4 ms·

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

by raverbashing 2y ago

varjag 2y ago
If you can displace the oxidizer/air remaining in the volume why not.
- littlestymaar 2y ago
  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.
  - shellfishgene 2y ago
    If it was really an oxygen/fuel mix burning I don't think you can do much of anything to stop that.
    - littlestymaar 2y ago
      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.
      - varjag 2y ago
        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.
        littlestymaar 2y ago
        Not an expert but I'm not too sure about shockwave in a confined space. How does Halon works?
        m4rtink 2y ago
        First stage (Super Heavy) is flushing the engine bay with massive ammounts of CO2.
        littlestymaar 2y ago
        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.
      - ben_w 2y ago
        > 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.
        littlestymaar 2y ago
        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.
        ben_w 2y ago
        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 https://en.wikipedia.org/wiki/Fire_point
        littlestymaar 2y ago
        It's not about the state itself, but about temperature. For things to burn you need to have three elements: - a fuel - an oxidizer - enough heat It's the fire triangle.
        ben_w 2y ago
        > but about temperature Which is why I said water would raise the temperature because the oxygen is liquid oxygen — i.e. very cold. I mentioned solid phase because you were saying "if you mixed liquid oxygen and fuel nothing would happen". There are also videos of people starting fires by pouring LOX onto things. The fuel and oxidiser in a rocket are often pumped around the outside of the engine bell before reaching the injectors, in order to keep the engine bell itself from melting due to the heat of combustion. I'm not sure exactly what temperature the fuel and oxidiser are at when they hit the injector, but I've seen ground tests where there's frost on the outer wall while the engine is running. Also, one of the (rare) Falcon rocket failures was due to ice (IIRC oxygen ice) building up around the plumbing during flight: https://www.adastraspace.com/p/spacex-falcon-9-grounded https://www.adastraspace.com/p/spacex-falcon-9-grounded
m4rtink 2y ago
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.
- raverbashing 2y ago
  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
- Alive-in-2025 2y ago
  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 ;-).
  - m4rtink 2y ago
    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.
metalman 2y ago
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.
- vessenes 2y ago
  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.
echelon 2y ago
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_blew_up_in_front_of_us_had_to_divert/ https://www.reddit.com/r/aviation/comments/1i34dki/starship_...
psunavy03 2y ago
Aerospace fire suppression is generally Halon, which would purge the cavity with inert gas.
spandrew 2y ago
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.

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

varjag 2y ago

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

littlestymaar 2y ago
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.
- shellfishgene 2y ago
  If it was really an oxygen/fuel mix burning I don't think you can do much of anything to stop that.
  - littlestymaar 2y ago
    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.
    - varjag 2y ago
      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.
      - littlestymaar 2y ago
        Not an expert but I'm not too sure about shockwave in a confined space. How does Halon works?
      - m4rtink 2y ago
        First stage (Super Heavy) is flushing the engine bay with massive ammounts of CO2.
        littlestymaar 2y ago
        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.
    - ben_w 2y ago
      > 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.
      - littlestymaar 2y ago
        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.
        ben_w 2y ago
        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 https://en.wikipedia.org/wiki/Fire_point
        littlestymaar 2y ago
        It's not about the state itself, but about temperature. For things to burn you need to have three elements: - a fuel - an oxidizer - enough heat It's the fire triangle.
        ben_w 2y ago
        > but about temperature Which is why I said water would raise the temperature because the oxygen is liquid oxygen — i.e. very cold. I mentioned solid phase because you were saying "if you mixed liquid oxygen and fuel nothing would happen". There are also videos of people starting fires by pouring LOX onto things. The fuel and oxidiser in a rocket are often pumped around the outside of the engine bell before reaching the injectors, in order to keep the engine bell itself from melting due to the heat of combustion. I'm not sure exactly what temperature the fuel and oxidiser are at when they hit the injector, but I've seen ground tests where there's frost on the outer wall while the engine is running. Also, one of the (rare) Falcon rocket failures was due to ice (IIRC oxygen ice) building up around the plumbing during flight: https://www.adastraspace.com/p/spacex-falcon-9-grounded https://www.adastraspace.com/p/spacex-falcon-9-grounded

m4rtink 2y ago

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.

raverbashing 2y ago
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
Alive-in-2025 2y ago
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 ;-).
- m4rtink 2y ago
  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.

metalman 2y ago

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.

vessenes 2y ago
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.

echelon 2y ago

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

psunavy03 2y ago

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

spandrew 2y ago

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.