Starship Flight 7

I'm not sure there's fire suppression effective enough for this type of leak (especially given rocket constraints)

If you can displace the oxidizer/air remaining in the volume why not.

Actually the Super Heavy (first stage) already uses heavy CO2 based fire suppression. Hopefully not that necessary in the long term, but should make it possible to get on with the testing in the short term.

That's interesting

However if you see the stream you can see one of the tanks rapidly emptied before loss of signal

It seems this was not survivable regardless of fire or not

The initial tweet says:

> we had an oxygen/fuel leak

If that's correct, then you can't just remove air. The only option would be to cool things down so it stops burning.

just increased venting to keep any vapor concentrations of fuel and oxidiser below that capable of igniting, even simple baffling could suffice as the leaks may be trasitory and flowing out of blowoff valves, so possibly a known risk. Space x is also forgoeing much of the full system vibriatory tests, done on traditiinal 1 shot launches, and failure in presurised systems due to unknown resonance is common. Big question is did it just blow up, or did the automated abort, take it out, likely the latter or there would be a hold on the next launch.

If it was really an oxygen/fuel mix burning I don't think you can do much of anything to stop that.

If you cooled the mixture at low enough temperature, you'd stop it from burning (like when you pour water on top of a camp fire), but it's not clear how you're supposed to do that in a spaceship where you can't carry a few tons of water for your sprinklers.

There’s no way that was anything but the automated abort — it was a comprehensive instantaneous rapid event. Or I guess I’d say, however it started, the automated abort kicked in and worked.

Replying to this comment so people can see the incredible video of the breakup taken from a diverting aircraft:

https://www.reddit.com/r/aviation/comments/1i34dki/starship_...

Aerospace fire suppression is generally Halon, which would purge the cavity with inert gas.

There are other methods too, e.g. fire inhibitors (like Halon or whatever is allowed now) or shockwave to disrupt fire boundary. But I doubt they are very practical on a spaceship.

> If you cooled the mixture at low enough temperature, you'd stop it from burning (like when you pour water on top of a camp fire), but it's not clear how you're supposed to do that in a spaceship where you can't carry a few tons of water for your sprinklers.

Also water would make it hotter, given this is liquid oxygen.

What is a long term solution for this? Is there something more than "build tanks that don't leak"? I'm sure spaceX has top design and materials experts, now what ;-).

I think its likely not the tanks but rather the plumbing to engines and the engines themselves leaking (sense lines, etc).

Next engine revision (Raptor 3) should help, as it is much simplified and quite less likely to leak or get damaged during flight.

First stage (Super Heavy) is flushing the engine bay with massive ammounts of CO2.

It might not even be about fire suppression. Oxygen and different gases can pool oddly in different types of gravity. If oxygen was leaking, it may be as simple as making sure a vacuum de-gases a chamber before going full throttle.

We know nothing, but the test having good data on what went wrong is a great starting point.

It's not liquid at the point of ignition, that's the thing: if you mixed liquid oxygen and fuel nothing would happen expect the fuel would freeze. For a fire to take place the temperature must reach the fire point temperature, and if you manage to get your fire below this temperature then the fire stops. I don't know how low this temperature can be when the oxidizer is pure oxygen and maybe it's so low water wouldn't be enough, but then you can imagine using other fluids. The problem being the mass burden it adds to a spacecraft, I'm not it'd make any sense given that such q leak should happen in the first place.

Unless I'm misunderstanding you, it's not the same thing at all: in the case you're talking about you're shielding against nominal heat, which is not the same thing as contingency planning to extinguish a fire that shouldn't be there in the first place.

Not an expert but I'm not too sure about shockwave in a confined space.

How does Halon works?

I believe LOX is injected into the engine as a liquid, it gets atomised rather than boiled?

And you can have fires where both fuel and oxidiser are solid: thermite reactions.

"Fire point" seems to be more of a factor for conventional fire concerns, albeit I'm judging a phrase I've not heard before by a stub-sized Wikipedia page: https://en.wikipedia.org/wiki/Fire_point