On 6 Dec 2003 13:11:20 -0800, (Lou Parker) wrote:

:In many area's on my wood structure it calls for a filler. Usually
:spruce, but for no other reason but to fill a gap. These are not
:structural in the least, only to fill (i.e. on top of the spar a 1/4"
:strip of wood to keep the plywood skin from saging in between the wing
:ribs). Has anyone used Balsa wood to accomplish this to save on
:weight. There seems to be alot of little areas like this in my plans.
: Lou

On the prototype Berkut we used end-grain balsa as a core in a
fiberglass sandwitch structure. 3 years later one area, where water
pooled regularly inside the fuselage, had the balsa rot away. Other
areas were fine. We went to PVC foam, and later to SAN foam.