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Experimental/Numerical Evaluation of Integral Trailing Edge Flaps for Helicopter Rotor Applications

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Two‐dimensional wind tunnel tests were conducted in the NASA Langley 0.3‐m Transonic Cryogenic Tunnel (TCT) to identify a suitable trailing edge flap geometry for helicopter rotor aerodynamic/dynamic applications. Two pressure‐instrumented airfoils (9.5% thick, 12% thick) having 25% chord integral trailing edge flaps were tested. Airfoil and flap “inserts” were used interchangeably to yield flap “overhang” nose balance values of 35%, 40%, and 45%. Specific objectives of the tests were: (a) to investigate the effects of flap overhang nose balance on the aerodynamic characteristics of the airfoil/flap at moderate to high subsonic Mach numbers and, (b) to establish a comprehensive aerodynamic database for lifting‐line simulations of flapped rotors. Pre‐test analyses were conducted using a two‐dimensional Navier‐Stokes flow solver to evaluate the aerodynamic characteristics of a number of candidate flap geometries. Results from the wind tunnel tests/analyses affirmed the important effect of the flap percentage overhang on the hinge moments. At transonic speeds, prediction of secondary supersonic flow pockets on the shoulder of the flap was corroborated using the measured pressure data.

Document Type: Research Article


Affiliations: The Boeing Company, Mesa, Arizona

Publication date: 2005-01-01

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  • The Journal of the American Helicopter Society is the world's only scientific journal dedicated to vertical flight technology. It is a peer-reviewed technical journal published quarterly by AHS International and presents innovative papers covering the state-of-the-art in all disciplines of rotorcraft design, research and development. (Please note that AHS members receive significant discounts on articles and subscriptions.)

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    Authors can find submission guidelines and related information on the AHS website.

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