Answer: What does Composite construction mean?
Composites are materials combining two or more organic or inorganic components. One material serves as a "matrix," which is the material that holds everything together, while the other material serves as a reinforcement, in the form of fibers embedded in the matrix. Until recently, the most common matrix materials were "thermosetting" materials such as epoxy, bismaleimide, or polyimide. The reinforcing materials can be glass fiber, boron fiber, carbon fiber, or other more exotic mixtures.
The GlobalFlyer utilizes a carbon fiber skin on most surfaces.
For more information about the plane, go to http://www.sal.k-state.edu/globalflyer/theplane.htm