I've seen several threads that doscuss HPR booster separation but haven't seen any actual, workable designs or flights. The electronics to airstart and separate boosters pyrotechnically exist in several altimeters/flight computers so that is the relatively easy part. But the design/fabrication of the hinges/brackets/charge systems are still nebulous. My goal would be a ground-started 54mm long burn in a 3" airframe with 4x 38mm booster airframes with 29mm motors airstarted in pairs then separated. I have a few ideas but I would love to see any successful HPR booster sep designs that use pyro.