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SpaceX failure investigation update - October 28, 2016



 
 
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  #1  
Old October 29th 16, 12:45 PM posted to sci.space.policy
Jeff Findley[_6_]
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Default SpaceX failure investigation update - October 28, 2016



Below are updates regarding the anomaly that occurred in preparation for
the AMOS-6 mission:
October 28, 4:00pm EDT
http://www.spacex.com/news/2016/09/01/anomaly-updates

From above:

Through extensive testing in Texas, SpaceX has shown that it
can re-create a COPV failure entirely through helium loading
conditions. These conditions are mainly affected by the
temperature and pressure of the helium being loaded.

In other words, there is still hope (as was reported previously by
SpaceX) that this is an operational problem, not an engineering design
problem. By carefully controlling the temperature and pressure of the
helium being loaded inside the helium tank, it should be possible to
avoid an accident like this in the future.

Also, SpaceX isn't the only company that has had trouble with loading of
COPV helium tanks. It can be a bit tricky:

Similar issues at Armadillo Aerospace:
http://spacefellowship.com/news/art1...ce-2009-lunar-
lander-challenge-level-2-done-.html

From above:

While testing of this configuration, I hit on an idea that wound up
being very useful ? we set up a counterflow heat exchanger that ran
the lox vent through the outside, and the helium fill through the
inside. This let us get significantly more helium in the tanks,
and completely quashed any worries about overheating the helium
tanks. They actually start to frost over at the beginning.

Jeff
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  #2  
Old October 29th 16, 09:28 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Posts: 10,018
Default SpaceX failure investigation update - October 28, 2016

JF Mezei wrote:

On 2016-10-29 07:45, Jeff Findley wrote:

http://www.spacex.com/news/2016/09/01/anomaly-updates

From above:

Through extensive testing in Texas, SpaceX has shown that it
can re-create a COPV failure entirely through helium loading
conditions. These conditions are mainly affected by the
temperature and pressure of the helium being loaded.


The text mentions cryogenic helium. Is helium loaded as gas and
pressurized so much that it turns to liquid ?


Do you not know what 'cryogenic' means? It means COLD.


Or is helium pumped into tank as a liquid, which initially evaporates as
it falls into the tank, yieding very cold conditions ? In such a case,
is the tank venting while it is loaded ?


The COPV is designed, as you've been repeatedly told, to operate at
pressures of 10,000 PSI. I doubt there's any venting going on.


Or is the helium loaded after LOX has already started to flood the area
around the tank ?


I'd expect they're loading them at the same time. After all, part of
the reason for putting the COPVs inside the LOX tank is thermal
control.



In other words, there is still hope (as was reported previously by
SpaceX) that this is an operational problem, not an engineering design
problem.


Difficult to know whithout knowing exactly what was done differently on
this "flight". All I heard was that they tried to load colder than usual
cryos. But was order of loading changed ?


Did magic unicorns **** pixie dust into the tanks?


Looks to me like SpaceX found conditions that exceed the tank's
capabilities. So it will have to do a lot of tests to set new limits on
tank performance.


How things look to you is irrelevant, given your intellectual myopia.


By carefully controlling the temperature and pressure of the
helium being loaded inside the helium tank, it should be possible to
avoid an accident like this in the future.


or it may require helium be loaded only once the tanks are already in a
bath of LOX so that any heat generated by pressurining Helium in the
tank is absorved by LOX so the tank never gets hot. (at the cost of
warming the LOX and preventing supercold LOX experiments).


Just 'wow'. If there's a wrong way to interpret something, that's
where you go. Just what 'heat generated by pressurizing Helium[sic]'
do you refer to?


The fact that they have been able to reproduce the failure is a very
good sign though because they can then easily test for what the limits
really are, and then do the same tests to evaluate if an updated resin
or carbon layout design improves the situtaion and allows SpaceX to
raise the operating temperature/pressure ranges.


You can always make **** blow up. The question is whether or not the
ways they've found to make **** blow up are what actually happened to
cause **** to blow up.


--
"Some people get lost in thought because it's such unfamiliar
territory."
--G. Behn
 




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