A METHOD FOR PREDICTING THE TRIM CONSTANTS AND THE ROTOR-BLADE LOADINGS AND RESPONSES OF A SINGLE-ROTOR HELICOPTER
Abstract
The present effort was undertaken to extend the previously developed method by (1) including the blade inplane and torsional motions, and (2) treating the four trim constants (namely, the blade pitch-control settings and the rotor-shaft tilt angle) as unknowns. The trim constants are different for different flight conditions and are determined through the use of four appropriate, average equilibrium conditions of the helicopter. These equilibrium conditions are called the trim equations and are derived in the report, taking into account the inertial forces of the blades due to elastic deformations. Lagrange's equations for the blade motions are given. The generalized coordinates employed in these equations to represent blade bending are those which have deflection components in two mutually perpendicular directions. Orthogonality relations of vibration modes of twisted, rotating blades are derived and are used in simplifying the equations of blade motion. A successive approximation procedure was developed which, upon incorporation with the previously developed iterative procedure, yields the aerodynamic loads, the blade responses, and the required trim constants. Computed results are obtained for the UH-1A rotor at advance ratios of 0.26 and 0/08 and for the H-34 rotor at advance ratios of 0.29 and 0.18. Comparisons of these results with available measured results are presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1967
- Accession Number
- AD0666802
Entities
People
- T. T. Chang
Organizations
- Calspan