Wasn’t the booster fuel material more of a sludge as manufactured, that had to be poured into the casing? They couldn’t pour a 100 foot long tube without cracks or voids with would result in explosive failure, so they had to do smaller segments and stack them.
I don’t know, I read that sometime after the accident.
Yes, that's very common for solid propellant. It was perchlorate, aluminum, HMX (a kind of plastic explosive, heheh), and some kind of binder like butyl rubber cured solid...they could pour it and it would solidify in the case. Way easier. Of course when Feynman visited the factory they were certifying the casings cylindricality by measuring 3 points on the top, a total fail. I think a lot of modern standards for GD&T (geometric dimensioning & tolerance) are a legacy of lessons learned from the investigation.
They couldn’t pour a 100 foot long tube without cracks or voids with would result in explosive failure, so they had to do smaller segments and stack them.
Another plus for using segmented propellant, manufacturability. But the segmented approach was really optimum for the required mission performance.
The shuttle program was just using a standard approach. I've done the same thing in candy rockets, cast segments in a mold and slipped them into a heavy paper tube with a plumbers' putty gasket between each segment to protect the exposed paper. The propellant segments deform a little when you compress the stack and the putty bonds with the paper. Some people use PCB pipe with similar effect. Makes the math easier, that's for sure.