This paper presents aerodynamic optimisation of tiltrotor blades with high-fidelity computational
fluid dynamics. The employed optimisation framework is based on a quasi-Newton
method, and the required high-fidelity flow gradients were computed using a discrete adjoint
solver. Single-point optimisations were first performed, to highlight the contrasting requirements
of the helicopter and aeroplane flight regimes. It is then shown how a trade-off blade
design can be obtained using a multi-point optimisation strategy. The parametrisation of the
blade shape allowed to modify the twist and chord distributions, and to introduce a swept tip.
The work shows how these main blade shape parameters influence the optimal performance
of the tiltrotor in helicopter and aeroplane modes, and how a compromise blade shape can
increase the overall tiltrotor performance. Moreover, in all the presented cases, the accuracy
of the adjoint gradients resulted in a small number of flow evaluations for finding the optimal
solution, thus indicating gradient-based optimisation as a viable tool for modern tiltrotor
design
