The lift characteristics of a wing with an aspect ratio of 4.364, a taper ratio of 0.41, zero sweep of the trailing edge, and modified hexagonal airfoil sections parallel to the air stream were investigated in the Langley low-turbulence pressure tunnel at Mach numbers from 0.379 to O.896. Nonlinearities in the lift curves were obtained at small angles of attack for Reynolds numbers of the order of 1 x 106 at all test Mach numbers. Increasing the Reynolds numbers to 3 X 106 and 5 X 106 eliminated nearly all the observed nonlinearities. The addition of surface roughness to the test model at the lower Reynolds numbers also eliminated a large portion of the nonlinearities in the lift curves obtained for the smooth model. An explanation is offered of the boundary-layer phenomena probably responsible for the results obtained.
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