Sunday, November 13, 2011

Productive Sunday

I'm a week late on my Plaster Blaster 2011 entry but I'm still waiting for a few elements to come together.  I'll foreshadow a problem with an otherwise great M840 drag race flight last weekend: my Slimline motor retainer ring would not unscrew due to an impact with some harder soil.  Frank Hermes suggested that the retainer tube was probably out of round due to angled impact and I think he was right.  I started my Sunday trying to resolve that and get my motor casing out.

After 45 mins. of trying other methods I finally busted out my Dremel tool to grind a notch in the slot of the Slimline retainer ring.  I then used a chisel to wedge down into the threads and snapped the ring at that spot.  I was finally able to pop out the ring and extract my Pro75 6G casing. Although the retainer's threads are trashed I think I can drill into the sides of the retainer tube, tap them, and use tiny screws to retain future motors.  This is cool because I really didn't want to trash the booster despite a heavier-duty version being on deck:

Those who have flown moonburner reloads know that they rank among the more difficult cleanup jobs; especially when stuck in a booster and untouched for a week!  I was able to get the casing apart and the liner out without issue.  As expected some threaded parts and the casing interior were filthy despite liberal use of grease during assembly of the reload.  I emptied my tall-ish office trashcan, placed my casing into that, and poured hot, soapy water down into the casing.  I repeated the fill and then added a bit of white vinegar to the solution.  After soaking for a half-hour I flipped it over and started cleaning with a toothbrush taped to a dowel.  A few iterations later I then dried the casing and busted out the screwdriver to scrape and the brake cleaner to dissolve the crud.  This process took almost two hours in total today but my casing and parts are quite clean now.
    During the soak I started repairing other rockets.  My Madcow Squat suffered a minor zipper during the I445 drag race over a year ago. The short body tube is cardboard so I simply wrapped a swath of Gorilla Tape around the top of the tube.  It looks pretty cool and should survive another I445 flight.

    My '.38 Spatial' suffered a narrow Kevlar zipper in the payload section on its J350 flight.  I used a length of 38mm coupler, two layers of release film, a slice of 38mm body tube, and carbon-fiber-loaded-epoxy to patch that up.  I then wrapped the assembly in shrink tape and applied heat with a heat gun. This shrunk the film very tightly and I expect the gap to cure/fill quite nicely.

    On its last flight my Loc Bullet suffered a 1x2" zipper/chunk due to an excessively long J500 delay.  I used a technique similar to the above but this time I sandwiched a layer of carbon fiber fabric in the repaired area.  It's worth a try as I was about to trash this rocket and start again.

    I also scraped some unintended and ugly primer drips off of the 4' long payload section remnant of the otherwise lost Viciously Mean Machine.  It looks pretty cool now and I think I'll fly it with the Fity-Fo booster:

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