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Elon Musk: Faulty Strut May Have Led To Falcon 9 Launch Failure
garyisabusyguy writes: This Forbes article provides the best analysis of the loss of the last Falcon 9 mission based on information released by Elon Musk to reporters. Highlights include:
- 1. Sound triangulation led them to identify a strut holding helium tank as root cause where the falling helium tank pinched a line causing overpressure in the LOX tank.
- 2. The failure occurred at 2,000 pounds of force, and the struts were rated at 10,000 pounds of force. They initially dismissed this as a cause until sounds triangulation pointed back to the strut
- 3. Further testing of struts in stock found one that failed at 2,000 pounds of force, with further analysis identifying poor grain structure in the metal, which caused weakness
- 4. It will be months before the next launch while SpaceX goes over procurement and QA processes all struts and bolts, and re-assesses any "near misses" with Air Force and NASA
- 5. Next launch will include failure mode software, which will allow recovery of the Dragon module during loss of the launch vehicle since they determined that it could have saved the Dragon module in this lost mission
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Now THAT is how you summarize.
So after weeks of investigation it turns out it's a failure mode that even the most amateur of KSP players recognize.
They should have added a lot more of them, clearly. It's not like struts have any mass.
the heilum bottle would have shot to the top of the tank at high speed
That sounds a lot different than "a hose may have been pinched" Has anyone been able to find audio of the actual conversation?
Sell them faulty metal.
Or faulty parts made of metal.
It's just a thought, but would a competitor stoop to that? Even if not now, at some point in the future?
I'll see your senator, and I'll raise you two judges.
I am amused by the fact that a private company does better than our government at disaster transparency. That said, it is pretty stupid that Space X has not been testing random parts to confirm they meet the requested specifications. Spec verification is a basic part of outsourcing. All outsourcing fails if you can't verify that you're getting what they promised you.
"I will trust Google to 'do no evil' until the founders no longer run it." Hello Alphabet.
THIS is why aerospace and aeronatical parts cost so dang much.
Pilot wouldn't have needed to. Dragon 2 has automatic abort capabilities (even when unmanned). It would have separated from the second stage - probably firing its SuperDraco thrusters - and then automatically deployed parachutes once it was a safe distance away.
Dragon 1 doesn't have the SuperDracos (only the much smaller Draco attitude control thrusters) so it wouldn't have been able to put as much distance between itself and the booster, but from the video and the telemetry it looks like the capsule survived the (accidental) separation anyhow. It could have deployed its parachutes and probably survived the landing, but it wasn't programmed to do so. They have added it to the Dragon 1 programming now though.
Failures that occur high enough to land under parachutes, slow enough to get away from the inevitable explosion without heavy rockets, and early enough in flight that there's no time to manually enable the landing sequence are... really, really rare in rocketry. Usually you either fail at liftoff (see Orbital's last attempt to launch Antares), fail rapidly and catastrophically during liftoff (any number of examples), or fail once in orbit (often, though not always, at stage separation). In orbit you have time to make a decision and send orders. On the launchpad you can't land safely (without abort rockets). In midair you *usually* can't get away in time (without abort rockets). This was an exception to the "in midair" usual failure case; there were nine seconds from beginning of the failure to loss of vehicle, and in fact the capsule had already tumbled free (and probably *could* have used its ACS thrusters to put some extra distance between itself and the booster.
One thought, though: what about, in the case of a pre-separation second-stage failure, executing MECO 1 (Main Engine Cut Off, when the Falcon 9 first stage kills its rockets) early and doing an emergency stage separation? Normally there's no point - the first stage on most launch vehicles has no purpose if the launch fails and nowhere to go even if it separates safely - but the Falcon 9 first stage is designed for reusability. Emergency MECO, separate the stages, use the ACS and/or grid fins to steer clear of the second stage, and then fire up the main engines again and aim for the droneship or other landing pad. You'd need to be quick about it, and it might still not work, but if it does you've saved a booster worth $70,000,000 USD. Well, that and demonstrated the first successful first stage recovery ever, but assuming that becomes as routine as Musk wants it to be...
Actually, it would have been super cool if the first successful recovery of the first stage had been an emergency abort!
There's no place I could be, since I've found Serenity...
You think having the part designed to handle five times the load it actually experienced to not be "with sufficient margin"? How much of a margin do you want them to put, 100x?
RTFA. They were doing statistical-sampling quality control testing of struts. The problem was that most of them were just fine, but there were a very small number which were totally defective and broke at a tiny fraction of their rated value. And no, SpaceX did not make the parts, it was an outside supplier. And yes, SpaceX A) will now be testing 100% of them, and B) is ditching the supplier.
"You see, Government is a system that is based on weapons." -- Timster
TESTING requires destruction of this kind of thing as I read the article. They will NOT be doing 100% testing to failure of their stock of struts, except to prove to themselves how bad their supplier really was.
Nobody said they would be testing to failure. You can test every unit to say 150% of failure. If the material is rated for 1000% of failure then 150% should be safe. If it doesn't fail at 150% once it probably won't fail at 100% 100 times. So now you're at 99 times until mean failure instead of 100.
After the doge meme's 15 minutes of internet fame, your sentence actually much parses.
I can see the fnords!
And as an engineer, I know that most engineers want to act in good faith. Some are inept or inexperienced but they still have good faith. The problem lies in management. Once you get the lawyers and bean counters involved is when asshole decisions like that get made.
I'm an engineer but I'm also an accountant (aka a bean counter). I also am management in my company and I'm in charge of the engineering, production and accounting among other things. You are absolutely right that most of the time the fault for most failures ultimately is due to management decisions. At the end of the day the buck stops with them and that is how it should be. HOWEVER, management ultimately relies on the expertise of engineers and the reasoned opinions of those who report to them. If management gets bad information (happens all the time) then management decisions are more likely to be bad ones. That's not to say that management can't introduce cock-ups all their own (we all know they routinely do) but bad management decisions normally don't happen in a vacuum. Most serious screw ups in a company happen because people at multiple levels in a company made a mistake. It's not just management or engineering or accounting alone. Rockets blow up when all these mistakes made by multiple people line up in just the right way. Business is a team sport and most failures in business involve more than one person.
Engineering is kind of like playing chess. You can see the entire board and you know (or should) what is possible at any given moment because you have close to perfect information. If you are good enough mistakes are largely predictable. Management is more like playing poker. You rarely have perfect information and you have to guess based on your assessment of the probabilities and sometimes you'll be wrong even if you play the hand perfectly. The mindsets needed for success in each for each are very different and can be hard to reconcile at times.
It has also been my experience that there are FAR more inept engineers that most people realize. Specifically too many engineers are inept at product and process documentation. It's boring and despite its importance it tends to get overlooked and engineers often spend as little time with it as they can get away with. I run a contract manufacturing company that makes wire harnesses. I can count on my fingers the number of product drawings that I've received in the last 5 years from all our customers combined that I could manufacture without having to get substantial clarification from the engineering staff at our customer. I routinely see ambiguous dimensions, incompatible parts, improper or incomplete specifications, missing part numbers, internal part numbers (useless to anyone else), incoherent diagrams, unnecessary lookup tables, obsolete or hard to get parts, and more. Most engineers I've run into are really quite terrible at documentation. I see drawings daily that were clearly not written with the expectation that anyone else might ever read them despite the fact that someone else reading it is the entire point of the document.