A new disturbance-rejection continuous nonlinear control strategy is developed for the attitude and altitude channels of a tilting tri-rotor unmanned aerial vehicle(UAV), which is subject to parametric uncertainties and unknown external disturbances. The proposed control algorithm is based on the immersion and invariance methodology which is used to provide estimation for the unknown system parameters. Then a continuous robust algorithm is combined to compensate for the unknown disturbances and parametric estimation errors. Lyapunov based stability analysis is presented to prove the stability of the closed loop system and asymptotic tracking results. Real-time experimental results are included to validate the performance and robustness of the proposed control development.