In the paper the simple adaptive control approach is employed to designing the adaptive controllers of quadrotor angular motion. The adaptive controllers are synthesized based on the Implicit Reference Model (IRM) design technique. The 'shunting method' (parallel feedforward compensation) is used to cope with the unmodelled plant dynamics. Analytical justification of system stability is made by employing the Passification method. Quality of the closed-loop IRM adaptive control system is studied and compared with that of the proportionalderivative (PD) non-adaptive control system experimentally on two degrees of freedom (2DOF) quadrotor testbed and in-flight tests of the QuadRoy quadrotor for nominal and parametrically perturbed cases.