2000-01-03 – The Floating Island problem- The overall design

The structure of the system is not overly critical from a survival point of view, however, it will be safer and more desirable to maintain some rules.

Stability for heavy communal areas will be interesting, too. Such things as industrial lathes and the like will require massive amounts of extra support. From Wayne Gramlich’s page on Oceania (A better name, IMHO) which uses PET drinks bottles pressurised to 2 atmospheres, I have calculated a first approximation of the loading that can be supported.

This comes from each bottle having a volume of 2 litres, hence an upthrust in standard water of 2kg. Each of these units is about 35cm high and 10cm in diameter, including the neck. (The neck volume compensates for the weight of the bottle) The bottles are in sevens, one in the centre and six strapped around it. Each of these units is about 35cm high and 30cm in diameter, again including the neck. These are now hexagonal shaped units. Stacked neck to neck, in a close manner, three units deep per metre seems to be easily managed. This hexagon stack gives an incredible 144 bottles per square meter for one layer. Multiply by three for a volume of one cubic metre, and two litres for the volume of air in each bottle. This gives 867 litres of air per cubic metre. Multiply by ten for the depth (Ten metres is the limit for a bottle at two atmospheres. Higher pressures could of course be used below these.) and the total floor loading per square metre is 8670 kg, which is quite amazing. This would be sufficient for even a fairly heavy lathe or metal-work shop. Of course, a safety factor would be required, as would a very sturdy floorplate to prevent a sudden torque from tipping the supporting base or perforation by a dropped piece of white-hot metal. The safety factor would be very small, perhaps just the ten percent increase caused by saline having a higher density, as the floorplate would surround the area, and spread the load over adjacent cells, plus the actual number of cells that could be destroyed before anything became even noticeable would be considerable.

Note that again we are using Hexagonal Close Packing, mimicking the atomic structures of dense crystalline materials.

This HCP shape will help keep the colony stable, as well as maintaining the overall shapes.

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