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    For all of those in garden halls next year. Introduce yourselves. I'm from outside London, and looking forward to October.
    Any info on what our Accommodation might be like??
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    HI!

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    (Original post by Master Polhem)
    HI!

    u flamed some noob for noobish capitalisation. and you do this?!?!?!?!?!
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    (Original post by beetroot roots)
    u flamed some noob for noobish capitalisation. and you do this?!?!?!?!?!
    Why not? I am no noob, I have universal powers most only dream of, women most only dream of and intellect people would die for. Hypocrisy you say? Autocracy I say.

    Bring it on, *****.
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    (Original post by Master Polhem)
    Why not? I am no noob, I have universal powers most only dream of, women most only dream of and intellect people would die for. Hypocrisy you say? Autocracy I say.

    Bring it on, *****.
    chill winston

    just saying bro
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    You are all n00bs.
    End of.
    Will and can you argue over everything?
    Here's a riddle :

    Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

    stolen from xkcd.
    Man, i love that site. Anyone ever tried Geohashing?
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    (Original post by dvorak)
    You are all n00bs.
    End of.
    Will and can you argue over everything?
    Here's a riddle :

    Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

    stolen from xkcd.
    Man, i love that site. Anyone ever tried Geohashing?
    the airspeed across the wings is 0, no lift generated no liftoff. the aircraft is stationary in relation to the ground.
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    (Original post by dvorak)
    You are all n00bs.
    End of.
    Will and can you argue over everything?
    Here's a riddle :

    Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

    stolen from xkcd.
    Man, i love that site. Anyone ever tried Geohashing?
    Does it have snow chains?
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    (Original post by beetroot roots)
    the airspeed across the wings is 0, no lift generated no liftoff. the aircraft is stationary in relation to the ground.
    Of course it takes off. The aircraft won't need the wheels to speed up, the power comes from the engines, and doesn't go to the wheels. The friction of the wheels on the conveyor will slow the acceleration process a bit, but the aircraft will move forward and then fly. It wouldn't move if the power was sent to the wheels, but it isn't. The wheels freewheeling along the conveyor will just add a resistive force, but it won't match the force of the jet engines.
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    Does anyone elses Blackboard Table of contents on a module (on the left hand side) keep ****** disappearing?
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    (Original post by HCD)
    Of course it takes off. The aircraft won't need the wheels to speed up, the power comes from the engines, and doesn't go to the wheels. The friction of the wheels on the conveyor will slow the acceleration process a bit, but the aircraft will move forward and then fly. It wouldn't move if the power was sent to the wheels, but it isn't. The wheels freewheeling along the conveyor will just add a resistive force, but it won't match the force of the jet engines.
    i see what you mean. But if the conveyor exactly matches the speed of the plane, there will be no take of. The conveyor has to be exactly the same speed as the plane throughout. then there will be no take off.

    thats what i think, and im a stubborn ******
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    You guys are thinking about this question completely the wrong way.

    If it was possible, someone would've done it (seeing as the implications of such a system are huge, i.e. it'd be much cheaper to make airports (no need for huge runways, could have easy take offs from battleships and the such)).

    Thinking about it like a geek, your engine is only making your plane go forward. The thing that makes it go upward is the air around the wings. Without it moving, the air cannot lift it, no matter how fast the wheels are turning.
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    (Original post by aria57)
    You guys are thinking about this question completely the wrong way.

    If it was possible, someone would've done it (seeing as the implications of such a system are huge, i.e. it'd be much cheaper to make airports (no need for huge runways, could have easy take offs from battleships and the such)).

    Thinking about it like a geek, your engine is only making your plane go forward. The thing that makes it go upward is the air around the wings. Without it moving, the air cannot lift it, no matter how fast the wheels are turning.
    It hasn't been done for bloody obvious reasons. What is the point of having a variable slate of road that can haul a blooming 500 ton jumbo jet of at 300km/h, when it is billions of times cheaper to have a static runway. Can you imagine what kind of mechanical forces that would involve? They use steam catapults on carriers to haul jets that weigh 10-20 tons. You would need a steam tank the size of T5 to make that for a jumbo jet.

    I second your geek analysis as well.
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    (Original post by Master Polhem)
    It hasn't been done for bloody obvious reasons. What is the point of having a variable slate of road that can haul a blooming 500 ton jumbo jet of at 300km/h, when it is billions of times cheaper to have a static runway. Can you imagine what kind of mechanical forces that would involve? They use steam catapults on carriers to haul jets that weigh 10-20 tons. You would need a steam tank the size of T5 to make that for a jumbo jet.

    I second your geek analysis as well.
    'Bloody obvious'? i.e. cos it doesn't work

    With regards to the points you made: ITs not infinitely cheaper to make a bigger ship than to put in a fighter jet sized treadmill... It is infinitely cheaper to make a big treadmill than to completely change the design of the plane (i.e. harriets) You could even then fly off all kinds of aircraft, not just vertical take-off ones. Emergency responses would be incredibly quick, instead of planes flying off 1 by 1, they could all fly off at the same time, build their formation in seconds etc.

    Its also infinitely cheaper to make a treadmill the size of the wheels of a jumbo jet than it is to buy huge amounts of land in densely packed cities. If it could fly just by running on a treadmill, then there would be no need for this steam catapult that you speak of.
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    You misunderstand - the wheels are NOT WHAT DRIVES THE PLANE FORWARD. They just support its weight until it can get lift. A treadmill runway would not work. The plane needs to get enough forward speed for the lift under the wings to be sufficient. The treadmill would not prevent this.

    Look at it as a freebody diagram. The engines with several kilonewtons of force driving it forwards. They do not use the wheels to transfer the energy, they expel exhaust gases and this drives the plane forward. This is the forward force. The friction between the wheels and the treadmill going the other way will be very limited. It will be << the engine. Therefore, the plane will move forwards on the treadmill. The treadmill would marginally slow the plane down, and it would need to be longer than/ as long as a runway for it to take flight.

    The speed of the wheels on the treadmill are irrelevant. You could run the treadmill at the speed of sound, and it would make the wheels spin, but the amount of force that this actually applies in terms of friction will still be < the engine force. It goes forward on the treadmill, and would continue to accelerate. On the diagram, you have a big engine force, a relatively small friction force, then the air resistance.
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    (Original post by HCD)
    You misunderstand - the wheels are NOT WHAT DRIVES THE PLANE FORWARD. They just support its weight until it can get lift. A treadmill runway would not work. The plane needs to get enough forward speed for the lift under the wings to be sufficient. The treadmill would not prevent this.

    Look at it as a freebody diagram. The engines with several kilonewtons of force driving it forwards. They do not use the wheels to transfer the energy, they expel exhaust gases and this drives the plane forward. This is the forward force. The friction between the wheels and the treadmill going the other way will be very limited. It will be << the engine. Therefore, the plane will move forwards on the treadmill. The treadmill would marginally slow the plane down, and it would need to be longer than/ as long as a runway for it to take flight.

    The speed of the wheels on the treadmill are irrelevant. You could run the treadmill at the speed of sound, and it would make the wheels spin, but the amount of force that this actually applies in terms of friction will still be < the engine force. It goes forward on the treadmill, and would continue to accelerate. On the diagram, you have a big engine force, a relatively small friction force, then the air resistance.
    Easy to solve:
    Secure the wheels so make sure the plane doesn't move, then when it has enough 'speed' to lift-off, release the wheels. Same effect as the treadmill ;P
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    (Original post by aria57)
    With regards to the points you made: ITs not infinitely cheaper to make a bigger ship than to put in a fighter jet sized treadmill... It is infinitely cheaper to make a big treadmill than to completely change the design of the plane (i.e. harriets) You could even then fly off all kinds of aircraft, not just vertical take-off ones. Emergency responses would be incredibly quick, instead of planes flying off 1 by 1, they could all fly off at the same time, build their formation in seconds etc.

    Its also infinitely cheaper to make a treadmill the size of the wheels of a jumbo jet than it is to buy huge amounts of land in densely packed cities. If it could fly just by running on a treadmill, then there would be no need for this steam catapult that you speak of.
    It is not possible to make treadmill of that size and magnitude that would be cost effective. I.e. I would still need to be length of a carrier deck ~200m and and would be moving at a speed of 200+km/h. As for making jets fly of in groups you would then need to make the take off treadmill very wide. Effectively you now have a very large square with a sheet of flexible steel that is moving at a very high speed, you would need a couple of massive rollers on each end to support the moving track. In terms of engineering making a massive fighter jet treadmill is just stupid. STOVL (vertical take off and landing jets) jets were invented back in the day and they certainly would not have had the techniques required to make this super structure. And for all these problems there is probably the biggest one how are you going to get the planes onto the track? Turning it on and off would be ridiculous, rolling them on would rip of the back wheels and dropping them on? Nah..

    Why would the treadmill be the sizes of the wheels of the jumbo jet? It weighs 500 tons. Even if you had the treadmill take off the planes would still have to land and taxi off so you are still left with buying huge amounts of lands (Runway 3 at Heathrow would cost £13 billion). Hence the future is STOVL aircraft.

    + =
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    (Original post by Master Polhem)
    It is not possible to make treadmill of that size and magnitude that would be cost effective. I.e. I would still need to be length of a carrier deck ~200m and and would be moving at a speed of 200+km/h. As for making jets fly of in groups you would then need to make the take off treadmill very wide. Effectively you now have a very large square with a sheet of flexible steel that is moving at a very high speed, you would need a couple of massive rollers on each end to support the moving track. In terms of engineering making a massive fighter jet treadmill is just stupid. STOVL (vertical take off and landing jets) jets were invented back in the day and they certainly would not have had the techniques required to make this super structure. And for all these problems there is probably the biggest one how are you going to get the planes onto the track? Turning it on and off would be ridiculous, rolling them on would rip of the back wheels and dropping them on? Nah..

    Why would the treadmill be the sizes of the wheels of the jumbo jet? It weighs 500 tons. Even if you had the treadmill take off the planes would still have to land and taxi off so you are still left with buying huge amounts of lands (Runway 3 at Heathrow would cost £13 billion). Hence the future is STOVL aircraft.
    So either way, my original point saying 'if it could be done, someone would've done it' - whether from a physics, engineering, or economic point of view, was correct.

    Anyway, you only need this hypothetical treadmil to be in touch with the wheels only, not the whole plane. If you can match the exact speed at which they're rotating, then you only need it to be the size of the area that the wheels take up, as relative to the ship, the plane wouldn't move at all.

    Anyway, as HCD pointed out, treadmills are useless in this regard anyway. The wheels don't generate the force, the jet engine does. Having said that, you could always invent a 'blower system' for fighter jets that would cancel out the forces coming out of the jet engine, right up to the point where they've revved up enough to the RPM required to take off.
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    (Original post by aria57)
    So either way, my original point saying 'if it could be done, someone would've done it' - whether from a physics, engineering, or economic point of view, was correct.

    Anyway, you only need this hypothetical treadmil to be in touch with the wheels only, not the whole plane. If you can match the exact speed at which they're rotating, then you only need it to be the size of the area that the wheels take up, as relative to the ship, the plane wouldn't move at all.

    Anyway, as HCD pointed out, treadmills are useless in this regard anyway. The wheels don't generate the force, the jet engine does. Having said that, you could always invent a 'blower system' for fighter jets that would cancel out the forces coming out of the jet engine, right up to the point where they've revved up enough to the RPM required to take off.
    Ohh yes if it was a viable proposal the Americans would have been all over it but seeing as it is so ridiculous not even they have spent time on it.

    I think what everyone is forgetting is that it needs lift which if generated by the air stream on the wings.
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    (Original post by aria57)
    Anyway, as HCD pointed out, treadmills are useless in this regard anyway. The wheels don't generate the force, the jet engine does. Having said that, you could always invent a 'blower system' for fighter jets that would cancel out the forces coming out of the jet engine, right up to the point where they've revved up enough to the RPM required to take off.
    You don't seem to "get it". It's not the revving up of the engine that's the problem, that's not what generates the lift. You need the actual forward velocity of the whole vehicle to get the relative windspeed required for the lift. Treadmills or "blowers" would just be retarded, they'd lower your efficiency! The runway is required so that the craft can accelerate to the necessary speeds.

    For fighter jets without need of long runways, use a Harrier. :p:

    (Original post by aria57)
    Easy to solve:
    Secure the wheels so make sure the plane doesn't move, then when it has enough 'speed' to lift-off, release the wheels. Same effect as the treadmill ;P
    No, no, no, no, noooo. It's not "speed". It's actual damn SPEED. If the plane does not move, it has no speed! If there is no relative velocity 'twixt plane wings and air, there is no lift. Capiche?
 
 
 
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