PREDICTION OF ROTOR INSTABILITY AT HIGH FORWARD SPEEDS. VOLUME 4. TORSIONAL DIVERGENCE
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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A simple energy balance method for determining static stability was used to evaluate rotor blade torsional divergence boundaries, and a set of blade design charts was generated. To compare the results of this simple analysis with a more refined method, and to investigate the effects of parameters not included in the simple method, other calculations were made with the extended Normal Mode Transient Analysis. One type of practical rotor blade operating boundary is defined by peak-to-peak torsional stress. The static torsional divergence stability boundary usually approximates this practical operating limit, as verified by the Normal Mode Transient Analysis calculations. This approximation is valid for an important number of blade parameters. Recommended preliminary design procedures, incorporating the charts generated for the volume are given for the rapid definition of blades with adequate torsional stiffness.
- Fluid Mechanics