I'm feeling like a Quixote type character in pursuit of hard science fiction Traveller space opera instead of windmills. So far I've examined a variety of different options, some offer to solve the problem by throwing out half or more of existing Traveller works (adventures and such), others just don't make the bar for one reason or another, still others may require quite a bit of work refactoring trade and commerce even the value of a credit, finally there are a few that would sort of work but for one reason or another I just don't like. My last post concerned one such option, basically redefining the Traveller Jump drive operation to allow for the wilderness option. I'm still unsure as to the side effects of that option and it allows for the 'go anywhere' ftl style I really don't like.
Once again I'm drawn back to the Lares fixed point ftl and keyhole drive option. Accepting a certain degree of increased travel times and interface costs seems unavoidable. While earlier I examined the options of extending the handwave of ftl into a sort of slow stutterwarp or fast microjump those solutions felt clumsy. One option I've avoided examining very closely is that of extracting the underlying whatchamacallit in the handwavium ftl, defining its effects, and extending it to other technologies such as reaction drives. Traveller does this with practically every handwavium technology and also shows the pitfalls inherent in doing so; chief among them the tendency for handwavium creepage leading to setting domination.
I've discussed this with a friend who pointed out that extending the handwavium to incorporate the core technology whatchamacallit of the game Mass Effect would solve most of the problems. While I don't disagree that it is an option, I don't like the direction it leads. However, while considering it, I did think a bit about the handwavium of the Quantum Skip drive. The basic idea is that using a rather large but extremely short pulse of energy in a controlled fashion we somehow are able to distort the local frame of space time and trigger a quantum effect that does the actual work. Might earlier experiments along those lines have been aimed at increasing reaction drive Isp?
Now at some absurd tech level with 99.99% efficiency we might create a drive with an Isp as high as 2.93966571 × 109 or 816,573.8 G-hours of thrust per ton of fuel.. yeah. Of course even with 99.99% efficiency, generating any significant amount of thrust would require our ship to basically be all radiator to avoid vaporizing moments after engine ignition. The stock answer to the Isp, thrust, and heat issues seems to be either ignore it altogether or assume some handwavium to allow heat levels in the engine that would vaporize any known material nearby instantly.
Looking back to the math hacking I did the other day in 'An Ode to Simplicity', we can see that extending travel time for the trip between planetary orbit and ftl point to around two weeks each way brings us into the realm of plausible 3He2H magnetic bottle fusion engines. Well plausible to some. Call me cynical but we've seen fusion power as being on the near horizon for forty years now and really we don't seem to be much closer than we were shortly after starting. Then consider that turning a magnetic bottle fusion reactor into a rocket engine is at least one hundred times more challenging in engineering.
The next 'breakpoint' seems to come at around 49 days each way, with 0.05 m/s^2 of thrust as we could reasonably expect from an advanced magnetoplasmadynamic drive. Each transit would require about 212.1km/s delta-V, so to meet our 50% fuel load requirement we'd need an Isp of about 61200 which could also possibly be expected from the same drive. I like this point except 49 days is nearly 50% over what I'd really want to see as the maximum average.
My ideal drive would have a 27 day transit time (x2 = 54) and the same 50% fuel load requirement. This would require a constant acceleration of 0.17 m/s^2, a delta-v of 386km/s per transit, and an Isp of around 112000. This is a substantial improvement over our advanced magnetoplasmadynamic drive and may be past the capabilities of even advanced technologies based on known physics. On the other hand I have some oddball ideas, totally fictional of course, but what if you combined a NTR with a VASIMR? What if there was some quantum handwavium along the lines of the Quantum Skip drive technology that, in an earlier form, allowed some higher powered 'pulse mode' operation? At the same time, the acceleration/Isp requirements for this level of performance seem to be well within the range of plausible 3He2H magnetic bottle rockets.
Rather than get into detail about 'how it works', I could simply call it the standard deep space drive and let it go at that. That follows along with the idea in yesterday's post of packaging the interface engine into a simple to use drive package. I'll call it the AMPR (Advanced Magneto Plasma Rocket).
Monday, May 21, 2012
A different look at Traveller's jump drive
As I work towards creating a more realistic, harder scifi basis, alternate Traveller universe, I've found that seemingly small changes in travel times can have disconcerting effects on trade and commerce. The problem is that sticking to the travel times in the mainstream Traveller universe makes it impossible to have realistic reaction drives together with fixed ftl points such as Alderson points. For many reasons I greatly prefer fixed ftl points but not at the cost of realistic reaction drives.
From a hard science fiction standpoint the root objection is the 'matter density' basis for jump drive distance. While simple to calculate, it doesn't fit with common science fiction requirement of microgravity conditions for ftl drives. Then there is that whole mess with jump shadowing, jump masking, meh.. not something I want to deal with.
Traveller has two distances of note in regards to jump drive operation, the ten diameter and the one hundred diameter 'limits'. Let's assume a standard density size 8 planet was the basis for the original specification and examine what the gravity gradient is at the limit distances. For the ten diameter limit, that works out to roughly 0.024 m/s^2, and for the one hundred diameter limit 0.00024 m/s^2.
Earlier on I'd tried using the 100D limit to determine a ftl gravity limit but ran into problems in that the sun in our solar system has a stronger effect at earth's distance than the earth would at the 100D limit. That is, the sun's influence at 1 AU distance is 0.00593 m/s^2; greater than the 0.00024 m/s^2 influence of earth. This caused great confusion!
What if instead we say that as long as we are beyond the inner limit of the system's center (normally star) where the gravity influence is less than 0.025 m/s^2 that the nearest planetary body is the primary object of concern. In other words, the stellar influence is assumed in the ftl navigation calculations but individual planetary bodies have a destabilizing effect on the greater equation. So, +5 to misjump roll if inside the 0.00025 m/s^2 influence of the nearest planet, +10 to misjump roll if inside the 0.025 m/s^2 influence of the system's center, and +15 to misjump roll if inside the 0.025 m/s^2 influence of the nearest planet. This is a tad more complicated, though can be easily enough precalculated, and pretty much eliminates jump shadowing. As for jump masking, phfft, gravity only is of concern in transition between normal space and jump space - problem solved.
With that out of the way, to satisfy the wilderness scenario, we need a suitable reaction drive. My favorite candidate is the Trimodal Augmented Nuclear Thermal Reactor with scramjet option! Unfortunately, my earlier version of the TANTR needs reworked to be able to achieve surface to orbit for a standard gravity world. Let's see what our requirements are; we have three phases of flight - VTOL, scramjet, and orbital. A rocket normally needs about 10km/s of delta-v for surface to LEO given a standard world. With an airframe configuration we can probably knock off 1km/s. For LEO to jump point, lets call it a Brachistochrone trajectory with a constant 5 m/s^2 acceleration. That will require another 50km/s of delta-v. Now on the other side of the jump point, we'll need the 50km/s again plus another 1km/s (aerobraking for the rest), this gives a total delta-v requirement of 110 km/s.
Because of needing extra fuel during the vtol and scramjet stages, we'll call our total requirement 130km/s but use our normal cruise mode Isp figure of 1800. Oh wow, only need 1370 times our payload mass in fuel! Obviously this won't work. Ok, lets assume we only supply 30km/s of our delta-v with our TANTR+S engine, that requires a bit over 81% of our ship's total mass.. hmm.. see a problem yet?
If we somehow get back to our original 10km/s for the total surface to LEO and back again delta-V budget along with dropping our Isp to 1200 to reflect the additional fuel load, we find that only 57% of our ship needs to be fuel for takeoff and landing. Hmm.. rereading some SSTO literature, it looks like the effective Isp of scramjets may be much higher than I'd thought, rather than assuming a lower figure I should be assuming a higher one (than cruise mode). Assuming that, for a moment, lets suppose 1/4 our delta-v comes from 1200 Isp mode, 1/4 from 1800 Isp mode, and 1/2 from 3600 Isp mode. So 2.5 km/s from the 1200 requires 19%, another 2.5 km/s from 1800 requires 13%, and 5 km/s from 3600 requires another 13% for a total of 45% of wet mass in fuel. Obviously these are rough figures!
Now if we're willing to take our time, say 2.6 days, and use a cheaper orbit transfer to jump, we only need an additional 22.4km/s or 81.2% of our remaining mass.. hrrmm that not work either!! Ok, if we're willing to take 8.2 days!! we only need 7.1km/s and at 1800 Isp that needs 33% of our remaining mass. Going back and adding in 2x the 7.1km/s figured (round trip) to the 2.5km/s delta-v we needed earlier at 1800 Isp we get about 60% of the remaining mass required in fuel. Now watch me screw this up - total payload is then 81% x 40% x 87% x 81% or roughly 23%; 77% of the ship needs to be fuel.
Assuming the above analysis is remotely correct, TANTR+S is a marginal solution for the wilderness scenario and requires an extra couple of weeks in travel time. This doesn't necessarily kill the idea entirely. One possibility would be to use the TANTR+S only for the interface and have a higher efficiency drive for the LEO to jump point portion. At a cost of 5 tons of payload mass, a MPD driven by power from the TANTR+S in reactor mode would have an Isp of 36000. This would reduce the largest chunk of fuel required to only 2% instead of 60%! Total payload would then be 55% of the wet mass minus the mass of the MPD.
To make things simpler, I likely need to create standard engine packages that encapsulate the various modes and Isp's into something much simpler to use both in design and in play. The above process would rapidly drive me to distraction. Still, it has been a necessary step, coming to better grips with the actual environment before trying to create simpler abstractions of it.
PS: There's a much better look at Traveller's jump drive mechanics and a way of getting out of the stellar jump shadow mess with gravity based calcs here. Turns out this was a topic on the Traveller Mailing List a long time ago.
From a hard science fiction standpoint the root objection is the 'matter density' basis for jump drive distance. While simple to calculate, it doesn't fit with common science fiction requirement of microgravity conditions for ftl drives. Then there is that whole mess with jump shadowing, jump masking, meh.. not something I want to deal with.
Traveller has two distances of note in regards to jump drive operation, the ten diameter and the one hundred diameter 'limits'. Let's assume a standard density size 8 planet was the basis for the original specification and examine what the gravity gradient is at the limit distances. For the ten diameter limit, that works out to roughly 0.024 m/s^2, and for the one hundred diameter limit 0.00024 m/s^2.
Earlier on I'd tried using the 100D limit to determine a ftl gravity limit but ran into problems in that the sun in our solar system has a stronger effect at earth's distance than the earth would at the 100D limit. That is, the sun's influence at 1 AU distance is 0.00593 m/s^2; greater than the 0.00024 m/s^2 influence of earth. This caused great confusion!
What if instead we say that as long as we are beyond the inner limit of the system's center (normally star) where the gravity influence is less than 0.025 m/s^2 that the nearest planetary body is the primary object of concern. In other words, the stellar influence is assumed in the ftl navigation calculations but individual planetary bodies have a destabilizing effect on the greater equation. So, +5 to misjump roll if inside the 0.00025 m/s^2 influence of the nearest planet, +10 to misjump roll if inside the 0.025 m/s^2 influence of the system's center, and +15 to misjump roll if inside the 0.025 m/s^2 influence of the nearest planet. This is a tad more complicated, though can be easily enough precalculated, and pretty much eliminates jump shadowing. As for jump masking, phfft, gravity only is of concern in transition between normal space and jump space - problem solved.
With that out of the way, to satisfy the wilderness scenario, we need a suitable reaction drive. My favorite candidate is the Trimodal Augmented Nuclear Thermal Reactor with scramjet option! Unfortunately, my earlier version of the TANTR needs reworked to be able to achieve surface to orbit for a standard gravity world. Let's see what our requirements are; we have three phases of flight - VTOL, scramjet, and orbital. A rocket normally needs about 10km/s of delta-v for surface to LEO given a standard world. With an airframe configuration we can probably knock off 1km/s. For LEO to jump point, lets call it a Brachistochrone trajectory with a constant 5 m/s^2 acceleration. That will require another 50km/s of delta-v. Now on the other side of the jump point, we'll need the 50km/s again plus another 1km/s (aerobraking for the rest), this gives a total delta-v requirement of 110 km/s.
Because of needing extra fuel during the vtol and scramjet stages, we'll call our total requirement 130km/s but use our normal cruise mode Isp figure of 1800. Oh wow, only need 1370 times our payload mass in fuel! Obviously this won't work. Ok, lets assume we only supply 30km/s of our delta-v with our TANTR+S engine, that requires a bit over 81% of our ship's total mass.. hmm.. see a problem yet?
If we somehow get back to our original 10km/s for the total surface to LEO and back again delta-V budget along with dropping our Isp to 1200 to reflect the additional fuel load, we find that only 57% of our ship needs to be fuel for takeoff and landing. Hmm.. rereading some SSTO literature, it looks like the effective Isp of scramjets may be much higher than I'd thought, rather than assuming a lower figure I should be assuming a higher one (than cruise mode). Assuming that, for a moment, lets suppose 1/4 our delta-v comes from 1200 Isp mode, 1/4 from 1800 Isp mode, and 1/2 from 3600 Isp mode. So 2.5 km/s from the 1200 requires 19%, another 2.5 km/s from 1800 requires 13%, and 5 km/s from 3600 requires another 13% for a total of 45% of wet mass in fuel. Obviously these are rough figures!
Now if we're willing to take our time, say 2.6 days, and use a cheaper orbit transfer to jump, we only need an additional 22.4km/s or 81.2% of our remaining mass.. hrrmm that not work either!! Ok, if we're willing to take 8.2 days!! we only need 7.1km/s and at 1800 Isp that needs 33% of our remaining mass. Going back and adding in 2x the 7.1km/s figured (round trip) to the 2.5km/s delta-v we needed earlier at 1800 Isp we get about 60% of the remaining mass required in fuel. Now watch me screw this up - total payload is then 81% x 40% x 87% x 81% or roughly 23%; 77% of the ship needs to be fuel.
Assuming the above analysis is remotely correct, TANTR+S is a marginal solution for the wilderness scenario and requires an extra couple of weeks in travel time. This doesn't necessarily kill the idea entirely. One possibility would be to use the TANTR+S only for the interface and have a higher efficiency drive for the LEO to jump point portion. At a cost of 5 tons of payload mass, a MPD driven by power from the TANTR+S in reactor mode would have an Isp of 36000. This would reduce the largest chunk of fuel required to only 2% instead of 60%! Total payload would then be 55% of the wet mass minus the mass of the MPD.
To make things simpler, I likely need to create standard engine packages that encapsulate the various modes and Isp's into something much simpler to use both in design and in play. The above process would rapidly drive me to distraction. Still, it has been a necessary step, coming to better grips with the actual environment before trying to create simpler abstractions of it.
PS: There's a much better look at Traveller's jump drive mechanics and a way of getting out of the stellar jump shadow mess with gravity based calcs here. Turns out this was a topic on the Traveller Mailing List a long time ago.
Sunday, May 20, 2012
An Ode to Simplicity
Simplicity, which by and large we had with classic Traveller's initial little black books (LBBs), is hard to overvalue. In attempting to achieve the goal of injecting more realism into a hard science fiction version of a Traveller based setting, it is extremely easy to forget this. Complexity is alluring to some of us, Striker and later, Fire Fusion and Steel, gave us complexity in spades all in the name of realism. However, as much fun as it can be to mess around with those complex systems, they really don't do much if anything for role playing sessions. Which is, I think, kind of important for a role playing game.
High Guard gave us what to me is an upper bounds on desirable complexity, still some GM's believe it to be a bit too complex and favor the simpler LBB 2 starship construction rules. So for construction rules at least, we have examples of workable, usable, upper and lower bounds on complexity. It isn't an easy target to aim for, let alone hit, when pursuing 'hard science'.
The same considerations hold true for combat systems. Various Traveller products and adaptions of similar rule sets from other games have given us combat systems that span the range of abstraction levels and the scales of single ship to multiple fleet battles. Odd thing is, I can't remember, in all my years of role play gaming, ever needing to handle more than small scale battles of a few ships at most in a session and then my players and I were quite satisfied with a more abstract model of movement at least. More complexity just slows down play, whereas simplicity makes for more enjoyable, interactive, reasonably fast paced gaming sessions.
The same considerations once again hold true for many of us when it comes to skill systems and task resolution systems. Every time my players and I tried using more detailed skill trees and formally structured task resolution systems, the sessions bogged down into periods of searching through books for skill descriptions, rules lawyering over task resolution, and quickly became roll rather than role playing. Classic Traveller's LBBs give a good basic set of skills and a minimal set of rules that work quite well. Nice and simple. The hardest part seems to be players and GMs coming from other gaming systems that are overly complex and feel lost without all that legal structure. In the final analysis, once again, simplicity makes for a better game.
This topic has arisen for me because of another game I play. An open source game, its current crop of developers decided to make combat more realistic. In the process they've completely broken it and now need an entire new set of additions to get back to the same level of functionality we had in previous versions. The blind pursuit of realism should never get in the way of the playability and enjoyment of a game. Seems obvious, but it is a very easy misstep to make when navigating the narrow and rocky trails of game design.
So what does this all mean for the Dark Stars ATU? Well, once again I find myself waffling. By throwing out the civilization model underlying Traveller, I can make a playable setting that meets the hard science with one exception criteria. The problem is that in doing that I've just thrown out half or more of that body of work we call Traveller. In the abstract, it works and is quite doable, in reality it bogs down into needing a ton of detail work before it is remotely useable.
In an attempt to avoid the plunge headfirst into a man year or more of background and detail work, I am left with trying to find another solution to the wilderness scenario that meets the hard science with one exception criteria. As much as I hate it, the process is bringing me back around to giving serious consideration to some form of 'gravitics' pseudo-science. I really don't like that approach though. While it solves some problems it introduces myriad others and is at the bare edge of plausibility to qualify as anything remotely hard science fiction.
So I found myself reading about fringe science like the Heim-Droscher hyper-drive. If you've read much of my ramblings elsewhere on this blog you no doubt realize that I'm a layman when it comes to physics, somewhere around early to mid college level of knowledge - a bit further advanced with mathematics possibly, but I like reading about physics, especially quantum physics. In the process I've come to discover that our blind faith in Einstein is a little bit misplaced, special relativity shows some fraying around the edges so to speak. There are other theories.
Yeah yeah I've now lost all credibility with the loyal Einstein is holy camp. I'll let you in on a little secret, most of them don't understand physics either. In fact, no one does. What we have is a collection of theories that fit most observed data within certain error limits. Quantum physics is bringing everything we think we know into question.
So what does this mean from a science fiction perspective? Well, for starters it seems a bad idea to tie your shirt-tails to a fringe theory. Next year someone finally disproves the theory and there you sit looking like yet another casualty of technological progress. The best advice I've ever read on the subject is to concentrate on the effects rather than the cause. Say as little about the cause as you can get away with - you'll stay relevant longer and don't immediately set yourself up to be ridiculed by pessimistic no-space-ever fanatics.
Looking once again, hopefully with newly refreshed eyes, at the wilderness scenario (without re-imagining civilization) we can enumerate the effects of our mysterious scientific advance.
In order to address the effects seriously, it is necessary to define point 3 further. Just what form of ftl are we going to allow? I'm biased towards the general Alderson Point idea as I think the stock Traveller jump space ftl just opens up too many cans of worms to address with hard(er) science. In order to address point 4, we need to also define the average normal space trip time under the constraint of point 2 between low orbit and the ftl points. If we consider the jump points to be non orbiting locations ala Alderson Points, then we need to find the average distance between the average planetary orbit and the average jump point location.
Using the original Lares point/region idea for the first guess at jump point locations places them roughly 0.63 AU from Sol in our solar system assuming a 0.015 m/s^2 gravity threshold. Assuming we don't want to get closer to the star than absolutely necessary, our maximum travel distance between ftl points becomes just under 2 AU giving an average of 1 AU (keeping things simple) between ftl points. This works out to a bit over 3 days travel at 10 m/s^2 sustained acceleration. Our average distance from LEO to Lares point works out to about the same, maybe a hair longer. Let's call our average wilderness scenario surface to ftl point a 3.5 day jaunt. Now in stock Traveller each one-way section of the wilderness scenario takes roughly 8 days, so in answering point 4 we need to give our ftl method a transit time of 1 day between systems. We're back to Lares drive specs again.
Now for the 'fun' part. Assume for a moment that our maneuver drive is a reaction drive and that 50% of a vessel's mass in fuel will get us through one entire leg of the wilderness scenario. Now we need a total delta-V of... yikes! 6x10^6 m/s... requiring an Isp of only a bit under 900k. This is a bit of a problem since it is higher than the maximum possible Isp theoretically achievable with magnetic containment fusion. That figure is without regards to efficiency loss and material capabilities which serve to limit achievable Isp's to far lower figures. Congratulations, we've just reinvented HEPlaR.
Hmm.. try for a middle ground? Abandon the fixed point ftl idea and assume something remotely resembling stock Traveller jump drives but with a lower gravity gradient, say 0.005 m/s^2. This means that for Earth, Sol's gravity well predominates and the distance to jump point is roughly 13.3mkm distance. This is about 64 hours constant thrust at 1m/s^2 (assuming midpoint turnaround). Now we need a much more modest delta-V of around 500000. Given our desired fuel load, we can get away with an Isp of 66.5k. While we're now an order of magnitude below theoretical maximums, we're still about two orders of magnitude beyond current projected designs.
We're also neglecting for now the surface to LEO special requirements, but at least we are in the general ballpark with this most recent model. Our Isp requirements are about twice that of the projected maximums for VASMIR and some pulse fusion theoretical designs. We also may, however, be too dependent upon the specifics of our solar system for the distances to remain in the ballpark.
Let's aim for a more planetary dependent ftl point distance equation, the catch here is, basing on gravitational gradient, we require a threshold greater than 0.00593 m/s^2, otherwise in our solar system the sun's gravity would predominate. A threshold of 0.01 m/s^2 works out to just under 200,000 km. Even at a low constant acceleration of 1 m/s^2 this is only an 8 hour flight from low orbit. A catch with this is that now surface to LEO delta-V is no longer negligible so our total delta-V requirement is about 78000m/s, with our desired fuel load we get an Isp requirement of around 11,500. Ignoring the necessary high thrust component for surface to LEO for a moment, this is comfortably within range of projected technologies and efficiencies.
There are a couple serious problems with this last scenario, it is quite possible that ships would be able to launch ordinance at planetary targets immediately upon exit from ftl for one. Another is that space battles are, at best, confined to low orbit by the time you make intercept. Note that the ftl threshold with this last scenario is well inside the Moon's orbit.
When you consider hard science, the ftl threshold parameters get very dicey for any commonly applicable value to yield near habitable planet entry and exit points. Either you end up entirely too close to the planet for any kind of space battle, or else the entry and exit points are highly dependent upon the nature of the solar system. So, round robin style, we're back to looking yet again at the first scenario with fixed ftl points - dizzy yet?
With reasonable fixed ftl points, we're stuck with either HEPlaR like drives that even with a bit of handwavium break physics, or lengthening the transit times. Let's take a look at doubling the time first. We'll make our ftl transits instantaneous and allow a full week each way between average ftl point and average habitable planet. Using the 1 AU ballpark figure, we need a constant acceleration of, well lets call it 2 m/s^2. This gives an Isp requirement of around 350000, still pretty hefty but within 3He/2H fusion range. Up till now we've been ignoring the thrust requirement and have been looking just at the Isp. Even a measly 0.2g of thrust at these high Isp levels is, quite frankly, impossible given physics as we know it. It doesn't break physics to have such a device, but no one has a clue how to create one. Temperature levels are extreme using any straight up design even if all other engineering factors were accounted for.
Just for fun, lets double the time again. Two weeks each way. Now we can get by with 0.5 m/s^2 constant acceleration and an Isp requirement of about 175000. This makes 3He/2H fusion look a bit more realistic but doesn't open any new doors. Doubling again to a month each way, we get by with 0.1 m/s^2 constant acceleration, and an Isp requirement of around 70000. Ignoring the 'bang bang' engines due to manufactured fuel pellet requirements, while this doesn't open any particularly new doors for us it is interesting that we're just a little over twice the Isp of a magnetoplasmadynamic (MPD or VASIMR) drive.
High Guard gave us what to me is an upper bounds on desirable complexity, still some GM's believe it to be a bit too complex and favor the simpler LBB 2 starship construction rules. So for construction rules at least, we have examples of workable, usable, upper and lower bounds on complexity. It isn't an easy target to aim for, let alone hit, when pursuing 'hard science'.
The same considerations hold true for combat systems. Various Traveller products and adaptions of similar rule sets from other games have given us combat systems that span the range of abstraction levels and the scales of single ship to multiple fleet battles. Odd thing is, I can't remember, in all my years of role play gaming, ever needing to handle more than small scale battles of a few ships at most in a session and then my players and I were quite satisfied with a more abstract model of movement at least. More complexity just slows down play, whereas simplicity makes for more enjoyable, interactive, reasonably fast paced gaming sessions.
The same considerations once again hold true for many of us when it comes to skill systems and task resolution systems. Every time my players and I tried using more detailed skill trees and formally structured task resolution systems, the sessions bogged down into periods of searching through books for skill descriptions, rules lawyering over task resolution, and quickly became roll rather than role playing. Classic Traveller's LBBs give a good basic set of skills and a minimal set of rules that work quite well. Nice and simple. The hardest part seems to be players and GMs coming from other gaming systems that are overly complex and feel lost without all that legal structure. In the final analysis, once again, simplicity makes for a better game.
This topic has arisen for me because of another game I play. An open source game, its current crop of developers decided to make combat more realistic. In the process they've completely broken it and now need an entire new set of additions to get back to the same level of functionality we had in previous versions. The blind pursuit of realism should never get in the way of the playability and enjoyment of a game. Seems obvious, but it is a very easy misstep to make when navigating the narrow and rocky trails of game design.
So what does this all mean for the Dark Stars ATU? Well, once again I find myself waffling. By throwing out the civilization model underlying Traveller, I can make a playable setting that meets the hard science with one exception criteria. The problem is that in doing that I've just thrown out half or more of that body of work we call Traveller. In the abstract, it works and is quite doable, in reality it bogs down into needing a ton of detail work before it is remotely useable.
In an attempt to avoid the plunge headfirst into a man year or more of background and detail work, I am left with trying to find another solution to the wilderness scenario that meets the hard science with one exception criteria. As much as I hate it, the process is bringing me back around to giving serious consideration to some form of 'gravitics' pseudo-science. I really don't like that approach though. While it solves some problems it introduces myriad others and is at the bare edge of plausibility to qualify as anything remotely hard science fiction.
So I found myself reading about fringe science like the Heim-Droscher hyper-drive. If you've read much of my ramblings elsewhere on this blog you no doubt realize that I'm a layman when it comes to physics, somewhere around early to mid college level of knowledge - a bit further advanced with mathematics possibly, but I like reading about physics, especially quantum physics. In the process I've come to discover that our blind faith in Einstein is a little bit misplaced, special relativity shows some fraying around the edges so to speak. There are other theories.
Yeah yeah I've now lost all credibility with the loyal Einstein is holy camp. I'll let you in on a little secret, most of them don't understand physics either. In fact, no one does. What we have is a collection of theories that fit most observed data within certain error limits. Quantum physics is bringing everything we think we know into question.
So what does this mean from a science fiction perspective? Well, for starters it seems a bad idea to tie your shirt-tails to a fringe theory. Next year someone finally disproves the theory and there you sit looking like yet another casualty of technological progress. The best advice I've ever read on the subject is to concentrate on the effects rather than the cause. Say as little about the cause as you can get away with - you'll stay relevant longer and don't immediately set yourself up to be ridiculed by pessimistic no-space-ever fanatics.
Looking once again, hopefully with newly refreshed eyes, at the wilderness scenario (without re-imagining civilization) we can enumerate the effects of our mysterious scientific advance.
- It allows for cheap surface to low orbit.
- It allows for sustained 10 m/s^2 acceleration sufficient for round trips from orbit to ftl point.
- It allows some form of ftl.
- The total round trip times for the wilderness scenario closely matches classic Traveller.
In order to address the effects seriously, it is necessary to define point 3 further. Just what form of ftl are we going to allow? I'm biased towards the general Alderson Point idea as I think the stock Traveller jump space ftl just opens up too many cans of worms to address with hard(er) science. In order to address point 4, we need to also define the average normal space trip time under the constraint of point 2 between low orbit and the ftl points. If we consider the jump points to be non orbiting locations ala Alderson Points, then we need to find the average distance between the average planetary orbit and the average jump point location.
Using the original Lares point/region idea for the first guess at jump point locations places them roughly 0.63 AU from Sol in our solar system assuming a 0.015 m/s^2 gravity threshold. Assuming we don't want to get closer to the star than absolutely necessary, our maximum travel distance between ftl points becomes just under 2 AU giving an average of 1 AU (keeping things simple) between ftl points. This works out to a bit over 3 days travel at 10 m/s^2 sustained acceleration. Our average distance from LEO to Lares point works out to about the same, maybe a hair longer. Let's call our average wilderness scenario surface to ftl point a 3.5 day jaunt. Now in stock Traveller each one-way section of the wilderness scenario takes roughly 8 days, so in answering point 4 we need to give our ftl method a transit time of 1 day between systems. We're back to Lares drive specs again.
Now for the 'fun' part. Assume for a moment that our maneuver drive is a reaction drive and that 50% of a vessel's mass in fuel will get us through one entire leg of the wilderness scenario. Now we need a total delta-V of... yikes! 6x10^6 m/s... requiring an Isp of only a bit under 900k. This is a bit of a problem since it is higher than the maximum possible Isp theoretically achievable with magnetic containment fusion. That figure is without regards to efficiency loss and material capabilities which serve to limit achievable Isp's to far lower figures. Congratulations, we've just reinvented HEPlaR.
Hmm.. try for a middle ground? Abandon the fixed point ftl idea and assume something remotely resembling stock Traveller jump drives but with a lower gravity gradient, say 0.005 m/s^2. This means that for Earth, Sol's gravity well predominates and the distance to jump point is roughly 13.3mkm distance. This is about 64 hours constant thrust at 1m/s^2 (assuming midpoint turnaround). Now we need a much more modest delta-V of around 500000. Given our desired fuel load, we can get away with an Isp of 66.5k. While we're now an order of magnitude below theoretical maximums, we're still about two orders of magnitude beyond current projected designs.
We're also neglecting for now the surface to LEO special requirements, but at least we are in the general ballpark with this most recent model. Our Isp requirements are about twice that of the projected maximums for VASMIR and some pulse fusion theoretical designs. We also may, however, be too dependent upon the specifics of our solar system for the distances to remain in the ballpark.
Let's aim for a more planetary dependent ftl point distance equation, the catch here is, basing on gravitational gradient, we require a threshold greater than 0.00593 m/s^2, otherwise in our solar system the sun's gravity would predominate. A threshold of 0.01 m/s^2 works out to just under 200,000 km. Even at a low constant acceleration of 1 m/s^2 this is only an 8 hour flight from low orbit. A catch with this is that now surface to LEO delta-V is no longer negligible so our total delta-V requirement is about 78000m/s, with our desired fuel load we get an Isp requirement of around 11,500. Ignoring the necessary high thrust component for surface to LEO for a moment, this is comfortably within range of projected technologies and efficiencies.
There are a couple serious problems with this last scenario, it is quite possible that ships would be able to launch ordinance at planetary targets immediately upon exit from ftl for one. Another is that space battles are, at best, confined to low orbit by the time you make intercept. Note that the ftl threshold with this last scenario is well inside the Moon's orbit.
When you consider hard science, the ftl threshold parameters get very dicey for any commonly applicable value to yield near habitable planet entry and exit points. Either you end up entirely too close to the planet for any kind of space battle, or else the entry and exit points are highly dependent upon the nature of the solar system. So, round robin style, we're back to looking yet again at the first scenario with fixed ftl points - dizzy yet?
With reasonable fixed ftl points, we're stuck with either HEPlaR like drives that even with a bit of handwavium break physics, or lengthening the transit times. Let's take a look at doubling the time first. We'll make our ftl transits instantaneous and allow a full week each way between average ftl point and average habitable planet. Using the 1 AU ballpark figure, we need a constant acceleration of, well lets call it 2 m/s^2. This gives an Isp requirement of around 350000, still pretty hefty but within 3He/2H fusion range. Up till now we've been ignoring the thrust requirement and have been looking just at the Isp. Even a measly 0.2g of thrust at these high Isp levels is, quite frankly, impossible given physics as we know it. It doesn't break physics to have such a device, but no one has a clue how to create one. Temperature levels are extreme using any straight up design even if all other engineering factors were accounted for.
Just for fun, lets double the time again. Two weeks each way. Now we can get by with 0.5 m/s^2 constant acceleration and an Isp requirement of about 175000. This makes 3He/2H fusion look a bit more realistic but doesn't open any new doors. Doubling again to a month each way, we get by with 0.1 m/s^2 constant acceleration, and an Isp requirement of around 70000. Ignoring the 'bang bang' engines due to manufactured fuel pellet requirements, while this doesn't open any particularly new doors for us it is interesting that we're just a little over twice the Isp of a magnetoplasmadynamic (MPD or VASIMR) drive.
Friday, May 18, 2012
Occam vs Opera - Take 1
What if Franciscan Friar William of Ockham, known for bringing us Occam's Razor, had applied his tools to minimizing the distance between science fiction space opera and science as we know it?
Harry Turtledove had a leg up on a possible answer in his story 'The Road not Taken", where most of the races in the galaxy discover gravitics and, as it doesn't lead to anything except travel technology, stunted technological growth in other areas. Most of the races that is except human, but I won't spoil the story further.
At least one fringe of science has drawn a connection between gravitics and FTL travel, the followers of Burhard Heim's theories, in the Heim-Dröscher hyperdrive. Of course as weird as quantum physics has turned out to be, there may be other possible connections - or then again it might be all a load of excrement. However, for purposes of space opera, the gravitics-hyperdrive connection is made to Occam's order, one theory to bridge the gap, one piece - albeit large - of handwavium. This is rather handy since it allows us to engage in that category of science fiction known as 'hard science fiction with one exception'.
Does this mean we can reclassify Traveller as hard rather than soft? Eh, no not really. Unfortunately there are too many other pieces of handwavium thrown in. However, we might be able to use something very much like Traveller (minus a few bits and plus some others) and allow the handwavium of gravitics Heim style to give us the fundamental piece I call the 'wilderness scenario'*.
*The wilderness scenario is that fundamental part of soap opera science fiction where our protagonist jumps in his spaceship, takes off from one planet, out into space, into hyperspace, back out into space around another star, and lands on another planet. Then, without supporting infrastructure more complex than can be easily carried aboard to collect and refine fuel, turns right around and goes back to the starting planet.
Harry Turtledove had a leg up on a possible answer in his story 'The Road not Taken", where most of the races in the galaxy discover gravitics and, as it doesn't lead to anything except travel technology, stunted technological growth in other areas. Most of the races that is except human, but I won't spoil the story further.
At least one fringe of science has drawn a connection between gravitics and FTL travel, the followers of Burhard Heim's theories, in the Heim-Dröscher hyperdrive. Of course as weird as quantum physics has turned out to be, there may be other possible connections - or then again it might be all a load of excrement. However, for purposes of space opera, the gravitics-hyperdrive connection is made to Occam's order, one theory to bridge the gap, one piece - albeit large - of handwavium. This is rather handy since it allows us to engage in that category of science fiction known as 'hard science fiction with one exception'.
Does this mean we can reclassify Traveller as hard rather than soft? Eh, no not really. Unfortunately there are too many other pieces of handwavium thrown in. However, we might be able to use something very much like Traveller (minus a few bits and plus some others) and allow the handwavium of gravitics Heim style to give us the fundamental piece I call the 'wilderness scenario'*.
*The wilderness scenario is that fundamental part of soap opera science fiction where our protagonist jumps in his spaceship, takes off from one planet, out into space, into hyperspace, back out into space around another star, and lands on another planet. Then, without supporting infrastructure more complex than can be easily carried aboard to collect and refine fuel, turns right around and goes back to the starting planet.
Sunday, May 13, 2012
Soap opera scifi with a space based civilization
Yes I'm waffling again. The other day after some conversations I was about to just toss in the towel on the whole idea I'd had originally - or at least started with this time around. A friend remarked that all scifi soap opera anymore is sailing ships in SPAAAACCEE. That holds especially true for Traveller, it always has been that sort of setting.
When you start to introduce reality into the picture, or at least physics as we know it, even including some fringe physics, the fundamental barrier between soft soap opera scifi and hard scifi pops up and smacks you in the face. Initially you might think it is all due to slower travel times but that isn't it, the obstacle is the civilization model. Soft soap opera scifi concentrates on ye olde planetary civilizations connected by handwaviums. Handwaviums because otherwise the cost of interface operations (surface to orbit) is *huge*.
But wait you say, what about beanstalks, laser boosted launch, electromagnetic assists, etc? Well all of that certainly helps, those solutions reduce the problems by an order of magnitude. Too bad soft soap opera scifi settings require a reduction of at least two if not three orders of magnitude in interface costs.
Even worse, soft soap opera scifi includes what I call the wilderness scenario: a relatively small and cheap trading ship that can travel surface to orbit, orbit to interplanetary, FTL between the stars, interplanetary to orbit, orbit to surface - all on one fuel load in a couple weeks time. A few days later, refuel and do it all over again. I cannot find a realistic solution to this scenario even with using rather severe handwaviums in the interplanetary realm.
The last attempt with the Quantum Skip drive handwavium and using a somewhat realistic LANTR variant reaction engine still requires 80% of the ship's mass - that's mass not volume - which leaves precious little mass for cargo (as a percentage of ship) in any design that would be even remotely small and cheap. In fact, it'd be large and expensive, so large that it would probably have to use secondary 'shuttles' for the actual interface. That doesn't completely solve the problem either as now your shuttle has to make numerous trips.
At that point you realize that to keep anything remotely resembling the Traveller setting, you need to throw realistic physics out the window. Switching to the 2300AD setting helps a bit but still requires more of a handwave than I really am comfortable with for any remote claim to a hard scifi label. I'll admit it, at a certain gut level I don't care much for the stutterwarp idea. Perhaps its the feeling that stutterwarp is more of a arm wave than a hand wave. That and it puts the 'magic' center stage nearly all the time.
Way way back, though unfortunately the documents have been lost in time, I had been working on another hard scifi concept also named Dark Stars. That first version of Dark Stars was so wildly different in setting that this time around, aiming for a Travelleresque setting, the only thing I borrowed initially was the name. Well, turns out, maybe I need to borrow far more than just the name.
The original Dark Stars setting was so hard scifi that there wasn't even any FTL. In it, mankind used what is now called brown dwarfs (and similar interstellar planetary scale objects) as stepping stones to the stars. The idea came out of some astronomy reports regarding a few isolated but recorded instances of unexplainable obscuration of certain stars, the theory at the time was that the cause was planetary objects between small gas giant and true stars. I believe this was an early observation of what is now called brown dwarfs.
Obviously in the original Dark Stars setting, civilizations around the brown dwarf stepping stones weren't planetary civilizations. The setting's back story was that as mankind expanded into interplanetary space, civilization became less and less planetary bound until by the time deep space colonizes were first established orbiting the nearest 'dark stars' there were more people who lived their entire lives in deep space than those who had ever lived on planets. After that point, planets basically became irrelevant except as possible sources of raw materials that could not be obtained from lesser gravity wells. Even that slim importance fades away as technology progresses and it becomes cheaper to create heavy elements or replace them with lighter elements than dig and lift them out of a deep gravity well.
One interesting side effect of this model is that planetary defenses and slag weapons become irrelevant. Another is that it is hard to wrap your head around it as it is so foreign to the way we planet bound think. Evolution of civilization.
So the original Dark Stars setting ends up becoming a collection of hordes of space habitats clustering around energy and resource points in orbits that minimize the costs. You might well have specialized facilities in addition to habitats, such as facilities orbiting fairly close to stars in order to turn stellar output into a stored form such as antimatter. Other facilities might be in low orbits around gas giants engaging in various refining activities. Yet others are situated near larger rocks or collections of rocks in various places engaging in the processing of raw materials. Populations, and their habitats, are mobile. They shift with changing trade patterns and perhaps for other reasons as well. I'm reminded of the scifi story where I first encountered a form of the stutterwarp idea, hyper-assistance, in Asimov's classic Nemesis novel. In truth that novel, along with a few others, really laid the seeds for the original Dark Stars setting in my mind.
That first Dark Stars setting, while interesting, doesn't make for a good space opera on an interstellar scale. Without FTL and with realistic reaction drives up to and including antimatter, the time scales are rather beyond the space opera norm by a few orders of magnitude. The question of the hour becomes, what form of FTL would enable near space opera travel times between neighboring stars without widespread changes in the basic underpinnings of the setting? Further, at what technological point should it become available? Too soon and the setting doesn't have time to evolve to true planetary independent civilization, too late and the science becomes completely unrecognizable.
Before setting down the operational criteria for the FTL mechanism, it is a good time to realize something inherently different between the first Dark Stars setting and most all soap opera scifi settings. In Dark Stars a solar system's population and infrastructure is spread out all through the system, with varying densities near various points of interest. In traditional soap opera equivalent terms this turns every world into a Dyson's sphere! Traveller RPG is basically a collection of Kardashev I worlds into a Kardashev II civilization; the Dark Stars setting is somewhere between that and a collection of Kardashev II solar systems into a Kardashev III civilization. Population and energy usage in the Dark Stars setting are almost assuredly beyond those of core worlds in the Traveller OTU setting.
Along with that, the scale of travel across a 'world' is far different, roughly 5000 to 10000 times greater. It would be like being restricted to the speed of sail on each world assuming some relatively realistic fusion torch drive is commonly used in Dark Stars for interplanetary scale travel. This suggests that, to maintain the interstellar civilization soap opera feel, the maximum travel time between two points of interest orbiting adjacent stars should be no more than around three times the average 'across the world' travel time. That is, if it takes a month to go from one side of the system to another, it probably shouldn't take more than three months on average to go from a point of interest in one system to another point of interest in an adjacent system.
While a standard soap opera setting can have pre-space flight technology worlds, in a Dark Stars setting that makes little sense. There is a minimum tech level required to support civilization in space. In order to satisfy the evolution of civilization argument above, this tech level must be significantly less than that required for FTL travel.
In order for space opera style interstellar warfare to make any sort of sense, there needs to be some limitations on the FTL travel mechanism, either some sort of choke points, or some distance limitations, or both. To allow for manageable multiple star system empires, our speed of information transfer needs to be restricted as well. In the absence of FTL communications, the time for a packet of information to travel from one system to another through a third is expressible as 2Tt + 2Tc1 + 2Tc2; where Tt is average FTL travel time, Tc1 is communications between decision center and FTL courier, and Tc2 is the communications time between two FTL couriers, assuming that a single courier cannot be used as quickly as two.
If we consider our elapsed time for scale of travel desired and our elapsed time for interstellar communications desired, we can calculate how long our FTL travel between two adjacent star systems should take on average.
Now zooming out a bit to look at the shape of an interstellar civilization composed of a collection of space based civilizations, a few questions spring to mind. First, what differentiates one star system from another as far as desirability? Probably a combination of stellar type, availability of easily accessible hydrogen, and asteroid belts - the more the merrier, perhaps small planets and/or moons might also be a bonus as a raw material source. Beyond that location, location, location. Of course that depends on the topography of our FTL mechanism. While still zoomed out at this level, consider the ramifications of the FTL mechanism's topography on interstellar warfare as well.
I'll probably choose the Alderson point-ish Lares region type of Quantum Skip drive as the general FTL mechanism since a bit of time and effort has already gone into it. It also has a somewhat more hard-sciencey technobabble behind it. If the FTL points occur at roughly the 0.001 m/s^2 gravity gradient radius, that would put them around 2.5 AU from the sun in our solar system. That also puts them at a reasonable distance for the average travel time target given realistic thrust levels of high delta-V reaction drives. Now this assumes that the average interstellar tech level is a bit higher than normally found in Traveller, but given that is also a target criteria, we should be fine.
One aspect of this setting is that it gives us a bit of a way out with regards to our reaction drives and our power plants. We can sidestep most of the issues with magnetic bottle fusion and go to various forms of pulse mode antimatter initiated fusion.
I'll have to take more time and consider the pluses and minuses with this idea further. It seems to give a realistic hard scifi (with FTL exception) soap opera/RPG setting at the price of sacrificing the sacred cow of planetary based civilization.
When you start to introduce reality into the picture, or at least physics as we know it, even including some fringe physics, the fundamental barrier between soft soap opera scifi and hard scifi pops up and smacks you in the face. Initially you might think it is all due to slower travel times but that isn't it, the obstacle is the civilization model. Soft soap opera scifi concentrates on ye olde planetary civilizations connected by handwaviums. Handwaviums because otherwise the cost of interface operations (surface to orbit) is *huge*.
But wait you say, what about beanstalks, laser boosted launch, electromagnetic assists, etc? Well all of that certainly helps, those solutions reduce the problems by an order of magnitude. Too bad soft soap opera scifi settings require a reduction of at least two if not three orders of magnitude in interface costs.
Even worse, soft soap opera scifi includes what I call the wilderness scenario: a relatively small and cheap trading ship that can travel surface to orbit, orbit to interplanetary, FTL between the stars, interplanetary to orbit, orbit to surface - all on one fuel load in a couple weeks time. A few days later, refuel and do it all over again. I cannot find a realistic solution to this scenario even with using rather severe handwaviums in the interplanetary realm.
The last attempt with the Quantum Skip drive handwavium and using a somewhat realistic LANTR variant reaction engine still requires 80% of the ship's mass - that's mass not volume - which leaves precious little mass for cargo (as a percentage of ship) in any design that would be even remotely small and cheap. In fact, it'd be large and expensive, so large that it would probably have to use secondary 'shuttles' for the actual interface. That doesn't completely solve the problem either as now your shuttle has to make numerous trips.
At that point you realize that to keep anything remotely resembling the Traveller setting, you need to throw realistic physics out the window. Switching to the 2300AD setting helps a bit but still requires more of a handwave than I really am comfortable with for any remote claim to a hard scifi label. I'll admit it, at a certain gut level I don't care much for the stutterwarp idea. Perhaps its the feeling that stutterwarp is more of a arm wave than a hand wave. That and it puts the 'magic' center stage nearly all the time.
Way way back, though unfortunately the documents have been lost in time, I had been working on another hard scifi concept also named Dark Stars. That first version of Dark Stars was so wildly different in setting that this time around, aiming for a Travelleresque setting, the only thing I borrowed initially was the name. Well, turns out, maybe I need to borrow far more than just the name.
The original Dark Stars setting was so hard scifi that there wasn't even any FTL. In it, mankind used what is now called brown dwarfs (and similar interstellar planetary scale objects) as stepping stones to the stars. The idea came out of some astronomy reports regarding a few isolated but recorded instances of unexplainable obscuration of certain stars, the theory at the time was that the cause was planetary objects between small gas giant and true stars. I believe this was an early observation of what is now called brown dwarfs.
Obviously in the original Dark Stars setting, civilizations around the brown dwarf stepping stones weren't planetary civilizations. The setting's back story was that as mankind expanded into interplanetary space, civilization became less and less planetary bound until by the time deep space colonizes were first established orbiting the nearest 'dark stars' there were more people who lived their entire lives in deep space than those who had ever lived on planets. After that point, planets basically became irrelevant except as possible sources of raw materials that could not be obtained from lesser gravity wells. Even that slim importance fades away as technology progresses and it becomes cheaper to create heavy elements or replace them with lighter elements than dig and lift them out of a deep gravity well.
One interesting side effect of this model is that planetary defenses and slag weapons become irrelevant. Another is that it is hard to wrap your head around it as it is so foreign to the way we planet bound think. Evolution of civilization.
So the original Dark Stars setting ends up becoming a collection of hordes of space habitats clustering around energy and resource points in orbits that minimize the costs. You might well have specialized facilities in addition to habitats, such as facilities orbiting fairly close to stars in order to turn stellar output into a stored form such as antimatter. Other facilities might be in low orbits around gas giants engaging in various refining activities. Yet others are situated near larger rocks or collections of rocks in various places engaging in the processing of raw materials. Populations, and their habitats, are mobile. They shift with changing trade patterns and perhaps for other reasons as well. I'm reminded of the scifi story where I first encountered a form of the stutterwarp idea, hyper-assistance, in Asimov's classic Nemesis novel. In truth that novel, along with a few others, really laid the seeds for the original Dark Stars setting in my mind.
That first Dark Stars setting, while interesting, doesn't make for a good space opera on an interstellar scale. Without FTL and with realistic reaction drives up to and including antimatter, the time scales are rather beyond the space opera norm by a few orders of magnitude. The question of the hour becomes, what form of FTL would enable near space opera travel times between neighboring stars without widespread changes in the basic underpinnings of the setting? Further, at what technological point should it become available? Too soon and the setting doesn't have time to evolve to true planetary independent civilization, too late and the science becomes completely unrecognizable.
Before setting down the operational criteria for the FTL mechanism, it is a good time to realize something inherently different between the first Dark Stars setting and most all soap opera scifi settings. In Dark Stars a solar system's population and infrastructure is spread out all through the system, with varying densities near various points of interest. In traditional soap opera equivalent terms this turns every world into a Dyson's sphere! Traveller RPG is basically a collection of Kardashev I worlds into a Kardashev II civilization; the Dark Stars setting is somewhere between that and a collection of Kardashev II solar systems into a Kardashev III civilization. Population and energy usage in the Dark Stars setting are almost assuredly beyond those of core worlds in the Traveller OTU setting.
Along with that, the scale of travel across a 'world' is far different, roughly 5000 to 10000 times greater. It would be like being restricted to the speed of sail on each world assuming some relatively realistic fusion torch drive is commonly used in Dark Stars for interplanetary scale travel. This suggests that, to maintain the interstellar civilization soap opera feel, the maximum travel time between two points of interest orbiting adjacent stars should be no more than around three times the average 'across the world' travel time. That is, if it takes a month to go from one side of the system to another, it probably shouldn't take more than three months on average to go from a point of interest in one system to another point of interest in an adjacent system.
While a standard soap opera setting can have pre-space flight technology worlds, in a Dark Stars setting that makes little sense. There is a minimum tech level required to support civilization in space. In order to satisfy the evolution of civilization argument above, this tech level must be significantly less than that required for FTL travel.
In order for space opera style interstellar warfare to make any sort of sense, there needs to be some limitations on the FTL travel mechanism, either some sort of choke points, or some distance limitations, or both. To allow for manageable multiple star system empires, our speed of information transfer needs to be restricted as well. In the absence of FTL communications, the time for a packet of information to travel from one system to another through a third is expressible as 2Tt + 2Tc1 + 2Tc2; where Tt is average FTL travel time, Tc1 is communications between decision center and FTL courier, and Tc2 is the communications time between two FTL couriers, assuming that a single courier cannot be used as quickly as two.
If we consider our elapsed time for scale of travel desired and our elapsed time for interstellar communications desired, we can calculate how long our FTL travel between two adjacent star systems should take on average.
Now zooming out a bit to look at the shape of an interstellar civilization composed of a collection of space based civilizations, a few questions spring to mind. First, what differentiates one star system from another as far as desirability? Probably a combination of stellar type, availability of easily accessible hydrogen, and asteroid belts - the more the merrier, perhaps small planets and/or moons might also be a bonus as a raw material source. Beyond that location, location, location. Of course that depends on the topography of our FTL mechanism. While still zoomed out at this level, consider the ramifications of the FTL mechanism's topography on interstellar warfare as well.
I'll probably choose the Alderson point-ish Lares region type of Quantum Skip drive as the general FTL mechanism since a bit of time and effort has already gone into it. It also has a somewhat more hard-sciencey technobabble behind it. If the FTL points occur at roughly the 0.001 m/s^2 gravity gradient radius, that would put them around 2.5 AU from the sun in our solar system. That also puts them at a reasonable distance for the average travel time target given realistic thrust levels of high delta-V reaction drives. Now this assumes that the average interstellar tech level is a bit higher than normally found in Traveller, but given that is also a target criteria, we should be fine.
One aspect of this setting is that it gives us a bit of a way out with regards to our reaction drives and our power plants. We can sidestep most of the issues with magnetic bottle fusion and go to various forms of pulse mode antimatter initiated fusion.
I'll have to take more time and consider the pluses and minuses with this idea further. It seems to give a realistic hard scifi (with FTL exception) soap opera/RPG setting at the price of sacrificing the sacred cow of planetary based civilization.
Friday, May 11, 2012
Quantum Skip Drive, Lares reimagineered
The result of the 'name that drive' poll on COTI was the Quantum Skip drive. In a quick review, I'd decided to get around delta-v limitations that were going to seriously undermine any Travelleresque nature in the Dark Stars ATU with the introduction of a second mode of the old Lares drive. This second mode only works in interplanetary space as long as the gravity gradient remains above a certain rating. Initially I had the yet to be named interim drive working exactly as the Lares drive between stars but in a sort of micro-jump fashion in interplanetary space. This still left me with the need for reaction drives both near planets and beyond certain limits.
However, the more I examined it, the more I realized I was just complicating things for no good reason. If you are going to have realistic reaction drives in any sort of plausible mid term future setting, you're going to have months long transit times. If your setting cannot work with those times, then introducing a cheat mode of your FTL handwavium might as well just do the whole job from jump point to orbit. You will still need reaction drives for planetary landings and atmospheric operations but you won't need to spend half the role playing session calculating delta-V's.
The stutterwarp drive in 2300AD fits the bill except for the interstellar travel speeds. So functionally the Quantum Skip drive is identical to the stutterwarp drive without the speed boost of stutterwarp past the 0.001 m/s^2 gravity gradient. Like 2300AD's stutterwarp it cannot operate effectively in gravity fields stronger than 1 m/s^2. The second and major difference between the Quantum Skip and Stutterwarp drives happens at Lares points where the Quantum Skip drive can be operated in a second mode that, instead of making a jump of a few hundred meters, makes a jump between star systems.
The secondary, interstellar, mode of the Quantum Skip drive requires an energy pulse 1000x normal input levels. It also emits a correspondingly higher entrance and exit signature. Reconfiguring and charging up the drive for secondary mode requires anywhere from 20 minutes to an hour, depending upon available power. Reconfiguring, cooling, and properly discharging any stray accumulations of energy upon exit require a minimum of 20 minutes. Note that unlike stutterwarp drives in 2300AD there is no need to discharge 'gravity potential charges'.
One oddity of the Quantum Skip drive is that the skip always has a directional vector perpendicular to the plane of the drive's emitter array. This means that in combat, changing facing is the same as changing movement vector and requires the use of reaction thrusters (or thrust vectoring of a ship's reaction drive if it has one). This limitation has a great effect on any evasive maneuvering attempts as well as on targeting of any spinal mount or fixed forward facing weapon systems.
The largest effect on the Dark Stars ATU setting from this change is that the trade model gets a bit closer to that of stock Traveller and that combat is possible anywhere in interplanetary space. Lares points become the choke points of the setting. Travel between star systems requires 24 +/- 5 hours as before with Lares drive, and interplanetary times are governed by the maximum apparent (base) speed of 250000 m/s. Note that this is quite a bit slower than 2300AD stutterwarp speeds. It basically gives 1 AU per week in total movement. (Note: this is subject to change as I work out the details for the design sequence.)
Reaction drives aren't totally gone, just relegated to interface duties. The preferred reaction drive will be the advanced trimodal NTR scramjet design in the current design sequence. So I still get my nuclear rockets, just not quite the way I thought!
However, the more I examined it, the more I realized I was just complicating things for no good reason. If you are going to have realistic reaction drives in any sort of plausible mid term future setting, you're going to have months long transit times. If your setting cannot work with those times, then introducing a cheat mode of your FTL handwavium might as well just do the whole job from jump point to orbit. You will still need reaction drives for planetary landings and atmospheric operations but you won't need to spend half the role playing session calculating delta-V's.
The stutterwarp drive in 2300AD fits the bill except for the interstellar travel speeds. So functionally the Quantum Skip drive is identical to the stutterwarp drive without the speed boost of stutterwarp past the 0.001 m/s^2 gravity gradient. Like 2300AD's stutterwarp it cannot operate effectively in gravity fields stronger than 1 m/s^2. The second and major difference between the Quantum Skip and Stutterwarp drives happens at Lares points where the Quantum Skip drive can be operated in a second mode that, instead of making a jump of a few hundred meters, makes a jump between star systems.
The secondary, interstellar, mode of the Quantum Skip drive requires an energy pulse 1000x normal input levels. It also emits a correspondingly higher entrance and exit signature. Reconfiguring and charging up the drive for secondary mode requires anywhere from 20 minutes to an hour, depending upon available power. Reconfiguring, cooling, and properly discharging any stray accumulations of energy upon exit require a minimum of 20 minutes. Note that unlike stutterwarp drives in 2300AD there is no need to discharge 'gravity potential charges'.
One oddity of the Quantum Skip drive is that the skip always has a directional vector perpendicular to the plane of the drive's emitter array. This means that in combat, changing facing is the same as changing movement vector and requires the use of reaction thrusters (or thrust vectoring of a ship's reaction drive if it has one). This limitation has a great effect on any evasive maneuvering attempts as well as on targeting of any spinal mount or fixed forward facing weapon systems.
The largest effect on the Dark Stars ATU setting from this change is that the trade model gets a bit closer to that of stock Traveller and that combat is possible anywhere in interplanetary space. Lares points become the choke points of the setting. Travel between star systems requires 24 +/- 5 hours as before with Lares drive, and interplanetary times are governed by the maximum apparent (base) speed of 250000 m/s. Note that this is quite a bit slower than 2300AD stutterwarp speeds. It basically gives 1 AU per week in total movement. (Note: this is subject to change as I work out the details for the design sequence.)
Reaction drives aren't totally gone, just relegated to interface duties. The preferred reaction drive will be the advanced trimodal NTR scramjet design in the current design sequence. So I still get my nuclear rockets, just not quite the way I thought!
Tuesday, May 8, 2012
FTL Revisited - an alternative to Lares
I like the Lares drive idea, of course it's derived from Niven & Pournelle's Alderson drive so quite a few others seem to like the general idea too. However, there's a problem. Without a Langston field device, power levels are lower for both electrical and propulsion needs - also radiation shielding is a problem. So, especially early on in the Dark Stars setting, our poor carbon nanotube hulled and nuclear thermal rocket propelled spacecraft end up spending lots of fuel and time to get to a Lares region.
Now I've tried bending and redefining the Lares drive idea a bit but it still ends up with around three months average per system at the lower tech levels just to pass through. Twice that or more if you have to refuel! I thought about putting refueling and trade space stations near Lares regions but they need a fairly extensive (and expensive and fragile) investment in station keeping hardware and need quite a bit of mass devoted to heavy duty storm shelters since they're around 0.6AU from the sun in our solar system, and it is quite possible some systems would have higher radiation levels at the equivalent gravity gradient.
It is still possible to make Lares drives work in the setting, but it is starting to look borderline. So, since given the choice is change the current handwavium or add more handwavium to alleviate the problem, I started looking around for other FTL ideas.
I have a personal preference for point to point FTL, though I don't like forms that can be blockaded with minefields or that require an infrastructure in place. Put another way, I don't like 'go anywhere' drives. The reason is there are no choke points between harbors and surprise attacks are way too easy leading to widespread planetary destruction as the order of the day in warfare. Makes for a rather ugly story.
The stutterwarp idea as given in 2300AD and as alternate rules in FF&S is an interesting one but at the expense of pretty much eliminating interplanetary travel by ordinary means. Worse, it ends up taking space combat in a completely different direction. A good idea overall, but too pervasive for the Dark Stars setting.
Another option would be a version of the standard Traveller jump drives that take no fuel and have a gravity gradient threshold that puts them further away from planets for transitions to/from J-space. That is an attractive option except for one small wrinkle. Without the need for refueling between jumps, there are no longer any choke points.
My original idea for Lares drive was to give a nod to physics and relativity by restricting travel to that between causally 'safe' gravity wells. To escape the need for a Langston device, I invoked quantum physics handwavium and used virtual wormholes in the quantum foam. So, while admittedly a huge hand wave, it at least didn't break anything.
Since then I've run across another fringe physics theory that, while admittedly non-mainstream, gives me a little more wiggle room. It is called Lorentzian Relativity, alternatively LET, which basically says special relativity is wrong in respect to the non-existence of a special frame. Interestingly enough, there's nothing except Occam's Razor to choose between the two theories given current knowledge. You can, of course, spark a flame war quite easily by bringing up that point on any physics forum. Of course, with the existence of a preferred frame, causality problems vanish!
So handwavium theories in place to excuse some pretty strange departures from commonly accepted physics in regards to FTL, what can we make of them that solves our need for FTL travel in Dark Stars ATU better than the Lares drive? How about a hybrid Lares/Jump/Stutterwarp? Heh! Rube Goldberg physics, here we come!
Let us suppose that around each star there are two hollow spheres. The inner has a radius at the 0.024 m/s^2 gravity gradient, and the outer has a radius at the 0.00024 m/s^2 gravity gradient. Further, let us suppose that if you extend a tube with a radius of say 50 light seconds or so (0.1 AU) between the outer spheres of two adjacent star systems, the intersection of the interior of the tube with the surface of the outer sphere (give or take 0.1 AU) defines a safe path entrance/exit thru L^-1 space between the two stars for our new drive.
Sounds a lot like the original Lares drive mechanics or Alderson points so far right? Now for the wrinkle. Inside a star system, while within the boundaries described by the surfaces of the inner and outer spheres and not crossing the 0.00024 m/s^2 boundary of any local objects, the same drive can be used to access L^1 space. However where L^-1 space effectively gives a large multiple of light speed, L^1 space gives a small fraction of light speed.
There is an important artifact of jump space entry/exit, namely a burst of energy biased in the direction opposite the direction of the jump. Another limitation is that L^1 space has a fixed jump distance of about 100 light seconds. Incidentally, it takes just as much energy for each L^1 jump as each L^-1 jump, and just as much calculation.
So what happens if you engage this drive outside of the prescribed limits? No one knows. Every time it has happened the craft disappears with an omnidirectional burst of energy and never returns. Another failure mode is a little more common, at least in wilderness travel, and that is due to the poorly understood but nonetheless true fact that not all star systems have connections to all neighbors. In this second failure mode, the craft disappears with an omnidirectional burst of energy, and about 24 hours later returns in the same spot. There are also suicidal paths that have exit regions in non survivable environs, and there are the rare but verified one way paths.
So, our new drive, without a name yet, acts as a restricted FTL drive between systems, and as a STL but still useful drive within certain limits inside of a system. It doesn't require handwavium high Isp from our reaction drives in order to travel in space opera time frames, nor does it eliminate the need for either high Isp and high thrust reaction drives in normal space. As a side note, this new drive, like the Lares drive, supposes that the energy spent by the drive is merely used as a lever to unlock energies at the quantum level, it is those unlocked/leveraged energies that perform the work.
See the name that drive poll over on CotI..
Update: currently under consideration is the idea of extending the in system operational limits to the 0.000024 m/s^2 gravity gradient which would allow a bit more access deeper into the outer system (nearly 16 AU which in the Sol system would put Jupiter and Saturn within reach and nearly close enough to Uranus for reasonable travel times by reaction drives).
Now I've tried bending and redefining the Lares drive idea a bit but it still ends up with around three months average per system at the lower tech levels just to pass through. Twice that or more if you have to refuel! I thought about putting refueling and trade space stations near Lares regions but they need a fairly extensive (and expensive and fragile) investment in station keeping hardware and need quite a bit of mass devoted to heavy duty storm shelters since they're around 0.6AU from the sun in our solar system, and it is quite possible some systems would have higher radiation levels at the equivalent gravity gradient.
It is still possible to make Lares drives work in the setting, but it is starting to look borderline. So, since given the choice is change the current handwavium or add more handwavium to alleviate the problem, I started looking around for other FTL ideas.
I have a personal preference for point to point FTL, though I don't like forms that can be blockaded with minefields or that require an infrastructure in place. Put another way, I don't like 'go anywhere' drives. The reason is there are no choke points between harbors and surprise attacks are way too easy leading to widespread planetary destruction as the order of the day in warfare. Makes for a rather ugly story.
The stutterwarp idea as given in 2300AD and as alternate rules in FF&S is an interesting one but at the expense of pretty much eliminating interplanetary travel by ordinary means. Worse, it ends up taking space combat in a completely different direction. A good idea overall, but too pervasive for the Dark Stars setting.
Another option would be a version of the standard Traveller jump drives that take no fuel and have a gravity gradient threshold that puts them further away from planets for transitions to/from J-space. That is an attractive option except for one small wrinkle. Without the need for refueling between jumps, there are no longer any choke points.
My original idea for Lares drive was to give a nod to physics and relativity by restricting travel to that between causally 'safe' gravity wells. To escape the need for a Langston device, I invoked quantum physics handwavium and used virtual wormholes in the quantum foam. So, while admittedly a huge hand wave, it at least didn't break anything.
Since then I've run across another fringe physics theory that, while admittedly non-mainstream, gives me a little more wiggle room. It is called Lorentzian Relativity, alternatively LET, which basically says special relativity is wrong in respect to the non-existence of a special frame. Interestingly enough, there's nothing except Occam's Razor to choose between the two theories given current knowledge. You can, of course, spark a flame war quite easily by bringing up that point on any physics forum. Of course, with the existence of a preferred frame, causality problems vanish!
So handwavium theories in place to excuse some pretty strange departures from commonly accepted physics in regards to FTL, what can we make of them that solves our need for FTL travel in Dark Stars ATU better than the Lares drive? How about a hybrid Lares/Jump/Stutterwarp? Heh! Rube Goldberg physics, here we come!
Let us suppose that around each star there are two hollow spheres. The inner has a radius at the 0.024 m/s^2 gravity gradient, and the outer has a radius at the 0.00024 m/s^2 gravity gradient. Further, let us suppose that if you extend a tube with a radius of say 50 light seconds or so (0.1 AU) between the outer spheres of two adjacent star systems, the intersection of the interior of the tube with the surface of the outer sphere (give or take 0.1 AU) defines a safe path entrance/exit thru L^-1 space between the two stars for our new drive.
Sounds a lot like the original Lares drive mechanics or Alderson points so far right? Now for the wrinkle. Inside a star system, while within the boundaries described by the surfaces of the inner and outer spheres and not crossing the 0.00024 m/s^2 boundary of any local objects, the same drive can be used to access L^1 space. However where L^-1 space effectively gives a large multiple of light speed, L^1 space gives a small fraction of light speed.
What does that mean in English? For our solar system the radius of the inner sphere would be about 0.5 AU, the radius of the outer sphere about 5 AU, and no closer than 100 diameters of Earth (3x moon orbit). In system jumps travel 100 light seconds (0.2 AU) in 24 hours. Jumps between systems take about 24 hours.
There is an important artifact of jump space entry/exit, namely a burst of energy biased in the direction opposite the direction of the jump. Another limitation is that L^1 space has a fixed jump distance of about 100 light seconds. Incidentally, it takes just as much energy for each L^1 jump as each L^-1 jump, and just as much calculation.
So what happens if you engage this drive outside of the prescribed limits? No one knows. Every time it has happened the craft disappears with an omnidirectional burst of energy and never returns. Another failure mode is a little more common, at least in wilderness travel, and that is due to the poorly understood but nonetheless true fact that not all star systems have connections to all neighbors. In this second failure mode, the craft disappears with an omnidirectional burst of energy, and about 24 hours later returns in the same spot. There are also suicidal paths that have exit regions in non survivable environs, and there are the rare but verified one way paths.
So, our new drive, without a name yet, acts as a restricted FTL drive between systems, and as a STL but still useful drive within certain limits inside of a system. It doesn't require handwavium high Isp from our reaction drives in order to travel in space opera time frames, nor does it eliminate the need for either high Isp and high thrust reaction drives in normal space. As a side note, this new drive, like the Lares drive, supposes that the energy spent by the drive is merely used as a lever to unlock energies at the quantum level, it is those unlocked/leveraged energies that perform the work.
See the name that drive poll over on CotI..
Update: currently under consideration is the idea of extending the in system operational limits to the 0.000024 m/s^2 gravity gradient which would allow a bit more access deeper into the outer system (nearly 16 AU which in the Sol system would put Jupiter and Saturn within reach and nearly close enough to Uranus for reasonable travel times by reaction drives).
Sunday, May 6, 2012
Spacecraft design - C4ISTAR in Dark Stars
Overview
C4ISTAR is a British acronym for command, control, communications, computers, intelligence, surveillance, target acquisition, and reconnaissance. It seems every rule set for Traveller takes a different approach to addressing this aspect of spacecraft design. While classic Traveller basically just dumped it all into (rather oversized) Computers and Bridge, subsequent versions have broken it down into component parts with 18 different variations for each part.Having spent most of my life in some part or another of the IT industry, classic Traveller's treatment of computers doesn't sit well and hasn't since the mid '80s. On the other hand, I want to design spacecraft for use in a game, not specify subsystems for prototyping by a DOD subcontractor! So the later treatments of this topic fall flat for me as well. The root cause, for me, is that LBB2 was too detailed in this respect... that's right *too* detailed.
In Dark Stars I'm assuming that information technology is distributed throughout the various major systems and subsystems as well as the control areas. A TL9 spacecraft has better IT than a TL8 spacecraft. All electronic and computer systems on all spacecraft are automatically radiation hardened and fiber optic backbones for inter system communications is assumed from the get go. So no need for installing a 'computer'.. zip.. nada.. whew!
There are really only two components necessary in this section, the bridge; which includes various miscellaneous aspects of the spacecraft design such as airlocks, perhaps maintenance access ways, power distribution systems, and C3 links. Basically LBB2 already took care of this though I do think the minimum bridge size was a bit overboard.
The other component necessary in this section can be simply called avionics. This component is a collection of the communications, intelligence, surveillance, target acquisition, and - with the help of drones - reconnaissance. Yeah that's right - it includes sensors. It also takes care of mundane aspects like.. avionics! NOE capable avionics is assumed to be included with any airframe configuration spacecraft. Avionics should be available in a few 'flavors' - basic, civilian standard, military/survey, long range military, and advanced long range military. Other sets of names would work and that might be a little too many but it covers what needs covered, and covers it simply, smoothly, and without causing IT professionals to have indigestion.
Components
Bridge
The bridge includes crew stations for the on duty command crew as well as numerous miscellaneous aspects of the spacecraft, from airlocks to redundant C3 networks. It also includes basic avionics. Tonnage required is 2% of the spacecraft's wet mass. Minimum mass is 10 tons. Cost is MCr 0.005 per ton of spacecraft (wet mass).Avionics
The avionics section includes sensors and communications equipment along with any necessary specialized computers for navigation and sensor data analysis.| Code | Description | Mass | Cost(MCr) | Mount points |
|---|---|---|---|---|
| 0 | Basic | - | - | - |
| 1 | Civilian | 1.0 | 2.0 | 1 |
| 2 | Military/Survey | 5.0 | 10.0 | 3 |
| 3 | LR Military | 25.0 | 50.0 | 9 |
| 4 | Adv LR Military | 125.0 | 250.0 | 27 |
Note that Basic Avionics is included in the Bridge tonnage and cost.
And... that's all folks... C4ISTAR in Dark Stars.
Engineering Section
The Engineering Section
Beyond the obvious technologies removed from normal Traveller for the Dark Stars setting, a few assumptions are made about the rate of progress with other technologies. Among the most obvious of those is the delayed tech levels at which fusion power plants and drives become available. In the Dark Stars setting, pulse fusion drives do not become a reality until TL11, fusion power plants follow a tech level later at TL12, and finally at TL13 the fusion torch drive becomes practical.The Dark Stars setting also departs from standard Traveller in paying attention to waste heat management. Power producing drives and power plants require radiator areas on the hull. These come from the mount points calculated in the hull design sequence and are assumed to be armored with IR transparent variations of the hull armor. The mass and cost of these radiators is included in the mass and cost of the drives and power plants. Only the reduction in available mount points needs to be a consideration.
FTL
Quantum Skip Drive (QSD)
Quantum Skip Drives are available at TL10+. While the operational characteristics of the QSD are quite different than traditional Traveller Jump drives, the representation is nearly identical to a Traveller Jump-2 drive. The primary difference being the QSD requires no fuel (directly at least) and does not create a jump bubble of hydrogen nor require a jump grid of lanthanum on the hull. It does require some surface space however for field emitters. A QSD requires 5% of a spacecraft's wet mass at a cost of MCr 0.25 per ton of drive. It also requires 5% of the spacecraft's mount points (round fractions up) for the emitters. The drive requires 0.1 Mj per ton of spacecraft (current tonnage at jump time). This energy must be provided over a period of not more than four hours, although if sufficient power is available, the drive is capable of being charged in a minimum time of 30 minutes. Thus the power required is anywhere from 0.025 Mw per ton of spacecraft to 0.2 Mw per ton of spacecraft.Maneuver
Magneto Plasma Dynamic (MPD)
Available at TL8+, the mature version of the MPD engine has a variable Isp and in 'low gear' barely qualifies as 1m/s^2 capable requiring 10% of the spacecraft's mass (not necessarily its total wet mass) for the drive alone for each 1m/s^2 of acceleration. In addition, a MPD engine requires 0.25 Mw per ton of engine to be supplied by the craft's power plant (regardless of mode). The minimum engine mass is 5 tons, it requires 1 mount point per 100 tons of engine for nozzles (round up), and costs MCr 0.1 per ton.Were it not for two features, the MPD drive would be extremely seldom seen, however because of them it sees widespread use for deep space and bulk freight applications. The first feature is that it can use hydrogen, usually in the form of liquid hydrogen slush (LHS), as fuel as well as many other alternatives. The second is that it has variable specific impulse, and while performance is abysmal at the highest thrust levels, over the long haul it is second to none. In 'low gear' max thrust, the engine has an Isp of only 1800. However, in high gear, while the thrust drops to only 5% of low gear, Isp skyrockets to 36000.
Low gear produces 1 ton of thrust and consumes 2 tons of fuel per hour per ton of drive.
High gear produces 0.05 ton of thrust and consumes 0.005 tons of fuel per hour per ton of drive.
LHS fuel costs Cr50 per ton.
Metastable Metallic Hydrogen Augmented Solid Rocket (MMHASR)
Available at TL9+, the MMHASR is a solid fuel rocket technology that augments the chemical propellant with metastable hydrogen. While originally employed as a secondary thrust agency (booster) for STO spacecraft, it has become the propellant of choice for modern missiles. MMHASR has an Isp of 1200; divide the propellant mass by 3 to determine the thrust in ton/hours, maximum thrust in tons is 5000. MMHASR propellant costs Cr 2500 per ton. The minimum mass of a MMHASR engine is 0.5 tons.Trimodal Augmented Nuclear Thermal Rocket (TANTR)
The TANTR engines are the workhorses of the Dark Star universe. While earlier primitive variants exist, the combinations of technology required for safe, reliable, and ecologically friendly operation combined with near theoretical maximum performance does not occur until TL9+. The TANTR has three modes of operation, reactor mode giving no thrust but supplying power, cruise mode with an Isp of 1800 using Liquid Hydrogen Slush (LHS) fuel; and full thrust mode with an Isp of 1200, augmenting the LHS fuel with either Liquid Oxygen (LOX) fuel or compressed air (scramjet mode if available). The nuclear fuel supply is included in the mass and cost of the drive, it is sufficient for one year's operation. Refueling the nuclear fuel costs 10% of the total drive cost.Each 1m/s^2 of cruise mode acceleration requires 2% of the spacecraft's mass (not necessarily its total wet mass, more commonly its combat mass or cruise mass). In other words, each ton of TANTR produces 5 tons of thrust and consumes 10 tons of LHS fuel per hour. In full thrust mode, each ton of TANTR produces 12 tons of thrust and consumes an additional 26 tons of LOX fuel per hour. The engine produces a secondary electrical power output of 20 kw per ton in thrust modes and 100 kw per ton in reactor mode. Each engine requires 1 mount point per 50 tons of drive (round fractions up) for the nozzle. Radiator area required is 1 mount point per 2 tons of engine (round fractions up). Minimum engine size is 10 tons. Cost is MCr 0.1 per ton of drive.
Scramjet Mode:
TANTR engines may be equipped with scoops and compressors for scramjet mode operation, replacing half the LOX fuel requirement with compressed air while in a planetary atmosphere. This modification adds 10% to the engine's mass, requires 4 mount points per ton of engine, and costs MCr 0.25 per ton. This modification, while in operation, consumes all of the secondary electrical power that would normally be produced by the TANTR engine. This modification may only be installed on spacecraft with streamlined or airframe hull configurations.
LHS fuel costs Cr50 per ton.
LOX fuel costs Cr500 per ton.
Anti-proton Initiated Pulse Fusion (AIPF)
A practical, reliable, commercially feasible fusion drive was a goal that frustrated countless researchers until TL11. Even at TL11 it is considered by many to be a marginal technology as it relies heavily on infrastructure for both fuel and maintenance. On the other hand, this drive type obtains an Isp of 36000 using specially manufactured metastable metallic hydrogen (MMH) pellets and mere nanograms of anti-protons. Note that engine exhaust is highly radioactive.Each 1m/s^2 of acceleration requires 5% of the spacecraft's mass (not necessarily its total wet mass). Thus each ton of AIPF produces 2 tons of thrust and consumes 0.2 tons of fuel pellets per hour. The engine produces a secondary electrical power output of 20 kw per ton. One mount point for each 100 tons of engine is required for nozzle. Radiator area required is 1 mount points per ton of engine. Minimum engine size is 10 tons. Cost is MCr 0.25 per ton of drive. Sufficient anti-proton mass is included in the drive mass and cost for one year of operation. Replacement of the anti-proton initiator fuel adds MCr 0.05 per ton of drive to the cost of annual maintenance.
MMH fuel pellets cost Cr 2500 per ton.
Magnetic Bottle Fusion Drive aka Fusion Torch
Finally arriving at TL13+, fusion torch drives rapidly become the engine of choice for those who have access to the technology required. With an Isp of 36000 from a deuterium/helium3 (DH3) fuel mix, the fusion torch drive not only offers superior performance but adds the prospect of limited wilderness refueling operations. Like the AIPF however, the engine exhaust is highly radioactive.Each 1m/s^2 of acceleration requires 10% of the spacecraft's mass (not necessarily its total wet mass). Thus each ton of drive produces 1 tons of thrust and consumes 0.1 tons of fuel per hour. The engine produces a secondary electrical power output of 20 kw per ton. One mount point for each 100 tons of engine is required for nozzle. Radiator area required is 5 mount points per ton of engine. Minimum engine size is 5 tons. Cost is MCr 0.5 per ton of drive.
DH3 fuel costs Cr 5000 per ton.
Power
Nuclear Fission
While earlier version are available at half the output, three times the mass, and five times the cost; at TL8+ nuclear fission power plants become the most commonly used power source in space until the arrival of nuclear fusion at TL12. Fission power plants produce 0.125 Mw and cost MCr 0.02 per ton. One mount point is required per 25 tons of power plant for radiators (round up). Minimum power plant mass is 25 tons. Large scale fission power plants, of at least 250 tons mass, have twice the power output per ton. Fission power plants include sufficient fuel for one years operation, replacement costs 10% of the original power plant cost.Nuclear Fusion
Finally at TL12+ nuclear fusion power plants become a reality. Based on the deuterium/tritium cycle they produce 0.5 Mw and cost MCr 0.05 per ton. One mount point is required per 5 tons of power plant for radiators (round up). Minimum power plant mass is 5 tons. Fusion power plants include sufficient fuel for one years operation, replacement cost is included in the cost of annual maintenance. Fusion power plant efficiency varies with mass according to the following table.| Mass | Output modifier |
|---|---|
| 25+ | x1.5 |
| 50+ | x2.0 |
| 100+ | x3.0 |
Support
Fuel Tankage
Fuel tankage requires no additional mass beyond the fuel they contain but the tonnage must be specified at design time and costs MCr 0.001 per ton.Fuel Refinery
Onboard fuel refineries can be installed to refine LHS, LOX, and DH3 fuel from liquids, gases, or liquified solids. Each ton of fuel refinery can refine 0.1 tons of fuel per hour. Minimum refinery mass is 10 tons. Cost is MCr 0.01 per ton. If fuel scoops are desired, add one mount point per 10 tons of refinery and double the refinery's cost. Engines with a scramjet modification are assumed to already include fuel scoops. Note that DH3 fuel is refined at 0.01x the normal rate.Workshops
At a mass of 4 tons and cost of 0.25MCr per engineer, onboard workshops allow +1 to all repair attempts and allow a chance of ad-hoc replacement of irreparably damaged components.Frontier Upgrade
Drives (both FTL and Maneuver) and Power Plants may be installed which are modified for high reliability long duration service. These components mass 50% more than normal and cost three times as much. This upgrade gives +1 to all reliability check, +1 to all repair attempts, and extends the service lifetime to three years. If sufficient workshops are also installed, annual maintenance may be delayed without penalty to three years between overhauls.Radiator Wings
Spacecraft which need additional radiator mount points may install up to two radiator wings. Each radiator wing can provide an additional number of mount points of radiators up to a maximum of 50% of the spacecraft's normal mount points. They mass 1 ton and cost MCr 0.1 per mount point of radiator added. There are two options that may be used with radiator wings.1) Retractable radiator wings. If the spacecraft's configuration is not 0 (unstreamlined) it must use this option. This adds 20% to the mass and cost of the wings.
2) Armored radiator wings. The wings may be armored the same as the normal hull mounted radiators with IR transparent material. Calculating the added tonnage and cost of the armor is a bit involved. Using the same armor rating as the hull, the armor factor for the wings is Ar * 4. The structure rating for the wings is equal to Gt * Ga * 0.1, minimum of 1. The wing material rating is then equal to Sr + Af. The mass of the added armor is then equal to the radiator mass * Pc * Mr (see hull page). The cost per ton of the added armor is twice the figure given in the armor table of the hull page.
Heat dumps
When the total deployed radiator mount points is less than the required radiator mount points, the difference represents points of heat that must be dumped (else the craft turns into a can of stewed crew). There are two types of heat dumps, water ice dumps, and reactor coolant dumps. Each ton of water ice vaporized and ejected removes one heat point. Water ice heat dumps mass as much as the ice they contain and the water is essentially free. Reactor coolant heat dumps are twice as efficient removing two heat points per ton vaporized and ejected removes two heat points. However reactor coolant costs Cr250 per ton and may be difficult to replace in a wilderness setting. Regardless of type, heat dumps cost MCr 0.001 per ton installed.Notes
The above should be sufficient, at least to start. The numbers, of course, may need to be tweaked. Later on I'll probably add more to the power section: fuel cells, solar panels, and batteries are likely additions. The big test will come in a few days (or weeks) when I try to design the Frontier Survey Cruiser I have in mind to help me flesh out the Dark Stars setting via solo play.Update: The drives are currently being reworked, relatively minor changes but still needs cleaned up.
Hulls - Take 2 - Mass Effect?
Well, the first try at hulls wasn't too bad overall but wouldn't it be nice if the design of a reaction drive spacecraft could be entirely mass based? Of course the automatic answer to that it yes, but what about hull plating/armor and surface area considerations?
After much searching and way too much reading, I may have come up with a... not solution but perhaps a workaround. It seems that quite a few people who evidently are nearly as insane as myself, have calculated out the densities of various ships in Traveller. The figures seem to mainly fall between 4 metric tons per displacement ton and 7 metric tons per displacement ton. A value of 4 metric tons per displacement ton seems to be in the ballpark of the mass/volume budget I consider right for the Dark Stars setting.
This figure might seem high at first, given that 50% of your average deep space craft's mass is in fuel with a density of less than 0.1 but engine shielding and storm shelter shielding should go a long way to help make up for it.
So, if an average density around 0.29 metric tons per cubic meter is assumed, an enclosing hull can be designed for a given mass - which gives the surface area and hull plating/armor figures. Seeing as how they are guesstimates anyhow, I think it might be worth a try. While I'm at it, 1 m/s^2 seems a better fit to Dark Star as a drive rating than 2.5 m/s^2 so we'll refactor that in too.
Now the fun part is refactoring yesterday's hull design formulas into today's new and improved variant.
First we need a modified configuration table:
Our structural factor formula becomes:
Sf = (Mt/4000)^(3/2); where Mt is the total wet mass of the spacecraft in metric tons.
And our structural rating formula becomes:
Sr = Sf * Sm * Gt * Ga * 0.1; where Gt is thrust in m/s^2 and Ga is agility in m/s^2 (Gt >= Ga >= 1).
Our minimum Sr remains 1.
Now are armor multiplier formula becomes:
AMV = 10/(0.25*Mt)^(1/3)
And our armor factor is now:
Af = Ar * AMV * Sm; where Ar is the armor rating.
Note that for now I'm going to punt on the exact definition of Ar.
Our minimum Af remains 1.
And our material rating (Mr) is still:
Mr = Sr + Af
The craft percentage by tech level now changes to include a base price per metric ton.
Now the hull mass is given:
Mh = Mt * Pc * Mr; where Pc is the percentage of craft from the table above.
And the hull cost is:
Ch = Mh * Ct * Hcm; where Ct is the MCr per ton from the table and Hcm is the hull cost modifier.
Finally, because what I was formerly calling hardpoints may also be used for non weapon mounts, I decided to change the name to mount points. The formula for determining the maximum number of mount points also changes:
Mp(max) = 0.75 * (0.25*Mt)^(1/2); where Mp is the number of mount points.
Turns out I need a new mount point formula, the correct one follows:
Mp(max) = 0.75 * (Mt)^(2/3); where Mp is the number of mount points
So the entire Mp(max) column in the following table is kaput.
And... there we are folks, hull stats in mass based form. Assuming, of course, that 4 metric tons per Traveller displacement ton isn't too far out of line as a guesstimate of the total wet mass of a ship.
For the remainder of the design, volume is pretty much irrelevant. *happy dance*
Errata: I've discovered that I underestimated the number of mount points required once I started including radiators, engine thrust nozzles, etc along with weapons. I believe the above numbers should at least be doubled, perhaps more. Err make that x10, seems I forgot a few things!
Addition: It seems I do need a 'length' factor for a few things, most realistic combat hull configurations will fall within the figure given by the following formula within 25% or so, for others it doesn't really matter. Lf = 1.25*(7*Mt)^(1/3). It's a little more funky even than the other formulas but it should serve the purpose.
After much searching and way too much reading, I may have come up with a... not solution but perhaps a workaround. It seems that quite a few people who evidently are nearly as insane as myself, have calculated out the densities of various ships in Traveller. The figures seem to mainly fall between 4 metric tons per displacement ton and 7 metric tons per displacement ton. A value of 4 metric tons per displacement ton seems to be in the ballpark of the mass/volume budget I consider right for the Dark Stars setting.
This figure might seem high at first, given that 50% of your average deep space craft's mass is in fuel with a density of less than 0.1 but engine shielding and storm shelter shielding should go a long way to help make up for it.
So, if an average density around 0.29 metric tons per cubic meter is assumed, an enclosing hull can be designed for a given mass - which gives the surface area and hull plating/armor figures. Seeing as how they are guesstimates anyhow, I think it might be worth a try. While I'm at it, 1 m/s^2 seems a better fit to Dark Star as a drive rating than 2.5 m/s^2 so we'll refactor that in too.
Now the fun part is refactoring yesterday's hull design formulas into today's new and improved variant.
First we need a modified configuration table:
| Code | Atmospheric rating | Hull cost modifier | Material structure modifier (Sm) |
|---|---|---|---|
| 0 | Non-atmospheric | 1.0 | 1.0 |
| 1 | Partial streamlining | 1.2 | 1.2 |
| 2 | Streamlined | 1.5 | 1.5 |
| 3 | Lifting body | 2.5 | 2.5 |
Our structural factor formula becomes:
Sf = (Mt/4000)^(3/2); where Mt is the total wet mass of the spacecraft in metric tons.
And our structural rating formula becomes:
Sr = Sf * Sm * Gt * Ga * 0.1; where Gt is thrust in m/s^2 and Ga is agility in m/s^2 (Gt >= Ga >= 1).
Our minimum Sr remains 1.
Now are armor multiplier formula becomes:
AMV = 10/(0.25*Mt)^(1/3)
And our armor factor is now:
Af = Ar * AMV * Sm; where Ar is the armor rating.
Note that for now I'm going to punt on the exact definition of Ar.
Our minimum Af remains 1.
And our material rating (Mr) is still:
Mr = Sr + Af
The craft percentage by tech level now changes to include a base price per metric ton.
| TL | Percent of craft | MCr per ton |
|---|---|---|
| 8-9 | 2.0% | 0.10 |
| 10-11 | 1.5% | 0.15 |
| 12-13 | 1.0% | 0.20 |
| 14-15 | 0.5% | 0.25 |
Now the hull mass is given:
Mh = Mt * Pc * Mr; where Pc is the percentage of craft from the table above.
And the hull cost is:
Ch = Mh * Ct * Hcm; where Ct is the MCr per ton from the table and Hcm is the hull cost modifier.
Finally, because what I was formerly calling hardpoints may also be used for non weapon mounts, I decided to change the name to mount points. The formula for determining the maximum number of mount points also changes:
Turns out I need a new mount point formula, the correct one follows:
Mp(max) = 0.75 * (Mt)^(2/3); where Mp is the number of mount points
So the entire Mp(max) column in the following table is kaput.
| Mass of craft | Sf | AMV | Mp(max) |
| 50 | 0.01 | 4.31 | 2 |
| 100 | 0.01 | 3.42 | 3 |
| 150 | 0.01 | 2.99 | 4 |
| 200 | 0.02 | 2.72 | 5 |
| 250 | 0.02 | 2.52 | 5 |
| 300 | 0.03 | 2.38 | 6 |
| 350 | 0.03 | 2.26 | 7 |
| 400 | 0.04 | 2.16 | 7 |
| 450 | 0.04 | 2.08 | 7 |
| 500 | 0.05 | 2 | 8 |
| 600 | 0.06 | 1.89 | 9 |
| 700 | 0.08 | 1.79 | 9 |
| 800 | 0.09 | 1.71 | 10 |
| 900 | 0.11 | 1.65 | 11 |
| 1000 | 0.13 | 1.59 | 11 |
| 1100 | 0.15 | 1.54 | 12 |
| 1200 | 0.17 | 1.5 | 12 |
| 1300 | 0.19 | 1.46 | 13 |
| 1400 | 0.21 | 1.42 | 14 |
| 1500 | 0.23 | 1.39 | 14 |
| 1600 | 0.26 | 1.36 | 15 |
| 1700 | 0.28 | 1.34 | 15 |
| 1800 | 0.31 | 1.31 | 15 |
| 1900 | 0.33 | 1.29 | 16 |
| 2000 | 0.36 | 1.26 | 16 |
| 2500 | 0.5 | 1.17 | 18 |
| 3000 | 0.65 | 1.11 | 20 |
| 3500 | 0.82 | 1.05 | 22 |
| 4000 | 1 | 1 | 23 |
| 4500 | 1.2 | 0.97 | 25 |
| 5000 | 1.4 | 0.93 | 26 |
| 6000 | 1.84 | 0.88 | 29 |
| 7000 | 2.32 | 0.83 | 31 |
| 8000 | 2.83 | 0.8 | 33 |
| 9000 | 3.38 | 0.77 | 35 |
| 10000 | 3.96 | 0.74 | 37 |
| 12500 | 5.53 | 0.69 | 41 |
| 15000 | 7.27 | 0.65 | 45 |
| 17500 | 9.16 | 0.62 | 49 |
| 20000 | 11.19 | 0.59 | 53 |
| 22500 | 13.35 | 0.57 | 56 |
| 25000 | 15.63 | 0.55 | 59 |
| 30000 | 20.54 | 0.52 | 64 |
| 35000 | 25.89 | 0.49 | 70 |
| 40000 | 31.63 | 0.47 | 75 |
| 45000 | 37.74 | 0.45 | 79 |
| 50000 | 44.2 | 0.44 | 83 |
| 60000 | 58.1 | 0.41 | 91 |
| 70000 | 73.21 | 0.39 | 99 |
| 80000 | 89.45 | 0.37 | 106 |
| 90000 | 106.73 | 0.36 | 112 |
| 100000 | 125 | 0.35 | 118 |
| 150000 | 229.64 | 0.3 | 145 |
| 200000 | 353.56 | 0.28 | 167 |
| 250000 | 494.11 | 0.26 | 187 |
| 300000 | 649.52 | 0.24 | 205 |
| 350000 | 818.49 | 0.23 | 221 |
| 400000 | 1000 | 0.22 | 237 |
| 450000 | 1193.25 | 0.21 | 251 |
| 500000 | 1397.55 | 0.2 | 265 |
And... there we are folks, hull stats in mass based form. Assuming, of course, that 4 metric tons per Traveller displacement ton isn't too far out of line as a guesstimate of the total wet mass of a ship.
For the remainder of the design, volume is pretty much irrelevant. *happy dance*
Errata: I've discovered that I underestimated the number of mount points required once I started including radiators, engine thrust nozzles, etc along with weapons. I believe the above numbers should at least be doubled, perhaps more. Err make that x10, seems I forgot a few things!
Addition: It seems I do need a 'length' factor for a few things, most realistic combat hull configurations will fall within the figure given by the following formula within 25% or so, for others it doesn't really matter. Lf = 1.25*(7*Mt)^(1/3). It's a little more funky even than the other formulas but it should serve the purpose.
Saturday, May 5, 2012
Simple Complexity.. or is it Complex Simplicity..
Hard science fiction spacecraft design seems to necessitate complexity, but is that true? There is no doubt that some complexity is needed in order to reflect real world engineering limitations and physics, but does that mean the entire design sequence must therefore be complex? I think not.
The target here is a design process somewhere between CT Bk2 and CT Bk5 in simplicity but with the addition of a few items specific to the setting, inclusion of a few popular items, and removal of anything not supported by the setting.
Hull section replaced by:
Hulls - Take 2 - Mass Effect?
Hull
A Dark Stars hull specification has a size in displacement tons, an atmospheric rating, and a structural rating. The first is simply the overall size of the spacecraft in familiar Traveller (CT) displacement tons. The atmospheric rating is a combination of overall shape and atmospheric performance. The structural rating is a combination of armor value, maximum acceleration rating, and agility rating (basically rate of turning).
Unfortunately realistic hull designs require a fair bit of math. A table of common hull sizes is provided to alleviate this in most cases.
| Code | Atmospheric rating | Hull cost modifier | Waste hull volume percentage |
|---|---|---|---|
| 0 | Non-atmospheric | 1.0 | 0 |
| 1 | Partial streamlining | 1.1 | 2 |
| 2 | Streamlined | 1.2 | 5 |
| 3 | Lifting body | 1.5 | 10 |
The structural factor of a spacecraft is given by the following formula:Sf = (Td/1000)^(3/2); the square root of the cube of Td divided by 1000.
The structural rating is then given by:
Sr = Sf * Gq * Aq * 0.25 ; where Gq is the hull G rating in quarter G's, and Aq is the structure Agility rating in quarter G's. Minimum values for Gq and Aq are 1.
The minimum structural rating is 1.
The minimum armor value is 1 (corresponds to Striker AV32; AV2 would be AV40 or High Guard 0).
Armor volume correction = 10 / Td^(1/3); ten divided by the cube root of Td.
The armor material rating is the armor value multiplied by the armor volume correction factor.
The maximum armor value is equivalent to the tech level of hull construction.
The minimum armor material rating is 1.
The material volume required is given by multiplying the sum of the armor material rating and the structural rating by the material volume tech level modifier.
| TL | Percent of craft per material rating |
|---|---|
| 7-9 | 2.0 |
| 10-11 | 1.5 |
| 12-13 | 1.0 |
| 14-15 | 0.5 |
Hull cost is MCr 1.0 per Td of hull material multiplied by the hull cost modifier.
Maximum number of hardpoints =0.75 * Td^(1/2); three quarters of the square root of Td.
Turrets and fixed weapon mounts require one hardpoint each; 50 Td bays require three hardpoints each; 100 Td bays require five hardpoints each.
The following table gives structural factors, armor volume multipliers, and maximum hardpoints for a variety of common hull sizes.
| Hull size | Sf | AVM | Max Hardpoints |
|---|---|---|---|
| 10 | 0.01 | 4.65 | 2 |
| 15 | 0.01 | 4.06 | 2 |
| 20 | 0.01 | 3.69 | 3 |
| 25 | 0.01 | 3.42 | 3 |
| 30 | 0.01 | 3.22 | 4 |
| 35 | 0.01 | 3.06 | 4 |
| 40 | 0.01 | 2.93 | 4 |
| 45 | 0.01 | 2.82 | 5 |
| 50 | 0.02 | 2.72 | 5 |
| 55 | 0.02 | 2.63 | 5 |
| 60 | 0.02 | 2.56 | 5 |
| 65 | 0.02 | 2.49 | 6 |
| 70 | 0.02 | 2.43 | 6 |
| 75 | 0.03 | 2.38 | 6 |
| 80 | 0.03 | 2.33 | 6 |
| 85 | 0.03 | 2.28 | 6 |
| 90 | 0.03 | 2.24 | 7 |
| 95 | 0.03 | 2.2 | 7 |
| 100 | 0.04 | 2.16 | 7 |
| 150 | 0.06 | 1.89 | 9 |
| 200 | 0.09 | 1.71 | 10 |
| 250 | 0.13 | 1.59 | 11 |
| 300 | 0.17 | 1.5 | 12 |
| 350 | 0.21 | 1.42 | 14 |
| 400 | 0.26 | 1.36 | 15 |
| 450 | 0.31 | 1.31 | 15 |
| 500 | 0.36 | 1.26 | 16 |
| 600 | 0.47 | 1.19 | 18 |
| 700 | 0.59 | 1.13 | 19 |
| 800 | 0.72 | 1.08 | 21 |
| 900 | 0.86 | 1.04 | 22 |
| 1000 | 1 | 1 | 23 |
| 1100 | 1.16 | 0.97 | 24 |
| 1200 | 1.32 | 0.95 | 25 |
| 1300 | 1.49 | 0.92 | 27 |
| 1400 | 1.66 | 0.9 | 28 |
| 1500 | 1.84 | 0.88 | 29 |
| 1600 | 2.03 | 0.86 | 30 |
| 1700 | 2.22 | 0.84 | 30 |
| 1800 | 2.42 | 0.83 | 31 |
| 1900 | 2.62 | 0.81 | 32 |
| 2000 | 2.83 | 0.8 | 33 |
| 2100 | 3.05 | 0.79 | 34 |
| 2200 | 3.27 | 0.77 | 35 |
| 2300 | 3.49 | 0.76 | 35 |
| 2400 | 3.72 | 0.75 | 36 |
| 2500 | 3.96 | 0.74 | 37 |
| 2600 | 4.2 | 0.73 | 38 |
| 2700 | 4.44 | 0.72 | 38 |
| 2800 | 4.69 | 0.71 | 39 |
| 2900 | 4.94 | 0.71 | 40 |
| 3000 | 5.2 | 0.7 | 41 |
| 3100 | 5.46 | 0.69 | 41 |
| 3200 | 5.73 | 0.68 | 42 |
| 3300 | 6 | 0.68 | 43 |
| 3400 | 6.27 | 0.67 | 43 |
| 3500 | 6.55 | 0.66 | 44 |
| 3600 | 6.84 | 0.66 | 45 |
| 3700 | 7.12 | 0.65 | 45 |
| 3800 | 7.41 | 0.65 | 46 |
| 3900 | 7.71 | 0.64 | 46 |
| 4000 | 8 | 0.63 | 47 |
| 4100 | 8.31 | 0.63 | 48 |
| 4200 | 8.61 | 0.62 | 48 |
| 4300 | 8.92 | 0.62 | 49 |
| 4400 | 9.23 | 0.62 | 49 |
| 4500 | 9.55 | 0.61 | 50 |
| 4600 | 9.87 | 0.61 | 50 |
| 4700 | 10.19 | 0.6 | 51 |
| 4800 | 10.52 | 0.6 | 51 |
| 4900 | 10.85 | 0.59 | 52 |
| 5000 | 11.19 | 0.59 | 53 |
| 5100 | 11.52 | 0.59 | 53 |
| 5200 | 11.86 | 0.58 | 54 |
| 5300 | 12.21 | 0.58 | 54 |
| 5400 | 12.55 | 0.57 | 55 |
| 5500 | 12.9 | 0.57 | 55 |
| 5600 | 13.26 | 0.57 | 56 |
| 5700 | 13.61 | 0.56 | 56 |
| 5800 | 13.97 | 0.56 | 57 |
| 5900 | 14.34 | 0.56 | 57 |
| 6000 | 14.7 | 0.56 | 58 |
| 6100 | 15.07 | 0.55 | 58 |
| 6200 | 15.44 | 0.55 | 59 |
| 6300 | 15.82 | 0.55 | 59 |
| 6400 | 16.2 | 0.54 | 60 |
| 6500 | 16.58 | 0.54 | 60 |
| 6600 | 16.96 | 0.54 | 60 |
| 6700 | 17.35 | 0.54 | 61 |
| 6800 | 17.74 | 0.53 | 61 |
| 6900 | 18.13 | 0.53 | 62 |
| 7000 | 18.53 | 0.53 | 62 |
| 7100 | 18.92 | 0.53 | 63 |
| 7200 | 19.32 | 0.52 | 63 |
| 7300 | 19.73 | 0.52 | 64 |
| 7400 | 20.14 | 0.52 | 64 |
| 7500 | 20.54 | 0.52 | 64 |
| 7600 | 20.96 | 0.51 | 65 |
| 7700 | 21.37 | 0.51 | 65 |
| 7800 | 21.79 | 0.51 | 66 |
| 7900 | 22.21 | 0.51 | 66 |
| 8000 | 22.63 | 0.5 | 67 |
| 8100 | 23.06 | 0.5 | 67 |
| 8200 | 23.49 | 0.5 | 67 |
| 8300 | 23.92 | 0.5 | 68 |
| 8400 | 24.35 | 0.5 | 68 |
| 8500 | 24.79 | 0.49 | 69 |
| 8600 | 25.23 | 0.49 | 69 |
| 8700 | 25.67 | 0.49 | 69 |
| 8800 | 26.11 | 0.49 | 70 |
| 8900 | 26.56 | 0.49 | 70 |
| 9000 | 27 | 0.49 | 71 |
| 9100 | 27.46 | 0.48 | 71 |
| 9200 | 27.91 | 0.48 | 71 |
| 9300 | 28.37 | 0.48 | 72 |
| 9400 | 28.82 | 0.48 | 72 |
| 9500 | 29.29 | 0.48 | 73 |
| 9600 | 29.75 | 0.48 | 73 |
| 9700 | 30.22 | 0.47 | 73 |
| 9800 | 30.68 | 0.47 | 74 |
| 9900 | 31.15 | 0.47 | 74 |
| 10000 | 31.63 | 0.47 | 75 |
A couple of notes:
The maximum hardpoint figure is based on estimated surface area with a break even (to normal rules) at 5600Td.
Under 1000Td armor requires more volume for a given value, this reflects the non-linear surface area vs volume relationship.
The 1000Td figure is also the breakpoint for structural volumes, high G-rated, high Agility value large hulls require extensive structural support.
This is still a work in progress but I believe it is a good starting point.
Till next time,
Omnivore out
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