Thread: Build Log Dornier Do-335
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Old Jun 15, 2011, 02:02 PM
pmullen503 is offline
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United States, WI, Fond du Lac
Joined Sep 2008
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To make the wings I use the "laser method". I'm not sure who first developed it but I really like the method. It's primary advantage it that it builds a really accurate, lightweight wing. From a design stand point, it allows you to easily add structure to a tapered wing without having to develop every wing rib. It has all the advantages of a hot wire cut foam cored wing but without the weight of a solid foam core. Once you get into the 4 ft or larger W.S. the weight savings become significant. (The threads cited in post #2 describe the same process.)

Start by laying out the wing on the building board. Wing outlines, spar and the rib locations are penciled in and rectangular foam rib blanks are stuck to the board (about 3" tall in this case). I've done a number with double sided tape but this time I used dots of epoxy to stick the rib blanks to the board. If they are crooked it doesn't really matter except for the root and tip blanks. Take care to stick them down straight with a good 90 degree angle to the board. I use FFF for most ribs but used 3/4" foam for the root, tip, and the area where the LG mounts will be. There's also a partial rib where the end of the aileron cut out will be.

I used template to make slots for the main spar and dihedral brace. If I had designed a built up wing I would have had to design these slots into each rib. Here the hot wire makes sure they're all where they need to be. Next I clamp guides to either end and cut off about a 1/4" with the hot wire to make sure the top of the rib blanks are flat and co planar. Finally, I glue another board to the rib tops with more dots of epoxy.

Now you can add the root and tip templates. The templates have the dihedral and washout angles built in to them. You pretty much have to use separate templates for upper and lower wing surfaces. I reference everything from the spar slot rather than the TE or LE. Then you make the cut for the top surface with the hot wire. I used a home made Feathercut apparatus to accurately cut the taper. Otherwise, I'd have cut the building boards to match the wing outline so I could eyeball the taper. The taper on the Do-335 is around 2 to 1 which is tough for me at least, to cut by hand.
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