I am starting to build a Semroc Retro Repro of the Fire Fly and was curious about the "Passport staging" which Centuri claimed was more reliable than the standard (Estes?) method. Can anyone explain the reasoning?

Also, in the original instructions, as seen in on the ye old rocket plans, no need to tape the motors together was stated. In the Semroc version, it does say to tape the motors together.

Thank you for your reply.

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Bernard J. Herman Ohio RLS

Starport Sagitta Rockets
email bherman@sagittarockets.com

NAR # 97971 SR

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Passport staging allows the stages to separate more slowly due to allowing part of the gases to vent sideways.
This theoretically allows more burning particles from the booster to reach the nozzle of the upper stage.
The 'standard' Estes method (prior to plug-n-go gap-staging) with the engines taped together causes the pressure to rapidly rise, violently blowing the stages apart.

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I've never had a misfire from either method....

I've flown my Semroc Firefly over a dozen times, no taping, and it's always staged just fine. Usually use an A10-0T to A10-3T or 1/2A3-4T, but have also used A3-0T to 1/2A3-4T, A8-0 to A8-5 (shortened), and once on 1/2A6-0s to 1/2A6-4s. Check the fit of the couplers before building, it's much tougher to sand when built. I need to sand them a bit after each flight also.

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Paul
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