Calculation of unsteady forces acting on two-dimensional oscillating airfoils by Newtonian snowplow theory. A pressure formula, valid for linear and nonlinear oscillations is obtained, and comparisons are made with the gasdynamic theory for a hypersonic slender wedge undergoing small angle oscillations. The comparisons indicate that, while Newtonian theory is less accurate than simple impact theory, neither theory gives reliable estimates of unsteady stability derivatives in air.
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