System Identification of a Coaxial Ultralight Helicopter

This paper presents the synthesis of a flight mechanical model of a coaxial ultralight helicopter that features a teetering rotor system. The flight campaign, the identification process and the resulting model are presented. As a first step, the features that set the CoAX 2D apart from other helicopters are discussed briefly. A physical model that incorporates these features is developed and linearized to yield a state space model. Single axis inputs are used for the identification flight campaign. In the subsequent system identification, the parameters of the state space model are estimated in the time domain with a least-squares algorithm using measurement data. The results are validated in both the time and the frequency domain. The paper concludes with a model-based characterization of the helicopter