Hovering and Low-Speed Performance and Control Characteristics of an Aerodynamic-Servocontrolled Helicopter Rotor System as Determined on the Langley Helicopter Tower

摘要

Some type of servomechanism to control the blade pitch of a helicopter rotor may be desirable in certain cases, for example, in large rotors where excessive control forces and pitching moments may be encountered. Accordingly, tests were made on the Langley helicopter tower to determine the performance and control characteristics of an aerodynamic-servocontrolled helicopter rotor system. It was intended that an investigation of this configuration would give fundamental information of a general nature on rotors with such control systems. The rotor differs from conventional rotors by the unique method of controlling the blade pitch. In this rotor configuration, the blade is attached rigidly at the root, and pitch change is effected by twisting the blade at an outboard station by means of an aerodynamic flap instead of by rotating the blade at the root. This paper presents measurements of the rotor performance for hovering and low forward speeds. Measurements of the aerodynamic-flap servocontrol characteristics and the transient response of the rotor to various control movements are also included. The results of the measurements are discussed and, in a few cases, comparisons are made with conventional rotors with pitch actuation accomplished by rotating the blade roots.