Control algorithms initially developed for tilt-wing vertical take-off and landing (VTOL) aircraft are adapted to the tilt-rotor design. The main difference between the two types of planes is the more complicated interaction between propellers and wings in the tilt-rotor design. Unlike tilt-wing design, the tilt-rotor case varies the angle between the propeller disk and wing cord line, thus introducing a non-linear dependency of lift on thrust and tilt angle. In this paper we develop a precise control allocation method, utilizing Groebner basis algorithms to mask the non-linearity of the control action and allow the use of linear time-invariant control laws for attitude and velocity control architectures. The performance of our approach is discussed and quantified w.r.t. the accuracy of the developed propeller-wing interaction model.