Etude d'un rotor d'hélicoptère sans plateau cyclique avec des servopaddles actives

摘要

This thesis presents the design, fabrication, testing and analytical study of a novel concept of actively controlled Hiller type servopaddle to achieve rotor primary control. The blades on the swashplateless rotor are coupled to a servopaddle equipped with a piezo electrically actuated aileron located behind the paddle trailing edge. The aileron is deflected because of the actuator and generates a lift. This leads to a variation of the paddle pitch moment, as well as of the paddle pitch and lift. Hence, a change in paddle flap and in blade pitch via a mechanical linkage is created. The system {blade, paddle, aileron} is independent from any other {blade, paddle, aileron} assembly. Thus, the active servopaddle can generate both cyclic and collective inputs. Such a system presents the advantage of reduced mechanical complexity, parasitic drag and weight. The fuel consumption of the aircraft is thus expected to significantly decrease and its availability to increase. A small scale RC helicopter has been flown outdoor and served as a proof of concept. The system showed good hover capability under windy and non predictable conditions. A four degree-of-freedom analysis including aileron dynamics has been developed to predict the dynamic behavior and assess the feasibility of such a swashplateless rotor. The analysis is used to investigate the effect of system parameters on the blade control authority. Hover stand tests are performed in a more controlled environment. The aim of these tests is to validate the theory and to investigate the effects of different design variables on the blade pitch response. To this end, the system is equipped with sensors. In the case of both the outdoor and hover stand tests, the paddle actuation is achieved by a small swashplate to ensure a quick, affordable and simple design. The rest of design remains the same as described earlier. For a paddle of span equal to 40% of the blade radius, with a cyclic pitch input of 9°, a 5° blade cyclic pitch output was observed.