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Old Jan 20, 2012, 08:08 AM
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United States, OH, The Plains
Joined Jan 2011
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Quote:
Originally Posted by boingk View Post
Quick question guys... as you might have garnered from a previous post or two I'm building a flying wing glider using a Peter Wick airfoil. I've cut a stack of PW-106(?) ribs from 1/8" balsa and have my 1/4" spars ready to go, as well as all electronics for the build.

Now, how should I space these ribs out? Chord is 12 inches and I'm shooting for a wingspan of around 60 inches. I'm thinking of a rib spacing of around 4 inches, giving me approximately 16 ribs for the entire ~60" span.

I'm not looking for this thing to be overly aerobatic but would like it to be reasonably strong. The plan for spars is for them to be 1/4" square balsa, with one 2" back from the LE and another 2" behind it. LE will also be 1/4" square stock. TE will be the most suitable triangular stock I can find.

Does that sound about right to you guys? Any help is much appreciated.

Cheers - boingk
TheNightowl and Captain Canardly are pretty much on target here unless your building a free flight and are trying to save weight. Maybe I should ask, where are you wanting to fly this wing and under what conditions? If your planing on sloping on a nice grassy hill in moderate winds, you should be shiny with a strong LE (like 3/8" hardwood dowel or 1/4"x1" balsa strip) and D box. Now, if you plan on launching with A 2m high start into a headwind with a single hook close to the CG, your in trouble and it will fold up on you like a cheap suit. In either case, I would get the ribs closer together, like 2.5", even if your sheeting the entire wing with 1/16" basswood. Now,if you recall, I just mentioned "a single hook". If you use dual hooks, and a bridal tow,not a bad idea with any flying wing, your wing loading will be reduced by better than half (3 -5 x depending on wing and hook placement) I'm attaching a .pdf that will explain this a little. Still, getting rid of that first balsa spar and replacing with a basswood or spruce 1/8"x1/4" upper and lower with either "C" or better yet, "I" beam spar would be much better way to go. Here is a link on some testing done with spars. - http://www.rcgroups.com/forums/showthread.php?t=1431515. (worth reading ALL the way through). You have a build log anywhere? You also might want to take a look in the new Nurflügel forum here - http://www.rcgroups.com/nurfl-gel-762/ as there are several sail-wing projects going on, and these guys are serious about their wings.
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