The 260 inch solids predate the SRB program, and there were a number of 1 or 2
SRB monolithic shuttle alternatives examined. 3 of the 260s were fired.
But... Nothing that had flown.
George William Herbert
Sent from my iPhone
On Dec 25, 2015, at 8:59 PM, Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
On Tue, 22 Dec 2015, James Bowery wrote:
... Also, keep in mind NASA's major handicap: Politics. SRBs were, after
all, designed to meet political requirements (hence were segmented for
transport from Utah).
The extent of that is, in my opinion, exaggerated. While not denying that
there were politics involved, the #1 reason for segmented SRBs was that they
were the only form of *big* solid that was believed well-understood. There
was extensive operational experience with big segmented solids on Titan IIIC
and its derivatives, and virtually none with big one-piece solids. One area
of particular concern was achieving good matching of the two SRBs, given that
it's hard to handle more than about a 2-3% thrust imbalance; corresponding
segments of the two SRBs always come from the same fuel-casting run.
When NASA attempted to establish an SRB alternate source after Challenger,
there were bids for one-piece approaches, but a non-Utah segmented design
won. (And then its cost ballooned, and its schedule slipped, until Congress
ran out of patience and killed it, but that's another story.) Undoubtedly
technical merit wasn't the only factor in that choice either, but it's still
noteworthy.
If you're crazy enough to do manned launches on big solids, making them
segmented actually does make some sense.
Henry