3 ms·

To be clear, "pressurizing" is part of the "firing" process. It occurs ~200ms prior to ignition. It is not a step that would happen during every launch. It woul

To be clear, "pressurizing" is part of the "firing" process. It occurs ~200ms prior to ignition. It is not a step that would happen during every launch. It would only happen if the SuperDracos were fired (in an abort scenario). This was a serious flaw in a critical system, and the redesign was very important. It also advances the state of the art in engineering in these sorts of systems... the failure that took place was something that no one considered possible (specifically the Ti/NTO reaction). I was just responding to the fact that you mentioned the capsule had visited the ISS, which is totally irrelevant to the failure.

bumby 7y ago
No doubt this will still advance the state of the art in aerospace systems, but there's some old data by Boeing and NASA that seem to indicate some potential compatibility issues with Ti in the presence of a strong oxidizer. See PDF pg. 66 (not report pagination) https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720019028.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/197200... See PDF pg.11 https://apps.dtic.mil/dtic/tr/fulltext/u2/866010.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/866010.pdf
- SAI_Peregrinus 7y ago
  Or the classic book "Ignition!" pg 70-71. On December 29, 1953, a technician at Edwards Air Force Base was examining a set of titanium samples immersed in RFNA, when, absolutely without warning, one or more of them detonated, smashing him up, spraying him with acid and flying glass, and filling the room with NO2. The technician, probably fortunately for him, died of asphyxiation without regaining consciousness. There was a terrific brouhaha, as might be expected, and JPL undertook to find out what had happened. J. B. Rittenhouse and his associates tracked the facts down, and by 1956 they were fairly clear. Initial intergranular corrosion produced a fine black powder of (mainly) metallic titanium. And this, when wet with nitric acid, was as sensitive as nitroglycerine or mercury fulminate. (The driving reaction, of course, was the formation of TiO2.) Not all titanium alloys behaved this way, but enough did to keep the metal in the doghouse for years, as far as the propellant people were concerned. Different oxidizer from SpaceX, but still useful as a data point.

bumby 7y ago

No doubt this will still advance the state of the art in aerospace systems, but there's some old data by Boeing and NASA that seem to indicate some potential compatibility issues with Ti in the presence of a strong oxidizer. See PDF pg. 66 (not report pagination) https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720019028.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/197200... See PDF pg.11 https://apps.dtic.mil/dtic/tr/fulltext/u2/866010.pdf https://apps.dtic.mil/dtic/tr/fulltext/u2/866010.pdf

SAI_Peregrinus 7y ago
Or the classic book "Ignition!" pg 70-71. On December 29, 1953, a technician at Edwards Air Force Base was examining a set of titanium samples immersed in RFNA, when, absolutely without warning, one or more of them detonated, smashing him up, spraying him with acid and flying glass, and filling the room with NO2. The technician, probably fortunately for him, died of asphyxiation without regaining consciousness. There was a terrific brouhaha, as might be expected, and JPL undertook to find out what had happened. J. B. Rittenhouse and his associates tracked the facts down, and by 1956 they were fairly clear. Initial intergranular corrosion produced a fine black powder of (mainly) metallic titanium. And this, when wet with nitric acid, was as sensitive as nitroglycerine or mercury fulminate. (The driving reaction, of course, was the formation of TiO2.) Not all titanium alloys behaved this way, but enough did to keep the metal in the doghouse for years, as far as the propellant people were concerned. Different oxidizer from SpaceX, but still useful as a data point.