Effect of Blade Planform Variation on the Forward-Flight Performance of Small-Scale Rotors
Effect of Blade Planform Variation on the Forward-Flight Performance of Small-Scale Rotors

Author: National Aeronautics and Space Adm Nasa

Publisher: Independently Published

Published: 2018-11-04

Total Pages: 92

ISBN-13: 9781730861208

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An investigation was conducted in the Glenn L. Martin Wind Tunnel to determine the effect 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 forward-flight 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 advanced ratios greater than 0.14 for rotor lift coefficients C sub L from 0.004 to 0.007. Among the rotors with tapered blades and for C sub L = 0.004 to 0.007, either the 75 percent tapered rotor or the 50 percent tapered rotor required the least amount of torque for the full range of rotor drag coefficients attained at each advance ratio. The performance of the 94 percent tapered rotor was generally between that of the rectangular rotor and the 75 and 50 percent tapered rotors at each advance ratio for this range of rotor lift coefficients. Noonan, Kevin W. and Althoff, Susan L. and Samak, Dhananjay K. and Green, Michael D. Langley Research Center...

Principles of Helicopter Aerodynamics with CD Extra
Principles of Helicopter Aerodynamics with CD Extra

Author: Gordon J. Leishman

Publisher: Cambridge University Press

Published: 2006-04-24

Total Pages: 860

ISBN-13: 9780521858601

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Written by an internationally recognized teacher and researcher, this book provides a thorough, modern treatment of the aerodynamic principles of helicopters and other rotating-wing vertical lift aircraft such as tilt rotors and autogiros. The text begins with a unique technical history of helicopter flight, and then covers basic methods of rotor aerodynamic analysis, and related issues associated with the performance of the helicopter and its aerodynamic design. It goes on to cover more advanced topics in helicopter aerodynamics, including airfoil flows, unsteady aerodynamics, dynamic stall, and rotor wakes, and rotor-airframe aerodynamic interactions, with final chapters on autogiros and advanced methods of helicopter aerodynamic analysis. Extensively illustrated throughout, each chapter includes a set of homework problems. Advanced undergraduate and graduate students, practising engineers, and researchers will welcome this thoroughly revised and updated text on rotating-wing aerodynamics.

Effect of Planform Taper on Hover Performance of an Advanced AH-64 Model Rotor
Effect of Planform Taper on Hover Performance of an Advanced AH-64 Model Rotor

Author: Henry L. Kelley

Publisher:

Published: 1987

Total Pages: 16

ISBN-13:

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The hover performance of a 27-percent-scale model baseline rotor and advanced rotor with a 3:1 tapered tip (TR3) for the AH-64 attack helicopter was investigated in the rotor test cell at the Langley 14- by 22-foot Subsonic Tunnel as part of ongoing efforts to improve rotorcraft efficiency. The hover performance of the baseline rotor was compared with that of the TR3 rotor and with that of a previously tested advanced rotor with 5:1 tapered tip (TR5). Rotor thrust in hover at a rotor height-to-rotor diameter ratio of 1.46 was varied over a range of thrust coefficients for rotor tip Mach numbers of 0.63 and 0.57 respectively. The rotor with the TR3 blades had improved hover performance as compared with the rotor with the TR5 blades, and both the TR3 and TR5 blades were superior to the baseline rotor in terms of figure of merit for the range of thrust coefficients from 0.0020 to 0.0100. The additional margin in performance for the TR3 blades as compared with the TR5 blades was likely due to an increase in blade area and Reynolds number at the blade tip region brought about by the change in taper ratio from 5:1 to 3:1.