The requirements for simulating in a wind tunnel flutter conditions appropriate to high-speed flight are discussed, and an assessment is made of the desirable features of a wind tunnel suitable for flutter testing at transonic and supersonic speeds.nIt is concluded that such a tunnel should have either the' Mach number or the stagnation pressure variable during the tunnel run, and that it is of considerable advantage and for some purposes essential, for high stagnation pressures to be available. The stagnation pressure required to allow flight conditions to be simulated with a flutter model is considered to range from at least 2 atmospheres for transonic speeds to about 15 atmospheres for M = 4. No attempt to simulate kinetic heating is envisaged, although its effect on stiffness should be allowed for in the design of the model. To minimize uncertainties due to the variation of the model stiffness with temperature it is desirable that means for controlling the stagnation temperature should be incorporated in the tunnel.
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