LOC 7.5" Electronics Bay - tweaking the fit

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Well-Known Member
Jul 11, 2016
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Chicago, IL
So, there's only one thing to do when you smash the front half of your LOC Bruiser into a cornfield.... salvage the booster and rebuild it! I'm upgrading it to a dual deploy flyer, but having a hard time getting the fit correctly between the 7.5" electronics bay coupler and the airframe. I started sanding the inside of the booster airframe tubing, but it's getting fuzzy and the fit doesn't seem to get any better. I'm thinking of flooding it with thin CA and then continuing sanding, but wanted to get some other opinions before I kept going. I've only built fiberglass and small cardboard Electronics Bays before and not had to sand as much as this. What are you all doing for the large cardboard tubes?


Stop! :wink:

My advice fwiw. I've built a whole lotta Loc 7.67" rockets lately, and the couplers seem to have a larger-than-normal OD. Rather than sand the ID of the airframe, my recommendation is to peel the outer layer of the coupler. Then coat in a layer of epoxy resin; the thinner the better. In fact, I coat it, then wipe it all off with a paper towel. When dry, sand smooth with a palm sander or sanding pads until the fit is just right. I have done this with the last 4 or 6 7.67" couplers and the fit has been great! Sounds iffy, but it's been working great!
djs- 2 stager may be in my future... I have another booster ready to be used on this (i don't like to throw out the good parts of crashed rockets!). I've thought about a stubby rocket or parallel booster, but DD seemed the most logical next step...

EricC - Peeling the coupler makes a lot of sense - I thought about doing that but didn't want to lose the glassine smooth surface. Looking back on your build threads I see you doing this a lot. I have west systems epoxy to build it back up - do you think this will work?
I have found that PML 7.5 inch couplers OD are about 15 thousandths smaller then the LOCs 7.5 inch BT ID . With a single layer of 1.5ish glass , it fits like a glove .