For those of you who were in on the conversation at Extro4 regarding
the nozzles on the space shuttle solid rocket boosters, they do indeed
have two axis gimballed nozzles. see:
http://www.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html#srb-tvc
I thought they did, but allowed myself to be talked out of the notion.
I was going crazier, trying to figure out how they did the roll on
launch using only the three main engine nozzle gimbals, for it is easy
to estimate the position of the CG of the bird and knowing the thrust
of the three mains, and then to estimate how far from the CG the
thrust vector passes, and from there to estimate the moment of inertia
of the vehicle, and get an approximate maximum roll rate. Once
one does this, it is quite unclear that the graceful roll of the shuttle
on takeoff could be achieved without vectoring the SRB nozzles. I
had convinced myself that if they had fixed nozzles they must use
the aerodynamic control surfaces on the orbiter's wings.
bzzzzt. Back to school with you, spike. {8-]