Watch SpaceX's Starship SN4 prototype accidentally self-destruct in a rocket test burn In yet another setback for Elon Musk's beloved steel spaceship, a SpaceX Starship prototype has exploded on the pad during a rocket test burn. Starship SN4 – designed to ferry astronauts to the Moon and Mars – was undergoing a static engine fire test on Friday when, in scientific terminology, it blew the hell up. Footage of …
The video starts too late. If you look at other videos, you will see the full chain of events. The test fire for just a few seonds, then stops. The upper and lower tanks vent for about 40 seconds then stop. Nearly a minute later the upper tank starts venting and a couple of seonds later cryogenic fluid suddenly comes pouring out of the bottom of SN4, creating the white cloud around the base (this is where the linked video starts).This happens for nearly 30 seconds before the explosion, and is clearly an massive uncontrolled leak. Shortly after the masive leak, the upper tank starts emergency venting with a second outlet. SN4 doesn't deform or collapse, so I think Scott Manly is incorrect about the weight of the upper tank crushing the lower tank. SN4 is fully intact, and doesn't deform until the explosion shockwave hits it. Looking at varous videos frame by frame, it appears the igntion point of the explosion is external to SN4: for a few frames, the wavefront apears to defom around SN4 (which was fully intact), and only after then SN4 experiences RUD.
My guess is that the lower tank ruptured and an external ignition source triggered the explosion.
Still I'm sure valuable information was found. This is why they do testing.
Shortly after the masive leak, the upper tank starts emergency venting with a second outlet. SN4 doesn't deform or collapse, so I think Scott Manly is incorrect about the weight of the upper tank crushing the lower tank
I don't think that's what Scott was saying-
https://www.youtube.com/watch?v=BCUYG5SonCY
Slow-mo near the end seems to show venting from side, then much larger venting underneath, then ignition and the artificial mass block making it's break for orbit. Also curious if the second explosion was just that block coming back down to earth.
Also curious about what exploded, ie comments that it was mostly CH4 & atmospheric oxygen rather than LOX.. But it's also an interesting bit of reality vs Hollywood. So fuel happily vents until it gets to an explosive concentration & finds an ignition source.. Then the big bang & pink compression wave from the explosion followed by presumably the methane buring off in a typical Hollwood fireball. Also demonstrates why it's not always easy to make gas storage explode given the pressure of the escaping gas can blow out an ignition source, as it did with the flare stack.. And also how specialists sometimes deal with gas well leaks, ie using explosives to blow out the flame.
Spectacular videos, but somewhat to be expected during testing of a new design.
"I don't think that's what Scott was saying-"
Scott's hypothesis is that the fuelling lines broke loose - and he showed slowmo footage of the thing blasting itself into the ground when it vented methane out the top after pushing the 20 tonne mass adaptor sitting on top off at about 100km/h (which happened when the entire stack "jumped" thanks to the explosion under the base)
ie: This was a setup/ground crew error, not a rocket/vessel failure.
Yeh, the videos showed something leaking at the base for a while before the explosion. Curious if that was both CH4 and LOX, then evaporation allowing that to get to an explosive mix. Scott highlighted the horizontal shockwave & the hemispherical shockwave, one of which probably ruptured the vessel as well as launching the mass block. I guess it'd be possible to guestimate the force required to do that as a methane jet give or take knowing bulkhead strengths.
But not 'nominal'. Might mean snags with the defuelling process, or just something deciding to let go.. Which I guess is always a challenge working with cryogenic fluids & the kinds of heat cycling/stresses that are part of rocket science.
It looks like they will need to divide those tanks up into compartments, enough sections, so the full weight of the stack above doesn't cause it to collapse if one section was to have a catastrophic failure/leak below. How much extra weight that will add is anyone's guess, right now. Apollo seemed to use a corrugated design in the rings, maybe that is the way forward.
It's interesting watching all the historical footage regards the Gemini and Apollo programmes on YouTube, because you can see exactly the same empirical methods been used back then to solve problems, except now we can back it up with computer modelling, in terms of reiterating over the design.
Makes you think too, of the calm bravery of Armstrong, Aldrin and Michael Collins, as they headed to the launch pad of Apollo 11.
The Titanic reference I'm not sure about. The Titanic's problem was that it had a double bottom but not double bilges.
It was actually the Germans who went for lots of W/T compartments and that had its effect at Jutland/Skaggerackschlacht, another occasion on which superior German technology resulted in fewer German deaths than British ones, we never learn.
"The Titanic's problem was that it had a double bottom but not double bilges."
Bilges weren't so much of a problem so much as the "waterproof compartments" not being sealed at the top.
As each one filled up, the bulkheads were overtopped and water fillled the adjacent compartment. If they'd been sealed it would have been swamped but stayed afloat.
That's quite apart from the deficient crush structure White Star adopted vs P&O, in order to have the big open spaces internally and a reckless captain who treated the liners like speedboats (he'd already badly damaged Olympia off of Liverpool causing it to be dry-docked for months)
TItanic's best chance of survival would have been a head on collision with an iceberg - it would have killed the entire crew of ~200 stokers asleep in the forward compartments but the ship would have survived just fine. On the other hand we wouldn't have SOS and all the marine rescue stuff that resulted form the loss.
> yet another setback
Hardly. The only thing of importance that has been lost is time - and maybe 1 Raptor engine. These test bed rockets (although "rocket" is a misnomer since none of them have got off the ground¹ yet) are disposable rigs positively intended to find the weaknesses, faults and places for improvements. It is far better and much more cost-efficient to discover all these faults now than when these things have payloads or people on them.
Experience is another word for mistakes, learned from.
[1] in a controlled fashion
I was watching live, on the NASA spacefight stream, (I only do it for the 3 hours of flarestack action you know), and to me, the commenters on the stream, and indeed Scott Manley in his latest YT vid, the explosion looks more like it started in the region of the ground support system, the pipes and cables that connected SN4 to the rest of the world. I didn't see any signs of structural collapse in SN4 at all.
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Built by a South African with engineers from all over the world.
I celebrate the entrepreneurship and all that, but let's cut the jingoism, shall we?
In other words:
— The Russians put our camera made by our German scientists and your film made by your German scientists into their satellite made by their German scientists.
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