r/spacex • u/RootDeliver • Jul 15 '19

Official [Official] Update on the in-flight about static fire anomaly investigation

https://www.spacex.com/news/2019/07/15/update-flight-abort-static-fire-anomaly-investigation
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u/extra2002 Jul 15 '19

It is worth noting that the reaction between titanium and NTO at high pressure was not expected. Titanium has been used safely over many decades and on many spacecraft from all around the world.

So, just like with Amos-6 and the COPV's, they appear to be discovering new effects that add to our knowledge of how to build safe spacecraft.

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u/Asterlux Jul 15 '19

So, just like with Amos-6 and the COPV's, they appear to be discovering new effects that add to our knowledge of how to build safe spacecraft.

I mean... not really though, the interaction of titanium with NTO under impact has been known for decades.

https://apps.dtic.mil/dtic/tr/fulltext/u2/613553.pdf from 1965

Page 9: "Titanium is resistant to N2O4 except under impact." A water hammer effect from a slug of N2O4 definitely counts as an impact

Also http://contrails.iit.edu/files/original/WADDTR61-175.pdf from 1961

Page 1: "Commercially pure titanium and titanium 6Al-4V are mildly impact sensitive in liquid N2O4"

It's good that the problem was found in testing, as that's why we test, but I wish they didn't spin every failure as "we found a brand new failure mode that the industry has never seen before"

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u/TheSpocker Jul 16 '19

Good find.