Downwash modelling for three-lifting-surface aircraft configuration design

This paper introduces a semi-empirical model to predict the downwash gradient at horizontal tail of three-lifting-surface aircraft. The superposition principle applied well established formulations valid for two lifting surfaces is not reasonable approach calculate canard-wing-tail layout, and this demonstrates that such basic technique leads incorrect results. Therefore, an ad hoc prediction proposed considers combined nonlinear effects canard main wing inductions on downwash, being based full factorial design sweep CFD simulations obtained by varying geometrical parameters three surfaces. A suitable analytical formula through process data analysis factor extraction. presented extends validity available models traditional two-lifting-surface designs means correction factor. engineering estimation method introduced here exhibits acceptable accuracy, as relatively small errors, it conceptual preliminary studies three-surface layouts. value methodology confirmed validation with results numerical experimental investigations case study