[ExI] Engine anomaly on Dragon ascent

spike spike66 at att.net
Tue Oct 9 13:39:58 UTC 2012



>. On Behalf Of Dan
Subject: [ExI] Engine anomaly on Dragon ascent




>.Interesting that the anomaly occurred at all and that it didn't impact the
end result (yet).  Regards, Dan



There is an overall advantage in launchers for a design that tolerates
one-engine-out.  The obvious question is that if the launcher can work with
one less engine, then why not save the weight and eliminate it to start
with?  Answer: because if it can fly with one engine out, then you can push
the envelope harder on reducing weight in all the engines, edging closer to
the margin, trimming away more excess weight.  


The second reason is that in a launcher, the critical time where you really
need to burn fuel quickly is right at the start.  This engine didn't fail
until after max-Q (maximum dynamic pressure), where you can tolerate a
failure much more readily.  Soon after max-Q, they often need to throttle
back anyway: the rocket gets lighter as fuel is expended, so they can't stay
at launchpad thrust, otherwise the acceleration stress increases on the


I predict the overall mission will not be impacted at all.  Way to go,



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