Through some research, I got to know about the booster separation motors (BSMs) used on the space shuttle in order to separate the solid rocket boosters (SRBs). However I did not understand if this is similar to Hot staging on a rocket or does the separation and BSM firing take place simultaneously? and if so how?
It also wonder what other methods of booster separation have been used throughout time and which of them are used today?
The explosive bolts that held the Space Shuttle boosters on and the ignition for the Booster Separation Motors all used the same NASA standard detonators wired to the same trigger circuit (with lots of redundancies, of course). When the ordnance firing signal went off, the circuit energized, putting power into all the BSMs and all the explosive bolts at once. It all happened simultaneously, aside from any millisecond-scale variations due to electrical travel time and chemical ignition delay.
It's not really hot-staging, where the upper stage fires while still attached to the lower stage, because the purpose of hot-staging is to use the ongoing thrust from the lower stage to make sure the fuel stays at the bottom of the upper stage's tank, to avoid gas bubbles that could cause ignition problems. But it's similar in the sense that when the BSMs fire, the boosters have not yet physically moved away from the main tank (obviously, since that movement is what the BSMs were meant to accomplish).
As to other designs, I know the Falcon Heavy uses pneumatic rams to shove the booster Falcons away from the core (at which point aerodynamic forces finish the job). I'm not particularly familiar with the staging processes of other side-mounted boosters such as the Titan IV or the Ariane series.
It is a closely choreographed operation. Obviously it has to be or it would tear the core vehicle apart. Historically it was done with a liquid core that was already a launch vehicle in use that needed added lift. One of the easiest ways was to add more rockets to the stack so solids were by far the easiest solution. Light and go, don't need to worry about fueling, complicated engines, etc. So when they burn out, usually registered by internal sensors reading a specific low pressure value, they are separated by pyros at the attach bolts and then kicked away with small solids as there isn't really any other good way to do it. One smaller solid strap-ons spring devices were used to push the burnt out booster casing away from the rocket.I also just read the large GEM solids on the Atlas 5 just fall away when they burn out but that sounds odd because on the Starliner flight I also read they stayed attach for a minute after burnout to make certain they were completely burnt out and wouldn't affect the Atlas core.
