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Problem With a rotating cylinder, applying weight to one side and not the other will cause it to rotate off axis and give it a 'wobble' likely causing undesired gravitational effects. Now clearly there's a certain scale at which the miniature changes in weight as someone walking around aren't going to affect the rotational axis of the cylinder but over the long term of building buildings or growing trees you might have to start taking that extra weight into account.

Question I was wondering what ways are there of counteracting this weight distribution.

One possible solution Couple of ways I can think of include having a 'ballast' in the hull of large tanks of liquid or movement of solids that apply the same extra weight to the opposite side of the OC to stop the wobble.

Edit This is not referring to the wobble you would get which flips the cylinder back and forth but rather the wobble around the central axis due to a difference in weight around that axis. Think of a washing machine with too much weight on one side, they tend to oscillate.

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    $\begingroup$ Liquid ballast in the form of stored water was what I immediately thought of. A computer would probably continuously adjust to take into account every tiny change in the weight distribution. You answered your own question (there's a badge for that, if you care to actually submit it as an answer). $\endgroup$ – DWKraus Aug 3 '20 at 18:44
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    $\begingroup$ Your solution sounds good to me. Probably not solids though...solids can't be pumped through pipes unless you feel like making a dense slurry. $\endgroup$ – DKNguyen Aug 3 '20 at 22:30
  • $\begingroup$ Well you could do solids with like a rail system but thats way more elaborate than liquid, wasnt sure if liquid ballast would be enough and sourcing that much liquid for each OC might be a lil wasteful. $\endgroup$ – Phillip Roberts Aug 4 '20 at 11:37
  • $\begingroup$ @PhillipRoberts Or mercury. That's a buttload of mercury though. Then again, an O'Neil cylinder us a buttload of everything. $\endgroup$ – DKNguyen Aug 6 '20 at 19:08
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O'Neil cylinders aren't really practical in their original form, with windows and mirrors, because there isn't enough radiation shielding near the windows. Any practical habitable cylinder will need a pretty thick hull, and if it's intended to last, it will need substantial reserves of water, and of compounds that can be cracked to produce atmosphere.

The water is usable for adjusting the balance of the cylinder, provided there's space within the hull for it to be moved around. If we take a fair-sized cylinder for an example, 30km long and 4km radius, it has a surface area of 750 square km, and if its hull is 100m thick at density 2, at weighs about 150 gigatons. We should have room for 20GT of so of water and 80 cubic kilometres of space in the hull to move it around in.

However, building anything large inside the cylinder would risk upsetting the balance and there would have to be some mechanism to control this. A powerful urban planning organisation would be one answer, as might ingenious taxes.

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  • $\begingroup$ Oh yeah OC's by design have come along way since Island 3. Thats a good solution, say you want to build something of certain weight on one side you have to build something of similar weight and distribution on the opposite side. $\endgroup$ – Phillip Roberts Aug 6 '20 at 11:37

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