Talk:O'Neill cylinder

message: Rendezvous with rama was published in 1972? - cohesion★talk 07:17, 22 November 2005 (UTC)
thread_title:  rama 

message: I've started improving this a little.  I've put the items into approximate chronological order (some of them are in series that I'm not familiar with, so may have screwed up when within the series the habitats were introduced) to start with, and expanded the entry on Rendezvous with Rama to describe the similar placement of Rama's light strips to O'Neills windows, and indicate both its prior publication and likely independent origin.
I've also removed the reference to Greg Bear's Eon, which seemed somewhat far removed from an O'Neill cylinder, which is a very specific design, rather than the general concept of a rotating habitat.  I'm in two minds about Babylon 5, but left it in.  It is substantially more similar, but still feel it does not share enough of the characteristics of an O'Neill cylinder to be described as related to one.  I wonder if JMS et al read any descriptions of O'Neills work when designing it? JulesH 17:14, 1 May 2006 (UTC)
replies: text: "In the video game Halo, the Halo itself was a ring-shaped megastructure bearing some similarities to an O'Neill cylinder." If no-one has any objections, i would like to remove this... Halo is almost a ringworld, but certainly very different to an O'neill cylinder. WookMuff 07:04, 12 February 2007 (UTC)
replies: text: Agreed. Halo, as the name suggests, was a ring world, not an O'Neill cylinder. See the Ring World article (which for whatever reason is specific to the novel of the same name, but still contains good information on engineering of such a construct). In the classical sense of the term, a ring world would be large enough to encircle its parent star, though the Halo was considerably smaller than this, in its own orbit at what we assume to have been a planetary distance, with its rotation exposing different parts of its interior surface to the incoming light over the course of its "day". Azriphael 15:17, 20 March 2007 (UTC)
thread_title:  The list of science fictional uses 

message: What would be the maximum size of an O'Neil colony if it were made out of carbon nanotubes?
:Very, very large
::To about 2,000 Kilometers in any direction from what I've learnt from the Feasibility section of the Globus Cassus article.
:::Are you sure about that? Is there any known material whose tensile strength is great enough to support a cylinder with a diameter of 2,000 kilometers at 1G??? --Antred (talk) 16:19, 15 September 2014 (UTC)
replies: text: Assuming that one could make carbon nanotubes of any length, my calculations show that the design diverges at about 38km of radius. At that point, most of the material is supporting the simulated weight of the two cylinder halves, and the halves are quite thick (1.3? km), as well. It would probably be ridiculously expensive. The minimum size is more interesting. It's set by human factors, motion sickness. Relatively new research shows that it can be just a 100m of radius, and most people can get used to it. If it's put in a minimum-radiation orbit, low over Earth's equator, it doesn't even need a radiation shield. Ray Van De Walker (talk) 01:11, 12 February 2019 (UTC)
thread_title: Maximum size?

message: Could a Niven Ring be maximum size of an O'Neil colony? Could an O'Neil Colony be made of current technology? Niven Rings are made of Scrith, a fiction material. Are O'Neil rings feasible?  —Preceding unsigned comment added by 72.179.30.13 (talk) 18:39, 27 April 2008 (UTC)
replies: text: No. A Niven ring maintains 1G, and circles a sun.  Nothing known has a strength-to-weight ratio that can do that. Niven was assuming a material using nuclear forces in tension, and nobody knows how to make anything like that. Ray Van De Walker (talk) 01:14, 12 February 2019 (UTC)
thread_title: Link and comparison to Niven Ring?

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thread_title: Image copyright problem with Image:Babylon5 01.jpg

message: Why isn´t there a section like that? The "islands" in Gundam would be a prime example. --Lennier1 (talk) 14:20, 10 April 2009 (UTC)
replies: text: This is mentioned in Space stations and habitats in popular culture. Wronkiew (talk) 14:30, 10 April 2009 (UTC)
thread_title:  In Popular Culture 

message: I don't feel that the Halo franchise is a reasonable example of the O'Neill cylinder because the environment of the Halo world is more of a fantasy habitat for Aliens.
Probably the best use of the O'Neill cylinder was in the Gundam anime franchise where the actual colony itself was made popular in Japan. The cylinder was first shown in the original show Mobile Suit Gundam in 1979 and has been an iconic display of the Universal Century. The colonies have been separated in clusters within the Earth-sphere known as "Sides" and serve as provinces for the Earth Federation Government as well as Side 3 as an independent nation known as the Principality of Zeon.  — Preceding unsigned comment added by 143.200.88.131 (talk) 23:45, 28 November 2012 (UTC)
thread_title:  O'Neill cylinder in science fiction 

message: What are the supposed/proposed materials of construction?  What is the mass of the cylinder?  What is the wall thickness?  What justification is available for a "transparent" material capable of the required structural load?  How would the wall (or window) be repaired?  What about fatigue?  Corrosion?  Stress Cracking?  Temperature variations? Aging/diffusion? Chemical/biological attack of the materials of construction by the ecology?  Radiation damage? Meteor damage?  Radiation shielding?  How do you correct orbital perturbations?  Has anyone associated with this page ever heard of engineering?  how about quantitative data?173.189.74.9 (talk) 16:24, 27 May 2013 (UTC)
replies: text: These are actually quite well established in the nss.org sources.  Just gave a talk in the space museum last week.  O'Neil got most of these covered with people from Stanford University and MIT over viewed different design aspects.  —Preceding signed comment added by MythSearchertalk  15:25, 28 May 2013 (UTC)

text: Steel. Millions of tons. About 50cm. Personally, I think it would be impractically expensive due to the expense of material to resist hoop stresses from the atmosphere. O'Neil had an alternative design called a "crystal palace" that is much less expensive. It's made of lots of little small, ~5m spheres or cylinders; the skin thickness for these is about a 0.5mm. It's glass, supported by frames. The stress is only 7psi/50kpa. By robots. It's not under dynamic load, so fatigue is negligible as long as it's below tensile yield. Corrosion is a live issue, unsolved as far as I know; A really good bet is to cover (evaporate, plate or flame-spray) the inside with a mm of asteroidal nickel, and then inspect it like a bridge. Like a bridge, it will have to be retired at some point. (This is another advantage of many small habitats- they go out of service more cheaply.) Stress-cracking? See Fatigue. There will be a fixed temperature gradient, controlled by the rotation and thermal radiation from the cosmic ray shielding. Aging and diffusion.. see retired. Chemical/Biological attack- see corrosion. Radiation damage is negligible compared to corrosion. Cosmic rays are energetic particles, but there are not many moles (chemistry...) of them. Orbital perturbations are fixed by momentum exchange; I expect active momentum trading, using tethers, mass-drivers, bags of tailings, cargo and money. *ahem*- O'Neil's classes -were- engineers. NASA has lots of references, see above. The exciting part of the proposal is that the best available engineers could not poke holes in it. Ray Van De Walker (talk) 01:35, 12 February 2019 (UTC)

text: The relative pressure difference will still be only 1ATM at max, and we are talking about metal or reinforced glass walls that are like 10~20m thick. —Preceding signed comment added by MythSearchertalk  07:03, 15 August 2013 (UTC)

text: O'Neil was clever about the atmosphere, wanting to reduce the expense (nitrogen is rare and expensive in space), and prevent fires. He proposed (in High Frontier) pressure of a half atmosphere with 40% humidity (water is cheap), and a partial pressure of O2 and CO2 (relatively cheap) same as Earth to support plants and people. Ray Van De Walker (talk) 02:18, 12 February 2019 (UTC)

text: Please keep WP:TALK in mind. The article talk pages are for discussions in how to improve the article. If WP:RS are available for how the O'Neill cylinder is vague to the point of fantasy then I suspect people won't have any issues with a criticism section being added to the article. --Marc Kupper|talk 22:02, 13 December 2014 (UTC)
thread_title:  Vague to the point of fantasy 

message: I don't know how to link specifically to Elysium_(2012), the movie. Anyone to teach/correct?  — Preceding unsigned comment added by 84.25.253.61 (talk) 19:28, 23 September 2013 (UTC)
replies: text: "Elysium" gives you "Elysium". The year was 2013, BTW. And don't forget to sign: ~~~~.  TREKphiler any time you're ready, Uhura 23:07, 23 September 2013 (UTC)
thread_title: Linking to Elysium_(2012)

message: I had trouble understanding how the two cylinders would relate to each other, and the pictures didn't really make it clear.  At first I thought one inside the other, then I thought they might be at right angles, or parallel to each other (like fingers).  Eventually I realised they must be like nunchucks but with a rotating joint instead of a chain.  This article could really benefit from the use of the word "nunchucks" or some better explanation (or an image). --103.1.70.84 (talk) 19:49, 7 November 2014 (UTC)
replies: text: I suspect they are closer to nunchucks based what's said in the Attitude control section of the article. I agree that a picture would be very helpful as I was wondering the same thing as . --Marc Kupper|talk 22:08, 13 December 2014 (UTC)

text: They're parallel, with the axes held in place by struts. One end of the cylinders aims at the sun. The struts don't have to be huge, because there's no weight. One strut pushes the ends apart, and the other pushes them together, to keep the sunward cylinder-end facing the sun by precession. Each cylinder has a length that's probably less than 10x its width. There's a real danger that the cylinders will buckle if they are made too long. How long is subject to design. Dirigibles have similar issues and are limited to <10x diameter. Hope that helps. Ray Van De Walker (talk) 01:45, 12 February 2019 (UTC)
thread_title: What do the two cylinders look like?

message: I'm not an expert on space exploration, sci fi, or anything that touches upon this topic.  But I'm puzzled that there is no mention of Clarke's Rama.  Rendevouz with Rama came out before O'Neill's cylinder, right?  I know that they're not identical, but I look at these illustrations, and I can only think of Rama. Unschool 18:15, 7 February 2016 (UTC)
replies: text: No one has answered, so I'm going to go ahead and add some mention of Arthur C. Clarke.  After all, this article states that the cylinder idea came out of O'Neill's class, but that was years after Clarke envisioned and published the concept. Unschool 20:41, 4 June 2017 (UTC)
thread_title:  Rama 

message: Yes Sir certainly. Thank you.LOBOSKYJOJO (talk) 03:06, 30 December 2018 (UTC)
thread_title:  Thank you 

message: I'm sure plenty of people have come up with the same suggestion as Jeff Bezos, but I fail to see the relevance. No plans have emerged to do it, so it has had zero impact on the world so far.  — Preceding unsigned comment added by 128.77.131.20 (talk) 12:12, 7 January 2021 (UTC)
thread_title:  Relevance of Bezo's suggestion 

message: I believe that the preexisting usage was correct. Centripetal force is towards the center, while centrifugal force is away from the center.
:Centripetal
:Centrifugal
Note:Emphasis added.
Editor2020 (talk) 16:28, 17 February 2021 (UTC)
replies: text: Yes, I have read the articles already. The O'Neil cylinder article talks about how it implements artificial gravity; that article states that "artificial gravity, or rotational gravity, is thus the appearance of a centrifugal force in a rotating frame of reference (the transmission of centripetal acceleration via normal force in the non-rotating frame of reference)". It is the cylinder which is applying the centripetal acceleration, thus producing the reactive centrifugal force. As this is causing us confusion, and it not really within the remit of the cylinder article, I've been bold and removed it, leaving just the link to artificial gravity where readers can find out more if they wish. Bazza (talk) 16:57, 17 February 2021 (UTC)
replies: text: I think that is a great idea. Editor2020 (talk) 01:47, 19 February 2021 (UTC)
thread_title:  Centripetal vs. Centrifugal 

message: Since the Ringworld isn't a cylinder, I'm not sure if it should be listed here. Could anyone please tell me if I'm wrong? (I haven't read the book, so please don't spoil anything for me.)--Thylacine24 (talk) 04:11, 17 April 2021 (UTC)
replies: text: It's a ring, the size and position of a planet's orbit around a star, so no, it shouldn't there. Could be in "See also" though. Bazza (talk) 09:31, 17 April 2021 (UTC)
thread_title:  ''[[Ringworld]]'' in the "[i]n fiction" section