Thank you doc. Had a tooth pulled today so a little out of it. I will reread it a few times tomorrow though for sure. Adding a little bit of sweep is easy. The Carbon rod joiners is what i did in my big 8 ft zagi so will do that again. How far do you recommend the tubes go into each wing? Thanks for the tip about ballast in the joiner, that makes a sense and will save a lot of time adding other spots.
Thank you doc. Had a tooth pulled today so a little out of it. I will reread it a few times tomorrow though for sure. Adding a little bit of sweep is easy. The Carbon rod joiners is what i did in my big 8 ft zagi so will do that again. How far do you recommend the tubes go into each wing? Thanks for the tip about ballast in the joiner, that makes a sense and will save a lot of time adding other spots.
Sorry to hear about the tooth Nate.
For the spar I'd make it really simple:
1. Use whatever joiners you like and make the internal wing box or tube to suit them. Fill in any space above or below the joiner with vertical grain balsa.
2. Then bond the tube or box onto a full (wing core) depth spar made from 2 (tapered to fin along the wing core length) pieces of good 3/32" ply with vertical UD carbon sandwiched/epoxied/pressed in between. You can taper the plies along the length of you want so as to taper the compression/tension resistance.
3. Cut the wing foam along its length to let the spar in - spar is not very thick so no need to actually remove foam except where the joiner box goes.
4. The alignment or incidence pins only need to go into an extra piece of ply let into the wing root.
5. Finish it all with a nice 1/8" ply root rib and Bob's your Father's brother.
6. Depending on what UD carbon you have, can get, or even if you want to use it - make top and bottom spar caps tapering from about 2" at the root rip to about 1" at the tips.
7. You can layer three plies of UD carbon spar capping you want: 1 @ 30%, 1 @ 60%, 1 @ full-length. Note that the shorter ones are applied first.
If you want to be belt and braces you can also add a shorter spar of the same construction in front of the wing joiner or behind it.
Let me know if any of that is not clear - then once you have it down in your head - or whatever variable you like to make of it, we can talk about a really nice finish out of the bag.
For the wing tips you want to try to direct the isobars coming off the wingtips to where you want them to go, and not anywhere that the pressure is lowest - which is what they will try to do. So anything a bit rounded would be good - something like the pics attached here: Actually the blue/orange/white might be the most effective. Also its a good idea to stop the ailerons/elevons a good 4" away from the tips.
I'm happy to say more and more people are starting to realise that full length ailerons are not a really good example of clear thinking on a model sailplane design.
Cheers,
Doc.
