Jump to content

darthgently

Members
  • Posts

    3,006
  • Joined

  • Last visited

Everything posted by darthgently

  1. Do they do full duration tests of these pumps or what? Get with the program, Bruno
  2. The operative word is time though. The spiralling makes sense at normal or low TWR where time fighting gravity would pile up. But at some point as the design TWR increases the time spent fighting gravity will drop and reach a break even point. What am I missing?
  3. Headline: ...Don’t expect perfection on crew test flight Was anyone expecting perfection at this point? What an interesting headline. Hopefully people absorb this guidance better than they attend to the fact that SpaceX is testing things and that failures are possible. Expect excitement and education
  4. I have no way to know if every Raptor gets a full duration test in a stand, but they do routinely do full duration tests on Raptors. But individually, on a stand, and not currently at Boca Chica, but at McGregor (I think). Though the new test stand and deluge at at Masseys is probably what you mean and I'd guess you could be on to something there.
  5. Weapon lasers are problematic at distance as you note, but with enough relays sprinkled around, comms lasers could overcome the divergence issues and provide the DSN with fantastic bandwidth
  6. Deja Vu! This exact issue posed by exo has been addressed exhaustively and authoritatively over the last few months. It's like we are in a Moebius time loop!
  7. Perhaps you'd like SpaceX to also tell you the power levels that everyone else is testing their engines at while they are at it. I mean if you are going to hold them to a higher bar, might as well turn that bar up to 11, am I right?
  8. Some avatar images on this site are incredibly fitting
  9. A built-in cold gas small range maneuvering system would be nice. Just click on a tank for gas, or not if tethers are the order for the outing. I'm picturing tiny boot, wrist, and belt (near CoM) nozzles and a cpu to modulate flow to each depending on body position and desired attitude and velocity. Maybe ability to use suit oxygen for thrust in an emergency if no thruster gas tank attached or is empty
  10. I wonder how much fuel was in the booster at hot stage? Maybe more than required for boostback and landing burn. I could see a fully fueled ascent being a very high priority while not being as concerned with extra mass during the ocean "landing"
  11. To some extent, but the budget to do hopper testing is relatively small and with control circuitry cost, mass, and power consumption dropping exponentially at the time I think it fair to say many missed an obvious opportunity to at least test the waters with a few jumping grain silos. RC enthusiasts were doing amazing things making all kinds of programmable, autolanding, acrobatic helos, quadcopters, etc. I think what happened at SpaceX was simply grabbing low hanging computational fruit that many others simply were in denial was relevant, because ... tradition? Maybe?
  12. There are so many variables. They could have selected a launch profile that used more fuel so as to have less to deal with for this specific set of tests. People can speculate on the skeptical side all they want, of course, but it seems reasonable that they'd eventually take the historical record of SpaceX skeptics ending wrong and SpaceX making wonderful strides in spite of the skepticism into account at some point. Jeerleaders are expected and necessary to an extent for iron to sharpen iron, but when it veers into the unreasonable it undermines humanity's progress and motivations must be considered
  13. Nice sensationalist tabloid summary. Anyway... You are reading incorrectly what was written, twice. At the same point in F9 development, Starship has faster turnaround. Not comparing to F9 turnaround now. I truly hope this helps
  14. I have trouble comprehending the Oberth effect without seeing it through a vis viva lens. Different strokes I suppose. Well not so much Oberth per se but the fact that prograde burns at PE raise AP most efficiently
  15. No feathers ruffled here. Just honestly don't understand your statement
  16. Given your constraints the Oberth effect is pointless because your orbit is "changing"
  17. I disagree. The vis viva solutions merely change continuously given the thrust vector. They are still there
  18. 1. Still seems to only be relevant if your goal is local orbit as the DV req'd for that horizontal velocity isn't free either and keeps you in the atmo longer. Not sure the lower velocities make it worth it. Would depend a lot on design. But I'm persuaded strongly to your view by 2 through 5. I'm convinced. Thank you
  19. The more TWR early on the more you are burning at your initial "periapsis" re vis viva. The moment you leave the ground, vis viva applies and you are very close to your "periapsis". That is the aspect I'm looking at it from as a thought experiment. So if you can reach escape velocity going straight up in a short enough time going to orbit first would be more wasteful. Going to orbit first is purely limited by TWR for the same reason that very low TWR requires multi-pass Oberth burns to raise AP. Having trouble not seeing it this way. Convince me. The aero phase is problematic as drag goes up non-linearly with early TWR
  20. I think overall TWR and ascent profile for the non-straight ascent would make a big difference. Not to say the straight to escape is better overall, but to spend less time fighting the gravity well the higher your TWR must be. Another thought experiment is to consider that the most efficient apoapsis raising burn is done at periapsis. A straight out to escape burn is going to put some portion of your burn higher than your effective periapsis. Maybe some rough rule of thumb can apply. Like if your TWR is high enough to reach escape velocity before your altitude is greater than the lowest possible orbital periapsis (70.xx km kerbin) then straight out to escape could have a case. I'm guessing, so I better not see this posted as a "fact" someone "read somewhere" next year, lol. Does that happen to anyone else? You better have ablator on the nose cone.
  21. It might make landing reusable boosters simpler. Though they'd be coming mostly straight down from a higher apoapsis with a more compressed and intense aero experience I imagine, so not sure about if more or less fuel for booster return would be required. I'm already hearing in my mind the argument that going straight up means you are "fighting directly against gravity longer", but if your goal is solar orbit I'm not sure fuel spent going orbital around the launch body isn't just as wasteful. Good question! Looking forward to the responses
  22. Would there be any advantage to the pusher plate being parabolic with the focal point being the reaction zone? I'd think the angle of incidence of the explosion on the plate would make a difference, but would it be significant?
×
×
  • Create New...