Hey, if they can ever get around the solids having only two power settings (off and full-blast), they'd be perfect.
> if they can ever get around the solids having only two power settings
Solids *are* throttlable. Back in the '60's Aerojet and Thiokol built competing solids that could throttle on command, stop, and restart. Complex, but doable.
And the Shuttle SRB has a programmed thrust/time trace. It's not "full blast" until burnout.