An MDO-based methodology for static aeroelastic scaling of wings under non-similar flow

Overview & Synopsis

The classical aeroelastic scaling theory used to design scaled models is based on the assumption that complete flow similarity exists between the full aircraft and the scaled model. When this condition is satisfied, the scaling problem of the model can be treated as a structural design problem only, where the scaled aerodynamic shape is preserved. If, on the other hand, this hypothesis no longer holds if the scaled model is constrained to fly at low speed and low altitude, for example and both the aerodynamic shape and the flexibility of the structure are exactly scaled, then the static response exhibits significant discrepancies in the aerodynamic loads and structural displacement. To design a flying demonstrator with scaled static response when flow similarity cannot be fulfilled, we present a multidisciplinary optimization-based method that allows some freedom in the design of the wing shape (while keeping the scaled wingspan) to update the wing geometry and structural properties to ensure equivalent scaled loads and overall wing displacement. To illustrate this method, we apply it to a 1:5 version of the uCRM wing at subsonic flight condition. While the errors in air loads using the classical theory are around 16%, the presented method achieves errors lower than 1%, with a good agreement for the wingtip displacement.