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From: Sabrina Kilian
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 06:44:36
Message: <4ab60794$1@news.povray.org>
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SharkD wrote:
> Warp wrote:
>> A more complicated invention of antiquity is the so-called
>> south-pointing
>> chariot. A Chinese invention which is, basically, a chariot with a figure
>> on top which always points in the same geographical direction
>> regardless of
>> how the chariot is moved and turned. In other words, the figure acts as a
>> non-magnetic compass, obviously very useful for travelling long
>> distances.
>> The invention might be as old as from 2600 BC (although with certainty
>> it's
>> at least from 200 AD).
>
> It would have to be very heavy, otherwise it might bounce instead of
> roll around corners, and rotation information would then be lost.
>
> Also, I am having trouble visualizing how the device behaves differently
> on curved surfaces (i.e. the Earth) as opposed to a flat plane. I wish
> the article had some diagrams or animations.
>
> -Mike
I don't think the the curved surface causes the distance that each wheel
travels to vary. It is more the geometry of the problem. Start at a
point on the equator, with the compass pointing south, and go directly
north till you hit the pole. Turn 90 degrees left, and the compass
should point to your left. Walk to the equator. By now, the compass
would be pointing to the east.
Also it is a good example of how a triangle is not limited to 180
degrees outside of Euclidean geometry.
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From: clipka
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 08:50:43
Message: <4ab62523@news.povray.org>
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Darren New schrieb:
> clipka wrote:
>>> The invention might be as old as from 2600 BC
>
>> Quite a remarkable feat even for 3rd century I'd say.
>
> An even more remarkable feat for being built just days after Noah's
> flood subsided! ;-)
Yes, that's why I'm rather inclined to believe the 200+some AD assumption.
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From: clipka
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 09:14:05
Message: <4ab62a9d$1@news.povray.org>
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Warp schrieb:
>
> I don't think that the curvature of Earth played a significant role in
> the distances involved (probably like a thousand kilometers at most,
> relatively close to the equator).
Indeed. I guess they'd have "re-calibrated" the cart daily whenever
possible. Sunrise or sunset would have been a good opportunity. So the
device would have had to work for typical distances of, say, some 100
km: Two days' travel for a human (I don't think a traveling band would
have had the luxury of a cart ride for all at that time), allowing for
an occasional day good enough for traveling but too bad to get a vector
to the morning or evening sun and no chance of asking any locals where
exactly south might be.
And the precision required would have been quite a deal lower than for,
say, finding Baker Street 22a after having made so many U-turns - all
they needed was a rough vector to the next village.
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From: TC
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 10:14:00
Message: <4ab638a8$1@news.povray.org>
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Quite spectacular looking thingy - but the principle is the same as used
here:
http://de.wikipedia.org/wiki/Schiffshebewerk_Niederfinow
Have a trough (granted: a rather big one) filled with water and a
counterweight equal to the weight of trough and water. Ship moves in,
displaces water in trough equal to ship's own weight, balance achieved.
All needed to lift any weight you want is a big enough trough and some
electrical power to overcome friction.
About the cables: of minor importance - a cable can break but the Falkirk
Wheel's supports may break, too. Cables do not tend to break easily, if well
maintained.
The Wheel is looking much more impressive - but on the other hand it needs a
lot more space.
"clipka" <ano### [at] anonymous org> schrieb im Newsbeitrag
news:4ab4e792@news.povray.org...
>I think this is one of the most ingenious canal lock designs to date:
>
> http://en.wikipedia.org/wiki/Falkirk_Wheel
>
> Virtually all you need to do is overcome some friction (note that the
> thing does not dip into water at the lower basin, otherwise energy would
> be needed to displace water in that position). And there's no risk of
> breaking of any cables or hydraulic pipes.
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From: clipka
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 12:37:24
Message: <4ab65a44$1@news.povray.org>
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TC schrieb:
> Quite spectacular looking thingy - but the principle is the same as used
> here:
>
> http://de.wikipedia.org/wiki/Schiffshebewerk_Niederfinow
It appears a good deal more complicated in the actual implementation:
192 counterweights, double cables for safety, and not to forget the
additiona worm drives normally running "idle", just in case the second
set of cables doesn't hold either. All this is done away by the
exceptionally simple construction of the Wheel.
As an aside, by using another caisson as the counterweight you also get
effectively twice the capacity for the same total weight.
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From: Darren New
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 13:15:15
Message: <4ab66323@news.povray.org>
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Warp wrote:
> I don't think that the curvature of Earth played a significant role in
> the distances involved
The article does say something about it working for geodesics, too.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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From: TC
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 20 Sep 2009 18:13:42
Message: <4ab6a916@news.povray.org>
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Well, you are right - the technical execution is more complex.
But then the wheel only seems to be more impressive than the elevator
because it is better looking, a real beauty ;-)
And the principle is beautiful, too.
Let's compare the technical details:
(Provided the English wikipedia is correct for the Wheel, the German
wikidepia for the elevator)
Wheel / Elevator
Trough capacity: 2 x 250 t / 1 x 2500 t
Lift: 24 m / 36 m
Build date: 2002 / 1914
Basically the Wheel, impressive as it looks, is quite small compared to the
rather unspectacular looking elevator. The elevator can lift 10x more
tonnage. If you take in account that for smaller ships the wheel can bring a
little ship up and another one down, if there actually >are< two ships there
at the same time wanting to go into opposite directions, the elevator can
still shift 5x more tonnage in a single go.
Now, I am no architect, but I guess if you wanted the Falkirk Wheel to shift
10 times more load, across 1.3 times the distance, the wheel would become
very heavy indeed. If the troughs were made to hold 2500 t of water the
supports would have to carry 10x more load. You would have to increase the
Wheel's diameter to 49 m minimum, and this would add to the forces that
would have to be absorbed by the Wheel's wings.
A non-rhetoric question:
Has anybody here any idea how much the Wheel's wings or struts would have to
weigh to replicate the ship elevator's capacity?
"clipka" <ano### [at] anonymous org> schrieb im Newsbeitrag
news:4ab65a44$1@news.povray.org...
> TC schrieb:
>> Quite spectacular looking thingy - but the principle is the same as used
>> here:
>>
>> http://de.wikipedia.org/wiki/Schiffshebewerk_Niederfinow
>
> It appears a good deal more complicated in the actual implementation: 192
> counterweights, double cables for safety, and not to forget the additiona
> worm drives normally running "idle", just in case the second set of cables
> doesn't hold either. All this is done away by the exceptionally simple
> construction of the Wheel.
>
> As an aside, by using another caisson as the counterweight you also get
> effectively twice the capacity for the same total weight.
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From: Chambers
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 21 Sep 2009 00:34:07
Message: <4ab7023f$1@news.povray.org>
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Warp wrote:
> A more complicated invention of antiquity is the so-called south-pointing
> chariot. A Chinese invention which is, basically, a chariot with a figure
> on top which always points in the same geographical direction regardless of
> how the chariot is moved and turned. In other words, the figure acts as a
> non-magnetic compass, obviously very useful for travelling long distances.
> The invention might be as old as from 2600 BC (although with certainty it's
> at least from 200 AD).
Easy enough to gum up, though: just knock it over, and it loses its basis.
Impressive, nonetheless :)
...Chambers
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From: scott
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 21 Sep 2009 02:49:28
Message: <4ab721f8$1@news.povray.org>
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> Indeed. I guess they'd have "re-calibrated" the cart daily whenever
> possible. Sunrise or sunset would have been a good opportunity. So the
> device would have had to work for typical distances of, say, some 100 km:
FWIW modern cars today use the same principal. That's why if you have a car
with GPS (a built-in one, not an aftermarket one) it still knows which way
you are facing when driving around underground (eg parking garage or
tunnel).
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From: clipka
Subject: Re: How to lift 600-tonnes ships at virtually no energy costs
Date: 21 Sep 2009 09:44:27
Message: <4ab7833b$1@news.povray.org>
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Chambers schrieb:
> Easy enough to gum up, though: just knock it over, and it loses its basis.
"Houston, we're navigating close to gimbal lock!" :-)
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