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Barriers to the more extensive use of advanced composites in heavily loaded structure on commercial transports are discussed from a materials viewpoint. NASA-Langley matrix development activities designed to overcome these barriers are presented. These include the synthesis of processable, tough, durable matrices, the development of resin property/composite property relationships which help guide the synthesis program, and the exploitation of new processing technology to effectively combine reinforcement filament with polymer matrices. Examples of five classes of polymers being investigated as matrix resins at NASA-Langley will be presented, including amorphous and semi-crystalline thermoplastics, lightly crosslinked thermoplastics, semi-interpenetrating networks and toughened thermosets. Relationships between neat resin modulus, resin fracture energy, interlaminar fracture energy, composite compression strength, and post-impact compression strength will be shown.

Wind-Tunnel-Wall Interference Assessment and Correction (MAC) concepts, applications, and typical results are discussed in terms of several nonlinear transonic codes and one panel method code developed for and being implemented at the NASA Langley Research Center. Contrasts between 2-D and 3-D transonic testing factors which affect WIAC procedures are illustrated using airfoil data from the NASA Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT) and Pathfinder I data from the NASA Langley National Transonic Facility (NTF). In addition, very recently obtained 3-D transonic WIAC results for Mach number and angle-of-attack corrections to data from a relatively large 20° swept semispan wing in the solid-wall NASA Ames High-Reynolds Number (HRN) Channel I (1.92% solid blockage) are independently verified by 3-D thin-layer Navier-Stokes free-air solutions. Initial results from the 3-D WIAC codes are encouraging; research on and implementation of WIAC concepts will continue.

High-angle-of-attack flight dynamics of the X-29 configuration were studied using dynamic model test techniques. These tests identified phenomena including wing rock, spins, and tumbling which dominate the high-α behavior of the configuration and define its usable flight envelope. Results of these tests have been used to design flight control concepts to minimize adverse behavior. Planned high-angle-of-attack flight tests of the X-29 airplane will provide an opportunity to validate the model predictions.