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RELATED: "just had dinner with a credible source i trust that spacex is about 99% sure a COPV issue was the cause. 'explosion' originated in the LOX tank COPV

RELATED: "just had dinner with a credible source i trust that spacex is about 99% sure a COPV issue was the cause. 'explosion' originated in the LOX tank COPV container that had some weird harmonics while loading LOX." (COPV = Composite Overwrapped Pressure Vessel, they are titanium bottles wrapped in layers of continuously wound carbon fiber + resin) https://www.reddit.com/r/spacex/comments/545dju/unconfirmed_rumors_that_spacex_found_the_issue/ https://www.reddit.com/r/spacex/comments/545dju/unconfirmed_...

erikpukinskis 10y ago
I wonder if a general policy of using randomly fluctuating flow curves instead of flat ones would decrease the likelihood of harmonics.
vannevar 10y ago
Presumably, loss of the cryogenic helium through a "large breach" would lead to rapid warming of the liquid oxygen and equally rapid over-pressurization of the tank. So this is consistent with the source's contention that the explosion originated in the LOX tank, although the COPV may not be the root cause in that case, depending on the over-pressure it was rated for.
- emeraldd 10y ago
  Would it be the LOX or the HE rapidly warming? (I thought helium would have the lower starting temperature ...)
- dogma1138 10y ago
  The helium isn't "cryogenic" the LOX is, Oxygen is liquid at 182.9c, SpaceX cools it down to ~-206c when they load their fuel in cryogenic mode. Helium boils at -268.9c, basically when liquid helium meets liquid oxygen it boils and expands to 757 times it's volume, which means boom.
  - deleted 10y ago
    [deleted]
  - vannevar 10y ago
    Yes, I misinterpreted the article. Here's a clearer description from spaceflightnow.com (https://spaceflightnow.com/2016/09/23/falcon-9-rocket-explosion-traced-to-upper-stage-helium-system/ https://spaceflightnow.com/2016/09/23/falcon-9-rocket-explos...): "The Falcon 9 rocket’s upper stage liquid oxygen tank contains several composite helium vessels, each pressurized to about 5,500 pounds per square inch in flight. The helium is routed through the second stage’s Merlin engine, where the helium warms up and is injected into the rocket’s propellant tanks to pressurize the stage as the launcher burns fuel, keeping the tanks structurally sound."

erikpukinskis 10y ago

I wonder if a general policy of using randomly fluctuating flow curves instead of flat ones would decrease the likelihood of harmonics.

vannevar 10y ago

Presumably, loss of the cryogenic helium through a "large breach" would lead to rapid warming of the liquid oxygen and equally rapid over-pressurization of the tank. So this is consistent with the source's contention that the explosion originated in the LOX tank, although the COPV may not be the root cause in that case, depending on the over-pressure it was rated for.

emeraldd 10y ago
Would it be the LOX or the HE rapidly warming? (I thought helium would have the lower starting temperature ...)
dogma1138 10y ago
The helium isn't "cryogenic" the LOX is, Oxygen is liquid at 182.9c, SpaceX cools it down to ~-206c when they load their fuel in cryogenic mode. Helium boils at -268.9c, basically when liquid helium meets liquid oxygen it boils and expands to 757 times it's volume, which means boom.
- deleted 10y ago
  [deleted]
- vannevar 10y ago
  Yes, I misinterpreted the article. Here's a clearer description from spaceflightnow.com (https://spaceflightnow.com/2016/09/23/falcon-9-rocket-explosion-traced-to-upper-stage-helium-system/ https://spaceflightnow.com/2016/09/23/falcon-9-rocket-explos...): "The Falcon 9 rocket’s upper stage liquid oxygen tank contains several composite helium vessels, each pressurized to about 5,500 pounds per square inch in flight. The helium is routed through the second stage’s Merlin engine, where the helium warms up and is injected into the rocket’s propellant tanks to pressurize the stage as the launcher burns fuel, keeping the tanks structurally sound."