyor moves at the speed of the plane and not the wheels the wheels will just have to spin faster.
Doens't make a difference.
if the conveyor moves at the same speed of the plane, it will be the same as the wheels to 
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meemawuk
Member
Registered: 25th Jun 04
Location: East Dunbartonshire
User status: Offline
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quote:
Originally posted by Steve
Heres my pretty crappy demo
http://www.poisoft.co.uk/car.zip
Right click save as, rename it car.3gp
Watch how the wood is pulled back i can move the car along just as easily as if it were on solid ground
if you cant see it get Quicktime alternative
http://www.free-codecs.com/download_soft.php?d=1848&s=66
u can pull the car along, but then its moving faster than the wood below it. which isnt allowed by the question.
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Steve
Premium Member
Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
User status: Offline
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it is but i can go and do it with the wood moving faster and it would still do the same
[Edited on 24-05-2006 by Steve]
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dave17
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Registered: 3rd Sep 02
Location: Greater London
User status: Offline
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Someone write to top gear, theyl do it
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John
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Registered: 30th Jun 03
User status: Offline
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No darren you idiot.
The wheels do not have to be moving at the same speed as the plane.
This shows that you don't understand whats going on.
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
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But Jim, the wheels would prevent the plane from stopping dead, they would turn, and allow the plane to continue to move
reverse the theory, the plane can still move from a conveyor as the wheels allow it to
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meemawuk
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Registered: 25th Jun 04
Location: East Dunbartonshire
User status: Offline
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quote:
Originally posted by DarrenGSi
quote:
Originally posted by John
Even if the conveyor moves at the speed of the plane and not the wheels the wheels will just have to spin faster.
Doens't make a difference.
if the conveyor moves at the same speed of the plane, it will be the same as the wheels to
lol no they wont. plan and conveyor are moving opposite ways. the wheels will spin twice as fast as the plane/conveyor.
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DarrenGSi
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Registered: 11th Jul 05
Location: East Ayrshire Drives: Civic Jordan 381
User status: Offline
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when wheels are going at 50mph the plane will be to, if their going at 100mph the plane will be to, if there going at 150mph the plane will be to!
you cannot get the plane going 50mph and the wheels going 100mph, not possible, thats like saying the plane goes 50mph but the people inside it go 100mph!
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
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I don't get the question to be honest.
If the belt is moving, what is powering the belt? Its not the thrust, as this is moving the air in order to propel the plane forward, but its effect on the belt would be marginal.
Therefore the belt must be powered, and must be travelling at exactly the same speed at which the plane would be going. This doesn't make a blind bit of difference to the plane of course, as assuming it were able to move it would do, regardless of the speed of the wheels and therefore regardless of the speed of the belt.
This leads me on to asking - if the plane is not moving - what the hell is holding it down?
If nothing is holding it, it would take off exactly as normal. Belt or no belt.
If something is holding it then no - no air over the wings and thus no lift.
The gentle breeze wouldn't be enough - full forward thrust is being contained don't forget. If you discount engine thrust then of course the plane wouldn't take off with a gentle breeze in the same way that stationary planes don't all leap in the air when there's a slight gust across the airfield.
Get a better question IMO 
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SVM 286
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Registered: 13th Feb 05
Location: pain
User status: Offline
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quote:
Originally posted by DarrenGSi
Who honestly thinks im right?
I know you are correct Darren.
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
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think Jim, the word is think
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John
Member
Registered: 30th Jun 03
User status: Offline
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Darren thats your credibility gone out the window.
SVM who has already contradicted himself agrees with you.
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Steve
Premium Member
Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
User status: Offline
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quote:
Originally posted by Ian
I don't get the question to be honest.
If the belt is moving, what is powering the belt? Its not the thrust, as this is moving the air in order to propel the plane forward, but its effect on the belt would be marginal.
Therefore the belt must be powered, and must be travelling at exactly the same speed at which the plane would be going. This doesn't make a blind bit of difference to the plane of course, as assuming it were able to move it would do, regardless of the speed of the wheels and therefore regardless of the speed of the belt.
This leads me on to asking - if the plane is not moving - what the hell is holding it down?
If nothing is holding it, it would take off exactly as normal. Belt or no belt.
If something is holding it then no - no air over the wings and thus no lift.
The gentle breeze wouldn't be enough - full forward thrust is being contained don't forget. If you discount engine thrust then of course the plane wouldn't take off with a gentle breeze in the same way that stationary planes don't all leap in the air when there's a slight gust across the airfield.
Get a better question IMO
Ok Ian rephrase.
A normal plane is sat on a runway that is a conveyor belt, the conveyor belt has its own power but is set to increase in speed as the plane does.
The plane starts moving from its own thrust so does the conveyor belt in the opposite direction, does the plane move forward, and indeed take off?
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DarrenGSi
Member
Registered: 11th Jul 05
Location: East Ayrshire Drives: Civic Jordan 381
User status: Offline
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svm i think your wrong bout the landing theory but correct bout the take off,
if the plane is landing it will gradually slow down then go backwards the same speed as the conveyor, not stop dead tho
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gianluigi
Member
Registered: 9th Mar 05
Location: Ipswich, Suffolk
User status: Offline
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I think that Live Lee guy has the right idea
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
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If the plane is not being held by something then yes, the plane is propelled forward by thrust.
Ground speed is really not a factor.
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Paul_J
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Registered: 6th Jun 02
Location: London
User status: Offline
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quote:
Originally posted by Ian
I don't get the question to be honest.
If the belt is moving, what is powering the belt? Its not the thrust, as this is moving the air in order to propel the plane forward, but its effect on the belt would be marginal.
Therefore the belt must be powered, and must be travelling at exactly the same speed at which the plane would be going. This doesn't make a blind bit of difference to the plane of course, as assuming it were able to move it would do, regardless of the speed of the wheels and therefore regardless of the speed of the belt.
This leads me on to asking - if the plane is not moving - what the hell is holding it down?
If nothing is holding it, it would take off exactly as normal. Belt or no belt.
If something is holding it then no - no air over the wings and thus no lift.
Get a better question IMO
Exactly - at least ian can quite easily see both sides of the way the question can be taken and see that 1 way 1 lot of people are correct and 1 way the rest are correct.
As ian says, what's the magical resistant force that's holding the 26400 lb ft of thrust back?
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SVM 286
Member
Registered: 13th Feb 05
Location: pain
User status: Offline
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quote:
Originally posted by Paul_J
quote:
Originally posted by SVM 286
I won't be swayed until someone shows me a 737 taking off from a static position at full throttle on a giant conveyor belt that is matching it's speed.
And speed is the key here. We are discussing speed, not force.  
You will never see a plane sitting on a giant conveyor stationary and take off - As that's not whats being discussed here. IT's neither likely what we are discussing would ever happen either.
Please open your mind and review what people are saying, everyone else has gathered already the plane is not stationary.
Geographically it IS stationary Paul, because the belt compensates for any motive input from the craft.
All we know is that the belt travels at the same speed as the plane.
It's very simple.
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Steve
Premium Member
Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
User status: Offline
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thank you, ffs this really is like trying to educate PORK
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meemawuk
Member
Registered: 25th Jun 04
Location: East Dunbartonshire
User status: Offline
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lmao u can easily have a plne going one way at a certain speed but the wheels going the opposite way much faster. you are a stupid stupid person darren. i'll only be polite once
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
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info@braniac.co.uk
email it and ask the question, they'll answer it
[Edited on 24-05-2006 by robmarriott]
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Jules S
Premium Member
Registered: 24th Dec 03
User status: Offline
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In order to understand this you have to divorce the wheels from the plane.
To put a car analogy on it, its very easy for the wheels on a car to travel faster than the car itself (read wheelspin)
In the same way its easy for the plane to go faster than the planes wheels, since the plane is being thrust directly through its body and the surrounding air.
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RichR
Premium Member
Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
User status: Offline
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I'm assuming that the forward propulsion of the thrust jets - which causes the rotation of the wheels - is what drives the counter-rotating conveyour - and that it is not powered
if this is the case the velocity will never reach a level to produce forward momentum - for the reasons I've posted in my 80 odd posts thus far
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
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quote:
Originally posted by SVM 286
Geographically it IS stationary
Depends what you're measuring against. Relative to the ground, yes, but then as I've already said the ground is not important.
You could not stop a plan by spinning its wheels backwards. It wouldn't slow down.
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