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SpaceX destroys Starship prototype #7, as planned

Capitalism in space: SpaceX last night successfully pressurized its seventh Starship prototype to failure, as planned.

The culmination of three nights and more than 20 hours of concerted effort, SpaceX was finally able to fill Starship test tank SN7.1 with several hundred tons of liquid nitrogen before dawn on September 23rd. With just an hour left in the day’s test window, SpaceX closed the tank’s vents, allowing its cryogenic contents to boil into gas and expand with no outlet. At 4:57 am CDT, SN7.1 burst, bringing its lengthy test campaign to a decisive end.

I have embedded video of the test below the fold.

With the completion of this test the way is now clear for the 60,000 foot hop of Starship prototype #8, no earlier than October 11th.


Conscious Choice cover

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  • geoffc

    And SN8 has its fins/Elerons attached on the bottom half. There is a fairing with fins attached. The SPMT transporter is on site. It is looking real. They have scheduled road closures for the initial pressure tests.

    No word if Raptors are installed yet, but they usually install them on site. Nothing says good ole boys building rockets in a field as a Raptor engine on a wooden pallet, on a forklift driving down the road. (NASA would have built a 10 millin dollar transporter for them).

  • Joe

    Progress. Visible, public, and sometimes embarrassing. This is why SpaceX wins the hearts and minds of the public. We can’t get enough of this stuff. Scrappy company taking on the Universe. It works.

    Now if only other companies would try the same thing instead always hiding what they are doing. I get security and in some cases secrecy, but aerospace tends to overdo it a tad bit.

  • Stephen miller

    Robert Heinlein would have loved this.

  • LocalFluff

    How come it bursts at two places at the same time?

  • MDN

    Actually I find the symmetry of the failure pretty amazing. I expected a point failure but instead it blew out on opposite sides at essentially the exact same moment. That would seem to indicate that SpaceX has VERY consistent quality of the seam welding process, although we probably shouldn’t read too much into a sample size of one.

    Impressive nevertheless.

  • Alex Andrite

    … er … ah … VERY COOL … (-180?).

    What is the purpose of this test ?

  • geoffc

    They changed materials from 301 Stainless Steel to 304L stainless. THey need to revalidate the test that their basic welding technique still is sufficient to hold the needed pressures.
    Much cheaper to build a small module (It was 30 feet wide and 60 or so feet tall, so not quite small) than a full up model (30 feet wide, 100+ feet tall, with engines, legs, etc) and test that to destruction.
    This test module needed very little in the way of extra plumbing, electronics, power packs (They use two Tesla car battery packs, mounted on the top of the top dome) so it could be built quite quickly and tested and then thrown away for scrap.

    This one also differed in that it had a full thrust puck section. (Where the engine mount, but no engines installed for the test) whereas the SN2/3 poppers did not have the engine thrust section installed.

  • David

    There are some “after” pictures in the forums at NasaSpaceFlight, which show that the failure was not along welds, and in fact one split runs diagonally right across a weld. That, combined with the more or less simultaneous split at two opposite locations, implies that the failure point is part of their structural design, that focuses the stress on that part of the dome. They haven’t said what pressure level they reached on the test, but given the force of the eruption and the fact that it split steel, not welds, it’s highly probable that they hit very high pressure before it blew.

    I’d really love to know why it took them three attempts, each lasting several hours, to get to that point. We don’t know if the earlier tests encountered some kind of issue, if they couldn’t reach pressure, were seeing GSE issues, or were just deliberately getting measurements and data before going for the full pressure. Speculation on the live stream on the night of the final burst test was that one reason they were letting it sit so long after it was clearly nearly full and well frosted, is that they were trying to chill down the metal of the whole tank before full pressure for a “worst case” scenario.

  • Whitehall

    Interesting that the tank failed along the spring line where the dome meets the cylinder. Obviously a stress concentration pline.

    Nuclear power reactor containment buildings use the same configuration.

  • Edward

    Alex Andrite asked: “What is the purpose of this test ?

    Right now, the properties of the materials after construction are mostly theoretical. I don’t have inside knowledge of SpaceX’s test plans or purposes for their tests, but performing a test to failure can test the true properties, they discover a real safety factor, and can verify that the point of failure was where it was planned.

    On the other hand, even SLS was tested to destruction. Unfortunately, that test facility is not as available for public viewing as is the SpaceX facility. SpaceX is doing a lot of its work on shockingly small properties, and this means that their tests and minor equipment or test article moves are much more viewable than many other companies. This is why SpaceX fans post so many videos of even minor things. We can see so much that goes on at Boca Chica that we don’t get to see happening at virtually every other company.

    MDN noted: “I expected a point failure but instead it blew out on opposite sides at essentially the exact same moment.

    It is possible that the failure produced a shock wave that travelled to the other side of the tank and overstressed something over there.

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