The SpaceX Starship Mk1 prototype suffered a catastrophic failure during a cryogenic pressure test on November 20, 2019, resulting in irreparable damage. The failure was attributed to the connection of the bulkhead to the outer structure, which broke along the weld line, leading to an implosion of the methane tank. Future prototypes, including Mk2 and Mk4, are now effectively scrapped due to recurring technical issues, while Mk3 is expected to undergo test flights. SpaceX is refining its welding techniques and construction methods, shifting towards single steel sheets for ring stacking to enhance structural integrity.
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Strange decision. Driven by desire to reduce assembly and test costs may be. From strength perspective, the failure looked like methane tank broke along weld line. The staggered pattern of sheets would at least make failure slower...mfb said:They will keep stacking rings, but the rings will be single steel sheets.
Seems the Starship is using stressed outer skin architecture if not integral bulkhead.mfb said:The steel mills don't produce endless sheets and you can't transport sections well if they become too long.
What broke was the connection of the bulkhead to the outer structure, that is not the welding of the outer structure.
I split this into a separate thread.
I agree with sequence of events, but not with conclusion. The tank have imploded under differential pressure of no more than 70 kPa (likely about 20 kPa). This is not the way a well designed tank intended to withstand the stress of hypersonic ascent should behave. For example, Space Shuttle Max-Q dynamic pressure during ascent was 33 kPa. Therefore, i.m.h.o., the implosion failure mode do indicate a too flimsy construction of Starship fuel tank.etudiant said:No expert, but it seemed to be a failure at the bottom of the tank, presumably the place where the valve fittings are mounted. The actual tank structure appeared then to implode, presumably because the pressurized LN2 burst out of the breach leaving a near vacuum behind.
If correct, this should be fixable fairly quickly.
That is what i call "flimsy construction". balloon tank which do not tolerate even small damage. Initially SpaceX boasted construction to be much more stable and rigid than Atlas III at same fuel fraction, but after all Starship fuel tank seems to behave similar to Atlas III.mfb said:The dynamic pressure on ascent is along the direction of the rocket, not orthogonal to it. It's also nowhere near the tank section. The pressure on descent is orthogonal to the rocket axis but the tank will be pressurized to keep the interior pressure higher.
The failure was reportedly at the engine mounting, which was not adequately designed. The tank itself seemed just fine in both cases, just imploded after the failure at the fittings.mfb said:A comparison how quality improved over time:
SpaceX already has the key segments of the tank section (the parts where bulkheads need to be attached), so we can expect more tank pressurization tests soon.