Saturday, July 16, 2011

L-13 work

I'm finally getting back into building and repairing rockets, after a few months of not doing much due to school.

I started with my Goddard L-13. Last time, I fixed one of the scale details and added nose weight.

I started with a swing test this time. With a C6-3 (as heavy as even the 18mm D motors) inserted, I found the balance point and swung it on string to determine stability. It's an old standby, and good for rockets like this where simulation software doesn't work as well.

Because I built the aft end so heavy, it wasn't stable even with the additional 17g of nose weight from June. I added nose weight with quick links; it took an additional ounce (28g) before it was fully stable.

I cut two 1.5" lengths of .25" steel rod, then hand-drilled two more holes into the base of the nose cone. I glued them in and put a cap of wood glue on top to keep them very secure.

I also coated all remaining balsa areas of the nose cone with wood glue to protect them from ejection charges, especially since I find that I may need to add to the stock ejection charge of Estes motors since the body tube is fairly large. Previously, I have had no luck getting the parachute to unfurl.

The other remaining problem was the launch lug. The instructions have you place a single long lug near the bottom of the rocket. Which works okay if you build light rockets, but I build heavy rockets. So I took a short piece of launch lug and glued it higher up. (Both lugs are hidden among scale details). It's painted silver and now blends in.

Next: probably The Great Punkin.

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