PURPOSE The high static thrust and relatively low installed engine power for propellers has been a factor in their consideration as propulsors for vertical and short take-off and landing (V/STOL) aircraft. The simplicity and low cost of the propeller has historically been a factor in its selection for the majority of general aviation aircraft. With the increased emphasis on noise generated by all types of aircraft there has been an increasing interest in controlling the noise of new V/STOL and conventional transport aircraft as well as general aviation aircraft. To assist the designer of new aircraft as well as others interested in the noise characteristics of various propeller configurations the procedure described in this Aerospace information Report (AIR) has been developed.