Higher harmonic control system for X-Wing aircraft

In an X-Wing aircraft a dynamic higher harmonic control (HHC) system addresses the vibration which typifies a very rigid rotor and is implemented in two ways-a scheduled HHC and an active HHC. A scheduled HHC is located within the quadruple redundant portion of the flight control computers (FCC). Th...

Full description

Saved in:
Bibliographic Details
Main Authors FISCHER, JR.; WILLIAM C, ARIFIAN; KENNETH C
Format Patent
LanguageEnglish
Published 28.08.1990
Subjects
AEROPLANES
AIRCRAFT
AVIATION
COSMONAUTICS
HELICOPTERS
PERFORMING OPERATIONS
TRANSPORTING
Online AccessGet full text

Cover

More Information
Summary:In an X-Wing aircraft a dynamic higher harmonic control (HHC) system addresses the vibration which typifies a very rigid rotor and is implemented in two ways-a scheduled HHC and an active HHC. A scheduled HHC is located within the quadruple redundant portion of the flight control computers (FCC). This includes look-up maps for the second through fifth harmonic coefficients of the control equation as a function of airspeed and lift for rotary wing (RW) operation, and as a function of rotor speed for conversion (CV) operation. These are added to the collective and cyclic terms of the control equation and implemented through the pneumatic control valve (PCV) actuators. This flight critical portion of the HHC maintains vibration loads within structural limits. An active HHC, implemented in a dual redundant configuration, is added primarily to enhance vibration control during maneuver conditions and during conversions. It monitors vibrations at selected locations and in selected axes of the vehicle and generates corrective factors, which are added to the scheduled coefficients. The active HHC, representing a significant computational burden, is implemented in a separate dual processor computer section, complete with its own input/output signal processing.
Bibliography:Application Number: US19880257473