Hi David.
For the connection, a bit of 0.013" thick wood, wet and wrapped around the motor stick form will give you something you can cut to size, then insert inside the motor stick end. Glue it up, let dry, then add glue to the protruding end, insert into the tailboom, then align and let dry. I also glue the seam well. I know some with tissue wrap this too - Joshua Finn being one person I recall who advocates this step.
As for the rubber hook end, most designs are very simple: Vertical with some protrusion out the top for the bracing wire, typically with loop. Other side is bent at some arbitrary angle to get offset from the motor stick that makes the loop equal to the offset at the bearing. The vertical shear web balsa is between 0.013" (TOO THIN!) to 0.025" on most designs. I'd go with the 0.025". Use tissue wrap wherever the wire contacts the balsa shear web. I use silkspan on the bottom protruding bit as I am murder on that protruding balsa bit.
Now this simple design that most use - I don't like this design at all as I had three hooks fail on me one day. On the long drive back with Jeff Annis, we did some analysis on why this happened. I realized that the stresses are such that the shear web can compressively fail. He came up this this idea and I have used it in every single stick since and have never had one fail on me. The wire is a bit harder to bend and this method will weigh slightly more, but with the extra 200 mgs in the new rules, here is a logical place to put it. It is is better explained via picture - The attached is purely illustrative and not to scale. The top hook especially should be shorter or bent forward in line with the wire bracing. The key here is to attach the wire to the balsa, wrap the back with kevlar pulled from tow or fly tying line and glue. Tissue wrap can be done below the kevlar.
For attaching this to the stick, I glue the top/bottom well. Holes are cut for the parts that protrude, then inserted. Everything is glued well.
Regards.
Mike Kirda
Received on Wed Dec 30 2015 - 05:50:59 CET
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