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About KSK

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    The North Grove, Duna.

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  1. I'm trying to look on the positive side here. They must have got some decent data from the test and they had a good start up of all four engines plus a safe shutdown after the MCF (and better an MCF than an RUD). Also if this were a test by A.N. Other Space Company Inc., I'd be a fully paid up member of the 'this is why we test!' crowd, so its unreasonable and unfair not to be in that same place for SLS. But - with all that said, it's the prospect of a lengthy delay before the next test which makes my heart sink. (I presume there will have to be another test after a component failure, fo
  2. It would depend on the propellants being used I think. Nitrogen liquifies at -195.8 Celsius, so it’s no good for pressurizing liquid hydrogen, for example. Nitrogen also dissolves in oxygen so it’s not the best choice for pressurizing LOX. For other propellants it’s probably fine. Helium is inert, very low density (i.e. doesn't tend to mix with the propellants) and low boiling (good with cryogenic propellants), so it’s a good all rounder if you don’t mind the cost. I think.
  3. Best of luck. The writing part of writing is the hardest bit. Looking forward to seeing what you come up with!
  4. Actually having the impulse drive as a sub-light ‘warp’ engine makes sense given that a starship could reach 0.5c on impulse power (as I recall). If it was a pure rocket it would put the Epstein Drive to shame! I suppose the bit of plasma spurting out of the back does add a bit of thrust and proves that rocket ships are cool even in the 23rd century.
  5. It’s an interesting suggestion. I think a couple of those observations can be rationalised fairly easily without needing the Enterprise to hover. No loss of line-of-sight can be rationalised (to a reasonable degree by assuming that a ‘standard orbit’ is a stationary orbit for that particular celestial body. Stationary orbits are usually going to be high enough that you’ll keep line-of-sight with a respectable portion of the planet’s surface. Not having spacecraft whizz past each other at orbital speeds - most interactions between ships (peaceful or otherwise) are probably helped by
  6. Sort of. The ISS orbit is a compromise which both US and Russian spacecraft could reach whilst being above enough of the atmosphere that it doesn't need to be re-boosted to a higher orbit too often. The Space Shuttle was capable of around 200m/s delta-V once on orbit and it needed around 70m/s to deorbit. Not sure what the specs for Soyuz or Progress are. That limits/limited how much maneuvering they can/could do and limited how much higher the ISS orbit could be compared to the initial parking orbit for Soyuz or Shuttle (recall that a spacecraft will launch into a lower orbit before st
  7. Other way around. A craft launching from Earth will launch to a lower orbit than the ISS, then gradually raise its orbit until it makes rendezvous. Lots of technical detail for non-rocket scientists and a useful diagram (near the bottom of the page) here. In a bit more detail, the simplest way to raise your orbit is to carry out a Hohmann transfer. For simplicity, consider a spacecraft in a circular orbit. It fires its engine once to accelerate which converts its circular orbit to an elliptical orbit. The longer the burn, the longer the ellipse. Then, at the new highest point on its orb
  8. Whatever it is, it would make a nice upgrade from the old Apollo lunar rovers. Bet you could really kick up some regolith in one of those bad boys.
  9. *sticks fingers in ears*. I CAN'T HEAR YOU.
  10. I'll get right on those density calculations once I've rationalised the BattleTech economic system. But yes, I'm rather fond of BattleTech space travel. Don't look at the actual numbers too closely but I find that the system as a whole is fairly coherent and hangs together well enough for my suspension of disbelief. More to the point, those limitations on FTL travel work really, really well for storytelling. Warfare becomes at least as much about logistics and supply chains as it does about weaponry and shields, which places limits on how effectively a given faction can project fo
  11. Precisely my point. It sets limits on how far modern physics will get you and shows you where you need to stretch those physics, or outright ignore them to make your setting work. Besides without doing some calculations, even if they're very simplistic ones, then conservation of energy and especially thermodynamics won't help you at all when you're designing a sci-fi spaceship. And even then, they're not that much use unless you really want to put a lot of work into designing your craft from first principles. Especially thermodynamics - that's pretty esoteric stuff for a science-fiction
  12. I disagree. In my opinion the single most useful thing for a sci-fi spaceship designer to know is the rocket equation. It’s derivation is based on conservation of momentum rather than conservation of energy and it ties together spacecraft mass, propellant fraction, drive efficiency (specific impulse) and available velocity change in one nice neat package. All of which parameters are very helpful for keeping things consistent and sanity checking spacecraft designs. Combine it with a bit of internet searching to get an idea of the kind of specific impulse and thrust to weight rat
  13. Another thought - you could build a thermal generator with MMH. Start with a chunk of MMH, add system to controllably convert it back to molecular hydrogen, wrap the whole thing in thermocouples to generate electricity. Like a radiothermal generator but without the nuclear material. I have no idea how efficient it would be and you’d be leaking a drizzle of hydrogen gas whilst the generator was on which probably puts a practical limit as to how much MMH you want to decompose at a time, hence how hot your generator gets. But it’s sort of getting close to an MMH battery.
  14. OK let’s put all the usual comments to one side and assume, for the sake of argument, that metastable metallic hydrogen (MMH) is a thing. I think it would make a lousy battery but you could probably make a decent combined-heat-and-power system out of it. MMH can indeed store a lot of energy but a good part of that energy is released as heat when hydrogen atoms recombine into hydrogen molecules. In a rocket engine, for example, that’s not a problem but for a battery it is. Firstly you end up with a very hot battery and secondly that heat is effectively waste heat unless you have so
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