JF Mezei wrote on Tue, 23 Apr 2019
17:51:41 -0400:

On 2019-04-23 12:55, Rocket Man wrote:

It looked to me that the capsule had dissappeared after the explosion. Not
good. Not good at all.


Consider that rocket that was being test fueled and which exploded "for
no reason". SpaceX was fairly quick to isolate this to the filling
sequence of helium vs surrounding liquid oxyggen which caused
unpredicted behaviour of COPV tanks.


Why would I consider that? You're comparing apples and aardvarks.


Reverting to previous , proven filling sequence allowed return to flight
fairly quickly. Not sure if SpaceX later changed the COPV tanks to allow
the more desirable filling sequence or not, but if it did, it happened
in a transparent way without delaying the launches.


They changed the tank.


So the fact that the capsule was allegedly blown to smithereens


Got a cite for that? Who is 'alleging' this?


shouldn't be an indication of how long it will take to get back in
business. It all depends on whether they can find the cause and if this
is a simple fix. (or simple to avoid the use in a way that causes it to
go "kaboom".


It still comes down to, as I said, figuring out what the root cause
was.


One should also remember this capsule was being re-used, it wasn't brand
new. So the problem may be one of re-usability and not one of
design/safety for new ones.


What one should remember is that one doesn't go into a root cause
analysis with preconceived notions.


I would assume that they have high quality video of what happened as
well as lots of telemetry.


Probably a fair assumption.

I agree with OP that this could take a year to fix, not to mention the loss
of goodwill.

They've done engine tests before. Did they test engines after being
dunked in salt water?


I doubt it as there's no reason to do so.


Did they test engines after being in space
environment (temperature changes) ?


I would assume there were some 'shake and bake' tests for vibration
and temperature extremes.


I have to assume that when they
chose the materials used to 3d print the engines, they considered and
tested ability to survive the temperature extremes and vibration from
launch and salt water.


You seem to be assuming the entire engine was 3D printed. I don't
think that's the case. I believe it was only the combustion chamber
that was 3D printed. I'm pretty sure they didn't build it out of
styrofoam.


If the engines are deemed to not be re-usable, then SpaceX can operate
Dragon-2 as non-reusable at first,or perhaps always install new super
dracos before re-use if rest of capsule is reusable.


You are way, WAY ahead of yourself. There is no reason to leap to
your apparent assumption that it is something to do with
'reusability'. Hypergolic engines are simple and reliable and can be
restarted hundreds of times. It's the nature of the breed. You seem
to forget that the engines had already fired multiple times in this
test sequence before the anomaly occurred.


I can imagine the knifes are being drawn in Congress. I'm sure
this is exactly the thing Boeing / LockMart / ULA have been waiting for.

SpaceX has launched to the station aleady. So still ahead of Boeing.


That depends on just how long they have to stand down.


--
"Insisting on perfect safety is for people who don't have the balls to
live in the real world."
-- Mary Shafer, NASA Dryden