KerikBalm

So I've added a resource "cooling", massless like electric charge, and various modules that consume it. I'd like to add radiators that produce this resource. So far I've just copied solar panels and made them produce this instead of electric charge.... However, its still far from what I want. Sun tracking would be fine, if I could get them to always orient 90 degrees to the sun. However, I want them to work even (especially) when there is no sun exposure. I don't want them to be "always active", as the radiators should need to be retracted during high speed atmospheric flight. On the one hand, we have generators like RTGs and launch clamps: MODULE { name = ModuleGenerator isAlwaysActive = true OUTPUT_RESOURCE { name = ElectricCharge rate = 1 } } Is there something like "isActiveWhenDeployed" Because... that would be ideal, much better than: MODULE { name = ModuleDeployableSolarPanel animationName = bigsolarpanel raycastTransformName = suncatcher resourceName = ElectricCharge chargeRate = 18 powerCurve { key = 206000000000 0 0 0 key = 13599840256 1 0 0 key = 68773560320 0.5 0 0 key = 0 10 0 0 } } Right now, I'm thinking that I may just have it always be active, and the animation is just for show... The last option is to make them into very very very low thrust engines with an alternator *sidenote, what is "raycastTransformName = suncatcher" I notice only the static solar panels, and the gigantor panels use that

I'm on Mac OSX 10.5.8, hence no updates. I added a ton of control surfaces... my earlier designs I thought this was a problem, as when the control surfaces were used for anything other than pitch (ie, roll), the nose dipped.... but now, when I need to hold the nose down... it makes no sense. I have tweaked some stats/added some mods (in particular, back porting many .22 parts to .19, but nothing that I can think of that would affect the SAS.

First off, due to my OS, I'm still on 0.19. I've made a number of spaceplanes that just didn't seem to fly, I'd get off the runway, pitch up, hit "t" to toggle SAS (with an ASAS module on the ship), only to see the nose swing down and the whole plane crash into the ground. I've since made craft that I could mannually fly, having to constantly pitch up to maintain attitude, but I could fly them past 20km just fine, while the SAS/autopilot always nosedives.... I even made craft that had the CoL ahead of the CoM by a bit, and the SAS in this case seemed to maintaine attitude for a bit, then slowly starts pitching down, and then after some more time... nose dives.... Has anyone else had this problem? This always seems to occur on my designs that have a spacecraft slung underneath a spaceplane - with an inverted gull wing, and engines inline with the craft slung underneath... the thrust lines and CoM match well, and its quite controllable without SAS. I've made some small spaceplanes that handle just fine, and all my rockets, the SAS seems to work fine on. I can't figure this one out.

Piggy backed, with only docking ports holding it, was far too unstable in my designs. So I tried slinging it underneath from a raised midwing, with most of the mass (engines, fuel, etc) on the sides - but this turned out to be rather flimsy, and I couldn't get it off the ground, or get SAS to keep it in a climb if I managed to get it off the ground (I hear SAS got better post version 0.19 ?) Impressive to be sure, but very complex, I'm looking for simple designs, preferably ones that don't exploit the game's partially developed physics model (ie excessive air hogging), or use clipping - but not so much that I'd call it a "rule" for what I want. Hrmmm.... My ultimate goal is to use one of these designs as inspiration for a design with non-stock parts. I would like to place one of these "lifters" in orbit around every planet with an atmosphere, as a re-usable descent and ascent stage (fueling will be difficult, but thats where non-stock parts come in :-) ) for nuclear/ion powered pure spacecraft I want to make every launch vehicle reusable (not just recoverable on Kerbin) - that mainsail launcher couldn't really be re used unless it somehow lands tail sitting, ready to launch again after being refueled.

I've been struggling to design a certain craft, so I'd like to see what others can come up with... only stock parts, of course.... What I've been trying to make is really two craft: 1) A SSTO space plane that can carry a 2) pure space craft using a nuclear engine and supplementary ion drives I want (1) and (2) to be joined by docking/clamp-o-trons Basically, I'm looking for a space launch system enabling 100% re-use/recovery, but one that doesn't require wings and jets to be attached to everything I launch into space. I tried having my spacecraft on the front, docked to the space plane behind, but it was unstable. I even capitualted and gave it some wings and wheels for support, but no jet engines), and used a decoupler to attach it... still couldn't even get it off the runway. I tried a lifter design like "White Knight" (The carrier for Rutan's Spaceship 1), can't get that off the ground either... for added stability, I had a fore and aft docking port, so it was attached by 2 docking ports. So, for a more formal set of rules: 1) Nothing may be discarded or lost, no strut/fuel line connections may be broken. After reaching orbit and undocking the spacecraft, it must be possible to redock and have the set be the same way it was as on takeoff (minus some fuel, of course) 2) The craft to be lifted into orbit must have: a capsule big enough for 1 Kerbonaut (such as a mk1 pod, but a mk1-2 pod is also acceptable), anything may be used on the lifter, including probe cores 3) The craft to be lifted into orbit must also have at least 1 nuclear engine, at least 1 FLt-8000 fuel tank, at least 1 reaction wheel, 2 ion engines and the equivalent of 2 radial xenon tanks worth of xenon propellant, and enough power generation/storage to run the ion engines at full throttle for 5 minutes 4) The craft to be lifted must get to orbit with a full fuel load, and no wings.control surfaces/jet engines. 5) The winner is the one with the simplest (fewest part #) lifter craft, only stock parts

Yea, I tried the edit, but it wasn't there, after your post, I went back and looked closer, selected "advanced", then I could edit that part. Also, I'd like to thank DMagic and RadHazard, most of the other posts... well... I wasn't looking for an explanation of using reaction wheels, but rather if the ASAS/AdvancedInline Stablizer was basically completely redundant.... which as I suspected, it is.

Ok, backwards compatibility is the purpose, I wasn't missing anything else, thanks (PS, how do I change the prefix to answered)

According to: http://wiki.kerbalspaceprogram.com/wiki/SAS "All command modules, with the exception of the EAS-1 External Command Seat, include SAS capabilities." I'm still stuck on 0.19 but as I hope to upgrade my computer and OS soon, I have wonder.... Does this mean that there is no reason to use the ASAS module (now renamed to inline advanced stabilizer) except on vessels that only have the external command seat? Its got the same torque as the reaction wheel, and the SAS function is redundant, so, its just more mass for the same thing, no?

Hrmmm, lest someone read this and think its realistic, I realized I made a mistake. Reducing ISp by 10x increases the mass accelerated by 100x, but not the thrust, as you accelerate 100x as much mass per second to only 1/10th the velocity. The 7,000 ISP thruster would only get ~15 kN of thrust.... You'd need a 5 gigawatt reactor for that amount of thrust, a 500 megawatt one wouldn't be sufficient To get a mere 120 kN of thrust, it would be only 875 kN - not much better than the nuclear engine we've already got. Doube the thrust, sure (but I've set the weight to be nearly 2x higher for the reactor+ engine), and only ~10% more ISP... ah well, I'll go with it. A 5 gigawatt reactor weighing that little is not very realistic.

Couldn't you reduce that 4000 m/s a bit if you did some aerobraking? You don't need to go to a circular LEO, you just need your perapsis intersecting the upper atmosphere, a highly elliptical orbit should work

This is why median values are often worth talking about more than mean values. If you look at the median income, vs mean income of certain countries... you'll see some interesting things

Well, once is more or less accurate for Earth... the Homo lineage (neandertals and modern humans are more or less the same species... without getting into a discussion on what constitutes a species). We've been dominant for such a short time, I can't really imagine saying we're the reason that Earth has only produced 1 intelligent species in its nearly 4 billion years of harboring life. Apes for that matter, are also pretty recent, and I don't see any non-ape lineages showing much potential for becoming a technology using species (beyond very simple tools, like what crows have been shown to make with bendable wire to reach food placed out of reach). Toolmaking, intelligence, and *education* are a powerful combination. The ability to pass on ideas from one generation to the next, so each generation doesn't need to reinvent the wheel, etc. Humans aren't really smarter than we were 10,000 years ago, but our accumulated knowledge is. If you took a bunch of kids, had them sit around playing CoD all day, with zero education, then when they were adults, plopped them in the middle of the jurassiv... they would not survive. But if you took a bunch of people who had learned a trade, they'd quickly establish a society and become dominant. Considering that intelligence wouldn't increase overnight, nor would knowledge, it may be hard for intelligence to evolve at all. It seems we (Earth life) was stuck for a long time in the local optima of Brain vs Brawn, where brawn was favored, and decreasing brawn for a little more brain ended up being a worse condition.... the amount you'd need to go in the "brain" direction before being viable constituted a huge leap, that must also be done in tandem with the ability to manipulate objects (in our case, with prehensile hands). I can imagine a lot of worlds where the species at the top of the food chain is the species with the biggest teeth/claws.... not the one that uses tools. Few land animals in Earth's history could take on a group of humans with spears in a phalanx formation... and for those animals... a bit of rope/pits/traps would do the trick.

"even if intelligence only popped up every 1000 light years or so it would still be a rather large number of intelligences in just this galaxy, but it would be very difficult to find" 1000 light years.. the galaxy has a radius of 50,000 light years... the galactic habitable zone (this is not based on a specific life chemistry, but rather the presene of elements heavier than helium, vs intense radiation and such), is far smaller than that. Its between 4-10 kiloparsecs from the core. So thats between 13,000 and 32,000 lightyears from the core. Assuming its a flat disk(its about 1000 light years thick on average http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980317b.html) and since 1/2 pi cancels out, thats (32^2 - 13^2) = space for 855 intelligent species each with a 1000 light year zone around them (actually a cylinder rather than sphere with the "flat" approximation). Travelling at .1c, the galaxy would be "confluent" with life if those species spend even 10,000 years out of the last few billion years expanding. Again... there's been plenty of time for the galaxy to become full. They may not want earth, but there's no particular reason they wouldn't want to mine asteroids, or the Oort cloud. I'm assuming such a species wouldn't even particularly want to be planet bound. Why aren't they somewhere in our solar system already? If they were so close, it would be hard to miss.... So.... if there are billions and billions of "earths" in the galaxy, that would mean billions and billions of planets where one of the following is true: 1) Life doesn't evolve into a technology using species 2) A technology using species destroys itself before controlling fusion or 3) Does not use fusion to travel to nearby stars. You need less than 1000 of those billions and billions to decide to travel to nearby stars to fill up the galaxy in 10,000 years. Thats less than 1 in a million "Earths" producing a species a bit more technologically advanced than us, a tiny tiny tiny fraction of time sooner than us (If just a few took even 99% of the time it took us to get to this state, the galaxy would be full) To me it seems incredulous to say the galaxy is full of earth like planets, and full of intelligent species, but almost every single species comes to the same conclusion: don't expand. I think its far more likely some will decide that, and some won't - and with that idea, the Fermi paradox still stands very strong. That leaves us with the Rare Earth hypothesis (planets capable of supporting simple life may be common, but planets capable of *producing* *complex* life are very very rare), or some idea of a race of "First Ones" that have spread throughout the galaxy, but at low density, and they are actively limiting the expansion of other species, remaining silent and hidden until a newly evolved species has the capability to expand, at which point they assert themselves and tell the new species on the scene to follow their rules... *or else* The latter is pure speculation based on little evidence, while the Rare Earth hypothesis has much more evidence, but is still based upon speculation about what life needs, and what is conducive for evolution of advanced life.

So I found the problem... I made two types of jet engines, the standard and the turbojet... but only the standard was set to use "IntakeAirB" , and I used the turbojet version on my Duna plane.... I wondered why it still showed IntakeAir instead of IntakeAirB in the resources display (it now shows just fine) I just can't figure out how the engines worked at all on Kerbin, when the air intake should have only provided the "B" resource..... unless I don't remember right, and they didn't work at all. I'll zip off to Duna later today with an OP'd "lulz Drive" that runs on "lulz" to make it easier to test

"While the expansionist aliens may have spread, they're quite likely to have also been destroyed or collapsed due to natural disaster on a massive scale or just through mutation / evolution / loss of expansionist desire / stagnation or cultural drift." Once they've got the capability to move between stars (and actually used it), even a gamma ray burst wouldn't wipe them out. Even if they're still in their home system, if they've got self sustaining subterranean asteroid/moon/planets colonies (as is likely on bodies exposed to radiation belts already), they'd survive a gamma ray burst. And thats not even considering a "terminator" scenario where biological life is eclipsed by machines it creates. mutation/evolution would not lead to their extinction without an outside cause.

So if we have NERVA rockets, why not Nuclear jet engines: http://en.wikipedia.org/wiki/Aircraft_Nuclear_Propulsion Such an engine doesn't rely on combustion, and thus should work on Mars (or Duna)... so I set out to make one for KSP. I got to Duna... and found that my modded jet engines would not work, can anyone help? Here's what I've got: Added a resource: RESOURCE_DEFINITION { name = IntakeAirB density = 0.005 flowMode = ALL_VESSEL transfer = PUMP } Added an intake specifically for the Nuclear jet engine: MODULE { name = ModuleResourceIntake resourceName = IntakeAirB checkForOxygen = false area = 0.01 intakeSpeed = 10 intakeTransformName = Intake } RESOURCE { name = IntakeAirB amount = 0.2 maxAmount = 0.2 } added a nuclear jet engine: MODULE { name = ModuleEngines thrustVectorTransformName = thrustTransform exhaustDamage = True ignitionThreshold = 0.1 minThrust = 0 maxThrust = 150 heatProduction = 700 useEngineResponseTime = True engineAccelerationSpeed = 0.1 engineDecelerationSpeed = 0.42 useVelocityCurve = True fxOffset = 0, 0, 0.74 PROPELLANT { name = ElectricCharge ratio = 4 } PROPELLANT { name = IntakeAirB ratio = 1 DrawGauge = True } atmosphereCurve { key = 0 1000 key = 0.3 1800 key = 1 2000 } velocityCurve { key = 1000 0 0 0 key = 850 0.2 0 0 key = 0 1 0 0 } } (also added a power generating nuclear reactor, that is needed to keep that energy sucking engine working) Why won't it work on Duna.... I set the "check for oxygen" to false.... the intake should generate the resource "IntakeAirB", no?

One species may lose focus... but if they were all over the galaxy, it wouldn't take very long to fill up the galaxy. If I may make an analogy to microbiology here.... If you put one bacteria on an agarose plate, one colony forms, that gradually spreads... and takes a long long long time to cover the whole plate (its growth does not follow a simple exponential curve, as only those along the circumference grow, in which case its a much more linear growth) But if you plate about 1,000 bacteria on your plate (roughly equal distribution)... overnight you have a "lawn" of confluent colonies.... That we don't see "confluence" should mean that there aren't that many out there. And you're also assuming governments as fickle as the US government who can't agree on anything. If we have some sort of collective or single consciousness, then the time span is not such a big deal, and its likely the goal could be pursued longer, with a view towars the "bigger picture" It would also send out colonies to avoid using up all the resources, leaving the center to die while only the periphery is expanding. A more uniform expansion prevents the center from dying out so fast. I would say that generally speaking, life tends to spread... aggressively. Lets not just consider one case for one species (colonization of the Americas), but life in General... and even in the case of american colonization... they spread across the continent quite rapidly, and filled it in later. Like I think a species would do with our galaxy, before even considering an inter galactic expedition.

But do you need a station for that? what does it matter if you haul that fuel up in 1 trip or two? Doin it in one means no complicated docking maneuver and use of RCS. For that matter, you don't actually save any equipment or fuel if you do two trip and dock, or one staged trip. I see the point of landers for interplanetary craft.... so you don't have to decelerate your fuel and extra equipment down, and then lift it back up... Likewise i see the point of launching refueling craft from Kerbin to interplantary vessels.... At the moment, I'm using docking ports for pods/landers, and probe cores for my interplanetary nerva/ion vessels, so I just launch a pod up (and I browse the forums while SAS is on and physics warp to 4x on my ion burns...). I've thought about making stations, and bases on minmus... but I just can't see the point of having to dock my IP craft with a station, and then the "fuel truck" with the same station. At the moment, the only point I see is so that I don't have to have them in the same orbit at the same time, but either one can go up and just orbit while waiting for the other.... Twice as many dockings for the same effect. And of course... bases in grav wells.... ughhh....

Beyond looking cool... is there any purpose to bases in space/ other celestial bodies? The only resource one can extract... is electricity The closest thing to a station that makes sense to me... is having part of your ship stay in orbit when you send down a lander. Is there any real purpose to these bases? Something that can increase efficiency/effectiveness of the space program? If not.... Could anyone point me to a version 0.19 compatible mod pack (My mac is running Leopard, and no later version of KSP works on mine, but I've back ported some stock parts) that allows some resource gathering? I was thinking of something like Nuclear reactor module + atmosphre processor module + chemical lab + fuel storage tanks = a fuel producing station on planets with an atmosphere... or at least maybe something for Laythe that can convert intake air to oxidizer. Maybe a drill + refinery + chemical lab for solid bodies with no atmosphere?

As I already said.... "If its not one of 1-5, then there should be multitudes of technological civilizations with controlled fusion, whom can at least colonize their local solar system, and thus are likely to be extremely long lasting. It seems incredulous to me that of these multitudes, not one has embarked on an expansionist phase. Therefore I conclude the problem lies somewhere in 1-5." "it would also be conducive to defense... we'd start to establish a buffer zone between us an other potential alien civilizations... the best defense is a good offense and all that. If we start an expansion program, we're less likely to be swallowed by an alien's" "Survival of the fittest will surely operate galaxy wide (not that survival of the fittest = always war, there are many symbiotic relationships where each entity increases its fitness through cooperation). Species that expand will persist and become more prevalent, species that don't will disappear." If we assume technological civilizations are common, then it seems incredulous that not a single one has embarked on an expansionist phase. Also, add in the billions of years they have to change their mind, and potential advances beyond that (ramjets and Antimatter), that make it even easier and shorter to do so. If there are only a handful of such civilizations, this objection is reasonable... if there are millions of them... this is not reasonable. If there are millions across the galaxy, and they only spread locally, you'd still see the galaxy becoming pretty full, pretty fast. And there are strong incentives to expand locally... at least within the nearest 10 light years or so, where travel isn't *that* hard with sufficiently advanced slower than light travel. I don't buy the argument that the galaxy is packed full of technological civilizations, but not a single one has decided it would be a good idea to expand beyond their start system. Likewise, I don't buy the argument that the galaxy is packed full of technological civilizations, but every single one has decided to hide their existence or operates in a way that we can't detect them. These arguments can work if we assume only a few civilizations, but thats assuming some variant of Rare-Earth.

"Aliens come to take our minerals/water/women/whatever is so laughable." Yes, it is laughable... wouldn't they rather go to Ceres, or some other body with a low gravity well where it is easy to extract and you don't have to deal with potential biohazards? Imagine if Aliens came and just said "We claim everything in this system outside Earth's orbit" maybe they'd follow with an offer of technology to earth in exchange for Earth making some stuff for them to help kick start their colonization of our system (assuming a single colony ship arrives, and that the startup phase is a colony ships' hardest part) "In that case, there could be a missile heading our way right now to end our threat to interstellar civilization. A preemptive strike to ensure we never have a chance to become a threat." Also something reasonable at first, there's been some sci fi written on that premise, both where Earth does the killing, or gets killed. But again.... as soon as you expand beyond your home world, such a threat no longer makes sense. If 1-planet species A sends a KEW to wipe out the home planet of multi-system species B.... then Species A has ensured its own destruction. Before you send a KEW, you better be damn sure that they won't be able to strike back. If they have self sustaining industry on various moons and asteroids - then all you accomplish is stirring a hornet's nest. So a multi-star system species, or even a species that is confined to its home star but has self sustaining off-world colonies, are not so vulnerable, and thus likely wouldn't feel so threatened as to resort to genocide. They could in that case beam a simple warning: *insert stuff to allow them to decipher the language of the message* "Warning, we exist acorss multiple star systems, with colonies on multiple planets, and industrial capabilities on smaller cellestial bodies, we cannot be wiped out in a first strike, but you can. Do not attempt to leave your home system, or the planets in your home system will be destroyed by reletavistic KEWs" That threat of anihilation by KEWs, is precisely a reason to begin sending fusion/Ramjet/antimatter powered vessels to other stars (not to mention, those vessels can also function as KEWs themselves, and form part of your retaliatory capabilities). Expansion ensures the survival of the species. Survival of the fittest will surely operate galaxy wide (not that survival of the fittest = always war, there are many symbiotic relationships where each entity increases its fitness through cooperation). Species that expand will persist and become more prevalent, species that don't will disappear. I don't see fusion power as an insurmountable hurdle, and across the millennia, Epochs and Eons, of the last billions of years such a mentality surely would have won out eventually, long enough for a massive diaspora to start.... So.... we're back to the Fermi Paradox..... where.... are.... they???? Variants of the Rare Earth hypothesis + evolution being unlikely to lead to technological civilizations like ourselves, seem to be the only answers that make sense to me, and aren't incredibly pessimistic about our own future (technological civilizations destroy their ecosystem/themselves through industry and war, before leaving their home planet) Ultimately, every clade on Earth is doomed if we don't get off this rock. If we do, we'll surely take many of them with us. We are simultaneously the greatest threat to the survival of other species on Earth, and their only chance of long term survival (well, the extremophile archea and bacteria probably have ~4 billion years left... but the multicellular life may only have 1 billion)

"the fact that we don't see fusion-powered alien ships flying around our solar system suggests that interstellar travel might not so widespread." Yes, it certainly suggests that... but the question is why is it not? Is it: 1) Few planets actually suitable for life to arise/start? (habitable != conducive to abiogenesis) 2) Few planets actually suitable for complex life? 3) Evolution from simple (like single cells) life to complex (multicellular or syncytical for example) is infrequent or too slow given the life time of many stars? 4) Complex life rarely evolves into a species that establishes a technological civilization? 5) Technological civilizations rarely last long enough to achieve controlled fusion? 6) Civilizations that achieve controlled fusion rarely use it for interstellar travel? If its not one of 1-5, then there should be multitudes of technological civilizations with controlled fusion, whom can at least colonize their local solar system, and thus are likely to be extremely long lasting. It seems incredulous to me that of these multitudes, not one has embarked on an expansionist phase. Therefore I conclude the problem lies somewhere in 1-5. I'd say we're only a century or two away from controlled fusion.... and at that point we can begin sending drones carrying biological packages, etc, even if the voyage is too long for us. It would ensure our legacy, and it would also be conducive to defense... we'd start to establish a buffer zone between us an other potential alien civilizations... the best defense is a good offense and all that. If we start an expansion program, we're less likely to be swallowed by an alien's (for that matter, if we encountered aliens more primitive than us, I'd hope we'd study them, rather than exterminate them). When you think of other possible technologies, like bussard ramjets, the travel time (especially due to time dialation), shrinks a lot. Then if you consider a civilization that has some sort of collective consciousness (borg like?), then its even more likely that they would find it worthwhile to expand. Generally, the overall picture of life, is that it expands where it can. Why should technological civilizations be any different?

You're assuming that species never leave their home system. Any species that has mastered nuclear fusion will have the capability to colonize the entire galaxy in ~10 million years. If there was some alien species, spread throughout the galaxy... munching/mining on rocks in orbit around Alpha/beta/proxima Centauri, communication with them would be quite easy. So that means either: Earth like planets are very rare, or its very unlikely that we'll achieve controlled fusion before we destroy our planet, or are wiped out by some other event. One a species has fusion powered spacecraft, I'd say they are very very likely to persist, I can't imagine any extinction event that would wipe out a species/civilization that spans multiple stars - short of a concerted extermination effort by another sentient species. Either planets like ours are rare, or we're very very very likely doomed to self annihilation, or some combination thereof.

So I wanted your thoughts on this fusion drive system I've added (duplicating stock part models and changing their stats and names). I was basing it around a dense plasma focus reactor (I think these need more development, they look much more promising than toruses from what I've read). Anyway, these reactors #1) are approaching the conditions needed for P-B11 fusion, #2) are acheiving fusion rates of toroidal and ICF reactors many times their size, and thus wouldn't need to be scaled up as much to break even, #3) produce an ion beam stream that can be directly used for high ISP thrust, or decelerated against a magnetic field for direct generation of electricity. So my system has 5 parts: 1) A P-B11 fusion Reactor 2) A High ISP "nozzle" consuming P-B11 fuel 3) A 1/10th ISP high thrust engine consuming P-B11 fuel and Xenon gas 4) A P-B11 fuel container 5) Stock Xenon containers To make my fusion system work, I've added a resource "IonBeam" generated by the reactor, so you can only run 1 of the 2 engines at once. As for the stats.... I decided my reactor would be 50% efficient... or rather that it generates 2x as much power as it consumes - so it only has to decelerate the ion stream enough to remove 1/2 its kinetic energy. Given KE = 1/2 mv^2, this means approximately an ISP of approximately 70% the maximum listed over here at atomic rockets: http://www.projectrho.com/public_html/rocket/enginelist.php#hbfusion That results in an ISP of 70,000 (!!!) Next, I decided that a net output of 500 Megawatts was "reasonable", and a reactor weight of 3.5 tons was "reasonable", and calculated how much thrust I could get with that much power, at 70,000 ISP.... Skipping the calculations (I can show if you want)... I arrived at 1,428.6 Newtons... or 1.428 kN -> which I rounded to 1.5 kN.... 3x the thrust of the games Ion Engine (though these ion engines are already unrealistically powerful for gameplay purposes, since you can't time warp with active engines) - with a much much worse T:W ratio. Going back to 1/2mv^2 ... if you lower your ISP by 10x, you can increase your thrust by 100x... so I figured I'd do that, so I did some technobabble about how a high energy ion beam is used to superheat the Xenon propellant into a plasma... And I figured this system would be ~80% efficient.... so I made another thruster, this time with only 7,000 ISP (1/10th the max), and instead of 1.5 kN, I multiplied that by 80.... 120 kN of thrust.... Now we're talking:) It uses the Nuclear engine model, and adds another 1 ton (reasonable I think). You'd be surprised how many Xenon tanks you can go through with such an engine... but it easily achieves SSTO. It seems a bit OP'd I'm not sure this 1/10th ISP, 80x thrust engine is a good idea.... seems a bit unrealistic... but I did the math... and it seems to me that if one assumes a 500 MW reactor that fuses P-B11 (If you used Helium3-Deuterium, you'd get even higher ISPs!) is reasonable... then it seems this would be the result... maybe I need to crank up the reactor weight......

Suppose that Fusion power is achievable and practical (I'm very optimistic about Dense Plasma focus designs). A spacecraft with a Propellant: total mass ratio similar to the Saturn V, propelled by a fusion powered design, would be able to achieve speeds of a significant fraction of the speed of light (like 20% !!!). The galaxy is only 100,000 light years across... if you can get a spacecraft going 20% of the speed of light... suppose they save some delta V, and average 10%.... thats across the galaxy in a Million years.... life has been here on Earth for roughly 4,000 million years. Suppose during that time that they get bussard ramjets (at least for braking after accelerating using fusion propellant, allowing them to use more to accelerate and less to decelerate)... they'd likely get even faster speeds. Of course, speed to traverse the galaxy is not the speed it takes to colonize it.... lets assume that they spend roughly 10x as much time developing a colonies, as they do traveling to establish new ones (not unreasonable when traveling even at 10% the speed of light means voyages of hundreds of years)... 10 million years for a space faring civilization with fusion power to colonize the galaxy. Considering how easy it would be to move about a solar system with fusion, they may prefer asteroid belts and small moons to planets with large gravity wells - a completely space faring civilization - They could be everywhere, and they wouldn't need to hide their presence... like a single planet species might want to ensure its not discovered (as another single planet species may decide to kill it with a KE impactor to eliminate the threat, before the same thing happens to them). There's plenty of time for aliens to visit, and there's little reason to hide. Also consider: * The first generation stars, and their planetary systems would be deficient in the heavier elements needed for life. * The conditions at which life can exist, are not necessarily the same as those which allow for abiogenesis to occur (indeed, if the "radioactive beach" hypothesis is correct, and the major contributor, life could be very rare) * The conditions that allow for life are not the same as the conditions that allow for complex life possessing high metabolisms (Ie, even if Europa is habitable, no space faring life will evolve there * Life may not necessarily evolve in the direction of intelligence. There wasn't really any major evolutionary innovation between the end of the Permian, and now, as far as I can tell (ie, high metabolism, limbs that could be easily adapted to manipulate objects, brain structures), yet 300 million years passed before we have a species that has a chance at achieving fusion powered (or better, ie, antimatter) space flight. * The "habitable zone" around red dwarfs (by far the most common star type) means any planet there would be tidally locked... meaning no thermal cycling from day and night cycles (may have been important in abiogenesis). It also means that the atmosphere will need to be pretty thick, or almost entirely absent .... the night side will be extremely cold, and the atmosphere will freeze on the night side, and be locked away in icy deposits... or the atmosphere will need to be thick enough for sufficient heat transfer/insulation to prevent this * The emission spectrum of red dwarfs is primarily in the infra red, combined with the requisite thick atmospheres, and absorption spectra of gasses, there will be little opportunity for direct photosynthesis, which will limit the complexity of life there, and its not unreasonable to think that these conditions preclude space faring life. *larger stars burn out faster... for 3.5 out of nearly 4 billion years of life on earth, we didn't even have macroscopic multicellular life. This is an exceedingly long time frame, and given the replication time and expected diversity of life at that scale (its not like we're sampling only mammals, and looking for something very specific like verbal communication with grammatical structure), so I'd say on other earth like planets, its probably going to take a similar time - although this time is likely highly altered by the prevalence of extinction events - you want enough to break out of evolutionary local maxima, but no so many that ecosystems and diversity are constantly collapsing. * Our star only has about another billion years or so before its output increases to the point that Earth will be hostile to complex life. Life on Earth has gone 80% of the way through the usable life time of our star, without producing a space faring species. We have a chance to be that species... but it also seems likely we may wipe each other out, and set earth's ecosystem and life back so much it may be another 300 million years.... given our use of fossil fuels, I'd say we're Earth's only shot, and we're perpetually 1 major war away for annihilation. * Any civilization that decides not to expand, will be at a severe disadvantage to one that does expand. There will be strong selection pressure towards expansion (just like there was towards self replication during abiogenesis) Given the lack of heavier elements, we can conclude life likely didn't arise until billions of years after the big bang - when enough stars had gone super nova. We can also assume that it would be another 2-6 billion years for life to evolve to become space faring (assuming we are on the threshold, and applying a +/- 50% time scale to our own) - which may be too long. I'd say generally only G and K type stars would have a chance of producing spacefaring life. Given the time frames, its not unreasonable to think that we're one of the first (in the cosmic time scale) in our galaxy. Even if we take the metallically requirements and evolution rates into account.... I still see no reason we couldn't have had space faring life in our galaxy a billion years ago.... so If that life takes 10 million years to spread throughout the galaxy. That still leaves it as a 1% chance that we are here during the "expansion" phase of another civilization. So lets say thats unlikely. That means - there are no other space faring civilizations that possess fusion drives in our galaxy, or they're leaving us alone and we can't detect them. I think its highly likely that a species that gets to our technology level either a) destroys itself, or develops fusion power very rapidly (cosmologically speaking, even if its 10,000 years from now). Thus, a variant of "the rare Earth hypothesis" is what I conclude to be the most likely to be correct.