Design of vortex generators (VGs) on a tiltrotor aircraft infinite wing is presented using an adaptive surrogate modelling approach. Particular design issues in tiltrotors produce wings that are thick and highly loaded, so separation and early onset buffet can be problematic and VGs are commonly used to alleviate these issues. In this work, the design of VGs for elimination of separation is considered using a viscous flowfield simulations. A large design space of rectangular vane-type vortex generators is sampled and simulated, and a radial basis function surrogate model is implemented to model the full design space. An efficient adaptive sampling approach for improved design space sampling has also been developed that balances the properties of space-filling, curvature capture and optimum locating. This approach has been tested on the design of a VG on a highly loaded infinite wing, with a representative tiltrotor airfoil section, using a five-dimensional design space. Design of the VGs using this approach shows that elimination of the separation is possible whilst simultaneously reducing the drag of the wing with optimized the VGs, compared to the clean wing.