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A carbon fiber-epoxy wing box was constructed in order to study the behavior of a stressed-skin wing structure with anisotropic sandwich skins. Two wing skins, two spars, and three ribs made up the structure. The spars were designed to act primarily as shear webs so that the bending load in the structure would be reacted mainly by tension and compression in the skins. Linear, buckling, and nonlinear NASTRAN finite element solution sequences were implemented in the analysis of the structure. The structure was loaded as a cantilever beam and strain and deflection measurements were recorded. The finite element nonlinear analysis accurately modeled stiffness, but results for strains at a point were not as accurate.

The faculty and staff of the Raspet Flight Research Laboratory (RFRL) have concluded a project with an industrial customer to lead a group of engineers and technicians in a study of the “art” of developing a prototype composite aircraft. The objective was to produce a turbine powered, composite, pressurized, single-engine aircraft, which would introduce the team to the many aspects of a complex aircraft in a environment. The prototype Allison Soloy turbine conversion of the Beechcraft A-36 was chosen as the study aircraft. It was proposed that the A-36 structure be replaced with composite structures in three steps of increasing complexity. The sequence was to first design-build-test-fly the tail, then the wings, and finally the fuselage. To limit the difficulty of the project development and to allow a meaningful comparison between aluminum and composite structures, the configuration modifications were to be minor and to utilize existing RFRL Marvel II composite technology.