An Invistigation The Dyanmic Behavior Of A Helicopter Electro-Hydraulic Servo-Actuator

The present work deals with the static and dynamic performance of an Electro-Hydraulic Servo-Actuator (EHSA) equipped with jet pipe hydraulic amplifier, aswell as Hydraulic Servo-Actuator (HSA) with special design. These twocomponents are used in the flight control system of a helicopter aircraft. TheEHSA transmits the autopilot signals to the flight control system while the HSAtransmits the pilot commands.A nonlinear mathematical model of the jet pipe (JP) amplifier has been developed.This model along with published experimental results were used to predict the flowdischarge coefficients of the amplifier hydraulic circuit. Nonlinear mathematicalmodels of the EHSV and EH SA as well as the HSA were also developed.The simulation programs based on MA TLAB program were developed for theabove-mentioned mathematical models. Experimental work on the JP amplifierstatic performance and EHSA static and dynamic behavior were carried out.Validations of the computer simulation programs were conducted by comparingthe computational results with experimental data. Also the sensitivity of developedmodels to changes in operating conditions and geometrical parameters wasexamined.