Originally Posted by Knoll53
Box Beams are used in construction, often with a 2x4 top and bottom and plywood sides. Very stiff.
My experience of inspecting aircraft designed with box spars in the Jodel range of homebuilt aircraft and their series cousins Robin DR300/400 etc shows how quite large wooden wings can be built very strong whilst still light and stiff. CAD definitely useful in our model sizes to build a ply spar with tongues and notches as in Gerd's build to avoid the need for glueing battens.
Must get a CAD/CAM program somewhen, now that my fretsawing arm is not what it once was the fun seems to fade after cutting the first couple of feet, and certainly cannot match the consistent accuracy of a machine