01-18-2011, 02:12 PM | #1 |
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[Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
Greetings, all!
I noticed there's a shortage of power plants below TL7. Boilers are TL7 for some reason. Fuel Cell has no RAW analogues below TL7 . . . how much endurance would a power plant based on some sort of combustible fuel have at TLs 6 and below? Likewise, what stats should I use for the equivalent of WWI planes' propulsion, those barely exceeding a hundred mph? Would Ether Screws be a close enough fit? (They seem to provide more speed than the planes of the age had). Thanks in advance! Last edited by vicky_molokh; 01-18-2011 at 02:25 PM. |
01-18-2011, 02:49 PM | #2 |
Join Date: Aug 2007
Location: Vermont, USA
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
A TL5 Steam Engine (p. HT14) requires 250 lbs./hr. of wood and 400 lbs./hr. of water (and some amount of oxidizer without access to an atmosphere) for an 8,000-lb. engine. That implies that a Fuel Tank system would run a Steam Engine system for no more than 12 hours (depending on how much mass of oxidizer is required).
A TL6 Internal Combustion Engine (p. HT14) requires 8/3 lbs./hr. (and again, some amount of oxidizer) for a 125-lb. engine, so a Fuel Tank system would run an ICE system for no more than 48 hours. How much oxidizer do we need? I'm going to guess a 3:1 ratio of oxidizer to combustible by mass*. That gives us 3 hours per Fuel Tank of wood† for a TL5 Steam Engine system, and 12 hours per Fuel Tank of gasoline for a TL6 ICE system. As a reality check, the TL9 MHD Turbine (p. SS20) provides two power points for 24 hours on a Fuel Tank (comparable to one power point for 48 hours), so we're not busting any TL barriers here. If I've mis-estimated the amount of oxidizer required, use a different divisor. I don't know if the idea (or at least the production) of an oxidizer is appropriate pre-TL7 though. That might be why these aren't listed. * That's about what the space shuttle uses. For wood and gasoline, well ... it's been a long time since high-school Chemistry, but I can guess the end products of combustion are going to be CO2 +H2O, which is about 3:1 Oxygen to Carbon+Hydrogen by atomic mass. Is two Hydrogens per Carbon about right for wood and gas? I dunno. † Charcoal might double that endurance (p. LT27), and coal might multiply it by four (p. HT14). Last edited by munin; 01-18-2011 at 03:15 PM. |
01-18-2011, 03:16 PM | #3 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
The spaceships system is really too low granularity to deal with aircraft. Realistically, you don't get the required power density for viable aircraft before mid TL 6, at which point you're basically using the same power plants as you'd use at TL 7, just with lower performance.
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01-19-2011, 03:47 AM | #4 | |
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
Quote:
Hmm. ICE's 12 hours per Fuel Tank (which seems to imply 3 hours for Internal Fuel) seems quite good. In fact, it matches the rate of the Fuel Cell from TL7. Why is it TL7 then? |
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01-19-2011, 05:05 AM | #5 |
Join Date: Jul 2008
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
Would 3/4s of a system worth of TL6 ICE + generator be enough to produce a power point?
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01-19-2011, 05:40 AM | #6 |
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
I don't know, it seems comparable to two Passenger Seating of rowers (oars provide half the thrust of screws; screws eat a Power Point, oars eat the work of a system's worth of rowers). Do you think it should provide 1 PP per two systems and have no internal fuel? Provide 1 PP/system with no internal fuel? Or maybe provide 1 PP but consume fuel faster?
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08-04-2011, 03:26 AM | #7 | |
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
Quote:
You left out one important thing. What SM ship would make an 8000 lb engine roughly one system using Spaceships? Using 650 lbs per hour for 12 hours gives 7800 lbs which is between SM 5 and SM 6 fuel tanks of 3000 lbs and 10,000 lbs respectively. Assuming charcoal has double the energy density of wood doesn't affect the need for water, so it wouldn't double the endurance. |
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08-04-2011, 04:40 AM | #8 | ||
Join Date: May 2005
Location: Oz
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
Quote:
Quote:
n.{C6.H12.O6 + 6(O2)} —> n.{6.(CO2) + 6.(H2O)}Which suggests about 192 parts of oxygen to 180 parts of cellulose by mass, or 16 to 15 (that's 1.07) Burning charcoal is more like: C + O2 —> C.O2Which implies 8 of oxygen to 3 parts of fuel by mass. (2.67) And gasoline is something like: 2.(C8.H18) + 25.(O2) —> 16.(C.O2) + 18.(H2.O)Which implies 800 oxygen to 228 fuel by mass. (3.51)
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08-04-2011, 04:43 AM | #9 |
Join Date: May 2005
Location: Oz
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
8000lb is 4 US tons. One system is 1/20 of a ship. So we're looking at an 80-ton ship. That's about SM+6.
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08-04-2011, 06:07 AM | #10 |
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Re: [Spaceships] Non-TL^ Power Plants and air propulsion below TL7?
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