private double MachDragEffect(double M) { double multiplier = 1; if (M <= 1) { multiplier = 1 + 0.4 * FARAeroUtil.ExponentialApproximation(10 * M - 10); } //multiplier = 1f + 0.4f * Mathf.Exp(10 * M - 10f); //Exponentially increases, mostly from 0.8 to 1; Models Drag divergence due to locally supersonic flow around object at flight Mach Numbers < 1 else { multiplier = 0.15 / M + 1.25; //Cd drops after Mach 1 } return(multiplier); }