
SpaceX Starship SN4 launch vehicle prototype explodes after static engine test - edward
https://techcrunch.com/2020/05/29/spacexs-starship-sn4-launch-vehicle-prototype-explodes-after-static-engine-fire-test/
======
rrmm
If you catch the audio on this from the nasa space flight forum (I think?), it
was pretty funny. They were speculating if it was a lox purge (vs a methane
purge). They assumed lox, since if it were methane, the flare would.....
BOOOM.

The timing was very perfect.

EDIT:
[https://twitter.com/NASASpaceflight/status/12664420878489600...](https://twitter.com/NASASpaceflight/status/1266442087848960000)
has the audio with it.

~~~
Pfhreak
A bit later they run the tape back frame by frame and determined the fire
definitely didn't come from the flare stack. (Though in realtime it happens so
fast they weren't sure.)

~~~
ashtonkem
That video was almost certainly taken with a telephoto lens a long distance
away, and telephoto lenses tend to compress distance. The flare could’ve been
a long way away from the rocket, and a telephoto lens would make them look
much much closer.

~~~
Kye
Best illustrated with dolly zooms. Even side-by-side stills don't quite
capture how significant the effect is.

[https://www.youtube.com/watch?v=MeyjyZ6UZII](https://www.youtube.com/watch?v=MeyjyZ6UZII)

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Diederich
Disappointing to be sure, but it's why they already have SN5 (nearly?)
complete and SN6 is well on its way.

I like how Elon Musk contrasted past and currently planned human space
activity as 'Apollo' and the potential future as 'D-Day'.

The goal is to cheaply and quickly mass manufacture interplanetary space
craft. I think that imploding/exploding early serial numbers are an expected
early part of that path.

~~~
moneytide1
Not disappointing - the more things that go wrong during the extensive series
of tests developed and cataloged over the past several decades, the more we
can correct and cement into permanence.

I'm looking forward to SN747 (the number corresponds with one of Boeing's
standardized atmospheric flight models) sometime in 2024. I'm probably not
thinking big enough though.

~~~
lutorm
Believe me, it's absolutely disappointing. Not _unexpected_ , mind you, but
people would definitely prefer to not have things blow up.

~~~
missosoup
Musk was pretty clear in an interview that he _does_ want things to blow up.
He wants the testing to push and exceed the limits so those limits become well
defined. It sounds quite reasonable.

~~~
rumanator
> Musk was pretty clear in an interview that he does want things to blow up.

I get that fanboys are excited and they see the Musk world through rose-
tainted glasses.

But SpaceX was planning on flying this vehicle. And it exploded.

How does anyone anywhere believe in that? Obviously this outcome was not
planned. If anyone wants to fly a vehicle to test other stuff, they don't want
it to blow up prior to it.

~~~
missosoup
I'll reiterate a point I made deeper down: obviously the failure wasn't
planned or intended. But the overall process of being failure tolerant and
having a high rate of failures, was.

You can spend your resources on doing careful modelling and over-engineering
and conservative testing to always stay within limits, or you can go fast and
loose and discover those limits the kinetic explodey way. SpaceX chose the
latter strategy.

Also, not a fanboy. On a personal level the guy's a prick. But the strategy
that SpaceX is employing is sound and tested. It's the same R&D strategy that
was employed by Skunkworks, which is arguably the most successful aerospace
R&D story in the entire history of our species.

~~~
rumanator
> You can spend your resources on doing careful modelling and over-engineering
> and conservative testing to always stay within limits, or you can go fast
> and loose and discover those limits the kinetic explodey way. SpaceX chose
> the latter strategy.

Again, this baseless assertion is just plain wrong on many levels, and flies
in the face of basic engineering practices.

At best, you're confusing a consciencious choice of allocating piles of
resources to avoid bottlenecks and time constraints, such as losing a
prototype which is a project death sentence to your general aerospace research
project, with plain old incompetence.

Engineering 101 teaches that when in doubt err on the safe side. Your
assertion is the exact opposite because... Because what? What do you believe
is the trade-off of wasting time and resources trying to fly intentionally
half-baked designs that define the critical path of the project?

Please spend a moment thinking about what you've said to try to see how absurd
it is to waste time and resources for nothing at all.

~~~
missosoup
> Engineering 101 teaches that when in doubt err on the safe side.

Nonsense. You can't discover limits if you always stay within them. Commercial
engineering, sure. But R&D is by definition the process of exploring an
unknown parameter search space. And considering that spaceX have achieved what
STS has failed to do with 1/10th of the STS budget, I'd say they're not doing
terribly badly with their chosen R&D strategy. You seem to have a deeply
ingrained misconception about what R&D actually entails and how it's different
from both commercial engineering and designed experiments.

Erring on the safe side is what they're doing with their manned missions.
Cargo missions are medium risk and occasionally do dirt-cheap launches to
deliberately try risky scenarios. R&D ops is deliberately high risk and low
process overhead. They rather someone just try something and see what happens
instead of spending 6 months writing an experiment plan and getting it
validated etc. as you would see in the pharma industry for example. I'm not
sure why you're struggling to comprehend this fairly simple and fairly
standard strategy.

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visviva
Would it have really killed their schedule so much to push this until _after_
tomorrow's crewed flight? They're obviously unrelated, but it sucks to have
this is the headlines the day before they launch astronauts.

~~~
ghostpepper
The astronauts are both veterans and one would assume they understand that
this was not only a prototype ship but a prototype engine. Falcon has 50+
successful flights over four years since its most recent failure.

Hopefully they're not phased by this.

~~~
visviva
> Hopefully they're not phased by this.

I doubt they are - my comment is about the PR impact.

~~~
Kye
I get cynical about people sometimes, but I have to believe the average person
can understand the difference between a bleeding edge test and the launch of a
proven system. They don't stop driving when someone dies trying to break the
land speed record. I don't see a PR problem.

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bryanlarsen
This is the 4th Starship that has imploded or exploded. They only lost 3
Falcon 1's before their first successful flight, and Elon has publicly stated
that a 4th failure would have bankrupted the company.

Those three Falcon flights were attempts to reach orbit with rockets that
weren't prototypes so the failures were more significant, and they probably
blew up a bunch of Falcon prototypes behind closed doors prior to the launch
attempts, but it's interesting how three failures on Falcon was a big deal but
four failures on Starship isn't. SpaceX is certainly in a different and much
less precarious position now than it was in 2006-2008.

~~~
Dylan16807
The difference between some test parts on a stick vs. a full rocket is so vast
that I don't think you can make any coherent/interesting comparison of the
numbers.

It's like comparing 4 millimeters to 3 inches. It doesn't matter at all that 4
> 3.

~~~
beambot
Wat? It's totally meaningful to compare two length measurements, Even if
expressed in different units.

I get what you're trying to say (and you are right!), but that's a bad
analogy.

~~~
Dylan16807
You compare the actual length.

Not the _raw number, with unit ignored_.

What's wrong with the analogy? Please explain.

~~~
beambot
Comparing the test rig to a full rocket is more like comparing 4 liters to 3
inches. They're simply not comparable.

~~~
holyDictionary
Both analogies are correct and usable in this context

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101404
Too bad, especially because only yesterday they put a weight simulator onto
it. So it looked like it was going to fly.

Well, it did fly, just not in one piece.

~~~
justaguy88
rapid unscheduled hop

~~~
101404
... multi-directional hop

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watersb
Rocketry is unforgiving. That's why they test.

~~~
trca
Best way to figure out how complex things fail is to keep pushing them to
their limit and observe

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phkahler
This on definitely started at the bottom. It almost looks like a leak created
a FAE (fuel air explosive) mixture around it.

It also blew out the methane flare on the right.

~~~
dreamcompiler
Looks like the methane flare is what lit it, although it's difficult to judge
distance in the video.

~~~
davidmurdoch
It didn't. You can play it back frame by frame and see that it started beneath
SN4.

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londons_explore
I notice all the broken bits of rocket are in square panels.

That indicates the welds failed rather than the steel sheets in the explosion.

If you want to design something to be as strong as possible for the weight,
you make the welds as strong as the sheets. In most cases, that means making
the weld lines thicker than the rest, since the weld is typically formed in
less ideal conditions so weaker.

There are tricks to doing that like zig-zag weld lines, overlapped sheets at
the weld, etc.

Surprising spaceX hasn't done this, considering strength to weight is critical
in rocketry.

~~~
scollet
Can you provide references supporting thicker welds as well as reinforcing
patterns? I have done introductory welding and am genuinely curious of the
ramifications of both.

~~~
scollet
Addendum: preferably video instruction.

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danso
I know these kinds of explosions aren't _disasters_ per se, but at what point
in development do these kind of destructive results become very unwanted? Or
was that classic Calvin and Hobbes comic about bridge testing less of a joke
than I had though?

[https://www.gocomics.com/calvinandhobbes/1986/11/26](https://www.gocomics.com/calvinandhobbes/1986/11/26)

~~~
sacred_numbers
When you start making the same mistakes over and over. As long as they learn
new things with each iteration it doesn't matter if they blow up 5 or 50
ships. The actual material cost of these prototypes is probably in the low 6
figures. The biggest cost is the labor, but by iterating rapidly they are
learning new manufacturing techniques, so if they weren't blowing up these
prototypes they would be stacking them in a field or tearing them down
anyways, since the value is in the process, not the final product, at this
point.

Also, there are only an estimated 300 employees building Starships (although
there are probably more working on engineering), so on-site labor costs are
probably about a million a week. Since they can pop out a new iteration every
few weeks they cost is probably only about a few million per ship. That's a
lot of money in some industries, but it's a rounding error in rocketry. They
could build dozens or even hundreds of prototypes for less than the cost of a
conventional disposable rocket, like SLS.

The idea that the cheapest way to build a rocket is to blow up dozens of
prototypes is a bit counterintuitive, but I believe it's the future.
Organizations that move more slowly to avoid failures will fall further and
further behind, since the tortoise only wins if the hare falls asleep, which
SpaceX shows no signs of doing.

Civil engineers are able to use mathematical models to develop bridges because
we've been building bridges for thousands of years, and they can build in huge
safety factors. Fully reusable rockets have never been built before and can't
afford the luxury of large safety factors due to the Rocket Equation, so
testing to failure is the fastest way to learn, and when almost all of the
cost is labor, fastest = cheapest.

~~~
baking
The latest from the President and COO of SpaceX is that there are 900
employees working at Boca Chica alone.

~~~
Melting_Harps
> The latest from the President and COO of SpaceX is that there are 900
> employees working at Boca Chica alone.

Yeah, they expanded fast at Boca. Gwynne Shotwell doesn't get the attention
she deserves unless you're in the know, but she really is a total badass COO.
I really wanted to see her at the Cape for this momentous occasion but things
are Hawthorne are he priority.

I still remember that shot from her and the Team at HQ going crazy after the
first stage recovery, I threw my hands in the air like that watching the Live
stream for ORBCOMM 2 and just kept yelling 'they did it!'

~~~
Melting_Harps
Well, she made an appearance this time, she's at Mission Control in Hawthorne,
no surprise. Always cool to hear from her.

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Nerada
For some reason this link re-routes me to "advertising.com".

~~~
pmontra
All links to Techcrunch go to
[https://guce.advertising.com/collectIdentifiers?sessionId=1_...](https://guce.advertising.com/collectIdentifiers?sessionId=1_cc-
session_<an) uuid> and Blockada [1] blocks them on my Android devices. I
stopped visiting Techcrunch since they started to do that. I can always google
the same news on a different site.

[1] [https://blokada.org/](https://blokada.org/)

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risyachka
You can't invent anything new without lots of fails. Let's hope they will blow
them up as quickly as possible so we can see a flying one soon!

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jokoon
I wonder how many unfilmed explosions NASA had during the space exploration
period.

~~~
vntok
I'd wager probably none or a handfew at most. Frame-by-frame video was and
still is important to incident analysis.

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kerng
This thing should have blown up somewhere during launch, not while parked
basically. People not happy.

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unixhero
That's what tests are for.

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swarnie_
"That was not nominal"

Bloody brilliant. Hopefully they got some good data from that test

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SergeAx
Now, that's what I'm calling "move fast and break things"!

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unstatusthequo
Yeah given the delayed and soon upcoming actual human scheduled flight, this
would have been maybe nicer to put off a couple days... just optics but
still...

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darkteflon
Agreed - my first thought too.

~~~
whatshisface
Watch this:

"It's actually good optics that it exploded, because it shows they aren't
changing their schedules for the sake of optics. Political pressure to make
the schedule fit the public's feelings was a major contributor to the
Challenger disaster. So, having a tank blow up the day before a manned launch
shows that SpaceX has overcome the challenges of the past."

(See? That spin makes the turbopump look like a stator. If I have a point it's
that talking about optics is pointless, because you can make the optics
anything you want by casting the right light.)

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shireboy
Rapid unscheduled disassembly.

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ncmncm
Skip to "1:48 CT".

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kilroy123
All this time, I haven't been convinced that this steel approach is better in
the long-run than going the advanced composite route.

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blackrock
At some point during Research and Development, shouldn’t you figure out the
math first?

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unnouinceput
Funny article, it stressed at least 4 times this is different from the normal
flights ones they do regularly, otherwise covidiots/flat-
earthears/conspiracists will fill forums with their cries. And I'm not sure
they wont anyway.

