Fascinating, Brian, thanks.
Brings up a bunch of questions, about those ROCKETs in comparison. RE: Those solid boosters;
Looked like the solid boosters generally burn, in that center well, and so the question is, does that 'burn' extend all the way, up and down the cylinder ? (Rather than some pattern like burning the solid propellant from bottom up).
Of course, that would be, about, a 43 year old question, now.