Island One, Two and Three

From: Michael Capriola [mailto:capcartoonist@hotmail.com]

> Okay, if we postulate a Stanford habitat needs two rings rotating in
> opposite directions,

Please don't state this as a "need". It is not "necessary", as I
explained in another posting. Simply express it as your preference.

> Also note that it is because we want to avoid unnecessary waste of
> construction materials that the Stanford Torus is considered a better
buy
> than the Bernal Shpere.

It seems that you're picking your own unique dimensions for the
existing, published designs (your Stanford Torus is a bit smaller in
diameter, though you have two of them, and your Bernal Sphere is a good
deal larger). Not being an engineer, I can only work from the published
designs. The published designs for the Stanford Torus and the Bernal
Sphere had the same population (10,000; you're aiming higher), so that's
a basis for direct comparison. The masses listed in those studies were
10 million tons for a Stanford Torus and less than 4 million tons for a
Bernal Sphere.

As we scale upward, this ratio might change, but I don't really see it
reversing.

This would seem to suggest that a sphere is more efficient of building
materials than a torus. And I suspect that's the reason why O'Neill
presented the Bernal Sphere as a better alternative for a 1st generation
habitat than the Stanford Torus.

O'Neill came to different conclusions than the Ames Study because
someone on the Ames study felt strongly that any rotation rate beyond 1
RPM was asking for trouble. This pushed them toward a larger diameter,
and then toward reducing hull mass by going with a torus. O'Neill felt
we had good data supporting that up to 3 RPMs would be OK for most
people, and that 2 was a good compromise. So his 1st generation design
is a smaller-diameter sphere rotating around twice as fast.

Regards,

Mike Combs