Sonic Boom Minimization Through a Simplified Approach for the Preliminary Design of Civil Supersonic Aircraft

In this paper a simple approach aimed to the definition of a supersonic configuration optimized in terms of sonic boom signature will be presented. This approach is based on the application of Carlson’s method that is a simplified method for the calculation of sonic-boom characteristics for a wide variety of supersonic airplane configurations and spacecraft. Sonic-boom overpressures and signature duration may be predicted for the entire affected ground area for vehicles in level flight or in moderate climbing or descending flight paths. This prediction technique is based on simplification of the purely theoretical methods, which are able to provide quite acceptable estimates of sonic-boom phenomena for a wide range of flight conditions for conventional airplane configurations. Experimental measurements have shown that this approach describes properly sonic-boom properties for extremely blunt bodies at high supersonic speeds, providing reliable numerical information at distances large relative to body dimensions. The effects of flight-path curvature and aircraft acceleration, however, are not considered, and the method is further restricted to a standard atmosphere without winds. Furthermore, it is assumed that the pressure signal generated by the aircraft is of the far-field type, the classical N-wave. The information required, for the calculations and the pressure-signature predictions provided by the simplified method, are: aircraft shape-factor; aircraft operating conditions; atmospheric data. The signature data provided by the method include: N-wave bow-shock overpressure; the signature duration; the location of the ground impact point relative to the aircraft position at the time the boom was generated. This approach has been adopted to evaluate the sonic boom properties of a supersonic reference configuration comparing the numerical results with a more refined CFD approach. Then an optimization procedure has been applied to minimize the maximum value of overpressure: the geometry of the reference configuration has been modified iteratively following the criteria suggested by the Carlson’s method and keeping in mind several operational constraints: this iterative method has permitted the definition, in a preliminary stage of design, of an optimized supersonic configuration.