Optimization of Rotorcraft Noise Abatement Trajectories

"A software suite is presented that aims to optimize rotorcraft trajectories with respect to the environmental impact on the human environment, with a strong emphasis on noise abatement. To model the asymmetrical noise characteristics of rotorcraft, a source noise. database is used, which is calculated offline. The propagation model, integrated in the optimization framework, is a semianalytical approach to raytracing which has been. developed especially for the purpose of trajectory optimization. The community noise impact is then assessed through amongst others doseresponse relationships, in. combination with a Geographical Information System containing population density data. The noise models, together with a rigidbody rotorcraft flight mechanics model and a fuel. and emissions model have been integrated in a gradientbased optimization framework.. With this method, environmentally optimized trajectories have been generated which take into account noise impact, fuel burn and gaseous emissions, while complying with a set of. operational constraints imposed on the problem. As numerical examples, a socalled. Simultaneous NonInterfering approach at Amsterdam Airport Schiphol is presented, as. well as a medical flight to an inner-city hospital. These cases show significant noise impact reduction, while maintaining the increased fuel burn to within acceptable levels with. respect to a fuel optimized case.. . "