Hovering Characteristics of a Rotor having an Airfoil Section Designed for Flying-Crane Type of Helicopter

Results of an investigation, conducted on the Langley helicopter test tower, of a rotor having an NACA 632A015 airfoil thickness distribution in combination with an NACA 230 mean line are presented. Comparison with a previously reported test of a symmetrical rotor blade efficiency was substantially improved over a wide range of tip Mach numbers. The maximum mean lift coefficient was essentially unchanged from that obtained with uncambered blades. Some data showing the effect of a distributed type of leading-edge roughness are also included

NACA Technical Notes

Report presenting an investigation to determine the low tip Mach number blade maximum mean lift coefficients and the high tip Mach number effects of compressibility for rotor blades with NACA 0015 tip airfoil sections. The characteristics of this rotor was similar to those from other investigations, which is that at low Mach numbers, there is a stable pitching moment past rotor-blade drag divergence. Results regarding hovering performance, synthesized rotor-blade section characteristics, rotor-blade pitching moments, rotor-blade profile-drag torque, comparison of profile-drag torque ratios, and a comparison of experimental and two-dimensional drag-divergence characteristics are provided

NACA Technical Notes

Report presenting an investigation in the helicopter test tower to determine experimentally the effects of compressibility on the hovering performance and blade pitching moments of a helicopter rotor with NACA 63(sub 2)-015 airfoil sections. The results indicated that two-dimensional airfoil-section data provide a reasonable basis for predicting the onset of compressibility losses and that the differences in Mach number for drag divergence between airfoils shown by two-dimensional data are realized in rotor tests

NACA Research Memorandums

Report presenting an investigation of a helicopter pressure-jet system. The effects of tip speed, fuel-air ratio, and pressure ratio on the propulsive characteristics of the pressure-jet system have been determined for a range of tip seeds, blade-root stagnation-pressure ratios, and fuel-air ratios. Results regarding tip-burner specific propulsive horsepower, propulsive horsepower per unit mean duct area, tip-burner specific fuel consumption, ratio of propulsive horsepower to equivalent air horsepower, effect of whirling on tip-unit thrust, effect of whirling on the tip-burner inlet pressure, effect of auxiliary fuel flow, power-off drag of tip units, and overall specific fuel consumption of pressure-jet system are provided

NACA Research Memorandums

Report presenting the propulsive and aerodynamic characteristics of a flat ramjet engine suitable for use on a helicopter rotor and compared with previous tests of an equivalent engine with a circular cross section. The results indicate that the flat engine has higher values of propulsive thrust plus power-off drag than the circular engine. The power-off and drag characteristics indicate that the flat engine has lift-drag ratios about 3 times those obtained with the circular engine

NACA Technical Notes

Report presenting a determination of the nonwhirling propulsive characteristics of a helicopter-type pulse-jet engine mounted on a simulated helicopter rotor blade in the 16-foot transonic tunnel. Propulsive characteristics as a function of fuel-flow rate at a variety of Mach numbers and angles of yaw. Results regarding engine propulsive characteristics, comparison of whirling and nonwhirling data, and effect of engine operation on airfoil surface pressures are provided