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An implicit finite-difference solver for either the Euler equations or the "thin-layer" Navier-Stakes equations was used to calculate a transonic flow over the NACA 64.4010 airfoil pitching about its 1/4 ciiard.An unsteady automatic grid-generation procedure that will significantly improve the computational efficiency of various unsteady flow problamc is described. The calculated results for both inviscid and viscous flows at Mach number 0.8 over the airfoil oscillating with reduced frequency referenced to one-half chord, 0.2, are compared with experimental datu measured in the h e s 11-by 11-Foot Transonic Wind Tunnel. Nonlinear, unsteady effects of the flow on the surface pressure variations, shod-wave excursions, and overall airloads are examined. Goad agreements between the results of computations and experiments were obtained. Calculations required relatively short computational times of 12.7 min for the inviscid flow and 130 min for the viscous flow on a CDC 7600 for one full cycle of airfoil oscillation.

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