Sport Rocketry

SPORT ROCKETRY MAY/JUNE 2022 7 based pivot I use on my LPR pads. Later I figured out that 1½" pipe, while a loose slip fit inside 2" pipe, was a close enough fit that with a couple of thumbscrews threaded through the 2" pipe to lock the smaller pipe in place, the two sizes could form the ba- sis of an adjustable-length tripod leg. is makes it possible, with a fixed rail-to-tri- pod attachment (the idea for which I stole from Frank Burke), to adjust the launch angle by a combination of adjusting the one leg and picking up the whole pad and rotating it on the ground. Aer using one this way for a bit, I concluded that having two adjustable legs (that can be both longer and shorter than the remaining fixed leg) is more flexible to use, so my current pads are set up that way. Another little problem to solve for these pads was what to use for a blast de- flector. I've seen some solutions that I didn't care for, but finally came up with an angled deflector that is both inexpensive and seems to work well for this duty. It uses a modified dollar store scraper/dough cut- ter, two rail buttons, a 2" 8-32 screw and some 8-32 nuts. I have had one of these deflectors burnt through by an AeroTech Redline motor that was right down on the it at ignition, but other than that one case, they've worked fine for both my club launches and TARC teams. e most recent addition to this pad design gets rid of the "slip" fit of the legs into the top of the tripod. Aer a few cycles of setting up a pad like this and taking it down again, the tops of the legs and the inside of the top piece get kind of dirty, which makes it progressively harder to disassemble at the end of a launch ses- sion. To solve this problem I turn these joints into threaded con- nections by taking advantage of the fact that fittings for use with PVC electrical conduit work also fit plumbing pipe. Also, at least for threaded adapters, they're much less expensive than compa- rable plumbing fittings (if they exist) even in the same big-box store. Sure, they're grey instead of white (PVC) or black (ABS), but so what? By combining these ideas one can build a sturdy tripod pad based on 2" (and 1½") ABS or PVC pipe that has screw-on legs, two of which have adjustable length, and which has an angled blast deflector that just slides onto the rail. Parts for one cost less than $50 plus the cost of the rail itself. is price is based on prices First flight off the pad. e finished tripod top assembly. e FORMUFIT 2" PVC 3-way elbow fitting is the heart of the pad.

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