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I was curious: Suppose we built an O'Neill cylinder with an air mixture similar to Earth's (not pure oxygen).

Does the air also get "thrown" down towards the floor of an O'Neill cylinder? If I started a campfire in an O'Neill cylinder would it behave the same way as on Earth?

HDE 226868
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Randster
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    Centripetal force would work on gas and imitate gravity, but there would be some interesting things happening related to Coriolis effect, I don't feel qualified to write full answer though – Mranderson Jun 05 '19 at 14:57
  • This site talks about the problem, but with focus on smaller habitats: http://www.projectrho.com/public_html/rocket/artificialgrav.php#id--Problems_with_Spin_Grav--Coriolis_Effect – Mranderson Jun 05 '19 at 15:01
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    -1 for using hard science for that one – MolbOrg Jun 05 '19 at 15:13
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    @MolbOrg, I don't follow your reasoning – L.Dutch Jun 05 '19 at 15:17
  • Yeah, it'll be something of a challenge to work out what a fire will do in a rotating system, but there's no reason that this shouldn't be flagged hard science. There's nothing magical about it. – Starfish Prime Jun 05 '19 at 21:31
  • @L.Dutch not sure how to answer that without discussion which comments aren't for and which I'm not interested in; Just out of the kindness of my heart informed OP about why, so he would not think it is a bad question, and pointing what I think is wrong with the question. Generally, a quite simple question, with a simple answer, but as for me not worth writing as HS and write the answer to that as HS will be challenging for anyone, so OP created a trap for people jumping to get free internet points. – MolbOrg Jun 06 '19 at 01:43
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    @MolbOrg Out of the kindness of my heart, I'm going to point out that you could have simply commented. "Hey, this tag probably doesn't work well for this question, consider removing it?" – Muuski Jun 06 '19 at 16:31
  • @Muuski thanks, very kind of you, and indeed it was one of the first things I tried before, I did in the past with those questions(not that I'm white knight guarding stuff), so as I attempted to be even more helpful for new users, like edit their questions to fit the topics better. And if I recall correctly L.Dutch was one who took a strict position it is the OP who define the tags, and to avoid war of edits, I decided to that my current approach. I still have some hope HS tag to be more respected one day, but it is an old problem. – MolbOrg Jun 08 '19 at 01:25
  • Possibly of use to you are some of the notes made in answer to this question. – Ash Jun 10 '19 at 12:49

1 Answers1

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The fire would look like a normal fire. However, the smoke would do weird things.

Here is a diagram of the O'Neill cylinder with a fire. (Darker blue represents higher air pressure.)

The radius of the smoke column will grow more than on earth as the altitude increases, since the centrifugal force decreases as the smoke reaches the inner part of the cylinder.

Smoke Rising

At this point, it looks normal. Then, it gets weird.

As the smoke reaches lower air pressure, it cannot rise because it is mostly composed of solids and liquids, and solids and liquids do not expand. The smoke will stay in the area where its density equals the density of the air, beginning to form a cylinder.

enter image description here

The new, high temperature smoke will displace the older smoke, pushing it down the O'Neill cylinder. Particles of smoke are held up by their high temperature. Since the cylinder of smoke is constantly losing temperature as it leaves the fire, the cylinder of smoke will undergo dry precipitation, "sinking" back to the edge of the O'Neill cylinder.

enter image description here

I hope my pictures helped to portray what I was saying. Please comment if you are confused.

Bilbo Baggins
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  • I am not accounting for wind or air movement, but other than that, this is accurate for an earth-like environment inside an O'Neill cylinder. – Bilbo Baggins Jun 13 '19 at 00:03