Swashplate-less Control

[Al_Hammer]

..............;)

[Jan Verhoeven]

An analytic model was developed for the response and trim of a swashplateless controllable twist rotor featuring a piezoelectric induced-shear tube actuator. First, a parametric study was conducted to determine the sensitivity of the actuation requirements for primary rotor control to blade structural properties. The study indicated that the rotor torsional frequency is the most dominant design parameter that governs control effectiveness. Next, an optimization study was conducted to explore the feasibility of developing an actuator configuration for a Mach-scaled model that satisfies the force and stroke requirements, subject to constraints of blade geometry, maximum allowable weight penalty and limitations of current piezoelectric actuator technology. The study indicated that for present piezoelectric materials (0.15% maximum strain) feasible solutions exist only for advance ratios up to 0.1 and blade torsional frequencies below 1.8/rev. To achieve feasible solutions at advance ratios that are more representative of cruise (~0.3), the required piezoelectric strain is about 0.23% (i.e. up to 50% improvement in current piezoelectric actuator capability is necessary).

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