Closed, rotating cylindrical habitats have been
built since the Interplanetary age; at first these were no more than a hundred
metres or so in radius, the smallest possible radius that could give Earth-like
internal centrifugal gravity while avoiding excessive coriolis effects. But over
time the habitats became larger, until they reached the maximum possible size
for habitats constructed with non-exotic materials.
A McKendree Cylinder is designed much like an
O'Neill Cylinder
but built with the carbon buckytube technology used in
Bishop Rings. As
such McKendree Cylinders with an interior gravity of one standard gee can have a
radius of 1,000 km and a length of 10,000 km. This radius and length will give a
single McKendree Cylinder more than 62,857,000 km^2 of living area or about 12%
of the surface area found on a
Gaian type
planet. [Please note; first century
hu are reported to
have lived on only 10% of the surface of eir home world (
Earth) due to inconvenient
surface features - oceans, mountains, deserts, icecaps, etc. On the other
hand these hu did draw on the planet's whole biosphere for life
support.]
However McKendree Cylinders can also be linked into
counter-rotating pairs (side-by-side like the original O'Neill colony design or
nested as in some other common designs) to double the living area and counter
gyroscopic effects so that the cylinders can be oriented in any chosen
direction. (For example; with their axis pointed towards the local star for
easier direct lighting.)
When multiple levels or floors are added to the
design a McKendree colony can quickly equal a Gaian type planet in total surface
area. 'Ceiling height' in a multi-floor colony is generally determined by its
psychological effects on the inhabitants but in the counter-rotating nested
designs an inner cylinder must clear the rimwalls and upper atmosphere of the
cylinder below it. This requires more than fifty kilometers between levels in a
standard gee habitat; habitats with lower values of gravity can be larger, but
the separation between the levels must be greater, as the scale height of the
atmosphere is greater in low gravity conditions.
A full-sized McKendree
habitat can be constructed from a large asteroid or dwarf planet, or from a
number of smaller objects. A typical dwarf planet of 1000 km diameter can
contain enough material to build 12 Mckendree cylinders, with a potential
population of hundreds of billions of sophonts.
The internal landscape of a McKendree cylinder may contain landscape
features such as seas, lakes, hills, and even mountains; but these
features add mass to the habitat and therefore increase the load on the
buckytube fibres holding the cylinders together. To cut down on the
additional load the landscape is constructed with internal voids
and arches, to make the hills and mountains as hollow as possible;
these internal voids can be useful for storage.
