"JF Mezei" wrote in message
web.com...
On 2017-10-27 06:27, Jeff Findley wrote:
Again, SpaceX has publicly stated the first reuse of a first stage cost
less than half the cost of building a new one.
Is that PR speak or "auditor" speak? The first reflown stage was not
the first landed stage. Say the first reflown stage uses some engines
that were refurbished from other recovered stages, and their reburb
costs billed to "R&D". Not saying this is what happened, but just one
way to skew numbers for good PR.
My understanding, but I have no reference for it is engines stay with the
booster.
Customers are already choosing to fly on refurbished first stages
because it gets their payloads in orbit faster
But lets wait until SpaceX actually delivers on a launch rate. Not
doubting it will, but the sample size right now is too low to allow
conclusions.
Actually delivers? They've done 15 flights this year and expect at least 4
more (I'm not counting Heavy as I expect that will slip).
That's a pretty damn good flight rate. They've shown an ability to have a
cadence of every 15 days. This is pretty impressive and does not appear to
have been a surge attempt, but simple operations.
SpaceX has done proof of concept. It appears extrememy promising. But it
hasn't yet proven it will deliver that launch rate.
Just because SpaceX has very good image that gives people confidence it
will deliver doesn't provide proof that it will deliver.
We are still talking about ODDs that SpaceX will deliver being very
high. So if you were betting, you'd bet SpaceX will deliver. But we're
still talking about odds because this is too new to have empirical
evidence.
Granted, we're still at the stage where any one failure still has a
statistically significant impact, but 41 out of 43 is pretty good.
AND that includes 378 flight firings of booster engines (one failure was on
the ground, so I'm not counting that one). And 41 in-flight firings of 2nd
stage engines.
This excludes all testing both on the stand and on flights like grasshopper.
Actually, I just realized my numbers are too low, since I'm forgetting the
refiring of the engines for landing.
So the engine numbers ARE statistically significant.
So they're making their numbers and giving us evidence.
--
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