Actuation Requirements for a Swashplateless Helicopter Control System

A helicopter primary control system with smart trailing-edge flaps was investigated numerically for its potential to replace a conventional swashplate system. Eliminating the swashplate and associated control system may lead to significant reductions in weight, drag and cost and an improvement of rotor performance. A comprehensive rotorcraft analysis based on UMARC was developed for analyzing the swashplateless rotor configuration, and was implemented to examine the actuation requirements for rotor primary control with trailing-edge flaps. A multicyclic controller was implemented with the swashplateless rotor analysis, and the feasibility of trailing-edge flap performing both primary control and active vibration control was examined. The baseline correlation of rotor control settings and blade sectional moments without trailing-edge flaps was carried out successfully with wind tunnel test data for a typical 5-bladed bearingless rotor system. Calculations of blade torsional moments and blade tip pitch, as well as trailing-edge flap hinge moments, were compared satisfactorily with predictions from CAMRAD II with an active trailing-edge flap input. Flap control inputs of a swashplateless rotor are presented at several advance ratios. With optimal selection of blade collective pitch index angle, the flap was shown to be able to trim the rotor with moderate flap inputs. Simulations of flaps performing both primary control and active vibration control were carried out, with the conclusion that trailing-edge flaps are capable of

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