A Flight Investigation Of Performance And Loads For A Helicopter With Nlr 1t Main Rotor Blade Sections

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ISBN 13 :
Total Pages : 62 pages
Book Rating : 4.:/5 (317 download)

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Download or read book Airfoil Dynamic Stall and Rotorcraft Maneuverability written by and published by . This book was released on 2000 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: The loading of an airfoil during dynamic stall is examined in terms of the augmented lift and the associated penalties in pitching moment and drag. It is shown that once stall occurs and a leading-edge vortex is shed from the airfoil there is a unique relationship between the augmented lift, the negative pitching moment, and the increase in drag. This relationship, referred to here as the dynamic stall function, shows limited sensitivity to effects such as the airfoil section profile and Mach number, and appears to be independent of such parameters as Reynolds number, reduced frequency, and blade sweep. For single-element airfoils there is little that can be done to improve rotorcraft maneuverability except to provide good static clmax characteristics and the chord or blade number that is required to provide the necessary rotor thrust. However, multi-element airfoils or airfoils with variable geometry features can provide augmented lift in some cases that exceeds that available from a single-element airfoil. The dynamic stall function is shown to be a useful tool for the evaluation of both measured and calculated dynamic stall characteristics of singleelement, multi-element, and variable geometry airfoils.