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Weedless V10 Rudder |
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Written by Paul Jacob
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Tuesday, 31 January 2006 |
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Page 3 of 4
Step 4 Shaping the rudder foil
The rudder needs to have a streamlined shape for least resistance. After some internet research I decided to use a NACA 0012 foil shape. This shape was originally developed for aircraft surfaces but works just fine for rudder shapes as well. This was the hardest part, trying to hand shape an aerodynamically efficient shape into the blank. I found a way to print out the cross sections I needed and then taped one to each end of the rudder as a guide. It's not perfect, but to the naked eye you'd be hard pressed to find the flaws.
After the blank is shaped, more 4oz fiberglass cloth was epoxied to the outside. This really stiffens it up and provides a hard outer shell to the balsa core. After the glass cures, more epoxy coats are added to fill the weave of the glass and provide thickness to sand to the final shape. Two fill coats were added and when they were hardened, I sanded the coats down to the final surface. Too much sanding and you'll expose the fiberglass cloth, too little and the surface won't be fair. After the final sanding, the rudder is ready for a trial run on the boat. |  | The blank before shaping...
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