info taken from EMRR website
twinsee: insert a motor into the motor tube so that 1/2" is sticking out the aft end, then tape it in place. Slip the other glider over the forward end of the motor casing and you're good to go
Cici two stage: Prep is easy in that there is no wadding or parachute and the engines don't even have to be friction fitted. However, attention to detail is required for taping the bulkhead and making sure everything fits. The booster engine is taped externally to the body tube with no engine block so it stays in the booster during glide. The sustainer engine is held in place only with thrust after the booster falls away and tape wrapped around the outside functions as a bulkhead for the booster. It's all held together by gravity on the pad. The sustainer engine ejects at apogee.
Gotchas:
I prepped for the first launch with 1/2 inch tape which is a standard size for external bulkheads on smaller engines. According to the description in the instructions on gap staging though, the half inch tape won't work because the vent holes are covered up internally by the engine and would block the escape of gases causing staging separation before ignition of the sustainer. So I removed the 1/2 inch tape and replaced it with 1 inch wide tape, which worked perfectly.
The instructions don't specify how far the booster engine is supposed to protrude, so you have to "guesstimate" using the photos. I left it protruding 1/2 inch or so, which was fine.
hope it helps
