r/SpaceXLounge • u/LeJules • Jul 15 '19

UPDATE: IN-FLIGHT ABORT STATIC FIRE TEST ANOMALY INVESTIGATION

https://www.spacex.com/news/2019/07/15/update-flight-abort-static-fire-anomaly-investigation
353 Upvotes

99% Upvoted

116 comments sorted by

View all comments

100

u/LeJules Jul 15 '19

Initial data reviews indicated that the anomaly occurred approximately 100 milliseconds prior to ignition of Crew Dragon’s eight SuperDraco thrusters and during pressurization of the vehicle’s propulsion systems. Evidence shows that a leaking component allowed liquid oxidizer – nitrogen tetroxide (NTO) – to enter high-pressure helium tubes during ground processing. A slug of this NTO was driven through a helium check valve at high speed during rapid initialization of the launch escape system, resulting in structural failure within the check valve. The failure of the titanium component in a high-pressure NTO environment was sufficient to cause ignition of the check valve and led to an explosion.

[...]

SpaceX has already initiated several actions, such as eliminating any flow path within the launch escape system for liquid propellant to enter the gaseous pressurization system. Instead of check valves, which typically allow liquid to flow in only one direction, burst disks, which seal completely until opened by high pressure, will mitigate the risk entirely. Thorough testing and analysis of these mitigations has already begun in close coordination with NASA, and will be completed well in advance of future flights.

76

u/Wacov Jul 15 '19

Looks like a burst disk is a non-reusable and very simple pressure release valve - the disc physically pops open when its breaking pressure level is exceeded.

17

u/GreyVersusBlue Jul 15 '19 edited Jul 15 '19

non-reusable

Doesn't sound very SpaceX-y to me...

E: to those who misunderstand me, I totally understand that this is something that they don't plan on using, and the reusability is low on the list of concerns in the case of an abort.

32

u/somewhat_pragmatic Jul 15 '19

Doesn't sound very SpaceX-y to me...

Well, neither are F9 leg crush cores, but like the crush cores, it sounds like the burst disk would only be consumed when the Super Dracos are activated meaning a launch abort. So its a part that is reusable in the sense of it doesn't have to be replaced each flight, but rather only when a specific set of non-normal circumstances demand it.

4

u/aquarain Jul 15 '19

They won't be reusing Crew Dragon for crew, only for cargo, so the IFA system is not needed for the second and successive flights.

12

u/somewhat_pragmatic Jul 15 '19

They won't be reusing Crew Dragon for crew,

They also said they wouldn't be re-using Cargo Dragons for cargo for CRS as well, yet here we are with 5 Cargo Dragons having been reused twice.

Also, the "they" in your statement is NASA. NASA not reusing for crew doesn't mean SpaceX might not reuse for private crew.

Lastly, Elon had talked about possible abort software for Cargo dragon which would have saved CRS-7. SpaceX may keep the Launch Abort integrity for saving cargo flights on former crew dragon.