Spaceship Design: What makes sense, and what's nonsense?

[Anthony]

Originally Posted by Michael Thayne

The video game Children of a Dead Earth claims to be rigorously realistic in almost all respects and the ships look pretty cool IMHO. Incidentally, the warships in that game tend to have pointy noses even though they're not intended to fly in atmosphere. Rather, the game is trying to model the benefits of using sloped armor.

Sloped armor won't be terribly relevant against beam weapons, or against kinetics at space combat speed (it basically increases defense by the same amount as it increases weight).

[Michael Thayne]

Originally Posted by Anthony

Sloped armor won't be terribly relevant against beam weapons, or against kinetics at space combat speed (it basically increases defense by the same amount as it increases weight).

A lot of ships in CoaDE are built for low-velocity intercepts. When I used to play the game, I tended to go for high-velocity intercepts myself, but I could never tell if this was a good tactic or if I had just found a blindspot in the AI.

[Fred Brackin]

Originally Posted by Michael Thayne

A lot of ships in CoaDE are built for low-velocity intercepts. When I used to play the game, I tended to go for high-velocity intercepts myself, but I could never tell if this was a good tactic or if I had just found a blindspot in the AI.

If you want intercepts and hard kills rather than rendevous and disables high velocity is great.

Armor on the other hand is pretty dubious. Even just abating the effect of high velocity KE weapons, ionizing beam weapons and nukes would be incredibly hard. Only a deeply spaced sort of honeycomb with many layers would be worthwhile at all (and they'd be ablative). Solid slabs of armor consisting of any sort of normal matter would just become a medium to conduct the blast wave or a source of secondary radiation.

Until there is a enough of a space-based economy to build big ships size is sharply limited. Just a SM+8 ship in Spaceships is a 1000 tons and that's 50 loads for the space shuttle (or similar vehicle) or 10 loads for the biggest heavy lift vehicle I think is realistic for Earth-launch.

A million tons is of course 1000x as many lunches required. If you've got enough space-based industry to handle that Earth-like planets are used as nature preserves or at perhaps luxury housing.

[Michael Thayne]

Originally Posted by Fred Brackin

Armor on the other hand is pretty dubious. Even just abating the effect of high velocity KE weapons, ionizing beam weapons and nukes would be incredibly hard. Only a deeply spaced sort of honeycomb with many layers would be worthwhile at all (and they'd be ablative). Solid slabs of armor consisting of any sort of normal matter would just become a medium to conduct the blast wave or a source of secondary radiation.

CoaDE is extremely conservative in tech assumptions—it doesn't even have everything GURPS calls TL9. So no x-ray lasers or charged particle beams, and even UV lasers are usually more trouble than they're worth. My memories of playing the game are that armor tended to be effective against (non-ionizing) lasers, conventional guns, and electromagnetic guns. It was not a remotely reliable defense against missiles, though rare occasions it might, say, save your butt against a small nuke detonated some distance from your ship. Though I don't think CoaDE tried to model transmutation due to neutron flux; nukes were treated purely as a source of electromagnetic radiation that would melt your ship at close range.

[Fred Brackin]

Originally Posted by Michael Thayne

C. Though I don't think CoaDE tried to model transmutation due to neutron flux; n

No one should. A high energy neutron from a nuclear explosion carries a lot of KE relative to an atomic nucleus. Any nucleus it hits will go flying and break the molecular bonds of a significant number of other nuclei that were in its' way.

When you're being hit by large numbers of those neutrons they should be treated as ionizing radiation rather than a source of heat. Individual atoms transformed by neutron capture are just anomalies in the ion cloud.

[hal]

If I were to design a probable history for the future, I'd likely go with something like this:

The Billionaire who shall not be named but is working in theory towards a Mars colony will invest in two types of technology:

1) Chemical propulsion to get out of the gravity well

2) Cheap interplantetary propulsion for the economics involved

#2 would imply something like solar sails or perhaps magnetic sails. #2 would also perhaps bypass the need for a Mars Cycler. If not, then I could see a Mars Cycler being put into play as well. The idea is to make moving mass materials from Earth over to Mars.

I'd also deal the Chinese in as being the first to actively build a Lunar Base. Whether the new functionality of satellites (Chinese) of being able to deorbit already existing satellites is a good thing or the prelude to war is in open debate at this point in time (orbital cleanup to avoid another Russian incident involving a warhead destroying a satellite and allowing its debris field to threaten the space station).

In the end? The designs for ships with sails would look decidedly different than those designs for chemical rockets. Any other form of propulsion will have its own issues, something that I think/hope can be dealt with via GURPS SPACESHIPS.

If as suspected, low gravity causes problems with hemoglobin production, then chances are that absent wonder tech that promotes gravity plates (TRAVELLER style) - then rotational habitats would become a necessity for long term space voyages. If you can place people in what amounts to hibernation (such as mammals experience in winter or suspended animation of some sort) then it is possible your "realistic" ships will have different design criteria.

So, Step 1 for any "Near future" Campaign universe? Earth experiences another space race, and one Billionaire's dream comes true with a Mars Colony, while another comes true with Luna. Space stations are put into orbits (Small affairs such as detailed in TRANSHUMAN SPACE) become commercialized in the production of manufactured low G materials. China begins to build a dual purpose Maglev on the Surface of Luna to send materials mined on the Moon back towards Earth - which causes some tensions to rise as such a peaceful "tool" could become a weapon turned against nations of Earth.

Detente follows - and Earth continues despite the perils involved - with both native born Humanity on Mars (and perhaps Luna) add to the population being transported to non-Earth worlds.

Use either TRANSHUMAN SPACE rules for building space craft, or use GURPS VEHICLES 2nd edition to build them, or even GURPS SPACESHIPS and see what you can come up with. Best of all? Try to justify WHY those spacecraft even exist and what it takes for a corporation to even BUILD those space craft in order to justify a return on investment as well as cost of operations.

THAT is what GEARHEADS love to do. Isn't it? ;)

[WingedKagouti]

Originally Posted by FenrisLoki

So realism is not really a strong point of Star Wars or Star Trek designs. Those are mostly aesthetic. Swoopy closed shapes are fine, but unless your FTL system has a fluid "drag" in its hypothetical physics, there's no real reason for it. People may decide to build that way, but it isn't a necessity.

It's worth noting that most Star Wars spaceships are (in-universe) intended to operate in many types of atmosphere as well as in (hyper)space. Of course, the actual designs are influenced far more by "will it look cool on screen" and "will the toy sell" than any actual workable real world engineering considerations.

[FF_Ninja]

Originally Posted by WingedKagouti

It's worth noting that most Star Wars spaceships are (in-universe) intended to operate in many types of atmosphere as well as in (hyper)space. Of course, the actual designs are influenced far more by "will it look cool on screen" and "will the toy sell" than any actual workable real world engineering considerations.

I believe George Lucas is quoted as something like "I want cars in space."

[FenrisLoki]

Originally Posted by FF_Ninja

I believe George Lucas is quoted as something like "I want cars in space."

I wouldn't doubt something like that. But Star Wars is essentially World War 2 with a skin of higher tech. Computing power is laughable, there is no internet, communications is difficult, and the fighters act just like airplanes in space.

[Fred Brackin]

There are some highly detailed level questions about shape for cross-sectional area and fields of fire for skin-mounted weapone (i.e. turrets).

For those factors the imperial Star Destroyer's "spearhead design" isn't a bad one. It minimizes frontal cross-sectional area while allowing all (or almost all) guns to fire directly forward. When you can't face your target head on having a thinner side (edge on) allows you to reduce area while still allowing at least half the guns to bear.

Of course all of this is "except for the superstructure". ISD's have that honking big superstructure sticking up from the back part of the hull because WWII and modern carriers do.

Oh, and the hull is covered by engineering nooks and crannies because some people really groove on detail. If stealth against active sensors was a factor the hull would be as smooth as you could make it. To make targeting critical areas under the skin as difficult as possible too.