Flight investigations of the effect of yaw on the intake and fan nozzle flow of a natural laminar flow nacelle

Two major technologies in aeronautics promise substantial improvements in the fields of economy and ecology. One is laminar flow technology and the other arises from new developments related to aircraft turbofan engines. The trend in turbofan engine development is towards engines prossessing higher bypass ratios. This, however, entails larger engine dimensions, leading not only to an increase in the skin friction drag but also to negative engine-airframe interactions. As a consequence, the need for laminar flow nacelles becomes all the more important as part of the general process of engine-airframe integration optimization for advanced transport aircraft. This paper deals with some results obtained from flight tests with a laminar flow nacelle demonstrator and specially addresses the topic of aerodynamics of intakes and nozzles. The results described relate to a European collaborative programme in which a natural