I used the D13's a lot back in the days. Never had any problems with it until I tried to launch my Estes 1/100 Saturn - V at a Regional Meet (in 1972, I think) when it catoed immediately after liftoff. Thanks to a nice patch of soft grass that happen to be right next to the launch pad, the model landed on its' side on that grass and sustained no damage. I still have my last D13-3 from that batch in my collection. Around that time, I flew my Cineroc/Omega two stager using the D13's a few times (no problems encountered).

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Dave, NAR # 21853 SR.