Model Forum / General / Rockets / October 2006

The big moisture problem, for KNSU, comes from humidity in the
air affecting the grain surface after the grain is cast. With
high humidity, the surface of an exposed grain will literally
dissolve into a syrupy goo in just a few hours. Storage in vacuum
bags or desiccant jars is standard.

Jimmy Yawn has some nitrocellulose lacquer coating tests on his
website. It seemed to keep the humidity out, but I don't know if
he has working motors with such a coating.

Sure, my first sugar motors were 4" long end burners modeled
after Estes motors (very short core to start with). But it
depends upon what you mean by "successful". Low thrust and very
inefficient; but they flew, every once in a while. ;)

They were nothing compared to the "great discovery" of core
burners, though. If you measure "success" against a modern BP or
APCP motor, the end burning KNSU PVC motor is just a big Jetex.
But I imagine that a catalyzed sugar propellant grain in a
properly designed (higher Kn) aluminum motor case would make a
usable, if not efficient, motor.

What, exactly, are you looking for in an end burning candy motor?