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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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Similar business practices have been used in the past. Rockefeller is a well-known example: He was an obsessive monopolist, unable to stomach the existence of any competitor to his Standard Oil empire. Among the tricks he used was to buy up manufacturers of components used in oil drilling and refining, and then refuse to sell replacements to competitors - driving them out of business when their expensive industrial machines eventually broke down and couldn't be repaired. With the competitor driven out of business Rockefeller easily purchased what was left and incorporated it into his company. He sabotaged one company by thus denying them access to oil-carrying carts for trains - and when they switched to shipping in barrels, he purchased the one company that could make a barrel sealing compound compatible with crude oil and altered the formulation to make it chemically unsuited.
Rockefeller's business practices went down in legend - you can thank him for modern antitrust laws: The first ones in the US were passed expressly in order to target him. He was the Bill Gates of the 1800s: Built up a fortune through unethical and at times outright illegal business practices, only to eventually retire and spend the rest of his life giving it away in huge grants to charitable causes.
It would be a lot harder to pull something like that today though - there are stricter regulations and laws against such things. It could be done, but it would need a great deal of legal caution and skill to avoid liability, or at least to ensure the liability lay with a collapsing shell company.
Stop using monospace, you're not a special snowflake.
Everybody who sees posts in monospace just skips over them.
I think you hit the nail on the head with that $250 hammer...
Space X has apparently having systemic Quality Control problems. A structural failure of ANY component that costs you a vehicle in flight is a SERIOUS issue with your process. Either they didn't recognize this component's critical nature in their design reviews and properly established safety margins for it's strength, or they unknowingly used substandard parts in the assembly.
Structural failure should NEVER be the cause of an accident. Structure is NOT rocket science, but well understood and easily tested before you put a design into the air. The loads on the structure should be easily calculated and the structure designed with sufficient margin to handle them. Testing the structure to the margin limits is not that hard and doesn't require you go fly the thing. Aerospace engineers are very familiar with the process.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Using sound to probe structures, materials and devices is a pretty ancient technique, it's just advanced with the tools available. Stonemasons used to check blocks of stone to locate faults by tapping on them and listening for sounds that would indicate cracks or other faults. One of my grandfathers tried to teach me how to listen for potential rot zones in wooden walls when I was a kid also. Now, with modern tools, we can just do it much faster, and with more precision.
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...
Nw expand that to all the parts
You mean expand it to the fraction of the 20% outsourced parts that weren't already being exhaustively tested? Most of those outsourced parts are electronic, because Elon Musk doesn't own a semiconductor factory (yet). All of those electronic parts are tested exhaustively and repeatedly, right up until the literal second of launch, as software verifies sanity in all systems. What's left are things like struts, that should be stupid-simple enough to be trustworthy. And apparently aren't.
So some fraction of a fraction of the parts will need newly exhaustive testing. Not free, but really, it's not that big of a bill.
And the depressing thing is that every one of them is there to prevent recurrence of a dishonesty that actually took place in the past.
And sometimes it's not even dishonesty, just stupidity. This was probably more true in the earlier days of aerospace. In a book about the design and construction of the Lunar Module (I think it's Chariots for Apollo, but could be wrong) there's a section on how many of the subcontractors had to be taught clean-room and quality techniques. There's one episode where one of the Grumman managers goes out to some paint pigment company who happened to get the contract for the silver-zinc LM batteries (because they had supplies of the right materials) and sees the batteries being assembled -- in a dirty shed by people who are smoking cigarettes while doing the assembly. (They threw out the entire batch, trained everyone how to do things the aerospace way, and set up a clean room, and AFAIK there was never a problem with the LM batteries.)
On the other hand the ladies sewing space suit pressure garments at the Playtex Girdle factory knew the astronauts' lives depended on what they were doing, and did it right the first time.
-- Alastair