Hi Lou,
I am currently in the process of rebuilding a Jurca Mj-5 that has balsa
as a filler in many areas such as the firewall, some areas in the
fuselage and the wingtips and elevator tips are also balsa. The
condition of the balsa after 15 years is just abysmal. I would go with
polyeurathane foam or spruce.
all the best
Sean Trost


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