975555_coleman

975555_coleman - NASA Technical Paper 3675 March 1997 A...

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National Aeronautics and Space Administration NASA Technical Paper 3675 A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research March 1997 Colin P. Coleman
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National Aeronautics and Space Administration Ames Research Center Moffett Field, California 94035-1000 A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research 1997 Colin P. Coleman, Ames Research Center, Moffett Field, California NASA Technical Paper 3675
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iii Contents Page List of Figures. .......................................................................................................................................................... v Nomenclature. ........................................................................................................................................................... vii Summary. .................................................................................................................................................................. 1 Introduction. .............................................................................................................................................................. 1 Definitions . ............................................................................................................................................................... 2 Research in the United States of America . ............................................................................................................... 2 NACA Langley Research Center . ..................................................................................................................... 2 De Lackner Helicopters, Inc. ............................................................................................................................. 4 Sikorsky Aircraft . .............................................................................................................................................. 5 Research in Russia . ................................................................................................................................................... 7 Research in Japan. ..................................................................................................................................................... 13 Hover . ................................................................................................................................................................ 13 Forward Flight . .................................................................................................................................................. 18 Research in the United Kingdom. ............................................................................................................................. 19 Research in Germany. ............................................................................................................................................... 21 Conclusions. .............................................................................................................................................................. 22 References. ................................................................................................................................................................ 23
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v List of Figures Page 1 Henry Bright’s 1859 coaxial design patent (ref. 1). ......................................................................................... 1 2 Scale effect on rotor 1 performance at 327 ft/sec, H/D = 0.093. Lines drawn through data (ref. 3) . .............. 3 3 Effect of solidity on rotor of merit (ref. 3) . ..................................................................................................... 3 4 Comparison of theoretical (solid line) and experimental static-thrust performance of rotor 2, H/D = 0.080 (ref. 3) . ........................................................................................................................................ 4 5 Experimental results and equivalent solidity single rotor theory for level flight. σ (coaxial) = 0.054, σ (single) = 0.027, H/D = 0.093 (ref. 4). ........................................................................................................... 4 6 Schematic of the advancing blade concept (ref. 7) . ......................................................................................... 5 7 Comparison of theoretical and experimental static-thrust performance of model ABC rotor, H/D not reported (ref. 7) . ................................................................................................................................. 5 8 Effect of rotor separation on ABC performance prediction (ref. 8) . ............................................................... 6 9 Underestimation of ABC rotor inflow at low speed (ref. 11) . ......................................................................... 7 10 Flight test rotor of merit for XH-59A in OGE hover (ref. 13). ....................................................................... 7 11 Induced power correction coefficient vs. blade linear twist for various taper ratio values (ref. 26) . .............. 8 12 Coefficients k T and k pr vs. blade taper ratio (ref. 26). .................................................................................... 8 13 Comparison of single rotor theory (ref. 26) with experimental results (ref. 3) as reported in reference 31. ..................................................................................................................................................... 8 14 Comparison of the coaxial with other helicopter types (ref. 31). ..................................................................... 10 15 Coaxial rotor in a wind tunnel (ref. 27). ........................................................................................................... 10 16 Areas of “unsteady flapping” motion for single and coaxial rotors (ref. 34) . ................................................. 10 17 Ka-32 blade separation distance as a function of advance ratio (ref. 34) . ....................................................... 11 18 Calculated velocity field for the vortex ring condition, H/D = 0.10, ν = 0.2 (ref. 28) . ................................... 11 19 Calculated velocity field for edgewise flow in longitudinal/vertical plane, H/D = 0.10, μ = 0.10 (ref. 28) . ........................................................................................................................................................... 11 20 3/rev vertical vibration of the Ka-25 at the center of gravity (ref. 33) . ........................................................... 12 21 Coaxial rotor phasing; (a) ULYSS-6 solution, (b) flight test solution. ............................................................ 12 22 3/rev vertical vibration of the Ka-50 at an unspecified location (ref. 33). ....................................................... 12 23 Effective increase of coaxial rotor disc area (ref. 32) . ..................................................................................... 12 24 Experimental results for coaxial and equivalent solidity, single rotors in hover, D = 8.2 ft (2.5 m), H/D not reported (ref. 32) . ............................................................................................................................... 12 25 Comparison of overall helicopter efficiencies (ref. 32) . .................................................................................. 13 26 National Defense Academy experimental apparatus (ref. 39) . ........................................................................ 13 27 Tip vortices from both the upper and lower rotor were seen to have a faster axial speed when compared to Landgrebe’s predictions, H/D = 0.105 (ref. 39). ......................................................................... 14 28 Effect of mutual interaction on rotor performance in hover, H/D = 0.132 (ref. 40) . ....................................... 14 29 System hover performance, H/D = 0.132 (ref. 40) .
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This note was uploaded on 01/05/2011 for the course DU 3 taught by Professor Frando during the Spring '10 term at University of Dundee.

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975555_coleman - NASA Technical Paper 3675 March 1997 A...

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