I bought the plans and followed them up to the transition between booster and sustainer. I could not get the card stock connection to work for me. I took matters into my own hands - collect as many photos I could that really showed what that looked like. With a block of balsa I carved something that should work.!since there is a gap between boosters and sustainer, I figured gap staging rules would apply here, I.e. venting exhaust just below sustainer motor nozzle. The ignition gases need somewhere to go (inside the nozzle preferably), so one needs to vacate the trapped air in that passage; venting hole just below the nozzle allows trapped air out, and hot gases passage to inside nozzle, theoretically. It looks great except for the transition - which looks kind of klunky. I am not a sculptor nor a whittler. I have not flown it tho’ I have had it 5 years or so. At the same time, I built, from pictures I found, the Russian Sam 75. Again a gap staged model. The booster is 24mm that transitions to 18mm with an 1/8” gap (using stilts) to keep the stages apart. The hardest part about that build was making the 4 small canards a uniform size, then shaping them aerodynamically, and then lining them up and keeping them straight. I should have made it bigger. It looks cool but there is no room for anything but a streamer. We launch in tall grass. A 2 stage model that is at best 10” long total will get lost - - easy!
Does any of this help?
