McKendree Cylinders (A1-0)

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McKendree Cylinders are closed, rotating cylindrical habitats up to 10,000 kilometers long, that reach the maximum possible size for habitats constructed with non-exotic materials.

Structure

McKendree Cylinders are designed in the same manner as a their much smaller O'Neill Cylinder counterpart, but built with the carbon buckytube technology used in Bishop Rings. As such, McKendree Cylinders with a standard interior gravity of 9.81 m/s² 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 km² of living area, or about 12% of the surface area of a standard, Earth-like planet.

However, McKendree Cylinders can also be linked into counter-rotating pairs in a similar manner to many O'Neill Colonies, and/or be nested with one or more counter-rotating inner cylinders that can provide additional stability to the megastructure. If a counter-rotating cylinder is included inside the outermost shell, the two layers must be separated by at least 50 kilometers of vacuum above the top of the atmosphere to eliminate atmospheric drag effects. Doubling the cylinder in this way increases the living area and counters gyroscopic effects so that the cylinders can be oriented in any chosen direction.

When multiple levels or floors are added, a McKendree Colony can quickly equal an Earth-like planet in their 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 an habitat with standard gravity; habitats with lower 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 kilometres diameter can contain enough material to build 12, maximum size Mckendree cylinders.

The interior 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; so, to cut down on the additional load, the landscape is usually constructed with internal voids, to make the hills and mountains and any other large-scale feature as hollow as possible. Importantly, these internal voids can also be used for storage or as additional habitats for species preferring subterranean environments and with an inclination for climbing.

Sources

• Orion's Arm: https://www.orionsarm.com/eg-article/48473a892041c
• Wikipedia: https://en.wikipedia.org/wiki/McKendree_cylinder
• Worldbuilding Stack Exchange: https://worldbuilding.stackexchange.com/questions/90432/stabilizing-a-mckendree-cylinder-habitat