09-19-2020, 05:54 PM | #1 | |
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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[Spaceships] Query: Activating Mag-Sails
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Dalton “who hates exposing his ignorance” Spence
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09-19-2020, 07:50 PM | #2 |
Join Date: Feb 2011
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Re: [Spaceships] Query: Activating Mag-Sails
I'd say it takes about an hour, maybe more if it's large or crude, less if it's small or advanced.
It's not a physical object -- it's a charged plasma field. |
09-19-2020, 08:38 PM | #3 | ||
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: [Spaceships] Query: Activating Mag-Sails
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Dalton “now only if my other questions are answered” Spence
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09-19-2020, 09:08 PM | #4 | |
Join Date: Aug 2007
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Re: [Spaceships] Query: Activating Mag-Sails
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The solar wind bouncing off the superconducting magnetic field of that cable transfers momentum to the cable and whatever is attached to it. This is similar to what happens at the periphery of the plasma sail but the two things are different ways of skinning the same cat.
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Fred Brackin |
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09-19-2020, 09:57 PM | #5 | |
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: [Spaceships] Query: Activating Mag-Sails
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Dalton “always interested in informed opinions” Spence
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09-19-2020, 10:11 PM | #6 | |
Join Date: Aug 2004
Location: Binghamton, NY, USA. Near the river Styx in the 5th Circle.
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Re: [Spaceships] Query: Activating Mag-Sails
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Possibly. It's a superconductor loop, so if that can be built with wire that wire may be coilable. OTOH, if it's made from something that's not flexible, like the ceramics used in modern superconductors, the loop may not be flexible; though such loops may be foldable. So it's very much materials dependent which is entirely dependent on your worldbuilding assumptions. It would have to be. As a magnetic superconductor the magnetic field would tend to push it into a circular shape. Trying to "reel it in" while it's charged would result in the magnetic field pushing back against you. Also, if you could manage to reel it in the coil would warm to the ships temperature, which could be above it's superconductor temperature... and would result in a boom. Big badda boom. (above the superconducting temp the charge generates resistance, which generates heat, which warms the loop more, which results in more resistance, which generates more heat, which quickly turns into a catastrophic failure of the loop). If it's a solid loop, breaking the loop (to fold it) would result in a catastrophic failure once the loop is broken. Discharging it would just be draining the electromagnetic field from it, which could be done as a direct energy drain or by using opposing electromagnetic fields, which would result in an electric charge being transferred to the opposing field generator. Either way you would wind up with energy which you could either use for something useful (charging batteries, firing weapons, running systems) or could be used to generate heat and dumped into an external radiator.
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Eric B. Smith GURPS Data File Coordinator GURPSLand I shall pull the pin from this healing grenade and... Kaboom-baya. Last edited by ericbsmith; 09-20-2020 at 01:32 AM. |
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09-20-2020, 06:58 AM | #7 |
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: [Spaceships] Query: Activating Mag-Sails
Thank you Eric, this is exactly what I needed. By giving me a valid reason why it might not be retractable you saved me modifying my Mars Trans-Orbital Taxi since it might be damaged when entering Mars atmosphere while it remains a good option for interplanetary craft that stay in space. Does the one hour at 1 PP activation time sound good to you?
Dalton “who loves reasons to mix up tech” Spence
Last edited by DaltonS; 09-20-2020 at 07:10 AM. |
09-20-2020, 08:19 AM | #8 | |
Join Date: Aug 2004
Location: traveller
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Re: [Spaceships] Query: Activating Mag-Sails
Sean Barrett's 1992 (!) Roleplayer article, "Stellar Windjammers: The Magnetic Space Sail Drive," has the following:
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Energy (MW-hrs) = 25.7 * sqrt((thrust in tons)^3) Note that since Mars lacks a magnetosphere, any magsail (or plasma sail, for that matter) maneuvering would be in relation to the solar wind, not the planet as such. Last edited by thrash; 09-20-2020 at 11:42 AM. Reason: Fixed radius equation. |
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09-20-2020, 09:20 AM | #9 | |
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: [Spaceships] Query: Activating Mag-Sails
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Dalton “Looks like I may have to retract my previous post” Spence
Last edited by DaltonS; 09-20-2020 at 08:40 PM. Reason: Added a link to the article and fixed radius equation. |
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09-21-2020, 08:41 AM | #10 |
Join Date: Aug 2004
Location: Hamilton, Ont. CANADA
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Re: [Spaceships] Query: Activating Mag-Sails
Just in case anyone is interested, here's a quick table of magsail radiuses and energy requirements.
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| Size Radius Energy|Size Radius Energy|Size Radius Energy|Size Radius Energy| | (SM) (miles) (PPh) |(SM) (miles) (PPh) |(SM) (miles) (PPh) |(SM) (miles) (PPh) | +--------------------+-------------------+-------------------+-------------------+ | +3 10.95 0.18 | +5.5 48.99 0.82 | +8 200.0 3.33 | +10.5 894.4 14.91 | | +3.5 15.49 0.26 | +6 63.25 1.05 | +8.5 282.8 4.71 | +11 1095 18.26 | | +4 20.00 0.33 | +6.5 89.44 1.49 | +9 346.4 5.77 | +11.5 1549 25.82 | | +4.5 28.28 0.47 | +7 109.5 1.83 | +9.5 489.9 8.16 | +12 2000 33.33 | | +5 34.64 0.58 | +7.5 154.9 2.58 | +10 632.5 10.54 | | Dalton “I hope this is helpful.” Spence
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