Carl
Just goes to show there really nothing new under the sun.
Powderburner
Right about the possibility to not have to use BP, particularly if you use a piston as Carl noted previously with the ESTES CATO.
I tend to be conservative. I know how to design a rocket to look like it CATOED (even more so than the ESTES kit), but I'm not sure that everyone can do it correctly. If I were the RSO and the builder could answer the recovery questions to my satisfaction, then it would fly, otherwise it wouldn't. My safety questions and concerns are two-fold.
In the solution I proposed, there is a relatively high (disassembly) velocity near the ground so it is important that the pieces slow down and tumble recover. While a commercial kit will be proven safe by the manufacturer, a scratch-built may not have been flown before. As RSO I would want know how the rocket comes apart inflight and what the recovery expectations are.
Also it is important to only use A or B motors to keep the velocity low. There is always a temptation to use bigger motors which if the design were unstable, could prematurely disassemble at low altitude and high velocity under power and then you have a burning motor to contend with. As RSO I would like to know the CG/CP relationships of the model.
Bob Krech