Carl
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Registered: 9th May 04
Location: Jimmy Bennett's la la land.
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My mate used to end daft arguements by saying.
"yes but would you wear it"
I feel it is an appropriate time to ask.
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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one further point is that the shear amount of money spent by the U.S. armed forces would highlight that this is either a) too expensive (that would mean ridiculously expensive 2-3 billion etc)
or b) simply wouldnt work!
otherwise it would have been done!
[Edited on 24-05-2006 by LiVe LeE]
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Paul_J
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Registered: 6th Jun 02
Location: London
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quote:
Originally posted by LiVe LeE
one further point is that the shear amount of money spent by the U.S. armed forces would highlight that this is either a) too expensive (that would mean ridiculously expensive 2-3 billion etc)
or b) simply wouldnt work!
otherwise it would have been done!
this just clearly proves YOU DO NOT UNDERSTAND what it is.
This conveyor belt idea is a riddle, it's not a idea that helps planes take off in a smaller space or stationary.
the runway with the conveyor belt would have to be AT LEAST the length of a normal runway, but I'd guess by the small resistance relative to the huge thrust of the wheels and the bearings on the wheels - it would take twice or more lengths of a normal runway to take off on.
HENCE it would be utterly pointless in the real world.
This is why no one has done it!
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John
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Registered: 30th Jun 03
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LiveLee if you have a degree in thermo and hydrodynamics you must be able to mathematically work out that you're wrong(or right).
Not 2 pages of numbers, it should be a pretty simple calculation from what i'm thinking.
You are only introducing one more variable.
Step away from the computer, have a cup of tea, and think about it from the side a bit.
All the conveyor belt means is the wheels on the plane have to move faster than they would on a stationary surface.
Edit to say thats probably not the correct title of your degree but you know what I mean.
[Edited on 24-05-2006 by John]
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Angie
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Registered: 27th May 04
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Yeah, Plus landing would be a bastard 
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SVM 286
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Registered: 13th Feb 05
Location: pain
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quote:
Originally posted by bradfincham
If an aeroplane is taking off but is on a conveyor belt that is moving at the same speed as the plane, would the plane take off?
No it wouldn't.
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Brett
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Registered: 16th Dec 02
Location: Manchester
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quote:
Originally posted by John
All the conveyor belt means is the wheels on the plane have to move faster than they would on a stationary surface.
But the point is. Whilst on the conveyor the quicker the wheels move (or quicker jet propels plane), the quicker the converyor belt will move in the opposite direction.
Surely the question basically states that there will be two equal forces going against each other?
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John
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Registered: 30th Jun 03
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The forces on the wheels are irrelevant to the planes jet engines though.
The equal forces going against each other would only stand true if the wheels were powering the plane.
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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SVM thank you - read that question - if the conveyor is moving at the same speed as the plane then it wont - in fact where has the issue of wheels come from?
infact who said it had wheels
in fact who said the plane was moving - it could be stationary and the conveyor would be stationary -and then it wouldnt take off!
and John - 2 sides of A4 easily - the calculation for the coefficients of Drag and Lift are sizeable enough!
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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no because the force the conveyor belt is acting on the plane is not equal to the forward thrust of the engines, in fact its hardly anything
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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the answer if its a riddle is that neither the plane nor conveyor are moving! so no it wont take off
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Cosmo
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Registered: 29th Mar 01
Location: Im the real one!
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the answer will be obvious...just work out if the jets can thrust more than the force of the friction between the wheels and the conveyor. If they can thrust more, can they get it to a speed to take off.
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John
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Registered: 30th Jun 03
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The force of the friction between wheels and conveyor is 100% totally irrelevant to this situation.
It would be a waste of time calculating that.
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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wheels arn't mentioned in the inital question; nor are engines, speed, size, weight, conditions.................
therefore - the plane is only preparing to take off; isnt in the process of - if the plane is stationary and the engines arn't running, and the conveyor is uder the plane then no it wont take off
no V means no L
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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it will be very minimal, and if we are talking imaginery situations then we could say frictionless
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John
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Registered: 30th Jun 03
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The landing and stopping dead has just been pointed out to me.
How do you explain that 1?
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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this should be on a gcse physics exam paper
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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I already have John - read on boyo
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John
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Registered: 30th Jun 03
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Sorry I didn't read on, I was trying to catch up and skimmed over about 7 or 8 pages.
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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but it doesnt matter - read the question - it doesnt say that the plane is moving - nor that the plane is actually in contact physically with the conveyor!
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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Il rephrase the question
If the plane is on a conveyer belt, with its engines on idle, and the conveyer belt isnt moving.
Then the conveyer belts starts spinning, when the aircraft increases its thrust will it move forward and take off? evn if the conveyer belt speeds up to match its speed?
the answer is yes
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Hammer
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Registered: 11th Feb 04
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quote:
Originally posted by Jules S
Funny,
I dont think anybody has mentioned landing on this mythical runway.
if what Lee is saying is true the plane would stop dead as soon as it touched the ground.
That sounds likely doesn't it?
this is a beautiful point which surely must end all arguments?
the people assuming that a conveyor belt and the plane going at the same speed will cause the plane to stay in exactly the same place, well if you landed on a conveyor which is coming towards you as the same speed as you are goin towards it will this cause you to stop completely dead?
it wont the wheels will just spin faster in between the aircraft and the ground...think of the wheels as a completely seperate entity and maybe that makes things clearer in your head
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Steve
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Paul_J
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Registered: 6th Jun 02
Location: London
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People are getting confused between the fact it says the CONVEYOR and PLANE SPEED WILL BE MATCHED.
IT DOES NOT SAY THE FORCE OF PLANE AND CONVEYOR will be matched. Since the wheels are free wheeling the only force given by the conveyor is a % depending on the friction between things like wheel bearings.
The thing pushing the plane is a constant at max (not including time to warm up engines) - 16000 thrust will constantly be pushing out the back, despite the fact that the the conveyor is going backwards at 1 mph. The plane will move forward - albeit accelerate slightly slower than before.
Notice also the plane takes longer to take off on conveyor than normal - the conveyor forces are just a estimate. The conveyor force would only be equal if wheels were locked on the plane. Even then the friction between the tires and tarmac on conveyor would break and the plane would skid forward.
NOTICE SPEEDS ARE THE SAME (which is what the question says)
BUT THE FORCES ARE NOT EQUAL - HENCE PLANE ACCELERATES!
GET THIS IN YOUR HEAD ALREADY.
[Edited on 24-05-2006 by Paul_J]
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Jules S
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Registered: 24th Dec 03
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quote:
Originally posted by LiVe LeE
one further point is that the shear amount of money spent by the U.S. armed forces would highlight that this is either a) too expensive (that would mean ridiculously expensive 2-3 billion etc)
or b) simply wouldnt work!
otherwise it would have been done!
[Edited on 24-05-2006 by LiVe LeE]
Lee, once again you are missing the point.
The plane will move forward on the conveyor belt and take off.....BUT it will still need a runway length run to get to the velocity required to achieve enough lift to take off.
Not surprising the Yanks aren't building runway length conveyor belts is it?
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