On 12/24/2015 3:54 PM, William Claybaugh wrote:
On Thursday, December 24, 2015, Henry Vanderbilt
<hvanderbilt@xxxxxxxxxxxxxx <mailto:hvanderbilt@xxxxxxxxxxxxxx>> wrote:
All due respect, but SRB's are simply not a useful reuse economics
model for soft-landing recovered liquid booster stages. As I
recall, between the effects of double-digit-G's water impact and
salt immersion, the only part of the SRB's NASA was actually willing
to reuse were the stripped steel casings, after they were scoured
out then checked for cracks.
Don't disagree with your first comment; they are, however, the only
reusable first stage data I have. Second comment is incorrect; all the
major forgings were reused until damaged.
So, it was essentially built-from-scratch SRB's every time, save for
steel casings that even new were a fraction of the overall cost.
Agreed, the economics of that were never likely to make sense.
It remains to be seen what level of teardown and refurb Blue's and
SpaceX's boosters will require, but the equivalent of an SRB
"refurb" is way over at the far end of the range of probabilities.
Agreed
Further, the amount of refurb needed is NOT some fixed constant. I
believe both Blue and SpaceX are treating this as an opportunity to
discover what parts of their boosters do or don't need beefing up to
reliably survive multiple flight cycles without refurb. IOW, the
results from these first recoveries are the start of an improvement
process, not some final result they'll have to build an economical
reuse operation from.
Fair but that is a development cost that--were either organization for
profit--would drive up the amortization per flight...which is usually
the highest cost (SpaceX appears to have found a way to thread that
needle, provided the costs you propose do not materialize).
Looking at these operations from a traditional industry perspective
can lead one to assume the designs are largely fixed and very
difficult to change, and thus must be factored into economic
calculations largely as-is. But SpaceX in particular has made it
very clear they're not following this traditional frozen-design
model at all, but rather one of continuous incremental improvement.
Assuming such incremental improvement won't be part of the process
of bringing reuse into the routine operation strikes me as very
likely to be a significant error.
Careful: the organizational effects of the launch failure have not shown
up in prices yet.