steveukman wrote:

...
Option 1. Wood.
Plenty of wood plans around, easy to build, but heavy (when you
consider the plywood, stiffeners &c.) and I am not sure of the ultimate
strength.

The ulitmate strength is whatever is designed into the plane. There is
more variation in wood than in metals, you need to carefully inspect
every stick for defects, runout in the grain and so onl

Wood rots, that is a consideration if the plane is not going ot be
hangered.

....

Question 2.
How could I join wood longeron to Al tube? At first glance I could
'splice' by insering the wood into the tube to a sufficient depth and
then drill & bolt ... and/or use Al gussets to clamp the wood outside
the tube. Is gluing wood to Al an acceptable practice?

Wood expands and contracts with changes in ambient humidity,
even when it is varnished. FIlm finishes are permeable to water vapor,
they slow the transpiration rate, but do not stop it. Aluminum
expands and contrants with changes in temperature.

Those differences spell trouble for a glue bond between wood
and aluminum.

In general any permanent joint between wood and metal should
be mechanical. Glue in addition to the mechanical fastening
would be fine, but never glue alone.

I've done woodworking and stress analysis so there are my two
decibucks. Others will comment on working with metals
and specifics to airplanes.

--

FF