This paper reports the experimental results of the dynamic modelling using MIMO closed-loop system identification, controller design and implementation for hovering flight of a radiocontrolled helicopter. The helicopter is set on our handcrafted supporting device, and it has the roll, side-to-side and up-and-down motions that controlled by the aileron and the throttle. Several dynamic models with defferent orders are derived from closed-loop system identification experiments with the MOESP-type closed-loop subspace model identification method (CL-MOESP). Then, we compared their model with the real system, and LQR with a full state observer is designed and implemented.