Linearization of the GenHel S-76D Model with Engine and Fuel Control Models

The Sikorsky S-76D™ helicopter was to incorporate a new automatic flight control system (AFCS). Linear flight dynamics models were needed to support design of the AFCS. The linear models were derived from the GenHel S-76D model. A requirement existed for governed rotor speed dynamics to be incorporated into the linear models used for AFCS design. Consequently, the process of incorporating the governed rotor speed dynamics into the linear models had to be developed. In this paper, the method used for incorporating these additional degrees of freedom into a linear model derived from the GenHel S-76D model will be discussed. In addition, the impact of these additional degrees of freedom on aircraft flight dynamics pertaining to AFCS design will be examined.