Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 02-04-2019, 01:28 PM   #131
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Materials

Quote:
Originally Posted by tshiggins View Post
Start small, maybe?

Use a hot-air gas-bag in a lifting body shape.

Sling a gondola beneath, with geared bicycle parts that drive propellers.

Only go up on calm days, or those with light winds. Use fuel to reach the desired altitude, and mostly rely on winds aloft to move the aircraft.

If the crew wants to go investigate something off their direct flight-path, they peddle like Olympic cyclists.

You want small crew-members with high strength-to-weight ratios, who are Very Fit. However, you only need one or two TL6-7 officers. The rest can be anyone small, strong and healthy enough.

It takes a looong time to map out a couple of hundred miles in each direction, but it gets done relatively safely, and mostly using the tech and magic you've defined. After that, the group has aerial reconnaissance and sentries -- which is a hell of an advantage.

For established routes, such a dirigible might make longer one-way trips, and crews rest up and re-stock before they return.

Best of all, for your purposes, it teaches the locals the needed concepts to build on later.
That's a good thought.

In my specific situation, the TL7 people brought along plenty of supplies, but not enough to have a refined petrochemical industry at first. But they could easily have brought some small and efficient early TL7 engines, broken down into man-portable pieces, and a some cans of fuel for emergencies. Still, they'd run out of fuel they brought along before they could refine more (which is a long-term goal, but not realistic until they have more educated locals).

If a TL7 design of a coal-powered engine that has no parts heavier than ca 150 kg would be an improvement over bicycling, they could have brought such engines over. They'll have locals digging coal from surface pits from the start. And coal-powered industry is part of their future plan at any rate, so building coal furnaces, steam engines and eventually coal power plants that make electricity is not merely spending scarce resources on airships, it's part of their core infrastructure project.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 02-04-2019, 01:47 PM   #132
Rupert
 
Rupert's Avatar
 
Join Date: Aug 2004
Location: Wellington, NZ
Default Re: Materials

Quote:
Originally Posted by Fred Brackin View Post
The local wood is in short planks hewn into shape with adzes too.
That's not necessarily so, but TL3 does mean no good plywood, and very limited ability to make the thin sheets you need for plywood.

For small lighter-than-air vessels, bamboo and sealed silk (or goldbeater's skin, which is possible at TL2-3, and was used historically even at TL6) might be sufficient.
__________________
Rupert Boleyn

"A pessimist is an optimist with a sense of history."
Rupert is online now   Reply With Quote
Old 02-04-2019, 09:39 PM   #133
Fred Brackin
 
Join Date: Aug 2007
Default Re: Materials

Quote:
Originally Posted by Rupert View Post
That's not necessarily so, but TL3 does mean no good plywood, and very limited ability to make the thin sheets you need for plywood.

For small lighter-than-air vessels, bamboo and sealed silk (or goldbeater's skin, which is possible at TL2-3, and was used historically even at TL6) might be sufficient.
"TL2-3" is different based on whether you've got Romans or Vikings but you'd need a Roman saw mill to have good wood for large structures.

Bamboo almost certainly is the best natural structural material you can get but it's not available everywhere and still limits you in size.
__________________
Fred Brackin
Fred Brackin is offline   Reply With Quote
Old 02-05-2019, 06:08 AM   #134
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Some Notes About the World for which I'd like to Consider Dirigibles

Quote:
Originally Posted by Fred Brackin View Post
"TL2-3" is different based on whether you've got Romans or Vikings but you'd need a Roman saw mill to have good wood for large structures.
That's very true. Take the myriad economic, technological and infrastructure differences between the Late Roman Republic / Early Empire and a typical TL2 Iron Age tribal culture, like proto-historic Hallstatt Celts or the even less technologically advanced Germanic tribes of the Nordic Iron Age, who may have iron, but are clearly not competative in any technological field with the Romans.

Either the TL progression could really use an extra TL between the prehistoric Iron Age and the High Medieval era, or the Romans should just be assigned TL3 for the height of their empire, as TL is often as much about economic and infrastructure factors as anything else and with the collapse of trade, maintaining a higher TL gets harder.

In any case, the specific world I was using as an example has Antarctic Space Nazis, with access to other worlds through the Irminsul / World Tree, settling the Northern European analogue of a world with some physical similarities with Earth, but apparently a totally different history.

The local tribes are proto- or quasi-Germanic and qualify as TL2 through being Iron Age, but their material culture is pretty sparse compared to neighbours with better trade networks who are closer to the cultural hub of a great inland sea, analoguous to the Mediterranean.

There are multiple Celtic-esque societies over most of the Europe-analogue, with material cultures ranging from Hallstatt-esque through La Tenč -like all the way to ahistorical examples that easily qualify for TL3^ through fine craftsmanship, thriving trade, centers of philosophy and learning, exceptional animal husbandry and magical talents that are incorporated into the work of master craftsmen and other experts.

Further away from the Antarctic Space Nazis are many other early to late TL2 cultures and some more TL3^ cultures, like a paleo-Balkan one with strong Celtic-esque connections, a number of coastal cultures that seem to mix Minoan survivals with Celtic, Thracian and Anatolian aspects, a couple of Semitic trading cultures, one with a strong nautical theme and another with long-established urban centers in an irrigation agricultural society, and so on and on.

What this world mostly doesn't have are very large empires or other unified polities of the size and power that distinguished the Classical period in Earth history. There are no Romans (unless some fairly small tribes speaking more-or-less related languages count) and not even any unified Hellenic culture around the inner sea. There are speakers of languages that seem related to Greek, but so far, not one culture speaks a language that is an exact match for any preserved or reconstructed language known to 1940s era German philologists. The best they get is a recognisable linguistic relationship, as broadly being classifiable in the same family as some known historical language, but no exact matches.

Even their local 'Germanics' are speaking a language that is clearly classifiable as being a Germanic language, but might belong to a branch of that language family that in our history does not have any modern languages that descend from it.

In any case, being Nazis and having access to more than one gate that opens into this world, the ASNs settle around an analogue of the Exernstein in an area that corresponds to Westphalia, and use two other gates to raid more distant cultures for skilled TL3 slaves. The early Iron Age 'Germanics' become one or more of a superior class of slave, a willing candidate for second-class citizenship, allied tribesmen or enemies to be broken, depending on how the individual tribes reacted to first contact.

The ASNs discovered this world in early 1944 and planned to emigrate there as they could foresee the fall of the Third Reich. Before 30th March, 1945, they had managed to transport some 30,000 short tons of supplies (though no individual pieces much larger than 400 lbs. and mostly handheld gear) and just under 40,000 adults to this world and two others. At that point, there was no further support from Earth forthcoming and the colonies were on their own.

They planned to construct an industrial civilization again, from the supplies they brought to bootstrap their industry, but until they've grown their own population and uplifted sufficient numbers of locals, they won't be able to sustain much more than TL4-5 infrastructure, even if tbey still have TL7 skills and lots smaller of TL7 equipment. But mostly no heavier vehicles than could be man-handled over the World Tree (bicycles, maybe a few off-road motorcycles) and little enough refined fuel, having made a conscious decision to use coal while they built up a local industry.

The early TL2 Germanic tribes are pretty much the least advanced locals they could have employed, but the are Nazis and völkisch. And at least they are using their thousands of inhuman, untiring 'zombie' stormtroopers to sejze as many TL3 and TL3^ slaves as possible. And they have a firm allegiance with a TL3^ culture on another world, numbering less than a million all told, but an important trade partner all the same.

Even with almost 40,000 adults, building up infrastructure for a high-rech society on a world almost entirely without any large-scale infrastructure is a huge task. And they couldn't bring airplanes, trucks, railway tracks or other heavy things like that. Nor, really, plants to constrjct them. The best they could do was tools to make plants to construct them someday, once they have a mining industry, steel industry, oil industry, etc.

Before that date, however, they would like something to explore and map their adopted worlds, as well as explore new worlds. Usefulness for transporting prospectors, surveyors and engineers to places their RPM divinations and dowsing says contain certain resources is also a factor. And, since their slave-taking has made enemies of almost all the locals, scouting for their constant warfare.

Airships seem, at least to me, to be sometning you can build with the limited infrastructure they have, especially with the help of judicious application of RPM rituals and the use of as much local-born labour and materials the locals can supply as possible.

It's not the best possible solution, but imperfect balloons and primitive airships within 2-5 years are better for their immediate needs than perfect transport planes, railways and autobahns in a century or so.

Quote:
Originally Posted by Fred Brackin View Post
Bamboo almost certainly is the best natural structural material you can get but it's not available everywhere and still limits you in size.
As none of the three gates my ASNs have to the only world that is at least somewhat similar to Earth opens anywhere that is not in a European climate zone, it's not obvious how they sould obtain a sufficient supply.

But I agree that in a general sense, it's a very suitable material for small LTA craft in the early stages of man-powered flight.
__________________
Za uspiekh nashevo beznadiozhnovo diela!

Last edited by Icelander; 02-09-2019 at 05:58 PM.
Icelander is offline   Reply With Quote
Old 02-05-2019, 02:11 PM   #135
tshiggins
 
tshiggins's Avatar
 
Join Date: Aug 2004
Location: Denver, Colorado
Default Re: Materials

Quote:
Originally Posted by Icelander View Post
That's a good thought.

In my specific situation, the TL7 people brought along plenty of supplies, but not enough to have a refined petrochemical industry at first. But they could easily have brought some small and efficient early TL7 engines, broken down into man-portable pieces, and a some cans of fuel for emergencies. Still, they'd run out of fuel they brought along before they could refine more (which is a long-term goal, but not realistic until they have more educated locals).

If a TL7 design of a coal-powered engine that has no parts heavier than ca 150 kg would be an improvement over bicycling, they could have brought such engines over. They'll have locals digging coal from surface pits from the start. And coal-powered industry is part of their future plan at any rate, so building coal furnaces, steam engines and eventually coal power plants that make electricity is not merely spending scarce resources on airships, it's part of their core infrastructure project.
I wouldn't use a steam engine. Water is heavy.

Instead, use an Ericsson closed cycle caloric engine, early on, and replace it with internal combustion later.

https://en.m.wikipedia.org/wiki/Ericsson_cycle

Those are highly efficient, although not as powerful, but they're a lot lighter -- especially if the ASNs use magic as the heat source.
__________________
--
MXLP:9 [JD=1, DK=1, DM-M=1, M(FAW)=1, SS=2, Nym=1 (nose coffee), sj=1 (nose cocoa), Maz=1]
"Some days, I just don't know what to think." -Daryl Dixon.
tshiggins is offline   Reply With Quote
Old 02-05-2019, 03:31 PM   #136
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Materials

Quote:
Originally Posted by tshiggins View Post
I wouldn't use a steam engine. Water is heavy.

Instead, use an Ericsson closed cycle caloric engine, early on, and replace it with internal combustion later.

https://en.m.wikipedia.org/wiki/Ericsson_cycle

Those are highly efficient, although not as powerful, but they're a lot lighter -- especially if the ASNs use magic as the heat source.
Hah!

That sounds like the Elemental Furnace (TL4^) that I ruled that the allies of the Antarctic Space Nazis in Svartálfrheim invented during the second generation of the settlement. It's pretty cool if the ASNs were using a non-magical version before their more magically-capable allies figured out how to power the engine with bound elementals.

Well, actually, I figured that they'd invent such a device between Year 10 and Year 20, with the ASNs managing to acquire the technology and make their versions about five years later. If the TL3^ people who are doing their best to reach TL4^ at Meji Restoration speeds had seen designs to work from used by their ASN allies, only lacking the magical power source, it sounds like Year 10 is more plausible than Year 20.

What kind of power-to-weight ratios would you get with TL6 to early TL7 versions of Ericsson closed cycle caloric engines? In kW/kg, if you know it?
__________________
Za uspiekh nashevo beznadiozhnovo diela!

Last edited by Icelander; 02-05-2019 at 03:36 PM.
Icelander is offline   Reply With Quote
Old 02-09-2019, 02:04 PM   #137
tshiggins
 
tshiggins's Avatar
 
Join Date: Aug 2004
Location: Denver, Colorado
Default Re: Materials

Quote:
Originally Posted by Icelander View Post
Hah!

(SNIP)

What kind of power-to-weight ratios would you get with TL6 to early TL7 versions of Ericsson closed cycle caloric engines? In kW/kg, if you know it?
Okay, that took forever. Everybody talks about how quiet and fuel-efficient they are, but nobody puts hard numbers on the power output. :p

Finally found something, though.

A Rider-Ericsson engine with a six-inch diameter bore and a three-inch stroke put out about 1/2 hp, or 0.373 kW at most, and weighed 625 lbs (283 kg).

That's using 1895 technology.

They're dead-simple, though, and used about a tenth of the fuel as a steam engine of comparable size. Unfortunately, the steam engine produced much more usable power.

The caloric engines were really heavy, and eventually wound up primarily used as emplaced engines to pump water at a very low cost in fuel.

The Rand Corporation did a study of their use in electrical power plants in 1979, and found that by running a sequence of them together, they could produce electricity very cheaply using only the heat from the burning fuel.

However, those weren't designed to operate vehicles, either -- they were the size of large buildings.

The basic principle is, the hotter the expansion chamber, the more efficient the engine, but the energy available from hot air just isn't as concentrated as what can be attained from steam -- even though heating the water consumes an ungawdly amount of fuel, by comparison.

Moreover, steam engines fail catastrophically and caloric engines don't, because the pressures are so much less -- which is why the energy is so much less.

If the ASNs can use magic to heat water without using fuel, and can produce safe-enough pressure vessels, then I think steam would probably serve them better -- not as well as internal combustion, but perhaps good enough for early dirigibles.

So, if we compare caloric engines with a steam engine of a similar size, we get about 8 times the performance for 10 times the fuel consumption, and an accompanied risk of catastrophic accident if the pressure vessel fails.
__________________
--
MXLP:9 [JD=1, DK=1, DM-M=1, M(FAW)=1, SS=2, Nym=1 (nose coffee), sj=1 (nose cocoa), Maz=1]
"Some days, I just don't know what to think." -Daryl Dixon.

Last edited by tshiggins; 02-09-2019 at 02:12 PM.
tshiggins is offline   Reply With Quote
Old 02-09-2019, 02:15 PM   #138
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Elemental Furnaces Power to Weight Ratios

tshiggins, below are my current thoughts on Elemental Furnaces, which bind fire elementals and either (or both) air or water elementals in a TL4 device designed to derive mechanical power from the physical interactions between the elements represented by the bound elementals. The specific designs vary, but will probably sometimes incorporate some form of steam and sometimes perhaps a caloric engine, but the ones that are most interesting to the ASNs are all closed-cycle designs in some way.

Quote:
Originally Posted by Icelander View Post
If I use the stats from Pyramid, a TL4^ Elemental Furnace would get about 0.022 kW/kg for a typical example, at whatever size I decide works out as most efficient.

If that's already assuming TL4 connection rod and flywheels, I can estimate that better materials and construction for the machinery that converts the mechanical work of the furnace into useful power would reach 0.03 kW/kg. If that's a theoretical maximum for TL4^, more typical examples might be 0.005-0.015 kW/kg. As the skill of the craftsmen and the power of the mage might vary considerably, I suppose that Elemental Furnaces (TL4^) exist in a fairly wide price range and have different theoretical max power as well as different levels of efficiency in translating that power to something useful, but will tend to range from 0.005-0.03 kW/kg.

The modern Svartálfrheim models used for industry on that world by Year 51 will be Elemental Furnaces (TL5^) that use fairly well engineered connecting rods and flywheels, but with less advanced materials than ASNs would use for something so valuable. They'd generally get 0.03-0.05 kW/kg and be available for sale to civilians, but so expensive that only senior SS men, successful farmers cum neo-feudal 'Junker' landowners, and Neue Ruhr industrialists could consider the purchase.

Elemental Furnaces (TL5^) combined with TL7 engineering for the machinery translating the theoretical maximum to useful work will be capable of at least 0.06 kW/kg, with designs that push the safety envelope, and require much more maintenance than lower-powered civilian types, possibly getting equivalent performance to real-world Zeppelin engines (which is awesome, when you consider that you don't have to carry fuel).

I imagine that TL6^ magitech steam engine designs are in the early development phase by Year 51, but those would not be Elemental Furnaces per se, but rather advanced real-world steam engine designs that make use of bound elementals, without necessarily being fairly low-pressure closed-cycle furnaces. I further imagine that given how magic and technology do not play nicely together, this field of research is about as safe as testing explosives in a fireworks factory.
__________________
Za uspiekh nashevo beznadiozhnovo diela!

Last edited by Icelander; 02-09-2019 at 05:57 PM.
Icelander is offline   Reply With Quote
Old 02-10-2019, 01:11 AM   #139
tshiggins
 
tshiggins's Avatar
 
Join Date: Aug 2004
Location: Denver, Colorado
Default Re: Elemental Furnaces Power to Weight Ratios

Quote:
Originally Posted by Icelander View Post
tshiggins, below are my current thoughts on Elemental Furnaces, which bind fire elementals and either (or both) air or water elementals in a TL4 device designed to derive mechanical power from the physical interactions between the elements represented by the bound elementals. The specific designs vary, but will probably sometimes incorporate some form of steam and sometimes perhaps a caloric engine, but the ones that are most interesting to the ASNs are all closed-cycle designs in some way.
Yeah, I'd use these. Steam engines that don't require fuel are pretty awesome.
__________________
--
MXLP:9 [JD=1, DK=1, DM-M=1, M(FAW)=1, SS=2, Nym=1 (nose coffee), sj=1 (nose cocoa), Maz=1]
"Some days, I just don't know what to think." -Daryl Dixon.
tshiggins is offline   Reply With Quote
Old 02-10-2019, 05:02 AM   #140
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Elemental Furnaces Power to Weight Ratios

Quote:
Originally Posted by tshiggins View Post
Yeah, I'd use these. Steam engines that don't require fuel are pretty awesome.
Until Year 10-15 at the earliest, the ASNs had no idea the concept was even possible and they couldn't make their own working Elemental Furnaces until the Year 15-25, depending on exactly how revolutionary I decide it is for TL3^ engineers with TL3+1^ in some fields, largely related to magical perpetual motion machines, to come up with the idea of binding elementals to make magitech versions of caloric or steam engines they learn about from the ASNs.

Which, in turn, depends on whether some form of non-magical caloric or steam engine would have been used by the ASNs in the earliest era of their history. I know the ASNs used coals as the primary source of energy from the first, but what kind of coal-fueled engine makes sense for power plants for early TL7 people forced to gear down in the absence of a world economy, industrial base, infrastructure and enough workers with higher TL, I have no idea.

I also have no idea what kind of engine the ASNs would use for their earliest LTA craft. The ASNs will arrive with firm plans for powered flight and a mandate to build observation aircraft as soon as possible, with something steerable and capable of transporting surveyors some hundreds of kilometers set to follow as fast as the hundreds of former Zeppelin engineers and technicians could figure out, with a workforce of thousands of TL2-3 people and the assistence of a few hundred TL3^ experts, with TL3+1^ in some limited technologies.

With the supplies the ASNs brought over, there would be all the hand tools they could want, plenty of smaller machines and anywhere up to a couple of hundred tons of TL7 engines of some sort they intended for the first LTA designs (as long they have no indicidual piece much over 400 lbs.). There can also be up to 500 short tons of TL7 fuel, but only if LTA flight is perceived as utterly impractical with some kind of fuel they could extract locally in the first few years.

In any case, relying on limited supplies of fuel you can't replace is bad design and if there is any possible non-magical engine technology that you feel would be possible to extract fuel for without any kind of existing petrochemical industry in their new home, I'd rather their early aidship designs relied on that, even if it made them much slower. Anything that allows more mobility and better scouting than walking or riding gives them a comparative advantage, anyway.

If there is some way to make airships that can use any kind of fuel that could be made, even in limited amounts, by maybe a hundred TL7 engineers and technicians with fairly light equipment, dedicated to that task alone, without needing a large scale TL5+ industrial base (TL2-3 labour would be available in vast hordes), it would be more efficient to bring more tools and macines for bootstrapping local industry and not waste vital transport capacity on consumable fuel that won't be replaced for a generation or more, so any technology that relies on it is a developmental dead end until then.

What would early TL7 engineers with extensive knowledge of airship design and history have planned to make in the first few years in the new world if they'd had 12-15 months on TL7 Earth to plan how to build LTA scouting capabilities without access to the infrastructure they were used to on Earth?

In addition to many of the former workers of Zeppelin and several senior people who worked on the most advanced Zeppelin airships in the 1930s, the 300+ TL7 experts devoted to the project of airships and their fuel includes people from the German Wunderwaffen projects, engineers like Ferdinard Porsche, physicists and materials scientists, metallurists from many German firms if needed, industrialists and engineers from many of Germany's biggest tech firms in WWII, chemists from IG Farben and anyone that the ASNs could recruit with specialized know-how useful in bootstrapping LTA technology.

And maybe a few hundred TL7 people who aren't genius inventors, doctors of engineering or airship experts, but who have spent the last few years as foremen, overseers, machninists and mechanics at factories where they had to teach unskilled workers how to make all sorts of TL6-7 stuff, as well as logistics officers and industrial managers used to having to work around wartime shortages and come up with alternate technological solutions that don't rely on resources they no longer have access to.

The most senior of the design team would be told about rune magic, alchemy and vril, and the design team would be assigned a few Ahnenerbe occultists as advisors while they were still on Earth, to work with them on determining what magic could contribute to airship design. The ASNs would not view magical power supply or engines as practical, but lightened and strenghtened low-tech materials would be something they'd consider very possible to make in their new homes, in large quantities if the materials are something TL2-3 people are used to working with.

Lightening hydrogen and warming it, so that it has almost as much lift as vacuum, is also possible. For that matter, with magic, even coal gas would have decent lift, for the earliest balloons, before the hydrogen team has established a supply. And the occultists could tell the engineers that using ritual enchantments and/or alchemical solutions, any kind of fabric could be treated to give a gas seal as good as goldbeater's skin.

What kind of LTA craft the ASNs initially build and what their future plans were for Year 10+ has a lot of impact on what kind of designs would follow once they get wind of Elemental Furnaces.
__________________
Za uspiekh nashevo beznadiozhnovo diela!

Last edited by Icelander; 02-10-2019 at 05:34 AM.
Icelander is offline   Reply With Quote
Reply

Tags
airship

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 02:08 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.