12 thoughts on “SpaceX Progress”

  1. “..LC-39A will be taken offline for 60 days to allow engineers to complete work on the pad’s Tail Service Masts (TSMs) needed for fueling and support equipment connections to the two side boosters for the Falcon Heavy.”

    I’m guessing it would take NASA a year to accomplish something like this and cost half a billion.

    1. Probably more than that as there would be at least two interim reviews resulting in requirements changes and subsequent design modifications. There would probably be resulting cost overruns also.

      I was kind of surprised to see that the first time FH will be test fired as a complete unit will be the static fire on Pad 39A. I can see augments for and against but it is surprising nevertheless. I’m pretty sure this is something today’s NASA would recoil from.

      1. “I was kind of surprised to see that the first time FH will be test fired as a complete unit will be the static fire on Pad 39A. I can see augments for and against but it is surprising nevertheless. I’m pretty sure this is something today’s NASA would recoil from.”

        I was afraid that would happen. It would probably be quite expensive for them to change the McGregor test facilities for a full size three-core rocket. Mind you this is one of the reasons why the N1 was such a big failure. They didn’t have the money to built a full scale test stand. The Soviets did even worse than SpaceX is doing here, they only tested individual engines. Still this is a 27 booster engine launch. I think there’s a fair chance (I would guess 10-20%) the vehicle will blow up on the pad on the first launch.

        1. Yeah, I agree. They really should do a full-duration three-core test fire at McGregor first. I’m frankly surprised they’re not doing that.

          I would assume that building the necessary test stand at McGregor would be cheaper than rebuilding 39A if something goes wrong.

          1. Yep.

            I’m voting with rickl, Godzilla and Michael — this is a significant risk they are taking by not having a full up test stand in McGregor. Hope it works out well for them.

      2. I don’t agree. The cores will be tested, individually, in McGregor. The main remaining risk would seem to be some sort of unanticipated harmonic interaction among the cores that produces an undamped positive feedback. This might occur either during hold-down, as the engines power up, or in flight at some point after liftoff. No test stand is going to definitively eliminate risk of the latter type. That applies to the late N-1 as well. It’s failures were all in-flight.

        A test stand like the one NASA built to test Saturn V 1st stages wouldn’t necessarily reveal a risk of the former type as the upper part of the stage was clamped into the stand. The test stand would have to allow for the FH 3-core stack to stand freely. Even then, it would have to physically resemble LC-39A so that reflected acoustic energy impingements were comparable, etc.

        I suspect SpaceX have determined the risks to be low enough to rely on engineering simulations and individual core test firings in assessing the overall risks to the first FH mission. Engineering simulation capability has come a very long way over the past half-century.

        I think FH is going to work.

        1. The Russians had to relearn their lessons over again with the Bulava missile a couple years ago. They cheapened out and didn’t want to build a test rig and the result was a string of failures. It’s a lot cheaper to recover from mistakes if you catch them early. The test stand is an important aspect of this. In SpaceX’s case they have less risk since they have a modular launcher and the individual modules are being tested. But it’s still a risk.

          As for the N1 had they built the test stand and did a full duration 1st stage burn they would have caught a lot of the issues (e.g. the plumbing and resonance issues) before the flight and would quite likely not had a rocket fall down over the launch site as it happened. Though it wouldn’t solve their major remaining issue, i.e. the control system for the engines, which arguably was too complicated to solve with an analog system. Plus only the engines in the middle could do TVC and that proved to be insufficient. So perhaps the whole design was wrong in the first place.

          1. A test stand might catch high-frequency resonance issues, but it’s low-frequency resonance that tends to be most destructive of large structures (e.g., Tacoma Narrows Bridge). Test stands don’t catch this because the hold-down provisions can change key resonances.

            How certain are you that the Bulava missile had no test stand? The Wikipedia entry for Bulava makes reference to a ground test failure along with several in-flight test failures.

            Russia was never very good at building large solids which is why they were 25 years behind the U.S. in showing up for that particular party.

            The only passably successful solid ICBM Russia built was the Topol series. The engineering for that was done during Soviet times.

            Bulava used Topol as a jumping-off point, but the program was post-Soviet and started a decade after the end of the original Topol development which, itself, took nearly 10 years. One can be permitted to doubt that many of those involved in the relatively successful Topol effort were still in harness at the time Bulava was ginned up.

            Combine that with what we now know to be the pervasive quality control issues in the Russian military-industrial complex during much of the post-Soviet era and one has to wonder just how much less trouble the Russians would have had with Bulava merely by making more use of a test stand they apparently did build. The Wikipedia article blames both the early and recent failures of Bulava on manufacturing problems.

            As to the N-1, a test stand might have helped with the engine control issue, but inadequate thrust vector control authority is just bad basic engineering. It’s hard to see how test stand runs would have helped ameliorate that.

  2. I do not know about your odds, not saying they are wrong – just have no basis for evaluation, but yeah 27 engines does give one pause. But then so might three. To go blasting off into the sky based on a 3 whole second test boggles my mind. Presumably SpaceX has enough data to make a rational decision.

    But it does raise an interesting point regarding logistics vs tactics a la Dick Eagleson …. if LC39A is put out of commission Dragon 2 will be up the creek. But that could as easily happen with a F9 as a FH.

    I guess the real lesson to be learned is if you set out to conquer the universe you really ought to have more than one pad.

  3. A FH launch will be quite a sight, but it’s not even the most impressive thing SpaceX has in the works. Once Raptor is ready, all sorts of new configurations are possible.

  5. I was surprised to learn from the article that the side boosters of the first FH will both be “flight proven” Falcon 9s. I knew the side boosters were based on the Falcon 9, I did not know they were precisely the same hardware such they are completely interchangeable and a given booster can be used single stick and then as part of a Falcon Heavy. Go, man, go!

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