From: Julia Thompson <[EMAIL PROTECTED]> "Robert J. Chassell" wrote:
> By the way, does anyone know why so many science fiction writers > descripe spinning space habitats as being longer than they are wide? > Such habitats are intrinsically unstable. But habitats that are wider > than they are long are intrinsically stable > > I know that the habitats are supposed to have stability controls -- > just pump water around. Nonetheless, it is easier to keep an > instrinsically stable system stable than to stabilize an unstable > configuration.
It probably makes for an environment that the reader is more comfortable visualizing.
It also makes for more interesting crises.
So, from a writer's & reader's standpoint, it may be desirable, even if it isn't from an engineering standpoint.
Thinking about this a bit, I was wondering if there was a benefit in useful surface area (at 1 G) or in useful volume (say, over a range of 1G to .25G) in the cylinder (cigarette) shape vs the disk (tuna can) shape. The inner surface area is directly proportional to both radius and length, but the interior volume is proportional to r-squared but increases linearly with length. So smaller changes in radius can buy bigger changes in volume, which might argue for the tuna can shape.
Also, as radius increases, the rotational speed to attain 1G can be slower, which seems to be an advantage for increasing radius instead of length.
One advantage I see to the cylinder/cigarrete shape is that the material cost for enclosing the structure increases roughly proportional to radius-squared, but only increases linearly to the length.
(This is assuming you enclose the whole disk/cylinder, rather than do a spoked-ring Space Odyssey design.)
Another benefit I see to the cylinder shape is that the internal floor plan (at the 1G level) can be more "square" than the disk shape: For the disk shape, length (L) must be <= 2*radius (r), the floor plan's aspect ratio is 2*pi*r X 2r (or less) ==> giving something greater than a 3.14:1 ratio, or in other words, a long, narrow floor plan in even the best case.
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