Zipperless drogue deploy

[el traveiso]

Ok my latest build is a zipperless drogue deployment. This is my first . I been launching dual deployment for awhile, and always, always ground test using online formula which always gotten me close without wasting alot of BP and ematches. The aft section of the rocket weights close or over6lbs. I'm using primary and redundant altimeter. My question is there a formula to used for amount of BP to use to blow out the entire aft section to release the drogue. I always have used motor ejection for the drogue. What is good formula to use without wasting to much powder which is getting harder to find. What would be right amount to start off with. Thank you in advance for help.

 

[Handeman]

My L2 cert rocket was built that way. I used the same formulas for BP calc that I used for any other volume. My booster tube volume was 18"L x 4"Dia, plus what ever part of the 54mm MMT wasn't filled. I adjusted and finalized on 1.5g of FFFFg for the drogue side. Never had an issue with drogue deployment. The rocket was retired after 50 flights.

One thing about the zipperless fincan, it spun very fast on the way down, I would estimate it at 100 RPM or more. I used a good HD ball bearing swivel between where the cord and fin can connected. Even with the fincan spinning so fast, I never had issues with the shock cord twisting up when using a ball bearing swivel.