RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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Thrust through a jet = pressure of air*duct area*Jet velocity*(Jet velocity - Ground speed)
from Savitsky Planing Theory and 2D/3D Lift Theory
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meemawuk
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Registered: 25th Jun 04
Location: East Dunbartonshire
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quote:
Originally posted by DarrenGSi
THE QUESTION STATES THAT THE PLANES WHEELS AND THE CONVEYOR BELT IS AT THE SAME SPEED, THEREFORE THE PLANE WILL BE STATIONARY.
DO YOU NOT GET IT JOHN?
the question states:
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?
Mongo?? 
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Paul_J
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Registered: 6th Jun 02
Location: London
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quote:
Originally posted by SVM 286
quote:
Originally posted by Greg_M
AND THE PENNY HAS DROPPED
I finally understand. yes it would take off
It wouldn't Greg, the conveyor belt matches the speed of the craft.
As soon as the plane tries to move off, the belt starts rolling.
The faster the plane tries to push itself forwards, the faster the belt turns maintaining the plane's location and preventing lift.
The wheels will be going very very very fast and the engines can be flat out with afterburner on too, but she aint going anywhere. 
no mate think about what your saying. It says the belt matches the planes speed. So plane at 10 mph = belt at 10 mph yes?
what force is being pushed against the plane at 10 mph? well considering the wheels can freely spin, not much.
If there is 26400 lb ft of thrust force - which is what pushes the plane forwards. and considerably less force being pushed against it - the plane will move forward.
SVN your thinking the same as dave. but you gotta think what is actually being matched - not the force, but merely the speed of the plane ACTUALLY moving forward. If as you say it's stationary (hence no lift) then the belt will be stationary.
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Hammer
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Registered: 11th Feb 04
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quote:
Originally posted by LiVe LeE
Thrust through a jet = pressure of air*duct area*Jet velocity*(Jet velocity - Ground speed)
from Savitsky Planing Theory and 2D/3D Lift Theory
why try and overcook everything with numbers and scientific mumbo jumbo that is completely irrelevant to anything?
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DarrenGSi
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Registered: 11th Jul 05
Location: East Ayrshire Drives: Civic Jordan 381
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quote:
Originally posted by SVM 286
quote:
Originally posted by Greg_M
AND THE PENNY HAS DROPPED
I finally understand. yes it would take off
It wouldn't Greg, the conveyor belt matches the speed of the craft.
As soon as the plane tries to move off, the belt starts rolling.
The faster the plane tries to push itself forwards, the faster the belt turns maintaining the plane's location and preventing lift.
The wheels will be going very very very fast and the engines can be flat out with afterburner on too, but she aint going anywhere.
thats the way i see it svm, it would make the plane appear stationary apart from the wheels which are rolling.
its the same as a treadmill, treadmill goes at 7mph, your legs run at 7mph therefore this is the reason you appear to run on the spot.
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RichR
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Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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no I'm proving the connection between thrust and speed - as was previously written off by Paul
and how is it irrelevant - its infront of me and is from a guy that developed the design of jet engined planes and boats
[Edited on 24-05-2006 by LiVe LeE]
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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THINK
or look here http://www.corsasport.co.uk/board/viewthread.php?tid=286564
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John
Member
Registered: 30th Jun 03
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Darren and SVM are just totally wrong in general.
None of you are understanding the question.
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Jules S
Premium Member
Registered: 24th Dec 03
User status: Offline
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quote:
Originally posted by LiVe LeE
Thrust through a jet = pressure of air*duct area*Jet velocity*(Jet velocity - Ground speed)
from Savitsky Planing Theory and 2D/3D Lift Theory
Funny how everytime you ask me a question and I answer it you ignore me to perpetuate you misguided thinking.
Whilst you are eloquent in your posts, the facts you are peddling are twaddle.
Read my post/explanation on the previous page and answer that 
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Paul_J
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Registered: 6th Jun 02
Location: London
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quote:
Originally posted by DarrenGSi
quote:
Originally posted by SVM 286
quote:
Originally posted by Greg_M
AND THE PENNY HAS DROPPED
I finally understand. yes it would take off
It wouldn't Greg, the conveyor belt matches the speed of the craft.
As soon as the plane tries to move off, the belt starts rolling.
The faster the plane tries to push itself forwards, the faster the belt turns maintaining the plane's location and preventing lift.
The wheels will be going very very very fast and the engines can be flat out with afterburner on too, but she aint going anywhere.
thats the way i see it svm, it would make the plane appear stationary apart from the wheels which are rolling.
its the same as a treadmill, treadmill goes at 7mph, your legs run at 7mph therefore this is the reason you appear to run on the spot.
If a treadmill is at 7 mph and you have roller skates on, and you hold onto the sides (just sitting there free spinning) then your mate (called thrust) pushes you from behind, will you not go forward - regardless of the speed the treadmill is set at?
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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the engine isnt pushing the plane in relation to the conveyor belt, its pushing it in relation to the surrounding air.
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Hammer
Member
Registered: 11th Feb 04
User status: Offline
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quote:
Originally posted by LiVe LeE
no I'm proving the connection between thrust and speed - as was previously written off by Paul
and how is it irrelevant - its infront of me and is from a guy that developed the design of jet engined planes and boats
[Edited on 24-05-2006 by LiVe LeE]
oh right didn't spot that, do apologise
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DarrenGSi
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Registered: 11th Jul 05
Location: East Ayrshire Drives: Civic Jordan 381
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thats bollocks, it will only take off if the plane can go faster than the belt, but they are both the same speed
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Carl
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Registered: 9th May 04
Location: Jimmy Bennett's la la land.
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you have all missed a vital point though! Are the seat layed horizontal or up vertical, if they are horizontal the plane will fly, if not the weight will become an issue.
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
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fbvhnweiubgueg
there must be a vid somewhere
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Hammer
Member
Registered: 11th Feb 04
User status: Offline
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quote:
Originally posted by Carl
you have all missed a vital point though! Are the seat layed horizontal or up vertical, if they are horizontal the plane will fly, if not the weight will become an issue.
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Steve
Premium Member
Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
User status: Offline
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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
[Edited on 24-05-2006 by Steve]
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John
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Registered: 30th Jun 03
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The conveyor could be going at 5 million miles an hour.
It is totally irrelevant.
The planes wheels wheels will then turn at 5 million miles an hour + the speed the plane is travelling at.
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SVM 286
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Registered: 13th Feb 05
Location: pain
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quote:
Originally posted by Sxi04
...can you tell me what would happen if the conveyor underneath the aircraft is moving at five times the speed of the aircraft itself? discounting tyre blowouts and other variables
Yes Mr. 04, the craft would exit the rear of the conveyor unless the engines were powered up to compensate.
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DarrenGSi
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Registered: 11th Jul 05
Location: East Ayrshire Drives: Civic Jordan 381
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the question states that the plane and belt are going the smae speed. the plane is at max speed therefore no thrust, can it take off now?
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John
Member
Registered: 30th Jun 03
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No it woudnl't.
It would stay stationary unless the brakes were on.
You have just proved yourself wrong.
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RichR
Premium Member
Registered: 17th Oct 01
Location: Waterhouses, Staffordshire
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Its all down to wether the wheels would spin at a higher velocity than the speed of the plane due to thrust
I think, due to the mass and gravitational pull that the two wilol act pretty much the same and as such there will be no velocity of advance; no forward momentum and no take off
if however the two are to be believed as acting seperately then the plane chassis could exceed the pull of the conveyour
I do see understand the supposed reasons why the plane would take off but i disagree that they would occur and even if they did - the likelyhood of reaching the 180mph required for take off is almost impossible
supposing that the plane does break the conveyour speed restrictions - it would need engines capable of supplying twice the required power - as a ground speed of 360 mph would be required for take off in order top equate a 180mph air speed
almost un-achieveable by my estimations
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John
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Registered: 30th Jun 03
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Even if the conveyor is moving at the speed of the plane the wheels will just spin faster.
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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John has it right there
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
User status: Offline
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someone email boeing
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