What size nuts do they pass through their engine? Every engine before it goes to space has to have a nut passed through the system? Like a 12mm "go into space" grade nut or a little itty bitty nut like I might find holding down a heat sink assembly in a 1998 vintage motherboard?
Actually I'd rather have such "bonkers" tests than the other extreme, like NASA not thinking about what could happen if pieces of foam from the external fuel tank impacted the Space Shuttle on launch until it was too late (https://en.wikipedia.org/wiki/Space_Shuttle_Columbia_disaste...).
The really shitty thing is they knew early on the O-rings were slipping and partially extruding themselves, which wasn't part of the original design. They shrugged and ignored this, which then opened the door for disaster when the O-rings behaved differently (and still wrong) when cold. If they had pumped the brakes when the initial deviation from the design was discovered, it wouldn't have ended in disaster.
"Boisjoly wrote a memo in July 1985 to his superiors concerning the faulty design of the solid rocket boosters that, if left unaddressed, could lead to a catastrophic event during launch of a Space Shuttle. Such a catastrophic event occurred six months later resulting in the Space Shuttle Challenger disaster."
Engineers objected and were ignored for the foam strike as well. What I don't know is how many engineers object, are ignored, and everything goes fine anyway. Maybe these are the only 2 times engineers objected. Maybe they get 100 objections for every launch.
That one is a classic example of normalization of deviance. They knew there were temperature limits, but they'd pushed the boundary a bit in the past with no ill results, and so began to feel complacent about the risks of pushing them even further.
Probably more "qualification of the design", like those bird ingestion tests they do on airliner engines. And the test probably doesn't look too interesting, the nut might not even come out the other end.
Let us know what you find. I find it not 'bonkers' but a great idea, and hope they are qualifying with the largest nuts found upstream, in 'go to space' grades.
Robustness and anti-fragility may not be so critical for an expendable vehicle that operates once for something like 12 minutes, but seems a key attribute for a refuel-able and reusable spacecraft?
Oh I agree it's not bonkers from the perspective of "wait you want to put people on that bomb and then explode it?"
You can make all sorts of rules about what's not allowed to happen, but often those things happen.
I'm just ... astonished if they've got a little practice room somewhere in their factory where they give each of their new rockets a nut to process... "Okay kid here's your graduation test!". A "we need screens to cope with big things and filters to deal with small things" is probably smart for any anything that's going to be reused.
A nut's probably in some ways easier to deal with than a blob of wd40 (in your lox tank).
> I'm just ... astonished if they've got a little practice room somewhere in their factory where they give each of their new rockets a nut to process... "Okay kid here's your graduation test!". A "we need screens to cope with big things and filters to deal with small things" is probably smart for any anything that's going to be reused.
That's what their McGreggor test site in Texas is for. It's a long, boring, two hour drive from anywhere or anything.
"anti-fragility" is probably not a design goal for Merlins and Falcon.
Anti-fragility means more than robustness, it means that the system is getting stronger with each adverse event, and it is not a realistic goal that ingestion of a nut should make the engine better/stronger etc.
Of course, not for individual rockets on individual flights (but self-repairing would be way cool!).
But Anti-Fragility as you define it definitely should be a goal for their overall organization and system of building and operating the fleet.
Each issue or incident should feedback into the engineering of new units and updating of existing units so that they are improved, stronger, less likely to create issues, more able to handle issues, etc. on each iteration. This actually seems to be the case at SpaceX, including this incident.
Oh yes, that is an excellent observation. The components themselves cannot be antifragile, but the development process certainly can.
Thinking about that, an important feature of that antifragility is not to risk human lives during the process if that risk can be avoided. Even though space exploration is inherently risky, any actual fatality is a huge setback.
The tradition of passing nuts comes at least from the history of developing engines for Soviet Moon launcher, N-1. The engines used on all four launches, NK-15, were notoriously unreliable, and the suspicion was that their turbopumps, having quite tight clearances, sometimes had rotors touching walls during work. In oxygen-rich environment that led to engine fire. The engine which fixed those problems, NK-33, was working much better, and to demonstrate that it's robust for the problems like turbine misalignment, some metal parts, like nuts, were intentionally dropped into the propellant flow.
What size nuts do they pass through their engine? Every engine before it goes to space has to have a nut passed through the system? Like a 12mm "go into space" grade nut or a little itty bitty nut like I might find holding down a heat sink assembly in a 1998 vintage motherboard?
I'm off to the googles to find videos...