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Everything posted by Terwin
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Ideal SSTO's Versus Two Staging...Settled?
Terwin replied to Spacescifi's topic in Science & Spaceflight
Sorry, my google-fu failed me. (if only I had some common-sense to back it up) ISS orbital velocity: 27,600 kilometers per hour -> 7 2/3 km/s (ref: https://planetseducation.com/international-space-station-orbit/ ) So it only takes ~24 2/3 km/s of delta-v to follow the specified trajectory(assuming little or no atmospheric drag for take-off) As we have seen in Star Trek, Star Wars, Battlestar Galactica and other science-fantasy; this is clearly not an issue, and vehicles the size of a large van or small bus can repeatedly make such trips with a cargo fraction of 80%+ In the real world, Falcon 9FT is 549t and can loft 15.6t (22.8t expended) for a cargo fraction of ~2.8%(~4.2% expended) Stage 1 dry-mass: 22.2t - 1 falcon9 engine no longer needed on 2nd stage: 0.47t =21.7t cargo capacity without staging: -6.1t (1.1t expended or 0.2% ) Giving the STSO ~4.8% of the efficiency of the tsto using this rocket(the most updated version of one of the most recently developed rockets that currently exists) Also note that this is fully expended, so actually being able to land again would greatly reduce this. Even if we assumed that the first-stage tanks are massless after their normal separation point and we only need to carry 8 additional engines to orbit(engines are only ~19% of the first stage dry-mass btw), that puts us at 11.8t or ~75% of the tsto performance in this scenario(and this requires either staging 21.7t of empty tanks or a ~80% dry-mass reduction only applied to the SSTO) So yes, a fantasy-tech ssto can indeed beat out a real-tech tsto, but if they both have access to the same technology, then the TSTO will trounce the SSTO every time.(Martians and Lunites can have useful SSTO with current tech, but even there TSTO will be more efficient) -
Ideal SSTO's Versus Two Staging...Settled?
Terwin replied to Spacescifi's topic in Science & Spaceflight
I would suggest that your meaning is not nearly as clear as you seem to think it is, thus the questions/suggestions. Earth orbital velocity: just under 30km/s Time to orbit: 8.5 min(for the shuttle) 8.5*60*9.8=~5000m/s (used as gravity loss estimate) means we need at least 70km/s without aero-breaking (or accounting for air friction during launch) So just calculate the fuel fraction for the isp of the engine you want to use and see if it is feasible(and no, anti-mater + pusher-plate is never feasible under the laws of physics as we currently understand them, so use something else) -
totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
Isn't that just a miniature lab? So if you want the bigger version, just use the stock lab(2 scientists, and lots more science storage, but not inflatable) -
The Death Of The Heavy Scifi Battle Spaceship
Terwin replied to Spacescifi's topic in Science & Spaceflight
In fiction, the author defines the laws of the universe to suit the story. In historic fiction or hard sci-fi, most of the changes are social rather than playing around with physical laws. On the other hand, if the author wants giant transforming humanoid mecha spamming missiles, then they add some sort of change that makes such things practical(reflex technology in the case of Robotech/Macross for example). If the Author wants fireball spells, dragons, and magic swords, then they add Magic to the mix. In short, you identify what you want for your story, then choose if you want to just hand-wave it into existence with no explanation, create a cultural or technobabble reason for what you want, or use existing period-appropriate technologies(does not work beyond technologies currently in-use). Anything else is pretending expertise and foreknowledge that you do not have and which will be transparently stupid to those who know better. For examples look at the science fiction hall of shame thread. -
For Questions That Don't Merit Their Own Thread
Terwin replied to Skyler4856's topic in Science & Spaceflight
Looking at Cost-per-science accounting by itself, probes currently make a lot more sense than humans. Even if a human can get and order of magnitude more science done than a probe in a given time-frame, a probe is probably two orders of magnitude cheaper per time-frame(in part because they can last an order of magnitude longer(or more, looking at you voyager and opportunity) using rtg/solar and in part because it is probably an order of magnitude cheaper without life-support or the ability to come home). The primary value delivered by human space flight over probes is more related to inspiration(and leveraging national pride to get funding in the first place), not maximizing science per dollar spent. After all, how many people remember the Luna probes, Ranger probes, or Pioneer 4 compared to Neil Armstrong? -
I took that statement as an expression of frustration from someone embracing a fail-fast philosophy encountering real-world processes that do not support that philosophy. I am sure it does not help that it is probably expensive to scrub when otherwise ready to launch.
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For Questions That Don't Merit Their Own Thread
Terwin replied to Skyler4856's topic in Science & Spaceflight
That does not clarify much, as a low-density but electron-rich 'plume' could easily be visible if against a dark background. Also, the temperature of the plasma maters a great deal. Even though your fire-place poker has little to fear from a wood fire, it was originally created by being melted in a different(much hotter) fire, and it could be vaporized by an even hotter fire. And all of those fires have plasma much cooler than the plasma in the heart of the sun. -
Solar Power Satellites (split from SpaceX)
Terwin replied to SpaceFace545's topic in Science & Spaceflight
Economic inertia can be a powerful force, and it can take a visionary with deep pockets to disrupt it(see Elon Musk regarding reusable rockets) I would not expect Thorium plants to enter common use unless and until uranium is no longer easily available(which likely also involves digging up old 'used' fuel rods and re-processing them). But if you are talking about 'limited stocks of uranium to fuel nuclear fission' then Thorium has a place in the discussion, as it is an entirely viable option for once the fuel cost of using uranium gets too high. -
Solar Power Satellites (split from SpaceX)
Terwin replied to SpaceFace545's topic in Science & Spaceflight
neutron+Th232-> Th233 (hl 21 min)-> Pa233(hl 26 days)-> U233 U233 produces 2.38 neutrons per neutron capture, allowing this process to be self-sustaining. (Ref: https://www.radioactivity.eu.com/site/pages/Thorium_Fuels.htm ) I find it odd that you would classify the fertile fuel source to be a passive element. Sure the easiest way to kick-start a thorium reactor is using either plutonium or previously produced U233, but that is just the kick-start. There was a research device where they omitted the breeding blanket in favor of taking neutron measurements where the concept was proven to work: https://en.wikipedia.org/wiki/Molten-Salt_Reactor_Experiment I did a quick check of https://en.wikipedia.org/wiki/Fusion_power and it only lists Hydrogen(including duterium and tritium), helium, and boron as potential fuels. Would you care to provide a link where fission provides anything more direct than providing the electricity to run the lasers to initiate fusion? Unless I missed it, it seems that no one has bothered to update Wikipedia with this approach that you claim has been the best option for fusion power for the last 40 years. The molten salt reactor design should be able to most if not all of the thorium. The only hybrid fission-fusion devices I have ever heard of are nuclear bombs, not reactors, there is a *big* difference. Not all reactors waste fuel the same way, the reasons fuel pellets are not re-processed to extract the remaining useable fuel are cost and politics, short term it is cheaper to just discard them, long term is it more expensive, but balance sheets are reported quarterly, not per decade. Those 'highly radioactive fluids' are molten, and would quickly solidify if exposed to an uncontrolled environment, basically containing themselves. If you wish for me to consider any additional replies, please include references to support your claims, in particular that 'hybrid fusion-fission reactor' design that you have been touting as the cure-all for the world's future power problems. -
Solar Power Satellites (split from SpaceX)
Terwin replied to SpaceFace545's topic in Science & Spaceflight
Th produces U233 which then splits and turns more Th into U233. You need some neutrons to start, but after that it is self-sustaining. Liquid Salt is the preferred design for Thorium reactors, this includes a fuel reprocessing step that separates out the U233 to send into the core and the used/poison fuel which can be dumped. As we are dealing with liquids instead of specifically designed fuel pellets, it is a lot easier to keep using the 'unburned' fuel, as you need to chemically separate out the U233 already, so removing the depleted fuel at the same time is not a big addition. Not being able to afford to dispose of the Thorium ore as 'radioactive waste' is a big part of why rare earth mining in the US could not compete with rare earth mining in china. Turning that cost center into a profit center might well help resume rare earth mining in the US. Outside of nuclear bombs, I am not aware of any fusion designs that utilize fission for ... anything. When you say we need to reserve fission fuel to use for fusion reactors, to me it sounds a bit like saying we need to reserve horse-feed for use in automobiles. (Or that you want to scour the earth clean of complex life using fission pumped fusion bombs) -
The KSP Caveman Challenge 1.11.x - 1.12.x
Terwin replied to JAFO's topic in KSP1 Challenges & Mission ideas
As someone who finished without even going orbital, not sliding off of ladders seems like something that would already be pretty much solved by those taking advantage of orbital reports, so I do not see it mattering much as far as I am concerned. You still need to keep them from being pushed off by drag or other forces, even if they no longer slide around once in orbit. -
Solar Power Satellites (split from SpaceX)
Terwin replied to SpaceFace545's topic in Science & Spaceflight
According to This Article we currently know about roughly 230 years worth of uranium fuel at current usage, and further exploration is likely to double this.(not including things like sea-water extraction) But Uranium is not the only option for fission, Thorium is more common than Uranium and roughly 100% of Thorium is useable as nuclear fuel(as opposed to 0.7% of uranium). There was a research thorium reactor that showed Thorium can be a safe and reliable power source, extending the potential life-span of nuclear fission by more than 100 fold(into the tens of thousands of years). Fusion will be great if/when we can get it to produce power in an economic fashion, but we are not there yet, and there are a lot of hurdles yet to pass to get there. Perhaps fusion will be our power source in 20, 50, or 500 years, but for today, nuclear fission is the safest, most reliable, and least polluting power source currently available. (most co2 pollution from nuclear plants comes from making the cement used to build them, similar to Hydro, but dams use more cement per kwh) -
totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
Flex-tubes are kraken bait. RD implemented disconnected bases just to prevent this sort of issue. -
For Questions That Don't Merit Their Own Thread
Terwin replied to Skyler4856's topic in Science & Spaceflight
Sounds like a combination of the subconscious recognition of eyes looking at you and drivers trying to be aware of their surroundings.(or pedestrians trying to be aware of the large metal murder machines near them) I try to look around on a regular basis when driving so as to A) be better aware of my surroundings and B) prevent 'roadway hypnosis'. I also tend to look around when walking if I hear vehicles near-by. -
1) the system need not be static, it could easily accelerate to closely match the current speed of SH 2) SH can hover, so there need not be any significant velocity at initial contact, nor any significant initial load, as they can reduce thrust after initial contact until the last engine shuts down.(sort of like one parent letting go of the baby after the other parent has a firm grip)
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I think I remember an idea about putting a large spinning magnet at a Lagrange point to deflect solar wind? Not terribly practical as I think it would take multiple SS loads just to get it to orbit, but certainly possible.
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I could see an argument that the ejecta of a sub-orbital, fully depleted stage would provide less total hazard than the same stage, mostly depleted and in a lunar orbit(probably not long-term stable)
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Building engines in higher quantity will generally reduce the per-unit cost, be it a singe or multiple use engine. A commercial jet engine is deigned for high reliability, low maintenance, and a high rate of use(possibly even more run-time than non-running time: running for multiple hours then refueled and re-started after a quick maintenance check). Orbital rocket engines burn for tens of minutes(if that) then coast for hours and may or may not burn for a few more minutes. SH *might* get below a 1:5 burn:idle ratio (10 min burning up, 5 min burning down out of a 25 minute flight and < 50 minute time on the pad before the next launch might be a best-case scenario for re-use) Also, for an airliner with 2 engines, 'engine out' capability is not something you want to be relying on, but with >25 engines on SH, even one failed engine per launch is not critical, just annoying. (and long-run-time reliability is very expensive)
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totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
Flex tubes are kraken bait. The recommended approach is disconnected bases(supported by MKS) which are supported by WOLF support bases. -
And when 10 of those houses don't want to pay, three of which prefer it the way it is and sue you to leave it alone? The lawsuits and permitting often cost more than construction, especially when you are talking about messing with someone's view/property. The US is the most litigious country in the world, and NIMBY is very big here.
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totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
Most USI converters slowly consume machinery and loose efficiency based on how much machinery remains. If you have excess machinery, you can place an engineer in an assembly(?) module and have them re-fill the machinery in the converters with automated daily maintenance. Alternately, you can turn off machinery consumption in the settings(effectively switching to MKS light). At the very least turning off machinery consumption should allow you to verify that this is the source of your unexpected efficiency losses. -
totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
Those would be modules on the part config. They can also be added by module manager scripts. -
totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
The part you showed is for creating routes in the released version and I believe it has been replaced by the cargo crates and passenger berths in the pre-release version. I have not used the pre-release, but I would recommend looking under utility if it does not show up under WOLF(and if not there, look in your research tree to see if it is still locked) -
totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
I have not heard anything about it being removed. Having a Home timer of 49 years and descending sounds like you have a big luxury space station and departed from it on a smaller vessel with less habitation, and now the home timer is counting down from max set by the 'best' vessel the kerbal has been on. But in that case the Hab timer should be less than 50 years, as a hab time of > 50 years should stop the timer. Is it possible that some of your habitation modules turned off or ran out of colony supplies perhaps? I have the latest release version, and my GameData\UmbraSpaceIndustries\LifeSupport\setings.cfg file has the following to lines: ScoutHabTime = 9180000 PermaHabTime = 459000000 where 9180000 = # seconds in 425 days of 6 hours each(sounds like about a kerbal year to me) and the higher number is that times 50. So as far as I can tell, the default is 50 years and 1 year for scouts. I think you can modify this in a given save, so you should check your in game USI-LS settings as ell as your settings file, just to make sure. Is it possible that your vessel only has 49 years of hab time, but you only see this once it gets above the 'HomeWorldAltitude'? (default is 25km above kerbin) You may need to switch on one or more habitation parts after leaving the VAB. -
totm may 2024 [1.12.x] - Modular Kolonization System (MKS)
Terwin replied to RoverDude's topic in KSP1 Mod Releases
A single engineer in your hab module can run all 50 of your assemblers and all 80 of your refineries. In fact, if you have 3 engineers (*, **, and ***) then the *** engineer will perform all work on all modules that benefit from engineers, and the other two are more useful going on a trip to get more experience so they can run their own industrial bases.