AN EXPERIMENTAL STUDY OF THE PERFORMANCE AND STRUCTURAL LOADS OF A FULL- SCALE ROTOR AT EXTREME OPERATING CONDITIONS
Abstract
Two sets of strain-gage instrumented full-scale rotor blades were tested in the NASA/Ames 40 feet x 80 feet Wind Tunnel. One blade set was a CH- 34 rotor with -8 degrees twist while the second set had zero twist. Advance ratios to 1.05 and tip Mach numbers to 0.93 were tested over a wide range of collective pitch and shaft angle. Effects of twist, Mach number, and advance ratio on performance and stress are examined, as well as correlation of measured and predicted performance. Negative twist blades improved performance in all propulsive force modes. The zero twist blades had generally lower stresses with little or no performance penalty when rotor lift and propulsive force requirements were decreased. Predicted power rate of increase due to compressibility was somewhat greater than measured in the rotor propulsive mode. Blade vibratory stress and control loads increased sharply at high subsonic Mach numbers. Reductions in power and disc loading optimized lift-drag at high advance ratios, as predicted by theory, although drag calculations were low by 1 to 2 square feet of parasite area. At high advance ratio, blade stress increased primarily in the flapwise mode. The onset of stall is slower than predicted by theory and the inclusion of induced, boundary layer, and unsteady effects could improve performance prediction.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1968
- Accession Number
- AD0674187
Entities
People
- Andrew H. Logan
- Vincent M. Paglino
Organizations
- United Technologies Corporation