Accession Number : AD0859806

Title :   Isolation of Helicopter Rotor-Induced Vibrations Using Active Elements.

Descriptive Note : Final rept. Jun 66-Feb 68,

Corporate Author : BARRY WRIGHT CORP WATERTOWN MA BARRY CONTROLS DIV

Personal Author(s) : Calcaterra, Peter C. ; Schubert, Dale W.

Report Date : JUN 1969

Pagination or Media Count : 170

Abstract : Results of an analytical investigation of the feasibility of isolating helicopter fuselages from rotor-induced vertical vibratory forces while limiting the relative displacements during transient maneuvers and landing are presented. Electrohydraulic elements are combined to provide better than 90 percent isolation at the critical rotor frequencies. System parameters are selected for single-rotor helicopters ranging in weight from 2,000 to 80,000 pounds. Results of the parametric study show the response of the electrohydraulic notch isolation systems to the various types of dynamic excitations in terms of rotor and fuselage transmitted accelerations, relative displacement between the rotor and fuselage, stability margin, power requirements, and estimated isolation system weight. System performance and requirements are evaluated as a function of helicopter weight, blade passage frequency, number of notches of isolation, stability, changes in fuselage weight and rotor speed, and maximum allowable relative displacement during landing. Recommendations are made regarding experimental verification of system performance, incorporation of approach into practical hardware, and isolation of combined vertical and in-plane rotor-induced vibrations. (Author)

Descriptors :   (*HELICOPTERS, VIBRATION), (*HELICOPTER ROTORS, VIBRATION), FEASIBILITY STUDIES, FUSELAGES, VIBRATION ISOLATORS, MANEUVERABILITY, AIRCRAFT LANDINGS, PERFORMANCE(ENGINEERING).

Subject Categories : Helicopters
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE