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Super Big Bertha on three 24mm motors

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scott johnson

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I'm planning on building a Super Big Bertha and installing three 24mm motor mounts. Will I need to vent the ejection charge of two of them or will it be okay if all three are ejecting into the body? I've seen where multiple motor rockets have ejection charges vented rearward, as in the Cluster Duck. Any thoughts/ideas would be appreciated!
 

downhill_D

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Estes pro series had a rocket called maxi force -it was a d motor cluster rocket and all 3 charges were used for deployment but the rocket was about 2.5” in diameter and somewhat tall so it had a fairly large volume to fill. You can see the plans here: http://www.oldrocketplans.com/estes/est2065/est2065.htm and there are motor mount ring templates available for it-it was a tight fit.
 

kuririn

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I would have all three blowing into the main body. What if you vent two of the three and the third one doesn't ignite? Your recovery laundry would not eject, and the SBB does not do well with tumble recovery.:p
 
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You can use a longer delay (if available) or plugged versions on one or two of the motors to reduce the amount of ejection force.
 
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