YUH-60A Stability and Control

This paper covers the development and flight evaluation of the UH-60A handling qualities. Considerable Sikorsky and Military flight testing of the YUH-60A has been accomplished, and the resulting flying qualities are discussed herein. Powered and unpowered wind tunnel tests, conducted at the United Technology Research Laboratories, have allowed a good understanding of the aerodynamic forces involved and have provided data for analytic models. Key results from 1/10th and 1/4th scale wind tunnel tests are presented and the impact of this data on the stability and control and design of the UH-60A are discussed. The flight control system on the UH-60A provides crisp aircraft response to pilot commands. The controls were designed to provide ballistic resistance without resorting to override springs. The three axis SAS on the UH-60A provides added damping and a separate longitudinal actuator provides positive stick gradient with airspeed. The operation of the stabilator evolved through the various design and development stages to the point where it is an integral portion of the control system and is noteworthy in its contribution to the overall excellent handling qualities and maneuverability of the helicopter. The automatic flight control system on the UH-60A is structured for full independence of subsystems with the digital computer acting as the monitor on all of the electronic systems. The force feel and trim system, the airspeed and other hold features, the coordinated turn-feature, the stabilator system, and the stick gradient feature are all discussed in terms of design and operational characteristics.