AH-1G Helicopter Aerodynamic and Structural Loads Survey.
Final rept. Jun 74-Apr 76,
BELL HELICOPTER TEXTRON FORT WORTH TEX
Pagination or Media Count:
Accurate prediction of helicopter system loadings required detailed knowledge of rotor aerodynamic environments and structural dynamic responses. This report describes a flight test program of an AH-1G helicopter where airfoil surface pressure, leading edge stagnation point, local flow magnitude and direction, blade accelerations, bending moments, and the attendant responses in the control system and airframe were measured simultaneously. The hardware development, instrumentation techniques, test conditions, and initial data analyses are discussed. The development of a rotating frequency-division multiplex, capable of regulating and conditioning over 300 transducer signals, and the component testing and calibration of those transducers are described. Samples are presented of pressure distributions, leading edge stagnation point versus azimuth, and surface flow magnitude and direction. Aerodynamic forces and responses in the rotor and control systems are presented and compared with predicted analytical values. Acoustic signals and airload fluctuations are used to locate and define the origin of rotor noise during high-speed flight and in operating regimes of strong wake interaction.