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>My prediction: SpaceX will have a 5th 100% successful launch of Starship before the SLS has a 5th successful launch. They'll just have ten not-100%-success lau

• ralusek 4y ago
  They meant "will have worked out enough of the kinks by their 5th successful launch so as to be operating at a high success rate." Lots of falcons failed, but you don't see anybody worried about their payload or crew on Falcon 9 these days.
  • bumby 4y ago
    >will have worked out enough of the kinks by their 5th successful launch so as to be operating at a high success rate." I agree with the first part, but the second half extrapolates too far IMO. One successful launch tells us very little about operational reliability.
    • frumper 4y ago
      And SLS is that much further behind
      • bumby 4y ago
        No doubt, but operational tempo is a different issue than system reliability.
    • ethbr0 4y ago
      But the apples to oranges here is >1 launches (SpaceX, some successful and some unsuccessful) vs 1 successful launch (traditional modern aerospace). From an outcome perspective, it's hard to ever see the lower launch rate dominating from any perspective. You don't have economies of manufacturing scale, because your assembly rate is so low it doesn't make sense not to treat each as exquisite. You don't have rapid iteration on manufacturing improvements, because the tyranny of safety checks on manufacturing time balloons {time from fix to flight}, after a proposed fix is identified. And most importantly, you leave yourselves extremely vulnerable to unknown-unknowns, that you can't imagine in the design phase. For example, if NASA had been launching the shuttle more rapidly, with the bulk of those being uncrewed launches, they probably would have picked an uncrewed launch to test expanding the temperature bounds at Cape Canaveral, and Challenger would have exploded without a crew. As was, NASA's shuttle launches were so rare that there wasn't acceptable launch rate and weren't low-impact launch opportunities to do so. So they tested it on a crewed mission with disastrous results. Point being: they backed themselves into a low-volume/high-risk corner of their own strategic design SpaceX's most brilliant achievement was using Starlink to artificially boost launch demand and give them a minimally-profitable/break-even place to sink higher-risk launches.
      • bumby 4y ago
        I agree with many of your points, but it comes across as slightly biased because you don't acknowledge a single downside to any of them. >You don't have rapid iteration on manufacturing improvements, because the tyranny of safety checks on manufacturing time balloons Rapid iterations has obvious benefits. But there are also downsides because it makes it harder to arrive at a stable, reliable design, it introduces vendor issues, etc. Tesla is also known for iterating faster compared to their major competitors but it has resulted in logistics and reliability issues. IMO SpaceX's most brilliant achievement was leveraging govt contracts to work out the kinks of their designs, which could then be leveraged at a lower risk for Starlink. In effect, they let the public take the burden of the risk (because the govt is really the only entity capable of shouldering that size of a risk for an unproven quantity) and then transitioned to a private means of revenue in Starlink. (I'm not saying that as a slight btw, I think it's mutually beneficial).
        • XorNot 4y ago
          Frankly comparing Tesla and SpaceX is getting to be a tiresome argument. They're owned by one "eccentric" billionaire, but he's not an engineer, they don't share staff, facilities or manufacturing outside of "hey this alloy is pretty good". SpaceX's strategy for the Falcon 9 worked and it's one of the most reliable rockets in the world, flying the most often.
          • sidibe 4y ago
            I think the risk is that they are both driven by what the CEO finds cool which may or may not be what's most effective
          • bumby 4y ago
            >Frankly comparing Tesla and SpaceX is getting to be a tiresome argument. You're focused on the wrong takeaway. You're making this about a person, I'm talking about a process. I used Tesla because it's easy to see how one culture translates to the other. Insert any company that uses rapid iteration in place of Tesla if you prefer. The point is that there are certain circumstances where rapid iteration is useful and others less so. When reliability matters, rapid iteration may be working against you. (It's a continuum, of course, so the real question is where is that tipping point) >SpaceX's strategy for the Falcon 9 worked The point I'm driving at is there is a distinction to be made when finding out why certain iterations didn't work vs. just changing the design without fully understanding the failure mechanisms of the first. One leads to a greater understanding than the other. It's a difference in an engineers mindset and a scientists mindset.
  • toss1 4y ago
    As long as the organization has and maintain a culture that is aggressively seeking out problems large and small, and proactively fixing aprox. all of them, you will end up with a program with a high rate of operational success. It's the X-origin vs Slope issue - steeper slope always wins. The problem is maintaining that aggressive problem-seeking culture after long periods of success
    • bumby 4y ago
      This is part of the culture distinction. On one hand SpaceX is attacking problems, but IMO they often don't go towards attacking the root causal understanding. That means there's a possibility of unknown latent risk. As an example, they had issues with failures related to their COPVs rupturing. On the one hand, they addressed the problem by redesigning their system. On the other, they never really investigated fully why the COPVs were failing in the first place. Instead, NASA decided to fund that investigation on their own. One possible consequence is that their redesign didn't fully address the risk because they never fully investigated the root cause.
• simonh 4y ago
  That only matters after you’ve gone operational though. The difference here isn’t risk appetite for operational launches, it’s risk appetite for test launches. SpaceX expects to do many, many more test launches than SLS, in fact counting Starship upper stage launches they’re already well ahead.
  • bumby 4y ago
    Fair enough point. But the finish line isn't getting through a test, the finish line is having a reliably operational system.
    • HarHarVeryFunny 4y ago
      Sure - but the way to get a reliable system is to test it, learn from your failures, and iterate.
    • simonh 4y ago
      And Falcon 9 is now the world's most launched system, with the record for the longest run without failures. So their approach seems to be working.
      • bumby 4y ago
        At what confidence interval? I'm not asking as a 'gotcha' question, I'm acknowledging that the sample size matters. A lot of these statistics are bandied about without really elaborating on the full context of the way reliability is actually measured in industry. Without checking for the most up-to-date numbers, I believe the F9 is slightly better than Soyuz on raw numbers (successful flights / total attempted). But Soyuz probably has around 6-7x more flights, meaning we have much more confidence that the Soyuz numbers accurately reflect reality.
        • lutorm 4y ago
          This is true -- there is a lot of small number statistics in estimating the reliability of launch vehicles. And there are a lot of small risks you never see until you accumulate a lot of lunches. But that question is completely incidental to the design methodology. A new vehicle will always be unproven. But one that's flown 5 times in testing (4 of them unsuccessfully) before its first flight will have had more flight time on most of its systems than something like the SLS where you take 10 years to think about what could go wrong and then do one test launch and call it good.