The robust adaptive control of tilt-rotor aircraft is addressed using backstepping and θ-D based control design techniques. The designs specifically focus on providing high robustness to time-varying system parameters and disturbance effects from the environment to attain good disturbance attenuation properties in highly aerodynamically challenging environments such as shipboard environments. The control system is structured with a modular architecture combining adaptive backstepping and adaptive θ-D control algorithms and provides flexibility and customizability for various tilt-rotor aircraft configurations and operating environments. The overall control system and its constituent algorithms are designed to either be able to operate on their own to provide fully autonomous flight or to operate in conjunction with a human pilot or an existing baseline controller in a control augmentation fashion to provide additional robustness and reliability improvements under severe aerodynamic disturbance conditions. The robustness, stability, and performance of the proposed control algorithms are demonstrated through simulation based studies.