wumpus

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About wumpus

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    Spacecraft Engineer
  1. I'd be shocked silly if Hollywood still wasn't producing romantic comedies largely based on stalking and other court actionable activities (I haven't been watching many movies lately).
  2. The Economics of Platinum mining

    I completely doubt it. I can't take their insistence on fuel cells seriously, but it possible that they mean it. If so, they might just want to give this a try. If they have any such plans at all, they were likely low priority power points/white papers which might suddenly become possible with Falcon Heavy's cheap heavy lift capability. Don't expect anything to happen fast (also note that Mazda's new Skyactive-X should make fuel cells pointless. Getting "nearly fuel cell" energy out of gasoline will make building the infrastructure needed for fuel cells uneconomical at any cost). - Edit: the only reason I brought up Toyota is that mining the first asteroid will be unbelievably expensive and will have to return massive amounts of ore for the expenditure. Mining platinum this was would likely crash the market and thus flatten returns making it pointless to try this form of mining (of course, precious metals are a famous means of separating fools and their money). On the other hand, Toyota might very well "need" huge amounts of platinum and has the money to go and get it. Spaceflight is expensive: finding somebody willing to foot the bill can be well over half the battle. I've never heard of Toyota mentioning asteroid mining. They just keep talking about fuel cells that make no economic sense while platinum remains expensive (granted, I thought putting both electric and gasoline engines in a car was equally hilarious. I now suspect that doing such will remain superior (for US-style driving at least) for quite some time).
  3. The Economics of Platinum mining

    That was pretty much my point. If your business plan requires lots of cheap platinum, crashing the price of platinum isn't a problem (at which point selling raw ore is pointless, unless you need to stimulate the market of fuel cells). But Toyota is in a unique position of "needing" cheap platinum and having the deep pockets to really do asteroid mining (assuming you just need to send a probe to grab and return with a large asteroid, presumably using ion thrust, solar sails, albedo adjustment of said asteroid, or some combination of all the above).
  4. The Economics of Platinum mining

    To be honest, this is *exactly* the hope I had when reading the original post. Toyota has both the deep pockets and the face invested in fuel cells to actually go and do this to make fuel cells a reality. It may or may not make economic sense, but the real cost of such a project might be low enough that Toyota would rather do it than admit error. Also Elon Musk has had a lot of success in developing models that use a lot of vertical integration. There is a distinct transaction cost whenever one business buys from another, and avoiding this can greatly reduce costs. This seems to work at the size of Space-X and Tesla, but expect rival divisions to have similar transaction costs once you get to the size of Ford (at that size, it often makes sense to buy from *anyone* but your own company: the politics are too dangerous).
  5. Who used base 8? Babylonians used base 60 (can't remember if they inherited from Sumer, but a *lot* more things than you would expect directly derive from this), and there are obvious remnants of base 12, 20, and 100 left in English (dozens, scores, and hundredcounts). Granted, "base" can be a pretty nebulous term without a zero place, but many cultures listed counts by common groupings and leftovers.
  6. Kerbin is really dense

    The rockets [well, liquid engines and their tanks] still have really bad mass ratio " (too heavy by a factor of 3 to 8)*". This is either poor kerbal engineering or simply more dense ore. * according to "False KSP lessons" on the RSS/RO webpage.
  7. Ksp need to fix the performance

    First, anything using GPU acceleration [for consumer use, not dedicated supercomputer hardware] has to limit itself to single point precision. If Squad wanted to re-write the entire physics engine (and replace Unity), they would likely want double precision. Also GPUs really don't support multi-threading well. I suspect that your "coders who live for that" would wind up making a custom way to send small snippets of code for each needed calculation in one (or two) big threads (I think the latest nvidia GPUs can handle two threads in hardware). Worst case will be "full-stop non-parallelizable" and it shouldn't be terribly hard to construct a craft that will come rather close to it (although doing that with the many parts needed to kill performance wouldn't be quite as easy). I'm not sure how bad the common case would be, and how hard it would be to come up with an algorithm that would break the rocket into subassemblies that would be useful to compute separately (remember that dealing with 64 or so parts in parallel is trivial (you can access all the memory - if it fits in the local memory)). Squad isn't going to do this. I'd be really impressed if it was possible to mod that deep. Unity *might* try something like this, but I wouldn't hold my breath.
  8. Yes, recoverable systems will keep most of your kerbucks intact. I got really into this and burned out before making it to Duna. I've since come back and avoid most recovery issues. Kickers (big SRBs in general) are your friends. They provide plenty of thrust and a good bit of delta-v for dirt cheap. Drop a bunch of kickers before even thinking about recovering the rest. There was a challenge for the cheapest kg to LKO called the "cheap and cheerful contest". Most of the links are dead, but you should get the basic idea of what the winners looked like :
  9. I've been watching the Etherium ticker, waiting for a crash. The whole reason that the GPU market is out of whack is that etherium miners need GPUs (bitcoin miners use ASICs, but etherium needs the memory bandwidth such that it is only cost effective to use GPUs). Judging by the recent price drop, I wouldn't be surprised if there are a lot of idle rigs out there, waiting for the price to justify the electricity. Once that appears permanent, expect the GPU market to slowly regain sanity (and hopefully low prices on underclocked boards on the used market). (etherium ticker [I think I have the right one, I don't mine/trade the stuff]):https://coinmarketcap.com/currencies/ethereum/
  10. Expect that ceramic capacitors beat electrolytics in W/kg and lose badly in J/kg (they should be even closer to "ideal" capacitors with less equivilent series resistance). In practice this is meaningless (matching the equations makes them great for filters and similar where you don't want resistance at all, but you want more capacitance and can easily eat the electrolytic's resistance). I've never heard of Li-ion capacitors. I want a hyrbrid car with them (plus LiFePO4 reserve), and I want it now! It would even let a Leaf-style battery system have Tesla-level pep (assuming you could afford the motors. But I suspect that the battery system is the the hard part right now). The wiki for Li-ion capacitors is pretty weak, and if those are the real applications (because of other issues with the things) then it is dead (many of those would be better suited for even lead-acid batteries).
  11. Bad science in fiction Hall of Shame

    That isn't quite accurate. *Ecology* is pretty critical in Dune and I doubt it was all that inaccurate in the 1960s (and probably isn't even detailed enough be shown wrong now, just enough to describe the effects of extremely limited moisture on an ecology). Physics was only touched on enough to establish the setting (remember, space and time are warped by the psychic effects of guild navigators. Absolutely no attempt at hard SF in the hard sciences is ever attempted). Swords in space isn't exactly limited to Space Opera, I think one of the last battles in Forever War involved pre-gunpowder tactics. I'm blanking on the rest. Cavalry charges in late history: Crimean war (1854) Light Brigade Charges for completely unclear reasons. It does not go well. US civil war(1860s) at least one cavalry vs. cavalry battle takes place with one side using sabres and the other using carbines. This likely marks the end of sabre use in said war. Russo-Japanese war (1904-1905) I wouldn't put it past the Czars to field classic cavalry. At least one high ranking supply officer wasn't worried about the distinct lack of gunpowder going into the Great War as "it will decided, as always, by lance and sabre".
  12. While more Isp is better, don't overdo it. Ion engines don't exactly play nicely with the time acceleration system. Nuclear (LV-N) engines *are* that great, but fueling them can be a pain (insufficient fuel-only tanks) and you might want more than one for large vessels (or learn all about the Mangalyaan maneuver [sometimes called pe-kicking here]). I'd learn to use the terrier and poodle engines first (as second and/or third stages*). They still have reasonable thrust, low cost and the higher Isp of traditional rockets. Remember, you still need sufficient thrust when circularizing [you start coming down sooner than you might think] and I've found that the LV-N often can't get that job done. Once in orbit, while you don't have that issue, you lose efficiency as you have to burn long before and after your burn point (in near orbit of some body, out in deep space it doesn't matter). And consider the camel analogy. That is pretty much it. * while it isn't obvious from the equations that Isp matters more and more as you drop stages, you'll find that Isp doesn't matter as much for the first stage (I love big SRBs like kickers) and it becomes critical in your final stages (terriers work wonders thanks to how light they are). This is mostly because of all the stages above the first stage count as "dry mass" to that first stage: you are in the more linear regions of the exponential curve. As you have less and less dry mass above you, you go into the upper ranges of the exponential curve and Isp matters more and more.
  13. LM Descent Stages Today?

    Trans-Earth injection is equally "burn or die", but also used pressure-fed hypergolics (although possibly chosen to avoid cryogenic bleed-off). A high-power solid motor (to supply the majority of the thrust) followed by pressure fed systems should be sufficiently simple, but the LM ascent stage had an Isp of 311s. It would take some pretty extreme fear of evil chemicals to switch N2O4 - Aerozine 50 tanks out for an SRB. These were last used as shuttle maneuvering engines and scheduled for use in the Orion, so presumably they are somewhat available (you might have to scale them back down to LM size). Electrical pumps might have looked reasonably similar from the Tesla-Edison battles to the 1990s, but since then they have changed radically (ok, inductive motors might resemble Tesla's designs, but the power supplies typically supply a custom-created AC instead of what the power plant provides). Probably similar things could be said about radio transmission, but I suspect the changes started much earlier. No matter how old the tech, nobody is trusting an entirely new engine design never designed for crewed flight with a single successful flight.
  14. Certainly there were plenty of engineers inspired by Star Trek, and certainly more few gimicks that they still want. I remember somebody selling a hand held oscilloscope under the tag "Mr. Sulu, I believe you dropped something." Between the original posting (2014) and now there have been multiple articles on creation of medical tricorders (sic*), and I'm sure there are efforts to copy even more of their toys. * the tricorder was a device Mr. Spock used to analyze the atmosphere and other planetary analysis. The device in the articles is either the thing attached to sick bay beds that displayed vital signs (presumably, never explained) in real time or the "23rd century stethoscope" that McCoy would wave over a patient to determine "he's dead, Jim".
  15. LM Descent Stages Today?

    More thoughts: Ideally, if the Merlins aren't enough to send the mass to lunar intercept, your first choice should be a RL-10 (hydrolox expander engine). Storing enough hydrogen for the return flight might be iffy, but it is ideal for leaving Earth. While pressure-fed hypergolics are nearly always the way to go for ascent/descent engines, Rocket Lab's new Rutherford engine are small and throttlable (and far too bleeding edge to trust with human life). If the rocket scientists need any "add magic to reduce mass", they might be a way out of a tight spot. A more kerbal design might include a powerful main engine that would suicide burn to some safe altitude (100m?) and use pressure fed engines for final landing (and similarly use the main engine for ascent and the pressure feds for docking). If you are bringing hydrogen to the moon, an RL-10 based system would make an ideal "main engine" for this (I'm no fan of hydrogen past Earth orbit). "Two launches with lunar rendezvous" implies a lot of the stack aren't two stock Dragons, but designed for lunar operations.