GA Aircraft Wingspar

[Guptar]

On a small piston twin, such as a Piper Chieftain, would a Carbon Fibre Spar be any lighter than a conventional one. Are the any drawbaks such as

Cost

Complexity of attatching a Composite spar to aluminium wing ribs.

[pfflyers]

I'm a noob here, but I'll jump in 'cuz I do have some experience with aircraft composites. I think one of the bigger issues would be the fact that you probably couldn't use conventional rivets. The swelling that occurs during installation would damage the composite. Not necessarily a show-stopper, but it would require some re-engineering. All your connections would probably need to be screws and nuts (carefully torqued). Boeing had quite a time designing the wing-to-body attachments on the 787 to give them the strength and fatigue life they needed.

[Trim Stab]

The handling of the aircraft would be different due to the stiffer wing, and the ride would probably not be very comfortable in turbulence.

A certain amount of wing-flex is desirable, and carbon-fibre wingspars are very stiff. For example, DA42 uses carbon fibre widely in its construction, but the wingspars are GRP because CF would be too stiff. Also, if ever you get to fly a CAP10B (wooden spar) and a CAP10C (carbon spar) you will feel the difference.

Apart from that, there should be no reason why you could not use a carbon spar in an aluminium airframe. There are lots of ways to mechanically fasten carbon-fibre to metal components though, as noob points out, probably expensive and time-consuming to mass produce.