I plan to make a set of 149" wings for my sailplane, and needed wood for the wing spars. The wood that I purchased for this purpose is aircraft quality spruce from the Aircraft Spruce & Specialty Company, and I was impressed with the quality of their products. Wonderful quality wood. It should be perfect for this application. You can generally order thicknesses and widths for a reasonable price. Since this is spruce that is used to construct full scale airplanes, for modeling purposes the spruce trim panels are what I mostly looked at. You will be hard pressed to find better quality. You can visit their website at
www.aircraftspruce.com.
I've also got a Spirit 100 under construction, and plan to use the included basswood. It's lighter than spruce, and this since plane ends up very heavy when it's finished compared to other 100" sailplanes that I've built, any place where I can reduce weight is probably a good choice. For this plane, the basswood should work fine.
juggler