Bibliography for Ringworld series

In article <mLOdnfmNzcT-bd_eRVn-hQ.RemoveThis@speakeasy.net>, Erik Max Francis wrote:
> The tensile stress induced in a Niven ring is from "centrifugal force,"
> not air pressure.
>
This I am aware of.
What I was getting at is that the *lateral* force needed to keep
the atmosphere in place is a *lot* less than you'd need the stiffness of
"40-mile diameter half-cones" (paraphrase from "Ringworld Engineers").
Which implies that there is some other reason for over-engineering on that
scale.
My speculations about ring-edge buckling in the last message were
in the wrong sense - because the edge of the RingWorld is further from the
primary, but is constrained to follow the same rotational speed, then the
gravitational force counteracting the tensile stresses will be lower and
the resultant overall tensile stress in the Ring would be greater. So,
with the highest tensile stresses in the edges of the Ring, the most
likely place for buckles to form would be along the centre-line of the
Ring, where it is braced by the material under higher tension at the
edges.
If I were designing a ring and felt a need to protect against this
mode of failure, I'd do it by putting a rib of scrith along the
centre-line, on the underside. I'm surprised that the Hindmost's probes
didn't recognise it.
And again, it leaves the scale of the over-engineering of the
Rimwalls unexplained.

--
Aidan Karley,
Aberdeen, Scotland,
Location: +57°10' , -02°09' (sub-tropical Aberdeen), 0.021233
Written at Wed, 05 Oct 2005 08:48 +0100
 >> Stay informed about: Bibliography for Ringworld series 

In article <$31DBfF+YvQDFwDV@merlyn.demon.co.uk>, Dr John Stockton
wrote:
> so its lower anchorage will need to apply a thousand tonnes
> to it.
>
Hmmm, that's a bit above the range of present day materials, but
not by far. For your 1cm strip in bulk steel, you'd need in the order
of a metre of depth (eyeballing from 1000-ton support structures I've
worked with ; but they're in compression, not tension, so there's an
appreciable safety margin). You might be able to do it more
economically with aramids or carbon fibre. But steel is not insanely
out of consideration.

--
Aidan Karley,
Aberdeen, Scotland,
Location: +57°10' , -02°09' (sub-tropical Aberdeen), 0.021233
Written at Wed, 05 Oct 2005 09:00 +0100
 >> Stay informed about: Bibliography for Ringworld series 

Aidan Karley wrote:

> My speculations about ring-edge buckling in the last message were
> in the wrong sense - because the edge of the RingWorld is further from the
> primary, but is constrained to follow the same rotational speed, then the
> gravitational force counteracting the tensile stresses will be lower and
> the resultant overall tensile stress in the Ring would be greater. So,
> with the highest tensile stresses in the edges of the Ring, the most
> likely place for buckles to form would be along the centre-line of the
> Ring, where it is braced by the material under higher tension at the
> edges.

You need to run the numbers here. The difference in tensile stress
between the edges of the ring due to tensile stress and at the
centerline are completely trivial compared to the ultimate tensile
stress required for a Niven ring to work at all.

--
Erik Max Francis && max.DeleteThis@alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
In the deepest sense, the search for extraterrestrial intelligence is
a search for who we are. -- Carl Sagan, 1934-1996
 >> Stay informed about: Bibliography for Ringworld series 

JRS: In article <mLOdnfmNzcT-bd_eRVn-hQ.TakeThisOut@speakeasy.net>, dated Tue, 4
Oct 2005 14:13:07, seen in news:alt.books.larry-niven, Erik Max Francis
<max.TakeThisOut@alcyone.com> posted :

>The tensile stress induced in a Niven ring is from "centrifugal force,"
>not air pressure. The air pressure is a measily 10^5 Pa at the surface.
> The tensile stress induced in the ring foundation material due to its
>rotation is ~10^17 Pa. The two are simply not comparable.

To get the tension in the Ring caused by the air pressure, one must
multiply by the radius and divide by the thickness. That's a factor of
150E9 m / not a lot, which is quite big.

--
© John Stockton, Surrey, UK. *@merlyn.demon.co.uk / ??.Stockton@physics.org ©
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
Correct <= 4-line sig. separator as above, a line precisely "-- " (SoRFC1036)
Do not Mail News to me. Before a reply, quote with ">" or "> " (SoRFC1036)
 >> Stay informed about: Bibliography for Ringworld series 

In article <1128503466.557667.170390.TakeThisOut@g44g2000cwa.googlegroups.com>,
wrote:
> The only difference that the position of the sun makes is the faintly
> higher gravity at the middle of the ring compared to the edges.
>
That's what I was thinking of ...
> I ran
> the numbers on this, and I it came to 0.00000164g difference.
>
I only ran the numbers as far as getting the difference in
radial distance (from the centre of mass of the system), before
realising that it wasn't going to be much difference. But it still
starts interesting modes of failure going through the mind.

--
Aidan Karley,
Aberdeen, Scotland,
Location: +57°10' , -02°09' (sub-tropical Aberdeen), 0.021233
Written at Wed, 05 Oct 2005 21:03 +0100
 >> Stay informed about: Bibliography for Ringworld series 

In article <UiCJdbWkrQSDFwGP.RemoveThis@smokering.freeserve.co.uk>,
Steve Charlton <steve.RemoveThis@nospam.freeserve.co.uk> wrote:
>In article <VA.0000097e.4f8dcf0f.RemoveThis@validemailaddresstoa.news.group>, Aidan
>Karley <doIlookDAFTenoughTOpost.RemoveThis@validEMAILaddressTOa.NEWS.group> writes
>> Ah, "Bigger than Worlds" has TTBOMK not been published on this side
>>of the pond (while I've been aware of Niven).
>TTBOMK?

To the best of my knowledge, I bet.
--
http://www.cic.gc.ca/english/immigrate/
http://www.livejournal.com/users/james_nicoll
 >> Stay informed about: Bibliography for Ringworld series 

On Sun, 9 Oct 2005 15:36:08 +0000 (UTC), James Nicoll wrote:

> In article <UiCJdbWkrQSDFwGP.DeleteThis@smokering.freeserve.co.uk>,
> Steve Charlton <steve.DeleteThis@nospam.freeserve.co.uk> wrote:
>>In article <VA.0000097e.4f8dcf0f.DeleteThis@validemailaddresstoa.news.group>, Aidan
>>Karley <doIlookDAFTenoughTOpost.DeleteThis@validEMAILaddressTOa.NEWS.group> writes
>>> Ah, "Bigger than Worlds" has TTBOMK not been published on this side
>>>of the pond (while I've been aware of Niven).
>>TTBOMK?
>
> To the best of my knowledge, I bet.

It could have meant something like "The Total Book Of Man-Kzin"
 >> Stay informed about: Bibliography for Ringworld series 

It's worth bearing in mind that although the difference in 'g' is
infinitessimal, if you try to remove this miniscule difference by
curving the ring floor laterally you end up with a 2,000km difference
which either gives you crushing barometric pressure at the middle, or a
hard vacuum at the rim walls. The sheer scale leads to some
counter-intuitive effects, when "correcting" a seemingly tiny
discrepancy can cause massive problems.

Phil Hibbs.
 >> Stay informed about: Bibliography for Ringworld series 

On 11 Oct 2005 05:22:24 -0700, snarks.RemoveThis@gmail.com wrote:

> It's worth bearing in mind that although the difference in 'g' is
> infinitessimal, if you try to remove this miniscule difference by
> curving the ring floor laterally you end up with a 2,000km difference
> which either gives you crushing barometric pressure at the middle, or a
> hard vacuum at the rim walls.

Why?

Doesn't the atmosphere follow the equipotential lines? If there's a g
diference between wall and middle, shouldn't the atmosphere be curved with
a flat floor?
 >> Stay informed about: Bibliography for Ringworld series 

snarks RemoveThis @gmail.com wrote:

> It's worth bearing in mind that although the difference in 'g' is
> infinitessimal, if you try to remove this miniscule difference by
> curving the ring floor laterally you end up with a 2,000km difference
> which either gives you crushing barometric pressure at the middle, or a
> hard vacuum at the rim walls. The sheer scale leads to some
> counter-intuitive effects, when "correcting" a seemingly tiny
> discrepancy can cause massive problems.

But there's no need to correct the difference by curving the ring. The
difference would only be detectable by instruments, so there's no need
to do it for the sake of the inhabitants. And the Niven ring can
already withstand 10^17 Pa of tensile stress; the difference due to a
minute change in gravity at the rims is completely negigible, so there's
no structural reason to do it either.

--
Erik Max Francis && max RemoveThis @alcyone.com && http://www.alcyone.com/max/
San Jose, CA, USA && 37 20 N 121 53 W && AIM erikmaxfrancis
In time of war the devil makes more room in hell.
-- (a German proverb)
 >> Stay informed about: Bibliography for Ringworld series 

>But there's no need to correct the difference by curving the ring.

Yes, I know, but I'd already done the calculations to refute the
suggestion that this might be necessary, so I thought I'd share the
amusing results.

Phil Hibbs.
 >> Stay informed about: Bibliography for Ringworld series 

In article <16xtzmxlzjmup$.dlg@rosspresser.dyndns.org>, Ross Presser
wrote:
> > To the best of my knowledge, I bet.
>
> It could have meant something like "The Total Book Of Man-Kzin"
>
Do you have an ISBN for that? Amazon don't seem to recognise it.

--
Aidan Karley,
Aberdeen, Scotland,
Location: +57°10' , -02°09' (sub-tropical Aberdeen), 0.021233
Written at Mon, 17 Oct 2005 10:30 +0100
 >> Stay informed about: Bibliography for Ringworld series 

On Mon, 17 Oct 2005 11:00:11 +0100, Aidan Karley wrote:

> In article <16xtzmxlzjmup$.dlg@rosspresser.dyndns.org>, Ross Presser
> wrote:
>>> To the best of my knowledge, I bet.
>>
>> It could have meant something like "The Total Book Of Man-Kzin"
>>
> Do you have an ISBN for that? Amazon don't seem to recognise it.

I was joking; there is no such book. I was just supplying an alternate
translation of the acronym TTBOMK.
 >> Stay informed about: Bibliography for Ringworld series