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Not really a true scratch build, but some modifications to a long oop kit... It's been quite a while since I've built a bigger rocket, I usually scratch build or make them from lightweight foam. This was a 6" PML bullpup kit that belonged to a good rocket buddy of mine named Monty Bennett who untimely passed away several years ago. It was gifted to me a couple of weeks ago by Tim Quigg and while I was stuck at home I finished her up with some great decals from sticker shock. It should be a nice flyer on J and K motors. It'll be right around 12 and 1/2 lb with a j 435 and 20 ounces for balast for my largest planned motor, a K-535. It's funny because a few months ago I was thinking my next project might be a bullpup missile.
First I removed the forward 2 inches of body tube that had the dado cuts for the forward fins because I just didn't think they were going to survive recovery, I then slotted the nose cone and mounted the forward fins in the cone. I removed the piston and put a parachute platform for recovery and to get the parachute weight up higher and reduce the volume needed to be pressurized. I basically inverted the piston and glued it 20" down from the top The coupler helps reinforce recovery loads on the bulk plate. I also installed a fiberglass plate/mount for my 54mm av-bay against the inside of the body tube. I use this mechansim for all my other rockets. The av bay sits on the parachute platform and mounts to the inside of the body tube against the fiberglass plate and is held in place with a screw and it vents externally via two vent holes. The av-bay is covered in nomex to protect it from the ejection charge gasses. I use single deploy at apogee and a backup charge, I don't tend to fly high enough for dual deploy. It has a 7' rocketman chute with deployment bag and 25' of kevlar recovery line with a screamer for location once it lands in the sage brush.
I only had to cut one bulk plate from 1/4" ply I had and buy one 2.25" U bolt. I had the rest.
First I removed the forward 2 inches of body tube that had the dado cuts for the forward fins because I just didn't think they were going to survive recovery, I then slotted the nose cone and mounted the forward fins in the cone. I removed the piston and put a parachute platform for recovery and to get the parachute weight up higher and reduce the volume needed to be pressurized. I basically inverted the piston and glued it 20" down from the top The coupler helps reinforce recovery loads on the bulk plate. I also installed a fiberglass plate/mount for my 54mm av-bay against the inside of the body tube. I use this mechansim for all my other rockets. The av bay sits on the parachute platform and mounts to the inside of the body tube against the fiberglass plate and is held in place with a screw and it vents externally via two vent holes. The av-bay is covered in nomex to protect it from the ejection charge gasses. I use single deploy at apogee and a backup charge, I don't tend to fly high enough for dual deploy. It has a 7' rocketman chute with deployment bag and 25' of kevlar recovery line with a screamer for location once it lands in the sage brush.
I only had to cut one bulk plate from 1/4" ply I had and buy one 2.25" U bolt. I had the rest.
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