Lower Bounds for Sonic Booms in the Midfield

This paper presents new lower bounds for sonic booms based on minimizing either the overpressure or the shock strength of the positive part of the boom wave. The results are not restricted to the limit of large distance from the aircraft. They reduce to the Jones lower bound infinitely far from the aircraft in a uniform atmosphere but they give reductions from the Jones lower bound of the order of 50% for planned supersonic transport conditions. This is because the asymptotic results of Jones are approached very slowly (as r~1/4) in a uniform atmosphere and are never reached in the real atmosphere. The direct application of these results depends upon additionally keeping the tail shock intensity less than or equal to that of the front shock.