space shuttle SRB gimballed nozzles

Spike Jones (
Mon, 09 Aug 1999 20:59:31 -0700

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:

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-]