Re: [Spaceships] TL10 Space RV
 

In for a penny, in for a pound. A 0.1g reactionless engine allows a SM+4 spacecraft to reach 370 mps after a week of acceleration, meaning that it is a potent kinetic energy weapon. No rational society allows random civilians to have vehicles that are the equivalent to 350 ktons of TNT (the drives may exist in a rational setting, but they will likely be reserved for military use).

That being said, you can make the same SM+6 design with 0.2g base acceleration, it is just slower. It costs around $2.5M when you replace the 2g engines with 0.2g engines, and requires around $50,000 a month in income to keep going. It takes a little less than 1 month to go from the Earth to Saturn (and back), meaning a maximum velocity of over 700 mps.

Re: [Spaceships] TL10 Space RV
 

No, The OP has been working with these numbers pretty carefully. Telling him he should multiply both his power ratio and weight by x10 without showing that the original version doesn't work is a touch pushy.



I am somewhat amazed that the .1G version seems to be capable of doing what its asked to. Its a ridiculous contraption that will take some odd infrastructure and lots of time, but it does seem doable, against my expectations.


I do think a .2G version will perform much better, and it adds landings to the moon, Io, Ganymede, Europa, and Callisto. You add 20% to the cost of the vehicle, which isn't too bad.

Re: [Spaceships] TL10 Space RV
 

Silly phrasing of a setting detail: "The traffic cops have nukes, and aren't afraid to use them." (See last paragraph of thread's initial post.)


That sounds like an entirely reasonable craft. (Though it probably only needs 1 external clamp system; SS8 suggests that one system covers all of a ship's external cradles. Or maybe even 0 systems, taking a telescoping robotic arm from SS8p9 instead.)

I expect that there are a lot of different designs that take advantage of the available tech, at least as many as in baseline THS, for just as wide a variety of purposes.


Amusing detail: It looks like the draft of the Space RV in post 26 could push itself up to 0.2c, and make it to Alpha Centauri in under 22 years, without completely ablating its armour. Surprisingly cheap STL colonization compared to a lot of settings - it wouldn't take much larger of a craft to carry enough armour to get a better coasting speed, and enough robofacs and gene-banks to start Von Neumanning.


Next on my to-do list: Dig up my old copy of GURPS Mars, to figure out how far along in the terraforming process the planet would have to be in order for the Space RV's wings to provide enough lift to allow for landing and takeoff. (I'd like to go with a slightly more realistic terraforming timescale than in baseline THS; probably lots of domes, the reactionless thruster tech has probably made it easier to divert some comets to impact into the Hellas basin...) I found one RAW implying that as long as the pressure's at least 0.01 Earth's, the craft can fly; which would only need to double Mars' atmospheric mass, which could be done with a single, fairly modest comet.

(I've also made notes from THS:In the Well and THS:Deep Beyond that the craft would melt if it got to Mercury's orbit or inside Venus's atmosphere; and that it could dive into a gas giant down to 339 bars of pressure, which is below Jupiter's cloud layers; which still leaves a pretty wide range of places to go.)


The current draft, on post 26, is 0.2G. :)

Re: [Spaceships] TL10 Space RV
 

Got another optimization question to ask the hive-mind;

For civilian meteor-defense, should I stick with Spaceships' very-rapid-fire improved laser, in a central turret (30 kJ, dDmg 1d-2(2) burn/dmg 6d(2), RoF 200/20s, rng C or 150/500 mi, $100k, 0.5 tons/1 space); or should I hit the THS vehicle design system, and replace it with a couple of 2.5 kJ lasers in pop turrets (dmg 3d Imp, 1/2D range in space 15.8 miles, Max range in space 22.7 miles, RoF 8 per second) (each turret also holds two E-cells, enough for 2,880 shots; and each pop-turret and its contents takes up 6 cf, 0.061 tons, and costs $11,050)?

Two such pop-turrets only take up about a quarter-space of mass, and the remaining saved space could be used to squeeze in a bit more cargo or built-in equipment. But I'm not really sure whether the lower damage and shorter range is good enough to handle the occasional micrometeor.

Any opinions?

Re: [Spaceships] TL10 Space RV
 

I think you may have misread the THS laser stats. A "light laser" in THS is 2.5MJ and weighs 5 tons. Unless you mean the 20kJ tactical lasers from Deep Beyond—in which case I would use the stats from Transhuman Space: Changing Times and basically treat them as cargo.

Re: [Spaceships] TL10 Space RV
 

Actually, I'm looking at In the Well, pages 130 and 108, for the 2.5 kJ laser's stats. (And meshing the THS build system with Vehicles, to turn the former's turrets into pop-turrets.)

Re: [Spaceships] TL10 Space RV
 

While not quite RAW, an old UT vs SS analysis I did implies that the full-power SS beam weapons could be used at RoF 10 instead of their current RoF 0.05 (thus RF would be RoF 100, VRF would be RoF 1000); I took this to mean the low RoF of SS lasers was due to power constraints - that is, 1 PP can only provide enough power for 1 shot every 20 seconds for a full power Major Battery. This was based largely on the blaster rifle, which has an appropriate weight and damage for a full-power SM+0 Major Battery, but has RoF 10 rather than the predicted RoF 0.05 of SS (other beam weapons of equal damage have roughly comparable weights, it's just the blaster rifle that hit it dead-on).

If that doesn't sound too reaching to you, you could boost your RoF by 200x without any loss of damage by giving up some cargo space for an array of rechargeable power cells. A 3 MJ laser (30d(2) burn damage, or 3d(2) burn dDmg) would get roughly 5 shots out of a 20 lb E cell at TL 10 (based on the 1/100th power blaster rifle getting 5 shots out of a C cell, which is conveniently 1/100th the power of an E cell), implying around 4 lb per shot. Sacrificing 1 cargo bay for 0.5 tons of energy bank would cost $20k, but would get you 250 shots (enough to continually fire at RoF 10 for 25 seconds), and shots would replenish at a rate of 1 shot every 20 seconds* for each PP you allocate to recharging the energy bank. If you'd prefer RoF 100 (or a Secondary Battery of 10 RoF 10 lasers), you could drop to 300 kJ (12d(2) burn damage, or 1d+2(2) burn dDmg), in which case that same energy bank would get you 2,500 shots, and shots would replenish at a rate of 1 shot every 2 seconds for each PP. In an emergency, the full energy bank can provide power to one rotary drive for up to 5000 seconds (a bit over 83 minutes), or to both of them for up to 2500 seconds (a bit under 42 seconds). Note you might be able to exploit this to avoid needing two fission reactors if you only have the second rotary drive for purposes of reaching orbit - you could power the second drive with the energy bank, then once you reach orbit spend some time (roughly as long as it took you to reach orbit) drifting to recharge your energy bank, then go on your way at 0.1G. That's only possible if you can reach orbit from the ground within 80 minutes (or at least can get to a point within 80 minutes that lets you use 0.1G to get the rest of the way); unfortunately, I don't know how long 0.2G takes to get you to orbit, as the equation from SS1:38 gives a negative number (?) if acceleration is less than the force of gravity and air speed is less than 80% of escape velocity.

As for how much of a punch you'd want from your lasers, SS5:39 implies most meteoroids that would be problematic have dHP around 0.006 (or HP around 0.06) - anything larger would likely be detected far enough away you could either alter course to avoid it or use your lasers from a distance to nudge it out of the way. Keeping in mind they're so small (SM -10), and even a personal holdout laser would vaporize them, the higher the RoF, the better. If you anticipate needing to deal with larger meteors or debris for whatever reason, going off the table from SS4:36 the 3 MJ laser requires roughly (going off average damage, and rounding hits up) 4 hits to stop (reduce to -5xdHP) a SM+0 chunk, 6 to stop an SM+1 chunk, 8 to stop an SM+2 chunk, 12 to stop an SM+3 chunk, and so on. A 300 kJ laser requires about twice as many hits, while a 30 kJ requires about 5x as many hits. You may want to base your damage off of the sort of chunks you anticipate encountering, but honestly 30 kJ (with up to RoF 1000) should be more than sufficient.

*Optionally, because TL 10 sees a x2 RoF for visible-light lasers in SS, you could argue for this being a recharge rate of 1 every 10 seconds, or one every second for the 300 kJ laser(s).

Re: [Spaceships] TL10 Space RV
 

Speaking of; I'm now pretending that SS4 lets me buy a secondary battery for a SM+4 ship; for a retractable, turret, very-rapid-fire, improved laser, that's all the way down to 3 kJ, which is close enough to the THS laser I was thinking of. Sell back eight of the ten, and I've got the lower-cost defense I was thinking of above.


It feels odd that not one of the Spaceships books included power cells, capacitors, or battery tech. I have to wonder if that was a deliberate choice, to direct ship-designers interested in chemical power-storage to use fuel cells or MHDs for the stats.


It didn't give me a negative number...

... Oh, are you treating that dash on the end of the line as a minus-sign? It's not really supposed to be there; just compare the equation to the one for escape velocity just below it.

... or maybe you didn't apply the text that a winged vehicle treats the planet's gravity as 0?

There's so many ways I've made mistakes with GURPS equations over the years. :)


I found some old notes of mine, for a ship with worse sensors, worse acceleration, and less damage per second; and was able to work out that for micrometeors moving at average orbital speeds, they were either too small to get through the armour, or were small enough to get shot down between when they were detected and when they impacted, or were big enough to get detected far enough out that the ship could move out of its way.



On a related note; for Ultra-Tech's fabricators, are there any costs or weights listed anywhere for printer cartridges? (I'm planning on throwing in a suitcase minifac for spare parts, and am trying to figure out how much weight to allot to its raw materials.)

Re: [Spaceships] TL10 Space RV
 

Roughly speaking, one system of UT power cells will, by my calculation, provide 1 power point for all of 80 minutes, which is pretty much nothing in Spaceships terms. Of course, there's also the issue that UT has vastly different assumptions - most SS power plants gain roughly x2 endurance 1 TL after introduction, while UT power cells gain x10 per +1 TL (additionally, at TL 12 UT Grasers use 10x as much power as an equal-output TL 11 X-ray laser or blaster, which use 10x as much power as an equal-output TL 10 laser; in SS, all beam weapons use roughly the same amount of energy, with those that have been out for over 1 TL being twice as efficient). Indeed, there are a lot of things that UT assumes is x10 that SS does as x2, like beam weapons 1 TL after introduction. Not having UT power cells may well have been a way to sidestep that particular issue.

That's the one. That in mind, it looks like, again assuming 200 mph, 0.2G will get you from the surface to orbit in ~76.9 minutes; seeing as the energy bank lasts 80 minutes, that leaves you with only 4 minutes, 52 seconds to spare. So, doable, but perhaps a bit risky.

Re: [Spaceships] TL10 Space RV
 

Where does it say that UT power cells gain x10 capacity every TL?