05-26-2006, 01:37 PM
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BARCLONE Rocketry
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Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
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Fin Patterns for Tradewind
As mentioned, here is a cutting pattern for the pieces needed to create the open fins of the Tradewind. This is perhaps the most complicated task in building this rocket. Some may feel this is an unnecessary step, but you have to remember the fin doesn't have all of the internal bulk to add strength. The grain of the balsa has to take all of the stresses of launch and landing. To give these fins as much strength as possible, you have to run the grain parallel to the leading, trailing, and tip edges. To achieve that, you have to use multiple pieces stitched together like a jigsaw puzzle. Or, maybe more correctly, think of the way a model airplane wing is built up. Same principle.
Addendum: I call out 3/32" thick balsa on this pattern, but I used 1/8" in the simulation (I just noticed this, BTW). Using 1/8" balsa gives a little more bulk in the structure of the fin, and tends to hold down the upper-end Dv using the "C" motors. 3/32" balsa will reduce the weight, and allows a very soft deployment using the "A" motor. It reduces the beefiness of the structure, however. It's a toss-up as to which thickness would be better.
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