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Abstract

(Maximum 200 words) An investigation was conducted in the Glenn L. Martin Wind Tunnel to determine the effects of blade planform variation on the forward-flight performance of four small-scale rotors. The rotors were 5.417 ft in diameter and differed only in blade planform geometry. The four planforms were (1) rectangular, (2) 3:1 linear taper starting at 94 percent radius, (3) 3:1 linear taper starting at 75 percent radius, and (4) 3:1 linear taper starting at 50 percent radius. Each planform had a thrust-weighted solidity of 0.098. The investigation included forwardflight simulation at advance ratios from 0.14 to 0.43 for a range of rotor lift and drag coefficients. Among the four rotors, the rectangular rotor required the highest torque for the entire range of rotor drag coefficients attained at advance ratios greater than 0.14 for rotor lift coefficients C L from 0.004 to 0.007. Among the rotors with tapered blades and for C L = 0:004 to 0.007, either the 75-percent tapered rotor ..