Hobbistar 60 Rebuild
The Hobbistar 60 is a favorite intermediate trainer/sport model for some of the R/C pilots. Our web site manager owns two of these models, one sporting a Magnum Pro 65 SE two stroke engine and the other a Saito 80 4-stroke engine.
One weekend, while flying in about a 20 Mile-per-hour wind, the 2-stroke engine quit (dead stick). The engine stoppage was later found to be caused by the clunk in the fuel tank getting stuck in the front of the fuel tank. (But we're getting ahead of ourselves).
Forced into a dead stick landing, and being over 50 feet high over the landing area, it was decided to turn the plane into the north wind. This caused the plane to stall (zero speed) and provided a spectacular single point landing on the nose.
The fuselage split at the nose like a banana and broke into six main parts. The engine was OK, radio components and wings were all ok. It was decided that rebuilding the fuselage was possible. Here's how it was done.
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The first step was to glue the large pieces back together. Anyone who likes jigsaw puzzles will appreciate this step. The fuselage looks really rough, and most flyers would probably throw this one away. But we're builders and almost every model can be rebuilt. It may not be worth the time, but... Since the fuselage sides broke cleanly into 6 large pieces, it was decided to glue the pieces together with epoxy. Notice the clamp used to hold the pieces as the glue set up. |
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6 oz/sq yard fiberglass cloth and carbon fiber were used with epoxy to reglue the pieces together. This results in a strong joint. The fiberglass was cut to width and length with a razor knife. The carbon fiber was cut to length with scissors. 45 minute epoxy was measured (each component in the 50/50 epoxy was weighed so it was 1/2 the weight of the fiberglass used for the repair.
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An acid brush was used to spread the epoxy, while a heat gun was used to help thin and spread the epoxy so that it saturated the fiberglass/carbon fiber and the damaged area of the original wood. This resulting patch was allowed to set for 24 hours before proceeding. The repair was accomplished over several nights. Taking your time, fitting all the parts as best you can, adding new parts (wood and composite in this case) and using slow setting epoxy results in a very strong rebuild. Care must be taken to minimize the added weight! |
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The model doesn't look as nice as it did before the inadvertent nose landing, but it flies well. The second maiden voyage was a success and the plane flew just as well as it originally did (great!) Notice the Fultz nose gear, three bladed prop (for ground clearance) and three-inch Sullivan Skylite wheels. We fly on grass fields. |
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