SpaceX SN4 Has Exploded

SpaceX Starship prototype SN4 has exploded after a static fire.

SpaceX is building these prototypes at a rate of two every month. Each destroyed prototype only causes a two week delay.

SpaceX expects to need 20 prototypes before they have a commercial vehicle finalized. Hopefully SN5 will finally have the first hop and SN6 or SN7 will fly to 20 kilometers.

SOURCES – LabPadre, SpaceXCentric
Written by Brian Wang,

14 thoughts on “SpaceX SN4 Has Exploded”

  1. The initial leak was likely LOX. You can see how as the vapor cloud passes by the flare stack the flame front is also pushed along. The flare stack only provides a controlled distribution of fuel gas designed to mix with atmospheric oxygen at the correct ratio to produce a stable flame. The flare stack flame is pushed away from the flare stack tip and out ahead of the vapor cloud is because the cold, dense conditions within the LOX vapor cloud are not able to produce the fuel/oxygen mixing or thermal conditions required to initiate and sustain combustion.

  2. I suspect that they forgot or ignored the lessons from commercial handling of methane and NASA handling of hydrogen, and tried to figure it out on their own. Otherwise I don’t see why they’re venting so much fuel within wind range from an open flame.

    In commercial handling, the tanks are flushed with CO2 first, exactly to prevent an explosive mixture, then chilled with a small amount of liquid methane, and then filled with the bulk liquid. There is very little venting of methane.

    In SpaceX’ case, they can flush and chill with LN2 instead, and they should only fill as much fuel as they need. If there’s an excess, maybe better pump it out than let it all vent. Then vent only the bit that can’t be pumped, and maybe only after diluting it with more nitrogen.

    At the very least, that open flame needs to be further away and higher up. And add a secondary torch on the opposite side so they can switch to whichever is upwind of the ship.

    Are we sure this is intentional venting, and they didn’t have a leak?

  3. Wow! That was the biggest whammy kablammy I’ve seen on a lunch pad. It outdoes the last Falcon 9 that blew up. There is going to be some SERIOUS collateral damage on this one!!!

  4. Yeah I noticed the from-rocket venting in a prior pressurization test and wondered how they would avoid an explosive mixture. I guess they didn’t.

  5. One of my coworkers brought up the venting issue, today, and I think you guys are on point with that. Not a ship failure, this was an external issue. Well, internal in so far as it was fuel from within the ship, but still not something within the ship that caused the detonation.

  6. It looks to me like what happened is that the vented fuel formed an explosive fuel/air mixture along the ground, and that mixture found an ignition source at some considerable distance downwind, then the explosion propagated back to the ship. You can clearly see the combustion propagating upwind at high speed in the video I saw. Not a ship failure, but again a test protocol failure. I think they may have to stop venting fuel at the ship!

  7. Yeap… Someone screwed up, directed the explosion everywhere and so the rocket moved everywhere(else)…

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