Mixing construction materials

In the " I wonder if this would work " department, I have a question
about mixing different materials in main airframe structures. To make
a long story short, I was wondering if some weight could be saved by
making a wing with a carbon fiber spar ( high strength, light weight )
with aluminum ribs and skins. Would the carbon and aluminum be
compatible? Of course an acceptable method would have to be devised
to attach the ribs and skins to the spar, but I don't see this as a
big problem. Since the spars are some of the heaviest part of the
wing, I thought this would be a good way to save some weight, and in a
case I have in mind, an easy way to join the spar to the fuselage,
especially if the fuselage is composite. I would want to keep the
rest of the wing aluminum mainly to save dollars, but also because of
the proven history. Would the weight savings be worth the effort?

Neal

"Neal Fulco" wrote in message
om...
To make
a long story short, I was wondering if some weight could be saved by
making a wing with a carbon fiber spar ( high strength, light weight )
with aluminum ribs and skins.

Why mess with aluminum? Check out the construction methods for the new
CAP-10C wing at http://www.capaviation.com/. I'm not quite sure where this
link will take you - you may have to drill down a bit to reach to correct
page.

Rich S.

Earlier, (Neal Fulco) wrote:

I was wondering if some weight
could be saved by making a wing
with a carbon fiber spar ( high
strength, light weight ) with
aluminum ribs and skins.

I'm pretty sure a way can be found to make it work. But one awkward
aspect is the mismatch in Young's modulus between the spar and the
skin. See my earlier post on this topic:

http://groups.google.com/groups?hl=e...g.goog le.com

[Huge nasty Google link. Must be all on one line.]

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

(Bob Kuykendall) wrote in message . com...
Earlier, (Neal Fulco) wrote:

I was wondering if some weight
could be saved by making a wing
with a carbon fiber spar ( high
strength, light weight ) with
aluminum ribs and skins.

I'm pretty sure a way can be found to make it work. But one awkward
aspect is the mismatch in Young's modulus between the spar and the
skin. See my earlier post on this topic:

http://groups.google.com/groups?hl=e...g.goog le.com

[Huge nasty Google link. Must be all on one line.]

Thanks, and best regards to all

As luck would have it, the day after I made this post, I received my
copy of Custom Planes which had an article about a modified Sukhoi
that had a carbon fiber spar with aluminum ribs, but it said it had a
composite skin.

Neal

Bob K.
http://www.hpaircraft.com/hp-24