2 years ago I decided to leave autocad for reasons of not being able to make complex 3d bodies with it (katana t30). I tried some free cad applications with no result.
Somebody gave me Solidworks2010 and I tought myself using it. Few months ago it began to show some flaws in some functions (all software degrades after some time) so I looked for a crack version of SW2012, found one
and installed it. After a few months it stopped starting up. It remains busy after loading the drawing board window. I cannot reinstall the one or the other after doing the usual tricks. (restoring windows xp? manually removing
all kinds of stuff left over by SW uninstall, shutting down virus scanner and much more).
Again went to free cad programs but they all seem to hide very well the things I need so bad(splines,guide driven lofting, sketching on predefined planes to mention some) so it seem they are just too weak for modelling curvy model airplanes.
I installed DraftSight from SW (it's for free).It's autocad-like but with no lofting, well it's better than nothing.
I think if someone could make a 3d program that is worth the name for a few hundred they would sell quite some licenses.
I can't afort to spend thousands of dollars on a decent 3d program with a lot of stuff I don't need . So I hope something will come up in the near future.

Other thing, I don't understand how the sketch-up specialist here manages to form the wing rib curves because I cannot find any tool to do it.