| Abstract |
Detailed engineering procedures are presented for estimating, sound pressure levels on or within a flight vehicle. The report Is oriented for use by the aircraft engineer In making preliminary estimates of noise levels on or in a vehicle, when the vehicle is still in the design stage. Therefore, the procedures are expressed in terms of general parameters (such as mechanical power, typical dimensions, forward speed) which may be obtained to a satisfactory degree of accuracy long before flight testing. The first step in the procedure is the estimation of noise levels exterior to the vehicle. Contributions from the various sources of noise that may be encountered are estimated. The effects of forward speed and altitude on exterior noise levels are considered in some detail. Next, the basic noise-transmitting properties of panel structures are studied. The effects of coincidences, resonances, damping, etc., are included. Finally, the particular vehicle geometry of interest is considered. The source and transmission properties already determined can then be combined, with appropriate geometrical corrections for the character of the receiving space, to yield the desired estimates of interior noise levels. Several examples are worked out in detail to illustrate the application of the report procedures to typical vehicle configurations. |
