an initial geometry for a nacelle provides an intake at the upstream end of the nacelle and an exhaust at the downstream end of the nacelle . the intake has in flow series , an intake lip and a diffuser . the intake lip has a highlight defining the boundary between the inner and outer surfaces of the intake lip . on all longitudinal sections containing the axis of the engine the inner and outer surfaces are tangency matched at the highlight , and the inner and outer surfaces have their maximum curvatures at the highlight .