[AR] Re: SpaceX F9 Launch/Update -- Live Link
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: arocket <arocket@xxxxxxxxxxxxx>
- Date: Fri, 25 Dec 2015 23:59:42 -0500 (EST)
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
Other related posts: