Go ____ throttle up

"André, PE1PQX" wrote in message
...
...Also I do not know the percentage of power the tree SSME's generate at
T-0 (launch) compared to the two SRB's.

Andre, at launch the SRBs generate roughly 85% of the liftoff
thrust, In theory the shuttle could lift off without the SSMEs,
however there is doubt the orbiter/ET attach struts are strong
enough.

The SRBs also provide most of the steering authority, since
the SRB nozzles gimble similar to the SSME nozzles, yet produce
much more thrust. The roll maneuver soon after liftoff is done
mostly with SRB steering.

Even at SRB separation, the remaining orbiter/ET
thrust-to-weight ratio is less than 1:1, which means
the vehicle theoretically couldn't hold itself up vertically on thrust
alone, However by that point in the ascent, the momentum
carries it upward as the SSMEs burn off fuel, finally reaching a 1:1
thrust-to-weight ratio.

-- Joe D.