Making wood propeller?

Inspired by a couple of articles on Bob Hoovers blog and the fact that
it's likely that my first homebuilt will be slow and VW-powered, I was
thinking of making a wood propeller. I have access to a 3-axis CNC
lathe which should be long enough for at least half a prop, so that's
not an issue.

Bob went ahead and got a couple of shelving boards made of pine and
glued them together. So far so good.

I probably made a beginner's mistake and went to the local home
improvement store (Bauhaus, a German chain) to look at the different
solid wood boards they offered. The good side: The choice is huge. The
bad side: I have no idea if the stuff is any good.

Woods available a
- spruce
- birch
- beech
- oak
- eucalyptus (which has neat coloration, btw)
- paulownia
and even more exotic stuff I had never heard of.

I guess spruce is widely used in aviation, dang cheap and the sticks
they use to make the shelving boards run the full length, which seems
good for strength. The problem I have with it is the huge number of
knotholes, which would weaken the prop.

The others are much more expensive, are made of smaller bits of wood,
and apart from birch plywood I have never heard of them being used in
aviation.

So I guess it's practicing on "box store" spruce. But what should I
use for the "real thing"?

Oliver, also trying to bring some life back into the group ;-)