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  • 1
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    Recent developments in rotor wake modeling for helicopter noise prediction (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: A preliminary test/theory correlation evaluation is conducted for wake measurement test results obtained by LDV for a B360 helicopter rotor, at conditions critical to the understanding of wake-rollup and blade-vortex interaction phenomena. The LDV data were complemented by acoustic, blade pressure, rotor performance, and blade/control load measurements.
    Keywords: AERODYNAMICS
    Type: In: AHS and Royal Aeronautical Society, Technical Specialists' Meeting on Rotorcraft Acoustics(Fluid Dynamics, Philadelphia, PA, Oct. 15-17, 1991, Proceedings (A93-29401 10-71); 16 p.
    Format: text
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  • 2
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    Observations on the dynamic stall characteristics of advanced helicopter rotor airfoils (1978)
    In:  CASI
    Details
    Publication Date: 2006-02-22
    Description: A significant amount of research was devoted to understanding the mechanism of dynamic stall delay as applicable to the flow environment of a helicopter rotor in forward flight. One aspect of such research deals with the unsteady characteristics of two-dimensional airfoil sections over a Mach number range from 0.3 to 9.6, since such characteristics can be meaningfully related to rotor performance and loads. This paper summarizes the results of several oscillatory tests carried out on conventional, transonic and BLC-equipped airfoils.
    Keywords: AIRCRAFT STABILITY AND CONTROL
    Type: NASA. Langley Res. Center Advanced Technol. Airfoil Res., Vol. 1, Pt. 2; p 701-715
    Format: text
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  • 3
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    Performance degradation of helicopters due to icing - A review (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Methodology developed to predict the performance degradation of rotating systems in natural icing conditions is described and discussed. Theoretical studies of the increments performance degradation due to icing involving the propeller, helicopter in hover and forward flight, and XV-15 propulsion modes are summarized. Related experimental studies on the NACA 0012 airfoil and model helicopter with/without generic ice shapes are reviewed. The results of these experimental and theoretical studies are used to suggest refinements to current methodology.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Format: text
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  • 4
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    Performance degradation of helicopter rotor in forward flight due to ice (1985)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: This study addresses the analytical assessment of the degradation in the forward flight performance of the front rotor Boeing Vertol CH47D helicopter in a rime ice natural icing encounter. The front rotor disk was divided into 24 15-deg sections and the local Mach number and angle of attack were evaluated as a function of azimuthal and radial location for a specified flight condition. Profile drag increments were then calculated as a function of azimuthal and radial position for different times of exposure to icing, and the rotor performance was re-evaluated including these drag increments. The results of the analytical prediction method, such as horsepower required to maintain a specific flight condition, as a function of icing time have been generated. The method to illustrate the value of such an approach in assessing performance changes experienced by a helicopter rotor as a result of rime ice accretion is described.
    Keywords: AIR TRANSPORTATION AND SAFETY
    Type: Journal of Aircraft (ISSN 0021-8669); 22; 713-718
    Format: text
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  • 5
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    Fuselage upwash effects on RSRA rotor systems (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effects of RSRA fuselage configurations on rotor performance and loads have been quantified analytically by means of currently available potential flow and rotor analysis. Four configurations of the Rotor Systems Research Aircraft (RSRA) were considered in this study. They were: (1) fuselage alone (conventional helicopter); (2) fuselage with auxiliary propulsion; (3) fuselage with wings (auxiliary lift); and (4) fuselage with both auxiliary lift propulsion. The rotor system investigated was identical to a CH-47D front rotor except that it had four instead of three blades. Two scaled-down versions of the same rotor were also analyzed to determine the effect of rotor scale on the fuselage upwash effects. The flight conditions considered for the upwash study are discussed. The potential flow models for the RSRA configuration, with and without the wings and the auxiliary propulsion system, are presented. The results of fuselage/wing/propulsion system upwash on performance and loads are also presented.
    Keywords: AERODYNAMICS
    Type: NASA-CR-177349 , NAS 1.26:177349 , D210-12359-1
    Format: application/pdf
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  • 6
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    Helicopter rotor performance degradation in natural icing encounter (1984)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The analytical model described by Korkan et al. (1982) for predicting the performance degradation of propellers in a natural icing encounter is used to determine the feasibility of predicting helicopter performance degradation in hover during natural icing. The flight condition selected for analysis involves an altitude of 3000 ft and a free-air temperature of 1 F. The values of degradation yielded by the model for rime ice accretion are representative of those experienced in actual flight.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 84
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  • 7
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    Performance degradation of propeller systems due to rime ice accretion (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A theoretical ice accretion model has been established applicable to both aircraft propellers and helicopter rotors to determine the effect of rime ice on the thrust, power, and efficiency as a function of exposure time in a natural icing condition. Comparisons have been made of theoretical performance levels with previously published experimentally determined propeller thrust and efficiency for five natural icing conditions. Agreement between test and theory was acceptable.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 82-0286 , Journal of Aircraft (ISSN 0021-8669); 21; 44-49
    Format: text
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  • 8
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    Design and analytical study of a rotor airfoil (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An airfoil section for use on helicopter rotor blades was defined and analyzed by means of potential flow/boundary layer interaction and viscous transonic flow methods to meet as closely as possible a set of advanced airfoil design objectives. The design efforts showed that the first priority objectives, including selected low speed pitching moment, maximum lift and drag divergence requirements can be met, though marginally. The maximum lift requirement at M = 0.5 and most of the profile drag objectives cannot be met without some compromise of at least one of the higher order priorities.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2988 , D210-11239-1
    Format: application/pdf
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  • 9
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    Rotorcraft aviation icing research requirements: Research review and recommendations (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The status of rotorcraft icing evaluation techniques and ice protection technology was assessed. Recommendations are made for near and long term icing programs that describe the needs of industry. These recommended programs are based on a consensus of the major U.S. helicopter companies. Specific activities currently planned or underway by NASA, FAA and DOD are reviewed to determine relevance to the overall research requirements. New programs, taking advantage of current activities, are recommended to meet the long term needs for rotorcraft icing certification.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-165344 , D210-11662-1
    Format: application/pdf
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  • 10
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    Two-dimensional wind tunnel test of an oscillating rotor airfoil, volume 2 (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: For abstract, see N78-16003.
    Keywords: AERODYNAMICS
    Type: NASA-CR-2915 , D-210-11188-2
    Format: application/pdf
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