Subject: (whorl) Asteroid & L-5 Numbers

From: m.driussi <m.driussi at genie.com>
Date: Wed, 08 Oct 1997 01:19:00 +0000

[Posted from WHORL, the mailing list for Gene Wolfe's Book of the Long Sun]

Reply:  Item #7581861 from WHORL at LISTS.BEST.COM@INET02#

Nope, the idea that the whorl was carved from an asteroid (rather
than being built up from beams and ship plate) did not arise outside
of the text in the minds of overeager readers--rather, it was told
specifically by an old chem soldier to someone else in the text.  This
was also the point where the weather-related rational for the tunnels
was divulged, I believe.  Somebody else can find it, no doubt.

Re: 9.80616 m/sec^2 as being equal to "78,986 miles per hour per
hour," hmmmm.  This looks odd, because Earth's escape velocity is "7
miles/sec, or 25,000 mph" (Adams, SPACEFLIGHT, 1958, p. 177).

I believe the question with a simulated g (as in a spinning cylinder)
is not so much overcoming the simulated g-force as it is in
overcoming the rotational speed.  [ . . . well . . . see later.]

THE SCIENCE IN SCIENCE FICTION (p. 19) offers a few L-5 space colony
models that might be of interest here:

          Length    Dia.     RPM    Population max
Model 1    0.62     0.12     2.85       10,000
Model 2    2.0      0.4      1.67      200,000
Model 3    6.2      1.2      0.95    2,000,000
Model 4   20        4        0.53   20,000,000

(simplified chart, using only miles.  RPM = Revolutions per minute to
create a simulated 1 g at the surface.)

Now let's look at the biggest one, No. 4.  Dia = 4 miles, thus
circumference = 12.56 miles; RPM of 0.53 therefore translates into
6.66 miles/minute or 400 miles per hour.

In contrast, No. 3's Dia = 1.2 means Circ = 3.76 miles; RPM 0.95 =>
214 miles per hour.

Well hey, that's pretty much what John Eric Ivancich came up with!
So nevermind my initial doubts, we agree on this much!  (BTW, Welcome
aboard John Eric Ivancich.)

In addition to all this, which still looks like a formidable speed to
overcome, there is the fact that a human being, a child even, can
actually jump up from the Earth.  Compared to a child jumping on the
whorl, the floater has two vectors: one horizontal (the "go" vector) and
one vertical (the "float" vector); as the simulated g force is reduced (by
travelling in the direction of rotation with the go vector) the float
vector faces less resistance.  The floater suddenly has the uplifting
capacity of a micro-helicopter (but not the aerodynamic shape, nor control
surfaces for true air flight).

So then, assuming my calculations above are close enough, we'll say
that 400 mph will cancel out 1 g(sim) in model colony 4.

Now, doesn't that imply that if we can reach 200 mph we will have only .5
g(sim) "holding us down"?  And at 100 mph we'd have only .75 g(sim)?

A blower that can hover a vehicle, and provide brief pop-ups of six
to eight feet to clear obstacles (as Grissom showed Silk that Blood's
civilian floater could do), such a blower could probably really loft
a vehicle that only weighs three-fourths as much, I'm thinking.

But yeah, yeah, Ringworld's a-going down, boys--everybody into the
lifeboats and let's pray that the rubber band powered warp drives
can holdout until we can get back to the green hills of Earth! :)

=mantis=

---

From: m.driussi <m.driussi at genie.com>
Date: Wed, 08 Oct 1997 05:38:00 +0000

Reply:  Item #9713026 from WHORL at LISTS.BEST.COM@INET03#

Uh, make that "moving =against= the direction of rotation rather than
with it."  That is, if I understand it correctly, the rotation is from
south to north, so that when one drives to the south one is subtracting
from the very velocity vector that provides the simulated gravity.

=mantis=