Wind-tunnel tests of a full-scale helicopter rotor with symmetrical and with cambered blade sections at advance ratios from 0.3 to 0.4

John L. McCloud, III, George B. McCullough
naca-tn-4367
Sep 1958

Wind-tunnel tests were made of a 44-foot-diameter, three-bladed helicopter rotor for the purpose of investigating the performance gains made available by delaying retreating blade stall by the use of blade sections with increased maximum lift.

An Adobe Acrobat (PDF) file of the entire report:
http://naca.central.cranfield.ac.uk/reports/1958/naca-tn-4367.pdf