COMPARISON OF THEORETICAL AND EXPERIMENTAL MODEL HELICOPTER ROTOR PERFORMANCE IN FORWARD FLIGHT
Abstract
An analytical and experimental program was conducted to determine the degree of correlation between theoretical and experimental model rotor performance over a range of forward speeds of 100 to 161 knots and tip speeds of 580 to 850 ft./sec. The theory utilized synthesized airfoil data derived from hovering tests, and included both stall and compressibility effects. The model blades were dynamically scaled from the Sikorsky S-56 main rotor blades. Theory and experiment correlate well below the theoretically predicted stall boundary, but above stall the theory is unduly conservative in estimating rotor power required. The effects of compressibility on rotor power loading can be accurately predicted. A rotor with an NACA 0012 airfoil section incurs severe penalties in profile power when the advancing tip Mach number exceeds 0.85 to 0. 90. Significant amounts of model rotor blade dynamic twisting (up to 5 degrees change in pitch at the 3/4 radius station) occur both in hovering and in forward flight. Such twisting must be taken into account to properly synthesize airfoil data from hovering tests.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1961
- Accession Number
- AD0273332
Entities
People
- John P. Rabbott Jr.
Organizations
- United Technologies Corporation