N.A.C«A. Technical Uemorandmn No. 618 7ig8.1,2,3,4»5 ^ Trme. … Tigore 5,-> Resonance frequencies of spring with nat\iral frequency of 7540/min« Tigure 4.- Section Nos. 260 to 430 indicated rotations per minute. through Hos* 29 to 17*5 indicate number of free the test apparatus» oscillations per rotation* a = test spring. fig^S.
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