Interesting discussion.Â* Another question for Bob K. and other experts:Â* If you saw crosswise (cross section) through a typical sailplane's main spar tongue/stub what would it look like?Â* Mostly foam surrounded by many layers of fiberglass?Â* About how much glass versus foam?Â* Just trying to envision a vital structural component that most of us take for granted and never see the inside of unless one is a designer or fabricator.