05-11-2018, 10:07 PM | #11 |
Join Date: Feb 2016
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Re: Why Dirigibles?
Vacuum dirigibles are an interesting idea, though I think they are really only feasible with TL9+ smart materials. At that point, smart structures would also allow for sufficient flexibility to survive the worst weather, so dirigibles might have a comeback at TL9.
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05-12-2018, 12:48 AM | #12 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Why Dirigibles?
Nah, vacuum is only sensible if you have unobtanium materials it takes too much strength to prevent it from collapsing.
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05-12-2018, 01:25 AM | #13 |
Join Date: Dec 2006
Location: Meifumado
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Re: Why Dirigibles?
The materials only have to resist a pressure differential of one atmosphere, and we've been doing much more than that with submarines for decades.
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05-12-2018, 01:45 AM | #14 |
Join Date: Feb 2005
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Re: Why Dirigibles?
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05-12-2018, 01:53 AM | #15 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Why Dirigibles?
Oh, we can do it. We just can't do it for less weight than filling it with helium.
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05-12-2018, 02:04 AM | #16 |
Join Date: Dec 2006
Location: Meifumado
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Re: Why Dirigibles?
I guess it depends on what you meant by unobtanium. I read it to mean a material that can't possibly exist or has purely fictional properties, whereas vacuum dirigible shells would have to be something that's only an order of magnitude or two better than what we can do now. That's either TL9 or some slightly divergent X-punk.
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05-12-2018, 03:22 AM | #17 |
Night Watchman
Join Date: Oct 2010
Location: Cambridge, UK
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Re: Why Dirigibles?
Aluminum and titanium were both eighteenth-century discoveries. The problem was production. You need to use magnesium to extract titanium from its ores, and magnesium and aluminum are both produced by large-scale electrolysis. That needs the development of large-scale electricity generation.
Large dirigibles weren't built until aluminum was available in bulk; the first Zeppelin had an aluminum frame.
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05-12-2018, 05:14 AM | #18 | |
GURPS FAQ Keeper
Join Date: Mar 2006
Location: Kyïv, Ukraine
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Re: Why Dirigibles?
Quote:
Probably not as cool in terms of actual aeronautical usefulness as it is in explanation too. Also wonder if it'll be misused for military purposes (such as lightweight armour)? |
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05-12-2018, 06:33 AM | #19 | |
On Notice
Join Date: Aug 2004
Location: Sumter, SC
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Re: Why Dirigibles?
Quote:
While ships were slower they could carry far more cargo. In fact even though airplanes are faster ships are still the go to for long distance cargo transport even in our modern day. |
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05-12-2018, 08:32 AM | #20 |
Join Date: Feb 2016
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Re: Why Dirigibles?
You can construct vacuum bubbles from modern steel alloys, the problem is the expense of constructing a vacuum facility large enough to produce the steel alloy bubble in a vacuum. Paradoxically, it is only affordable at TL9+, when you can use LEO production techniques to construct steel alloy bubbles in the vacuum of space (the steel also benefits from the lack of atmospheric contamination and gravitational defects).
The key thing is to reduce the density to 178.5 grams per cubic meter. A 10 m radius sphere possesses a volume of 4,188.8 cubic meters, meaning that your mass budget is 747.7 kilograms, or 545 grams per square meter, which is tin foil thickness. Your only choice is to go bigger. A 1 km radius sphere can afford 59.5 kg per square meter, which is 7.4 mm, which is sufficient for submarines Of course, more advanced materials could do it better, but you would probably need an advanced metallic laminate to create a vacuum bubble small enough for an airship. |
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