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About Starman4308

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  1. Starman4308

    When and why did you start modding KSP?

    Originally, likely just MechJeb for dV and some maneuver planning. After making a large Mun space station, and I think launching something towards Duna, I decided "This isn't hard enough", so I installed Realism Overhaul. I backtracked a bit, and went for 6.4x/Real Fuels. Haven't really looked back to stock-scale systems. They just feel too puny to me now.
  2. Remember when the Space Shuttle was going to fly a gazillion times a year, and come in on time and under budget, and the US government was mandating that satellites be launched on the Shuttle? Remember when the Falcon Heavy was going to be ready to fly in 2011? We've seen this dog and pony show before. Musk's timelines would be highly optimistic even without unforeseen events, like, say, a new booster design failing. Like they often do, something that would cause a significant interruption in schedule as the cause of failure is investigated, likely requiring redesign, causing the schedule to slip even further. A 2023 manned launch mandates these things: No new legislation to say "hey, we actually need safety standards now that NASA and Roscosmos are not the sole providers of manned launch services". No unforeseen delays. Starlink delivers on time, and customers actually buy their services. No unforeseen snags in re-use of the Superheavy and Starship. Nobody complains about the huge number of Starlink satellites, putting political pressure on Starlink/SpaceX. Venture capital and loan funding comes in on time in sufficient amounts. I put less than 1% odds on things working out this well for SpaceX. EDIT: Whoops, forgot commercial crew delivery isn't there yet.
  3. You do recall the bit where NASA refused to count anything other than Block 5 for validation flights for commercial crew? In software, if you change one aspect of the code, everything has to be re-tested. Man-rated launch vehicles are just about that strict. Very minor changes might be permitted, such as adding a redundant pump to prevent a repeat of CRS-16, but vehicle-wide upgrades such as have happened over the history of Falcon 9 are verboten, for good reason. Not only do you have countless parts on an orbital launch vehicles, each of them interacts with each other. For unmanned launches, if you do a thorough analysis of what a change might affect, you might get away with it. Manned launches are, for good reason, put to higher scrutiny. Either SpaceX freezes the Starship design way earlier than they should, or they're not launching people on it for many, many years after its introduction.
  4. I'll believe a 2023 manned launch when I see it. The timelines Musk predicts are widely known to be aspirational at best and outright pixie dust in many cases. Four years is not much time to go from technology demonstrator to a mature launch system. It took eight years for the Falcon 9 to go from its first flight to a mature configuration, and that was based on much more well-understood design principles.
  5. 1) Technically you have me there. Practically, substitute almost any other system of the vehicle in, and that's still something that could cause a failure. 2) Does it matter? With experimental vehicles, half the time it's not what you anticipate might be an issue that kills you: it's what you don't anticipate. 3) Failure of active cooling to the heatshield during reentry. I don't care how. Maybe a bolt shakes loose on reentry and hits enough adjacent pipes/valves that you get a local hotspot. The key point here is that rattling off a list of technical details doesn't matter. In vehicles this complex, being run this close to engineering limits, something will be overlooked. Even in the airline industry, overlooked failure modes have caused disasters. The difference with the airline industry is that they've made so many flights that, if there is something overlooked, it's such a strange, rare edge case that very, very few flights will be affected. Orbital launch vehicles? They don't have that track record. It's not the part you can think of that will fail you. It's the insulation foam falling onto your wing. It's a worker inserting an accelerometer backwards. It's the bellows surrounding the augmented spark injector encountering vibrations in the vacuum of space, that hadn't been an issue on the ground because of condensation (Saturn V Owner's Workshop Manual, pg. 149-150). It's an improperly secured nut that the prior worker used an extra-long wrench to firmly insert, while the new worker used the prescribed (too-short) wrench. With such massively complicated systems, the only way to get reliable failure-rate data is to go out there and launch some vehicles. Until SpaceX has that, it's criminally risky to put astronauts on something that doesn't have a bone-simple and robust launch escape system. EDIT: You want to know why Challenger and Columbia killed 14 astronauts? Really, it wasn't the foam, or the SRBs failing in cold weather. It was the poor management decisions combined with an overly experimental vehicle lacking good abort modes that killed 14 astronauts. Fix one problem, and another crops up. I can only hope that SpaceX's actual engineers are a lot more cautious than that.
  6. Independent engines-out are hardly the only failure mode imaginable. COPV fails, and ignites the tank (which, you know, happened on a Falcon 9). Control glitch cuts the Superheavy thrust half a second into flight. The active cooling on the Starship reentry fails, even on a small patch, leading to burnthrough and vessel breakup on reentry. And that's just known failure modes. Take the Columbia disaster as an example: nobody thought foamstrikes could be a failure mode until a foamstrike was a failure mode. The Starship is experimental technology, in a class known to be prone to failure. It's going to be a huge amount of effort to man-rate it.
  7. Because the Shuttle showed just how foolish that was. NASA at that point was overconfident. Apollo had gone through with only two major incidents, of which only one killed astronauts. They'd made that very tight deadline. On top of that, with Congress shrinking their budget, they realized they needed something cheap and affordable to make their ambitious goals such as space stations, Mars missions, etc. work. Add to that Presidential pressure to come up with something impressive on a budget, and you get a project which paid little heed to safety or economic practicality. Then so be it. If it takes some extra cash to keep astronauts safe, then that's the price that will have to be paid. Manned BEO missions (and even LEO missions) are of very questionable utility, and not worth putting people into experimental vehicles flying at the razor-thin edge of engineering margins without a decent escape system or very thoroughly tested vehicle.
  8. Because something on the scale of the Starship is necessary for those tasks does not show these two things: That the Starship can safely transport passengers to Earth orbit and beyond. That the task is necessary or economically practical given current technology. Do not let "but I want a colony on Mars" blind you to the potential issues with Starship/Superheavy. Or, for that matter, blind you to the potential issues with Mars colonies. Accept reality as it is, and hope for better... but plan for the worst. Do not plan on experimental technology working. This reminds me very, very strongly of the thinking that lead to the Space Shuttle. "We need something that looks like this to do X, Y, and Z. Therefore, the Shuttle will succeed at X, Y, and Z." EDIT: The Starship might succeed, but until the Starship has a very large number of launches under its belt, I consider it extremely risky to put astronauts on something that, to my knowledge, still doesn't have a robust launch escape system. That, and SpaceX's plans for rapid reusability are just that: plans. We'll have to see what happens when plans hit reality.
  9. Just like the Shuttle! I am reasonably confident the engineering will work out. The SpaceX team isn't stupid. What concerns me is what comes after the first few flights, on whether SpaceX can maintain their highly ambitious goals in turnaround time, minimal refurbishment, launch cadence, and the overall economics of the Starship/Superheavy. I'm also skeptical of plans to use the Starship/Superheavy for manned launches. Personally, I'd strongly prefer it if the astronauts were sent up on a separate F9/Dragon II, which is generally much more proven technology.
  10. This is seriously impressive. One minor point: it is possible to get a gravity assist off the planet you are ejecting from. It just requires a very counter-intuitive retrograde burn at apohelion (solar apoapsis) to set up favorable slingshot geometry. I believe Juno took such an approach to Jupiter: it ejected itself into a 2-year orbit, then burned about 800-900 m/sec retrograde at apohelion to set up a slingshot to Jupiter.
  11. While a perfect resonance generally doesn't happen, approximate resonances do. If, for example, you have an orbital period of 1.01 local sidereal days, it will take nearly 50 local days to map the body in question. This can be a factor if time is a significant factor.
  12. Starman4308

    SpaceFund Reality Rating

    So, out of likes today, but: Thanks for your analysis. It's not a field I have much knowledge in, so what you provided was quite illuminating. So, I'm guessing your analysis would be "there are probably companies with more reliable data and estimates... but they're not giving up that information without some dollar-signs attached"? I will confess: I was weirded out by a few of the choices made, but comments in this thread were what took it from "that's weird" to "okay, this might not be totally kosher".
  13. Starman4308

    ULA launch and discussion thread

    Not incredibly surprised. AFAIK, the transonic regime results in high aerodynamic stress, and if I did the calculations right, it has a 1.2 launch TWR. Combine that with the high specific impulse of hydrolox, and it gets going quite slowly at first.
  14. Starman4308

    SpaceX Discussion Thread

    Complexity is just as bad in software engineering as hardware engineering. It's something where the chance of this being necessary has to be weighed against the cost of developing and validating the software, plus the risk of the propulsive landing routine accidentally activating on a nominal landing, plus the risk of it somehow interfering with the parachute landing software, plus NASA bureaucracy.
  15. Starman4308

    Guide for optimizing staging

    While I can't comment on many things, since this thread is probably about stock launches (and not Realism Overhaul), this point I can address. The Saturn V shutting down its central F-1 had very little to do with efficiency, and everything to do with not squishing fragile astronauts and cargo. Granted, the Titan-Gemini stack was much worse at that, but even 4G accelerations can be hard on people.