SONIC-BOOM CHARACTERISTICS OF PROPOSED SUPERSONIC AND HYPERSONIC AIRPLANES

SONIC-BOOM CHARACTERISTICS OF PROPOSED SUPERSONICAND HYPERSONIC AIRPLANES IBy F. Edward McLean, Harry %[. Carlson,Langley Research Centerand Lynn W. HuntonAmes Research CenterSUMMARYExisting theoretical methods of sonic-boom estimation have been used to Idetermine the sonic-boom profiles of representative supersonic and hypersonicairplanes of the future. The sonic-boom characteristics of these future air-planes have been related to the sonic-boom characteristics of current super-sonic airplanes. In the supersonic climb and cruise phases of flight_ wherethe sonic-boom overpressure and impulse levels are relatively high, the use ofnear-field effects to modify the sonic-boom disturbance of these large futureairplanes has been considered. The near-field investigation indicates thatsome reduction in overpressure and impulse might be possible.INTRODUCTIONConsideration was given to the aerodynamic drag problem associated with thepressure disturbances about a supersonic airplane in reference I. As the pres-sure disturbances generated beneath the airplane propagate to the ground theygive rise to another problem - the problem of sonic boom. The noise and struc-tural excitations which can result from sonic boom have raised serious questionsas to the acceptability of routine flights of future supersonic and hypersonicairplanes over populated areas. Since these routine flights would be desirablefrom an economic standpoint, sonic boom has thus become a major considerationin the design and projected operation of these proposed airplanes.During the course of research on the sonic-boom problem, theoreticalmethods have been developed which can be used to relate the sonic-boom disturb-ance to the characteristics of the airplane (refs. 2 to 5). These methods arebased on the equlvalent-body principles discussed in reference 1. Procedureshave also been developed to account for the propagation of the sonic-boom dis-turbance from the airplane to the ground (ref. 6.). The purpose of the presentpaper is to utilize these existing methods to relate the predicted sonic-boomcharacteristics of the large, heavy supersonic and hypersonic airplanes of thefuture to those of currently operational supersonic airplanes. Another purposeis to explore some means which might beused to modify the sonic-boom disturb-ances associated with these proposed airplanes.ipresented at the classified Conference on Aircraft Aerodynamics, LangleyResearch Center, May 23-25, 1966, and published in NASA SP-124.