SpaceX’s Starship SN1 prototype blows up during pressure test on its Texas pad | Hacker News Reader

SpaceX’s Starship SN1 prototype blows up during pressure test on its Texas pad

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Elon just said this 12 hours ago: "Failure has to be an option. What you want is to reward success but there should be minor consequences for trying and not succeeding. And major consequences for not trying #AWS2020" [1]

They are rapidly iterating, and I expect them to destroy up a lot of Starship hardware in the next few months as they perfect it.

[1] https://youtu.be/dPwxfzvhlLA

Video shows cars driving along a nearby road seconds before the explosion, only several hundred feet away. Did they sign up for Elon’s trial-and-error strategy?

we've come a long way from "failure is not an option".

this is typical musk spin. of course we can't be afraid to fail, but that isn't what happened here. catastrophic failures should not be considered "oh well" situations. move fast and break things isn't a design and engineering approach worth subscribing to. i'd appreciate a more measured response from spaceX. the quote "Not much to worry about here" from spaceX is pretty annoying. a less dismissive tone would be better, because from my point of view, they just had a pretty large and expensive failure. that's bothersome from someone getting a ton of public funding.

a response of "we take failures very seriously" rather than basically "yea, that'll happen" would be more professional.

It's not a catastrophic failure, it's a failed pressure test. The pressure exceeded the structural limit and it popped, now they know.

You don't say your MVP is a catastrophic failure because it failed a stress test, you learn, optimize, and advance on.

Feel free to give everyone advice on how to never fail a test that is designed to either pass or fail.

I don't see how or why you're annoyed with their "tone".

Your entire comment seems petty in the scheme of space exploration.

What are you talking about. All of the major advances in aerospace happened due to iterating fast and having a culture that accepts failure as a necessary step in innovation.

If you don't own any SpaceX stock and aren't planning on flying on one of their spaceships when the time comes, why do you care?

How, exactly, would one own SpaceX stock?

https://www.baronfunds.com/product-detail

One of the Baron Funds invested in SpaceX.

> this is typical musk spin

Note that this was said at a conference before the unscheduled disassembly... the timing is coincidence not spin.

Would you call this wing test of an airplane a large and expensive failure?

https://youtu.be/Ai2HmvAXcU0?t=2m24s

The pressure vessel failed during testing with nitrogen, no explosion occurred.

This probably isn't that much of a surprise, they knew the welds were far from ideal and already had improvements on the way.

> We had the wrong settings! To make the welds super flat & strong, we’re building a heavy duty, custom planisher, but just having the right settings is a major improvement.

https://twitter.com/elonmusk/status/1232556310874533888

The next version is already being assembled right beside where this one failed.

It definitely was an explosion. I think you mean it wasn't a combustion.

>explosion > a violent expansion in which energy is transmitted outwards as a shock wave. > a sudden outburst of something such as violent emotion, especially anger.

Well, on the bright side, this was the first Starship that flew.

So I guess a better title would be that it popped.

If the SLS blew up during testing, it would set the program back a literal decade (or more).

If the James Webb telescope failed during deploy, it would be a $10-$20 billion loss -- and it would never be re-attempted.

NASA needs to re-learn from SpaceX's ability to iterate on cheap designs and flush out flaws quickly. I say re-learn, because they DID know how to do this correctly during the Gemini / Apollo eras (TONS of rockets blew up before they attempted human spaceflight).

But culturally, something went deeply wrong, perhaps when we reached the Space Shuttle era, and they lost the willingness to ever accept failure or pushing limits -- the same process we tell tell children is critical to ever learning.

Safi Bahcall's Loonshots describes the phase-change transition which happens in organisations as they grow in size and value safety over innovation.

https://us.macmillan.com/books/9781250185969

https://www.worldcat.org/title/loonshots-how-to-nurture-the-...

New Books Network interview: https://newbooksnetwork.com/safi-bahcall-loonshots-how-to-nu...

It would be interesting to apply those ideas to American society in general.

Giving things a "red hot go" doesn't exist in the vocabulary of bureaucrats. If you have no personal vested interest in success, the only thing to optimise for is to minimise risks, because failures are rewarded with a dressing down at a minimum, career dead end at worst.

Elon Musk is known for rewarding for success, not punishing for failure, but instead reserving punishment for those that didn't even both trying.

Meanwhile, "not even trying" is the default mode of operation for 90% of public servants I've worked with...

Yea but consider the cost. Just slinging weld on a tank costs time and material. How much money was wasted by not properly manufacturing this tank. I don't understand how he has succeeded with such rube goldberg engineering.

Isn't this the second pressure vessel to fail on pressure testing? Doing it wrong once is OK. Doing it wrong twice means you learned nothing from your first failure.

I think an important angle of "consider the cost" is that materials in R&D are pretty much ALWAYS cheaper than a team and time. For example here if the whole rocket was a 4mm thick 9m X 118m cylinder, the actual stainless steel would be like $700K [1]. While the rough headcount ceiling cost at SpaceX (7000 employees) is around $5M per day. And this way they get actual valuable engineering experience out of it, rather than just arguing in conference rooms like a more conservative company would have done. I think fail-fast prototypes are super valuable and are what good R&D looks like.

[1] https://www.wolframalpha.com/input/?i=%28pi+*+9m+*+4mm+*+118...

It’s a pressurized tin can. It’s not a rocket. The entire thing could get nuked from orbit and SpaceX would still lose less money cleaning up the radiation than they would if Starship failed - potentially with people on board.

They’re at a “throw stuff at the wall and see what sticks” stage in the engineering cycle. They’re using (and abusing) processes never meant to be used for spaceflight, so in a lot of ways nobody there really knows how to do things correctly without trying and testing it. Imagine trying to learn a language like Go without being able to access any documentation on it. You would waste a ton of time and utterly fail at simple tasks too.

People have been building pressure vessels since the days of the steam engine and cryogenic pressure vessels since the early 1900s. Robert Goddard's first liquid engine ran on liquid oxygen, that was in 1926. The metallurgy and processes are well understood, an explosion shouldn't have happened, yet Musk managed to have one twice in a row. Fire engineering and management, Space X is beginning to look like Boeing!

Its easy when you don’t have to worry about weight. Just make it thicker and stronger. Steam engines don’t often explode, but they aren’t going to make orbit either.

Actually, German TÜV was instituted after some boilers in the steam age blew up the factories and killed many workers. Overbuilding boilers is expensive.

If I had to choose I’d rather believe someone that accomplished rocket reusability with prices ridiculously low compared to all the competitors rather than someone that has no idea about the difference between a steam engine and a rocket and probably never heard about the rocket equation.

That's is the fandom talking. There was no indication that Space X expected failure twice in a row.

Elon Musk presided over a failure in static pressure testing of a steel vessel. No vibrations, no dynamic loading, no fluid flow, just simply pressurizing a steel tank. No exotic materials or difficult techniques like aluminium welding were involved, just garden-variety steel, the best-understood material of all. How do you manage to fail at constructing a piece of equipment as simple as this?

Care to state terms of a bet to see who will succeed first at commercial space transport for some number of humans? I'll have someone write up something and commit to the other side of the bet.

We can discuss terms here.

The Russians are flying commercially into space right now, and Soyuz vehicle has an excellent safety record, > 97 % success, no loss of life. With their recent track record no one should trust Boeing or Space X - Starship, Starline and Dragon all revealed what a shambles their engineering is.

> Fire engineering and management, Space X is beginning to look like Boeing!

If you don't own any SpaceX stock and aren't planning on flying on one of their spaceships when the time comes, why do you care?

>Yea but consider the cost. Just slinging weld on a tank costs time and material

Sure, but its what, A few 10's of thousands of dollars for steel and welding for the test? If it saves a day of double or triple checking to just ""see if the damned thing blows up "" you have to weigh success odds and lessons learned vs. overhead costs. I wonder what a few days or weeks of overhead costs a company like SpaceX that would have had to be spent to make sure the test succeeded.

As a rule of thumb, calendar time is generally more expensive than equipment and man-hours - even in hard tech.

> Doing it wrong twice means you learned nothing from your first failure.

Edison failed thousands of times building an electric light bulb filament.

> Doing it wrong twice means you learned nothing from your first failure.

And yet falcon 1 failed how many times before they got falcon 9 up?

Besides all the points other people already made, the money saved by being able to switch to deploying the Starlink constellation via SuperHeavy/Starship (very likely to be cheaper in $ per satellite-to-orbit) instead of F9 earlier makes taking risks and iterating faster even more appealing.

If your compiler throws an error twice, it doesn’t mean you are a failure, just that something else went wrong.

How do you iterate cheaply on a large telescope mirror and associated precision components?

You're right. Iteration comes when you plan on building lots of something. If there was a plan to have 100 JWT type telescopes in orbit, then you build lots of prototypes and narrow down the manufacturing process. When there's only one of something, we see what we have now: years of delays and over-budget because the thing (JWT) absolutely has to work or the entire project is a failure.

> If the SLS blew up during testing, it would set the program back a literal decade (or more).

It just did, a few weeks ago: https://www.nasa.gov/exploration/systems/sls/nasa-engineers-....

Maybe somebody can explain this to me.

Welds are supposed to be tested at the weld level, not at the vehicle level. So what is wrong with their process or QA?

You are right. At the very basic levels we have PT. This is a test with dye sprayed on the weld and a developer sprayed on to show the defects. This is very commonly done.

Next we have UltraSonic(UT) testing. This requires expensive equipment and a good examiner to interpret.

Third we have X-Ray. This is used on welds that are very important as it is also hard to do and interpret. It also requires the weld to be ground smooth to distinguish flaws from ordinary weld.

I am sure there are a variety of other non destructive testing (NDT )techniques. These are the common ones used in industry.

I do want to mention that pressure vessels are hard to make. Especially something so large. This could actually be a design problem and not welds. Pressure vessels are often tested at 5/3 their working pressure. So failures at testing are not uncommon.

Dye penetrant is another NDT that highlights cracks for visual inspection too, but it's proven to be less effective than ultrasonic and x-ray (hence the changes some years ago in the inspection and rebuild manuals by AD's for many (it should be all) turbofan engines). I knew a German engineer consultant who did this on piping, welds and pressure vessels in the field for nuclear plants.

You can use all three of these NDT techniques, where are used in nuclear energy and turbofan engine applications, but still fail to detect weak welds or metal fatigue because of improper calculations or conditions in the real world.

There's no substitute for DT to validate the engineering and manufacturing, such as by overpressing a pressure vessel (which are also covered by ASME BPVC).

Oddly enough, I knew a civil engineer (PE) who was an expert witness and wrote code interpretations for BPVC to the tune of $40-60k per for a few hours of work (but having his experience on large industrial projects is an important prerequisite). IIRC, he had a massive house in Saratoga.

NDT = Non-destructive Testing

PE = Professional Engineer

ASME BPVC = American Society of Mechanical Engineers Boiler & Pressure Vessel Code.

Thank you

Boeing avoids welded seams on airplanes because they are very difficult to reliably inspect. Riveted seams, however, are straightforward to inspect.

I assume riveted seams don't work for pressure vessels? Would the air plane cabin be welded?

Rivets were the fastener of choice for pressure vessels in the steam age.

The pressure bulkheads in an airliner are riveted.

I really don't understand the build method they use. Ideally you would use a turntable to rotate the cylinder while welding the sections together with a sub-arc machine. https://www.youtube.com/watch?v=j-hfExEmGsE

Elon blaming "settings" seems like a silly explanation. There should be weld engineers and destructive testing done before the first beads are welded on an actual tank.

I've set up automated welding cells, and the "settings" excuse sounds totally reasonable to me haha. There are indeed a million settings (weld weave pitch and amplitude, wire feed speed, linear feed speed, gas flow rate, amperage, etc.) that are hard to tune 100% correctly and don't have "analytic solutions" (i.e. you tune some values like a monkey until it gives the result you want). Seems like this tank failure was their "destructive testing," although most people would probably have used smaller samples to save money. As someone else said: pressure vessels are hard!

> Ideally you would use a turntable to rotate the cylinder while welding the sections together with a sub-arc machine. https://www.youtube.com/watch?v=j-hfExEmGsE

Uh, at least in the video that steel is pretty thick. Starships skin is slightly less than 4mm thick... while in that video they have a 2cm deep groove, would the same technique actually work?

For what it's worth, ULA stainless steel (<1mm thickness) upper stages are resistance welded instead https://www.youtube.com/watch?v=o0fG_lnVhHw&t=41m10s

That said, I think a lot of the decisions right now are based on "what can we quickly experiment with" not "what is a good long term plan". Building a 9m turntable (diameter of the rocket) would take a long time.

I agree a 9m turntable would take some time to make. But once made you could crank these vessels out very fast. 4mm skin sounds OK and I am sure there are some structural supports inside to keep it from collapsing. I am not a weld engineer so I cannot say if Sub-Arc would be the best technique. I know that ships skins are being built with it.

You’re talking about production engineering. You don’t really do that until your design starts to be nailed down. It’s not.

Tory Bruno in an interview says ULA does between 1.1 and 1.25 safety factor for pressure vessels.

I'm not a welder, but you're talking about

A prototype that was manufactured in a tent and in a field, with welds being done in that field only a few days ago. I doubt much QA or weld level testing was done.

A prototype on which they knew welds were less than ideal...

And specifically a prototype of a rocket being built with new materials and new manufacturing methods. Rockets have the nearly unique distinction of having to be strong enough and no stronger because being stronger wastes mass which lowers the very important payload to orbit number. Bursting a few pressure vessels as they figure out where that point on the strength curve is seems pretty reasonable to me.

We don't (yet) know at what pressure this burst at, if it burst near the total pressure needed to achieve their safety margin I imagine they will be ecstatic. I wouldn't interpret this test failure as a process, or QA failure without more information.

> Rockets have the nearly unique distinction of having to be strong enough and no stronger

More precisely, airplanes are designed to being 50% stronger than the max load it would ever see. Rockets are designed to something like 10% stronger.

SpaceX is apparently aiming for a 1.4x safety factor: https://twitter.com/elonmusk/status/1215719463913345024

But my point here actually was the difference between "at least x times stronger than it needs to be", and "exactly x times stronger than it needs to be". Usually things are manufactured to the first spec, rockets are much closer to the latter spec because keeping weight down is so important.

I suppose airplanes must also be closer to the latter spec than most things, but they should still be more forgiving than rockets.

> A prototype that was manufactured in a tent and in a field, with welds being done in that field only a few days ago. I doubt much QA or weld level testing was done.

What you're describing is how farm tractors are repaired, not how aerospace mfg. is conducted.

You can't "test out" bad metallurgy, welding or mfg. in rockets.

What I'm describing is literally how this rocket was made... literally the whole thing is being live streamed by people living nearby with both 24/7 cams on the facility and frequent higher quality closer films and pictures being taken. Occasionally there are tweets from Elon about the process too.

You are far from the only one who is skeptical that this is a valuable process, but there isn't any room to debate that it is what they are doing.

Edit: Here is a recent timelapse of some of that welding, as an example: https://www.youtube.com/watch?v=J7bIvLhI1hY

I keep thinking of the story "Have Space Suit—Will Travel", except it now it is "Have Welders—Will Construct Space Craft". What SpaceX is doing is both crazy complex rocket science, yet it's also quaintly pedestrian. It makes space feel more accessible to me.

What's a rocket but a tractor with a few tens of thousands of lbs of fuel and oxidizer strapped to it?

There's a reason SpaceX is eating "big aerospace's" lunch and tests like this are part of it.

Isn’t the entire prototype part of the QA?

How much has SpaceX had to “start over” from what NASA and others have researched over the decades?

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