

SpaceX Falcon 9 Statement on First Stage Engine Anomaly - ceejayoz
http://www.spaceref.com/news/viewsr.html?pid=42263

======
ballooney
Note additionally it's being reported that the secondary payload on this
flight, an Orbcomm sat, did not get deployed into the correct orbit because
the Falcon upper stage insertion burn failed. No info on whether or not this
was a related failure. Info at the moment just seems to be social networks,
can't find anything more solid:
<https://www.facebook.com/jsrpage/posts/10151048911726680>

~~~
sounds
Bad Astronomy [1] has a comment saying the Orbcomm satellite is a test unit
(not the production unit yet) and that a second-choice orbit is possibly where
it will be released.

[1]
[http://blogs.discovermagazine.com/badastronomy/2012/10/08/sp...](http://blogs.discovermagazine.com/badastronomy/2012/10/08/spacex-
falcon-9-lost-an-engine-on-the-way-up-dragon-on-its-way-to-iss/)

~~~
ballooney
I read it as that they have already deployed rather than will be. But yes, the
comment seems to suggest that the idea of trying to put it into the nominal
orbit was abandoned, the speculating being that the 2nd stage had to burn for
longer to get the dragon/ISS primary payload as it should be, and so not
leaving enough fuel left over for the secondary payload nominal insertion.
That sounds plausible, but equally SpaceX haven't said anything so it's all
just armchair speculation, which is fun anyway.

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bane
" I believe F9 is the only rocket flying today that, like a modern airliner,
is capable of completing a flight successfully even after losing an engine."

Brilliant! By equating the rocket with an airliner (the statistically safest
way to travel), this turns what could be a mark against into a huge mark for.

~~~
anonymouz
While this is indeed an awesome feature to have, it doesn't by itself mean
much. The total reliability of course also depends on the probability that one
engine will fail, a rocket that needs all its engines may still be more
reliable than one that is capable of of flying with two failed engines, but
regularly has to do so.

What makes the airliner seem safe is that it can fly with a failed engine
_and_ it very rarely loses an engine.

I guess we will have to wait for some more flights till we have decent
statistics on the reliability of the Falcon 9. Of course, I'm hoping that it
will turn out to be an awesome rocket!

~~~
jlgreco
For whatever it may be worth, it seems right now the engine failure rate for
Falcon 9 is 1 in 27.

~~~
tisme
Is there a similar rate known for regular jet engines?

~~~
jlgreco
No idea. I am sure it is astronomically small though.

~~~
ballooney
A lot of Western aviation qualifying authorities specify a maximum allowable
mean time between failure (MTBF) of 1 per 100000 flight hours. I imagine most
rocket engine designs would be more like one per hour! That said, they only
have to operate for about ten minutes though before they are disposed of, in
the case of expendable launch vehicles.

In Falcon 9's case, and totally from memory and probably incorrect and very
approximate, we've had 4 launches, each has had 9 Merlin C engines on the
first stage, the first stage burn time is 170s or about 3 minutes. There have
been two failures - a non destructive engine shutdown on the previous ISS
mission on the pad at T-very_little, and the rather more messy rapid
disassembly failure of something near the engine or the engine itself on the
most recent launch.

So, for this first stage engine the MTBF (remember this is all a bit silly and
inaccurate and just for ballpark comparisons with the airline industry) the
MTBF has been:

9(engines/launch) _4(launches)_ 0.05(3 min burns in hours)*0.5(2 failures) =
0.9, i.e. a MTBF of 55 minutes for Merlin 1C lower stage, vs most regulators
requiring mtbf > 100000 hours on commercial jet airliner engines.

So there's a bit of a way to go yet!

~~~
DigitalJack
I agree that there is plenty of room for improvement, but you can't launch a
rocket with commercial jet engines.

I don't know if it makes sense to normalize for thrust or not, but it seems
like thrust should be included somehow.

~~~
saraid216
They're not saying, "commercial jet engines are more reliable; therefore we
should use them". The issue is that the Merlin 1C engine simply hasn't had
enough flights to build up its denominator.

It doesn't make sense to normalize for thrust here. This is just failure rate.
There's nothing wrong with having a comparatively high failure rate when the
sample size is several orders of magnitude smaller: the statistical
significance is just weaker; we acknowledge that and move on.

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ColinWright
Doesn't seem to be the whole story, since the video clearly shows a
significant amount of debris. A simple shutdown wouldn't produce debris,
although the loss of internal pressure on the engine bell could cause it to
collapse and possibly disintegrate.

I look forward to seeing a more complete analysis.

~~~
danielweber
From what I understand, engine exhaust is too hot for any material to
withstand without active cooling, which is done as a side-effect of feeding in
the fuel. If you just turn it off, then, it's no longer actively cooled, and
will rapidly melt from all the other engines around it still going full bore.

This is just a theory.

~~~
InclinedPlane
The engine exhaust is very highly directional, it doesn't just go everywhere.
For example, the supporting structures around the engines are exposed to the
same level of exhaust as a shut-down engine would be, and they are completely
uncooled.

------
vsearch
Here's the latest statement from SpaceX:

SpaceX CRS-1 Mission Update: October 8, 2012
[http://www.spaceref.com/news/viewpr.html?&pid=38825](http://www.spaceref.com/news/viewpr.html?&pid=38825)

"Approximately one minute and 19 seconds into last night's launch, the Falcon
9 rocket detected an anomaly on one first stage engine. Initial data suggests
that one of the rocket's nine Merlin engines, Engine 1, lost pressure suddenly
and an engine shutdown command was issued immediately. We know the engine did
not explode, because we continued to receive data from it. Our review
indicates that the fairing that protects the engine from aerodynamic loads
ruptured due to the engine pressure release, and that none of Falcon 9's other
eight engines were impacted by this event."

No explosion according to them.

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ceejayoz
More info and a video from The Bad Astronomer (Phil Plait):
[http://blogs.discovermagazine.com/badastronomy/2012/10/08/sp...](http://blogs.discovermagazine.com/badastronomy/2012/10/08/spacex-
falcon-9-lost-an-engine-on-the-way-up-dragon-on-its-way-to-iss/)

------
Roritharr
"There was no effect on Dragon or the Space Station resupply mission." - Elon
Musk

Just for those who didn't closely follow the events.

------
vsearch
I think we'll see an expanded statement later today when they've had time to
analyze the data more thoroughly.

~~~
jballanc
I would hope that it would be later than later today, and that they would take
an appropriate amount of time to analyze all the data...

~~~
vsearch
There will be a full investigation however the video clearly shows more than
just an engine shutdown. Something else happened and this needs some
clarification. There's a lot riding on this mission both politically and
financially.

~~~
jballanc
Yes, and it is for that reason that I hope they take their time. SpaceX is
very much a pioneer in this space, and how they handle each situation will set
the benchmark, for better or worse, for those that come after.

I thought the way they handled the launch abort during the last mission was
done very professionally. Likewise, I hope they handle this situation in a
manner that underscores the complexity of putting things in space, but also
instills confidence that they are up to the task. If they have to walk back
any early mis-diagnoses, it could tarnish their image more than a delay in
releasing the full details.

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kiba
How many engines does it take to cause failure?

~~~
confluence
I believe Falcon 9 has 2 engine out capability.

~~~
DeepDuh
probably not _any_ 2 engines though, right? I'd guess if the two engines on
one side fail it can't recover, since it could only proceed with 1/6th
capacity through the middle engines. (They have 6, right?)

~~~
ProblemFactory
I'm not familiar with the specifics of Falcon9 redundancy. But in theory,
losing many engines can be completely recoverable, because all 9 engines share
a single fuel tank.

Outside of atmosphere, a rocket's final speed and orbit depend on three
factors: the mass of the payload, the mass of the fuel, and the inherent
engine design efficiency. Notably, it does not depend on _thrust_. Burning one
engine for 9 seconds results in a speed boost equal to burning 9 engines for 1
second.

Even if an engine fails and another one is set to reduced thrust, the fuel is
still there, and can be burned by remaining engines.

Of course, this is a huge simplification, and loss of thrust while still in
atmosphere or near the ground might be a problem.

~~~
ckg
I think thrust counts to a degree, as you'll lose velocity from gravity drag
if the time to orbit is too high. The degenerate case would be if your thrust
is less than the weight of your rocket (i.e. not moving).

------
baq
everybody interested in why rocket engines have the amazing ability to turn
thrust into fireworks when least expected should read this excellent book on
rocket propellant history:
<http://library.sciencemadness.org/library/books/ignition.pdf>. to spark your
interest, foreword was written by isaac asimov.

~~~
hinathan
This thread is pretty cold by now but I wanted to thank you for the link to
Ignition — it's a really neat window into some of the chemistry and practice
of 20th century rocketry. Reminded me of Max Gergel's "Excuse me sir, would
you like to buy a kilo of isopropyl bromide?"
[http://library.sciencemadness.org/library/books/gergel_isopr...](http://library.sciencemadness.org/library/books/gergel_isopropyl_bromide.pdf)
which, now that I look at the link, is hosted at the same server.

