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I read this was a manufacturing pathfinder. Manufacturing and assembly of high strength hardened steel is near black art. Pathfinders do exactly what they say

I read this was a manufacturing pathfinder. Manufacturing and assembly of high strength hardened steel is near black art. Pathfinders do exactly what they say, they lead you through unknown territory to the outcome of the manufacturing journey you embarked on. Often things go boom, you find out why, add it to your corpus of black art knowledge, and keep pathfinding until you run out of budget / succeed / change mission. So as manufacturing pathfinder, this is what success often looks like.

Roark66 7y ago
Why would they be using hardened steel for a pressure vessel that has to deal with vibrations? Also, someone on twitter said a horizontal weld failed. If this is true I'm surprised they didn't do two things: - tune their welding procedure by destructive testing with the same type of steel - and X-ray (or use another non-destructive method) the welds after assembly. Welding (including more interesting metals) is my hobby so I had an opportunity to see that there a huge amount of knowledge in the field. There are routine testing procedures that ensure situations like this one don't happen.
- 19870213 7y ago
  As far as I know the type of steel they are using increases in strength as it gets colder, so that should be ideal for the LOX.
- tinco 7y ago
  Maybe they did both things, and the weld still failed. The rocket's being engineered, which means they make it as weak as possible without it blowing up. Those welds might be perfect in the x-rays, they might've done all sorts of destructive analysis, and still the thing might fail in staging. Of course, they might also be on a deadline, and just went ahead and built it to spec and test it. But I don't think you can just say there's routine testing procedures that ensure rockets never blow up. If that were the case we wouldn't have needed SpaceX to reinvigorate the space industry.
  - Roark66 7y ago
    >Maybe they did both things, and the weld still failed. The rocket's being engineered, which means they make it as weak as possible without it blowing up. Those welds might be perfect in the x-rays, they might've done all sorts of destructive analysis, and still the thing might fail in staging. Yes, that is also a possibility. I'm not sure how likely is it that a pressure vessel would fail along a weld if that weld was without faults and as strong as other surfaces. Perhaps it matters that there is also a sharp corner there? >Of course, they might also be on a deadline, and just went ahead and built it to spec and test it. But I don't think you can just say there's routine testing procedures that ensure rockets never blow up. I agree if they are trying to make it as light as possible and pushing the boundaries a bit while experimenting. One can't innovate without risk. It would be good if they released more info about this incident.
    - labawi 7y ago
      AFAIK, during early development they are using a different, simpler welding process, including more welds and thicker off-the-shelf steel plates to compensate strength. The welding process probably isn't optimized or fully inspected and the weakest parts would expectedly be the welds.
- lutorm 7y ago
  They are using 301 stainless which, as far as I know, cannot be hardened.
combnoinipo 7y ago
What does pathfinder mean in the context of manufacturing?
- madaxe_again 7y ago
  A fuzzball of patches and “good ideas at the time”. It’s like the first iteration of an app that never sees the light of day, as you finish, sit back, go “ah, an abomination”, and rewrite the thing properly with what you learned from the prototype. I do this pretty much any time I’m doing something new - I have three revisions of a solar panel stand sat out on the lawn right now, each better than the last, as I needed to build the thing to see how it actually held up to forces as it’s easier and more accurate (ah, how do I fit a screwdriver in this gap to fasten this?) than doing an engineering simulation.
- celticninja 7y ago
  Essentially doing something for the first time, no one has built a steel structure of this size before, that will have to withstand the forces that this will be out through in normal operation.
- specialist 7y ago
  Tabu search thru a semi-dynamic design space. https://en.wikipedia.org/wiki/Tabu_search https://en.wikipedia.org/wiki/Tabu_search
- double0jimb0 7y ago
  At the highest level, the conversation looks like: The design engineer: "We know on paper how the product needs to function in terms of strength, weight, durability, etc" The manufacturing engineer: "We've never made something like this before. I've got a couple ideas how we can bend/shape/form/machine/weld these materials into the shape, but I don't know how those bend/shape/form/machine/welding operations are going to affect the underlying physical properties of the material. I know on paper these operations should be OK, and we can inspect them as we go, but again we've never done them before, we most likely will overlook something or discovery something new, so let's try one of them and break it early before we get too far down a potentially bad path." The test engineer: "Well it worked up until X point then failed, here's the data for you design engineer and you manufacturing engineer, better try something else". Design engineer: "Shoot, what we thought we were manufacturing isn't actually what got manufactured. Hmmm, is it even possible to make the part we need? Or do we now need to redesign the part because it can't actually be made. Let's try another approach. And maybe it's smart to pursue a few of these in parallel to increase our overall chance of success" Those 3 roles can be the same person or separate organizations of hundreds/thousands of people. Requirements documents, manufacturing/quality reports, test reports, inspection reports are the language of this technical interchange.
CPLX 7y ago
I must admit that Elon has done some fairly impressive things, and I respect his hustle and innovation. With that said, the cult that surrounds his projects where people say things like "this is what success looks like" when a big metal thing blows up unexpectedly or robot car goes flying off an exit ramp is a never ending source of amusement.
- ehnto 7y ago
  I guess the parent comment was pointing out that this actually wasn't unexpected, it was one of the expected failure modes for the test and it happened. I don't see any constructive reason to look at it negatively, failure is part of testing. We don't test to find success, we test to find failures so that we can get them out of our systems.
  - aedron 7y ago
    Fine, so don't call it "success!". It's a step on the way to (possible) success, but the hypersensitivity isn't helping anyone.
    - ehnto 7y ago
      Negatively responding to failure during a test is like negatively responding to someone asking a question. I am sure the circlejerk gets annoying, but it's at least got a constructive outcome. It's obviously not going to affect professionals and companies, but if you apply your view to students or people trying to work out new problems you could dissuade them from being inquisitive.
    - Ari_Ugwu 7y ago
      The semantics these days. Trade "success" for "progress"....but then also replace "accident" with "test result". Works both ways, so does the hyper-sensitivity. We are silly animals. Links I can't help but click on....comments I can't help to respond to. The algorithms are winning.
    - dwild 7y ago
      You sound like the one hypersensitive here...
hyperpallium 7y ago
Soumds similar to tracer bullet development.

Roark66 7y ago

Why would they be using hardened steel for a pressure vessel that has to deal with vibrations? Also, someone on twitter said a horizontal weld failed. If this is true I'm surprised they didn't do two things: - tune their welding procedure by destructive testing with the same type of steel - and X-ray (or use another non-destructive method) the welds after assembly. Welding (including more interesting metals) is my hobby so I had an opportunity to see that there a huge amount of knowledge in the field. There are routine testing procedures that ensure situations like this one don't happen.

19870213 7y ago
As far as I know the type of steel they are using increases in strength as it gets colder, so that should be ideal for the LOX.
tinco 7y ago
Maybe they did both things, and the weld still failed. The rocket's being engineered, which means they make it as weak as possible without it blowing up. Those welds might be perfect in the x-rays, they might've done all sorts of destructive analysis, and still the thing might fail in staging. Of course, they might also be on a deadline, and just went ahead and built it to spec and test it. But I don't think you can just say there's routine testing procedures that ensure rockets never blow up. If that were the case we wouldn't have needed SpaceX to reinvigorate the space industry.
- Roark66 7y ago
  >Maybe they did both things, and the weld still failed. The rocket's being engineered, which means they make it as weak as possible without it blowing up. Those welds might be perfect in the x-rays, they might've done all sorts of destructive analysis, and still the thing might fail in staging. Yes, that is also a possibility. I'm not sure how likely is it that a pressure vessel would fail along a weld if that weld was without faults and as strong as other surfaces. Perhaps it matters that there is also a sharp corner there? >Of course, they might also be on a deadline, and just went ahead and built it to spec and test it. But I don't think you can just say there's routine testing procedures that ensure rockets never blow up. I agree if they are trying to make it as light as possible and pushing the boundaries a bit while experimenting. One can't innovate without risk. It would be good if they released more info about this incident.
  - labawi 7y ago
    AFAIK, during early development they are using a different, simpler welding process, including more welds and thicker off-the-shelf steel plates to compensate strength. The welding process probably isn't optimized or fully inspected and the weakest parts would expectedly be the welds.
lutorm 7y ago
They are using 301 stainless which, as far as I know, cannot be hardened.

combnoinipo 7y ago

What does pathfinder mean in the context of manufacturing?

madaxe_again 7y ago
A fuzzball of patches and “good ideas at the time”. It’s like the first iteration of an app that never sees the light of day, as you finish, sit back, go “ah, an abomination”, and rewrite the thing properly with what you learned from the prototype. I do this pretty much any time I’m doing something new - I have three revisions of a solar panel stand sat out on the lawn right now, each better than the last, as I needed to build the thing to see how it actually held up to forces as it’s easier and more accurate (ah, how do I fit a screwdriver in this gap to fasten this?) than doing an engineering simulation.
celticninja 7y ago
Essentially doing something for the first time, no one has built a steel structure of this size before, that will have to withstand the forces that this will be out through in normal operation.
specialist 7y ago
Tabu search thru a semi-dynamic design space. https://en.wikipedia.org/wiki/Tabu_search https://en.wikipedia.org/wiki/Tabu_search
double0jimb0 7y ago
At the highest level, the conversation looks like: The design engineer: "We know on paper how the product needs to function in terms of strength, weight, durability, etc" The manufacturing engineer: "We've never made something like this before. I've got a couple ideas how we can bend/shape/form/machine/weld these materials into the shape, but I don't know how those bend/shape/form/machine/welding operations are going to affect the underlying physical properties of the material. I know on paper these operations should be OK, and we can inspect them as we go, but again we've never done them before, we most likely will overlook something or discovery something new, so let's try one of them and break it early before we get too far down a potentially bad path." The test engineer: "Well it worked up until X point then failed, here's the data for you design engineer and you manufacturing engineer, better try something else". Design engineer: "Shoot, what we thought we were manufacturing isn't actually what got manufactured. Hmmm, is it even possible to make the part we need? Or do we now need to redesign the part because it can't actually be made. Let's try another approach. And maybe it's smart to pursue a few of these in parallel to increase our overall chance of success" Those 3 roles can be the same person or separate organizations of hundreds/thousands of people. Requirements documents, manufacturing/quality reports, test reports, inspection reports are the language of this technical interchange.

CPLX 7y ago

I must admit that Elon has done some fairly impressive things, and I respect his hustle and innovation. With that said, the cult that surrounds his projects where people say things like "this is what success looks like" when a big metal thing blows up unexpectedly or robot car goes flying off an exit ramp is a never ending source of amusement.

ehnto 7y ago
I guess the parent comment was pointing out that this actually wasn't unexpected, it was one of the expected failure modes for the test and it happened. I don't see any constructive reason to look at it negatively, failure is part of testing. We don't test to find success, we test to find failures so that we can get them out of our systems.
- aedron 7y ago
  Fine, so don't call it "success!". It's a step on the way to (possible) success, but the hypersensitivity isn't helping anyone.
  - ehnto 7y ago
    Negatively responding to failure during a test is like negatively responding to someone asking a question. I am sure the circlejerk gets annoying, but it's at least got a constructive outcome. It's obviously not going to affect professionals and companies, but if you apply your view to students or people trying to work out new problems you could dissuade them from being inquisitive.
  - Ari_Ugwu 7y ago
    The semantics these days. Trade "success" for "progress"....but then also replace "accident" with "test result". Works both ways, so does the hyper-sensitivity. We are silly animals. Links I can't help but click on....comments I can't help to respond to. The algorithms are winning.
  - dwild 7y ago
    You sound like the one hypersensitive here...

hyperpallium 7y ago

Soumds similar to tracer bullet development.