View Single Post
Old Jan 20, 2012, 08:08 AM
Quick61 is offline
Find More Posts by Quick61
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
1,704 Posts
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. - (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 - as there are several sail-wing projects going on, and these guys are serious about their wings.
Quick61 is offline Find More Posts by Quick61
Reply With Quote