Paul_J
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Registered: 6th Jun 02
Location: London
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quote:
Originally posted by Paul_J
quote:
Originally posted by Paul_J
quote:
Originally posted by Paul_J
quote:
Originally posted by SVM 286
The imperative is that a factor opposing the craft, is in equilibrium to it's own generated force.
This will prevent the vehicle from progressing from a geographical stand point.
Where the factor that is supplying an equal force to the thrust? 
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dave17
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Registered: 3rd Sep 02
Location: Greater London
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quote:
Originally posted by SVM 286
If the plane was hovering, of course it could make progress.
It basically is though mate, as the wheels have no friction, they are just spinning beneath.
Im not ganging up on u either mate, just trying to help you see it would take off 
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Paul_J
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Registered: 6th Jun 02
Location: London
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Get the message? What is holding the 26400 (the force) of the plane pushing forward at a standstill?
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Ian
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Registered: 28th Aug 99
Location: Liverpool
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quote:
Originally posted by dave17
You could have the plane engines OFF, and the treadmill be going alone at 500mph and the plane would just stay in the SAME spot, would not move backwards.
Thats not strictly true, as in this instance the movement of the ground would have some effect. Its just not particularly difficult to overcome it once you turn on the engine.
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Jules S
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Registered: 24th Dec 03
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seems everybody has quoted me almost word for word in the last few pages from my posts in earlier pages 
The long and short of it is.
For the plane not to take off the conveyor would have to be spherical and envelop the whole planet.
the conveyor would also have to be able to negate all the thrust propelled by the engines.... Ie force about 26k's worth of thrust backwards into the jets...
getting it yet?
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Paul_J
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Registered: 6th Jun 02
Location: London
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If you put 26400 lb ft of force against a wall, it'd probably punch straight through the wall... So how is the conveyour belt which is not being gripped, as the wheels are just rolling over it - supplying a equal force in the opposite direction to the plane to hold it still?
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
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Yes but the 200mph head wind would matter.
The belt does not.
You keep telling me that the belt and plane are travelling at the same speed. I'm telling you repeatedly that the belt doesn't matter.
Really, it doesn't.
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Paul_J
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Registered: 6th Jun 02
Location: London
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Is that the sound of it clicking in svn's head? 
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dave17
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Registered: 3rd Sep 02
Location: Greater London
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quote:
Originally posted by SVM 286
It's geographically stationary Paul - Correct
It makes no physical headway through the surrounding air and as such attains no ground speed - Incorrect, all it has to do is turn up the power on the engines
Because of this it cannot attain lift and cannot take off - It can travel forwards as fast as it needs to go, enough to generate the lift
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Ian
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Registered: 28th Aug 99
Location: Liverpool
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quote:
Originally posted by SVM 286
It's geographically stationary Paul.
In order for it to be stationary, the forces must be equal.
In order for the forces to be equal, the wheels must cause as much drag as the thrust creates.
This is not the case.
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SVM 286
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Registered: 13th Feb 05
Location: pain
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quote:
Originally posted by Paul_J
quote:
Originally posted by SVM 286
The imperative is that a factor opposing the craft, is in equilibrium to it's own generated force.
This will prevent the vehicle from progressing from a geographical stand point.
Where the factor that is supplying an equal force to the thrust?
Not thrust Paul, SPEED.
The belt is moving under the craft at the same speed as the craft in the opposing direction.
If you were to stand on the tarmac next to the conveyor and watch the plane, it would be static from your perspective, but the surface of the belt would rush past you the same way it would from the perspective of a passenger.
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jr
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Registered: 20th May 02
Location: Kent
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SVM, he's right (ian that is)
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Robin
Premium Member
Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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if the answer to the last two questions id like that dave, the first one must be incorrect
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dave17
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Registered: 3rd Sep 02
Location: Greater London
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quote:
Originally posted by Ian
quote]Thats not strictly true, as in this instance the movement of the ground would have some effect. Its just not particularly difficult to overcome it once you turn on the engine.
ok maybe not 500mph, as im sure the bearings are not completely friction free past a point, but at a lower speed, im sure it could be at a standstill due to the weight of the plane. And as you say, it would need very little force to keep it on the spot if the belt speed was increased
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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 Paul_J
quote:
Originally posted by SVM 286
The imperative is that a factor opposing the craft, is in equilibrium to it's own generated force.
This will prevent the vehicle from progressing from a geographical stand point.
Where the factor that is supplying an equal force to the thrust?
Not thrust Paul, SPEED.
The belt is moving under the craft at the same speed as the craft in the opposing direction.
If you were to stand on the tarmac next to the conveyor and watch the plane, it would be static from your perspective, but the surface of the belt would rush past you the same way it would from the perspective of a passenger.
Jesus christ. NO IT WOULDN'T
An equilbreum is 2 EQUAL FORCES. Speed is not a force, SPEED is a measurement of DISTANCE covered by TIME.
THRUST IS A FORCE.
RESISTANCE / DRAG IS A FORCE.
THEY MUST BE EQUAL FOR PLANE NOT TO MOVE.
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Jules S
Premium Member
Registered: 24th Dec 03
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quote:
Originally posted by SVM 286
quote:
Originally posted by Paul_J
quote:
Originally posted by SVM 286
The imperative is that a factor opposing the craft, is in equilibrium to it's own generated force.
This will prevent the vehicle from progressing from a geographical stand point.
Where the factor that is supplying an equal force to the thrust?
Not thrust Paul, SPEED.
The belt is moving under the craft at the same speed as the craft in the opposing direction.
If you were to stand on the tarmac next to the conveyor and watch the plane, it would be static from your perspective, but the surface of the belt would rush past you the same way it would from the perspective of a passenger.
read my post above mate...
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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
Not thrust Paul, SPEED.
Speed is a product of force that way minus force the other way.
One is a fuck off big engine, the othre is some frictionless wheels.
While its possible to balance the two, the engine would win.
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dave17
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Registered: 3rd Sep 02
Location: Greater London
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quote:
Originally posted by robmarriott
if the answer to the last two questions id like that dave, the first one must be incorrect
eh?
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Robin
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Registered: 7th Jan 04
Location: Northants Drives: Clio 182 Cup
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you said that it was geographically stationary, agreeing with SVM, but for that to be true, you'd need to change the answer in the other two bits of the quote....
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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is svm the only one arguing this now?
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Paul_J
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Registered: 6th Jun 02
Location: London
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yup
He thinks if 2 things go at each other at the same speed they will be equal, regardless of forces, masses etc
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dave17
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Registered: 3rd Sep 02
Location: Greater London
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No, the plane is stationary when it is at low power. When the plane turns the power up, it is free to make its way down the belt and take off.
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SVM 286
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Registered: 13th Feb 05
Location: pain
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quote:
Originally posted by Ian
Yes but the 200mph head wind would matter.
The belt does not.
You keep telling me that the belt and plane are travelling at the same speed. I'm telling you repeatedly that the belt doesn't matter.
Really, it doesn't.
It does Ian.
It wouldn't if the plane had taken off but it hasn't so it does matter.
Aircraft need lift to take off.
If the 'ground' beneath the plane is advancing towards it at an equal speed, then the plane cannot attain speed in relation to the surrounding air to produce the lift required for take-off.
This is the point people are missing.
You HAVE to have X ammount of wind speed/pressure on the wings of an aircraft for it to take off unless it is a Harrier of a helicopter.
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Ian
Site Administrator
Registered: 28th Aug 99
Location: Liverpool
User status: Online
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I'm clear that lift is required.
I'm more concerned with how your stationary plane stays stationary when the forces acting on it are so imbalanced.
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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
You HAVE to have X ammount of wind speed/pressure on the wings of an aircraft for it to take off unless it is a Harrier of a helicopter.
I think SVN thinks we're all idiots.
I can imagine him sitting there quite smug. I think I met this guy at grasshopper he seemed a decent chap. Just can't believe he can't see what is staring him in the face.
In our scenerio the plane is moving - NOT standing still like in your head.
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