1. Free space oscillating pressure near the tips of rotatini propellers;Hubbard;NACA Report 996,1950
2. On the sound field of rotating propeller;Gutin;NACA TM 1195,1948
3. A theoretical study of the effect of forward speed on the free space pressure field around propellers;Garrick;NACA TN 3018,1953
4. Measurements of free space oscillating pressures near propellers at flight Mach numbers to 0·72;Kurbjun;NACA Report 1377,1958
5. Investigations of rotor noise source mechanism with forward speed simulation;Grosche;American Institute of Aeronautics and Astronautics Journal,1978