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softweir

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Everything posted by softweir

  1. That sort of throttle-down would be near useless for a SpaceX landing post-GTO launch: they are operating on the edge of not having enough fuel, and throttling down by throwing away fuel is an excellent way of making quite, quite sure there isn't enough fuel. The same applies to throttling down during launch. Yes, in other circumstances venting fuel from the pumps might be an option, but I can't help but feel it isn't an option for SpaceX. It makes much more sense to find some way to controllably spin-down the turbopumps while maintaining a flame in the combustion chamber. Much harder, yes, but if you can do it then that is much more fuel efficient and sensible. Finally, the vast majority of orbital-launch-capable SRBs don't reduce power by venting! They reduce power by careful shaping of plugs so that the area of grain available to burn reduces as the plug burns away. That's the way the Space-Shuttles and all other serious launch vehicles operate. SRB plug design is an art and a science - as is working out when you want the SRB to start to taper-off its thrust. SRB venting has been experimented upon, not as a routine way to reduce power but as an emergency measure to kill thrust in an emergency. I don't know of any rockets that have been commercially launched using that technology, as it is a very dramatic and dangerous way to kill thrust.
  2. You assume that fuel is free to leave the core tanks while crossfeed is active. There is no reason to believe that - in all probability there would be valves that switch from taking fuel from the crossfeed to taking fuel from the core. If so, then there would be no pressure against which to pump the fuel.
  3. There's more to logs than error messages and version numbers! It's best to provide them anyway - the mod developer knows what to look for, we don't. Anyway - this seems to me to be very unlikely to be a FAR glitch.
  4. By the time the boosters have been jettisoned, the core and payload will be high up, moving fast, and moving downrange faster than it is moving up. Most importantly, all that fuel has been lifted up high and got moving fast - that adds more than a little to the usefulness of its thrust and Isp. Regarding the complexity of fuel cross-feed: I can't find it now, but I remember a quote along the lines of "the turbines don't like it". Shutting off one source of fuel and turning on another is not a simple business - SpaceX have to make certain that there is no drop nor spike in pressure during that transition. An added complexity is that the fuel coming in from the boosters' tanks is coming through a more convoluted feed train, which is liable to slow it down. For the core's engines to work properly, SpaceX have to make sure that doesn't happen, without adding heavy and over-complex systems to the boosters. This is the sort of engineering task which can seem easy until it is tried, when the sheer complexity and number of unpredictable problems makes it clear that it is not easy.
  5. Dropbox. You can upload the logfile as-is or zipped.
  6. Indeed, and I couldn't agree more! But the pleonasm needed to be explained.
  7. Volcanologists and archaeologists know the answer: Some victims in Herculaneum of the famous eruption of Vesuvius were hit by a pyroclastic flow - a mix of gas and rock at temperatures approaching 1,000C moving at up to 700km/h. Their skulls exploded.
  8. a.k.a. by the much more common name of hydrochloric acid. Why call it muriatic acid?
  9. There is a fairing attached to the vehicle, so there should be a staging icon in the staging list. There is no staging icon. Ignore the fairing base tweekable.
  10. In that case, discuss it in the Support forum!
  11. That doesn't sound right! It might be worth checking the Support forum for other reports of this and see what is said there. A quick workaround might be to put a fuel tank between the heatshield and the science jr. It might even work to put a decoupler - one of those skinny, ring-like ones - between them, though the fuel tank would be more sure to absorb and insulate. You may find other parts are useful, such as battery packs. Finally, try the inflatable reentry shield instead of an ablator heatshield.
  12. If you look left or right and then use shift+space they will jump in the direction they are looking. (IIRC - only ever used it once and it may have changed.)
  13. Can I also recommend you to the FAR Craft Repository? That is the place for questions such as this!
  14. To be honest, we don't know. This is the sort of detail launch operators don't normally share.
  15. Not to mention that the first stage is mainly empty tank with a high drag-to-mass ratio, while the second stage still has very full tanks plus payload.
  16. How about linking to those articles you mention?
  17. He's talking about the lack of voxels on the surface of the fairing in the second image, not the base. The fairing ought to be covered with purple dots.
  18. LEGO and Squad both have lawyers to deal with this sort of thing. It is best that they hammer out the details of any agreement *if* the project gets sufficient support *and* LEGO decide the project is commercially viable.
  19. Pi is universal in any time-space which is sufficiently flat enough that circles can exist. Some races may use tau instead of pi, but if they do use pi and calculate it then they will get the same answer we do. And if they use tau and calculate it they will get twice the value we use for pi. Incidentally, tau is a better value than pi. And as for comparison with e, tau turns up in all sorts of weird places you wouldn't expect it either.
  20. Very true! To go further - in order to use base pi one has to be able to count the number of digits, simply because to know the value of a digit, one has to know its position. The only way round that would be to use entirely separate characters for each different power of pi. Trying to get this back to the OP: the question was about Arthur C. Clarke's intention in choosing those numbers, and whether there was any deeper meaning to it. There wasn't. He chose a sequence of numbers numbers that would be recognisable to a reasonably well educated but not specialised audience, so irrational numbers were out, and "counting in pi" so far out as to be in an as yet unexplored dimension of literature!
  21. Thanks for that correction! I've amended my post to say "integers".
  22. There is no real significance in it being a sequence of squares of primes integers. What was significant was that a) so far as the characters could measure the proportions were perfect, ie the builders had extremely precise manufacturing process, and b) the numbers were relatively easy for readers to understand, unlike (for instance) pi, e and other irrational numbers.
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