An Analysis of Once-per-revolution Oscillating Aerodynamic Thrust Loads on Single-Rotation Propellers on Tractor Airplanes at Zero Yaw

A simplified procedure is shown for calculating the once-per-revolution oscillating aerodynamic thrust loads on propellers of tractor airplanes at zero yaw. The only flow field information required for the application of the procedure is a knowledge of the upflow angles at the horizontal center line of the propeller disk. Methods are presented whereby these angles may be computed without recourse to experimental survey of the flow field. The loads computed by the simplified procedure are compared with those computed by a more rigorous method and the procedure is applied to several airplane configurations which are believed typical of current designs. The results are generally satisfactory

Full-Scale Wind-Tunnel Tests of Blowing Boundary-Layer Control Applied to a Helicopter Rotor

A full-scale wind-tunnel test was conducted of two boundary-layer-control applications to a 44-foot diameter helicopter rotor. Blowing from a nozzle near the leading edge of the blades delayed retreating blade stall. Results also indicated that delay of retreating blade stall could be obtained by cyclic blowing with a lower flow rate than that required for continuous blowing. It was found that blowing applied through a nozzle at mid-chord had no effect on retreating blade stall

Tests of Full-Scale Helicopter Rotors at High Advancing Tip Mach Numbers and Advance Ratios

As a continuation of the studies of reference 1, three full-scale helicopter rotors have been tested in the Ames Research Center 40- by SO-foot wind tunnel. All three of them were two-bladed, teetering rotors. One of the rotors incorporated the NACA 0012 airfoil section over the entire length of the blade. This rotor was tested at advance ratios up to 1.05. Both of the other rotors were tapered in thickness and incorporated leading-edge camber over the outer 20 percent of the blade radius. The larger of these rotors was tested at advancing tip Mach numbers up to 1.02. Data were obtained for a wide range of lift and propulsive force, and are presented without discussion

NACA Technical Notes

Report presenting the flow fields at the propeller planes of six 40 degree sweptback semispan wing-fusleage-nacelle combinations to provide data and to enable the study of the characteristics of the flow fields and their effect on propeller-oscillating aerodynamic loads. Results regarding the propeller flow fields, oscillating aerodynamic loading, and upflow angles at the horizontal center lines of the propeller disks are provided

NACA Technical Notes

Report presenting a procedure for predicting the upwash components of the upflow angles in the region above or below the wing-chord planes of sweptback wing-fuselage-nacelle combinations. Comparisons of predicted and measured upflow angles are shown for six semispan models with 40 degree sweptback wings

NACA Technical Notes

Report presenting wind tunnel testing of a 44-foot-diameter, three-bladed helicopter rotor to investigate the performance gains made available by delaying retreating blade stall by the use of blade sections with increased maximum lift. Comparison of the stall boundaries showed that blades with cambered sections were superior to blades with symmetrical sections due to the increase in lifting capacity and forward speed capacity. Results regarding the determination of retreating blade stall, stall boundary, and comparison of the rotors are provided