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ISBN 13 :
Total Pages : 58 pages
Book Rating : 4.:/5 (317 download)
Download or read book Hover Test of a Full-scale Hingeless Helicopter Rotor: Aeroelastic Stability, Performance and Loads Data written by and published by . This book was released on 1984 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781723454912
Total Pages : 26 pages
Book Rating : 4.4/5 (549 download)
Download or read book Hover Test of a Full-Scale Hingeless Rotor written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-24 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance and aeroelastic stability in hover of a 9.8-m diameter, hingeless helicopter rotor system was evaluated. Rotor performance and inplane damping data were obtained for rotor operation between 350 and 425 rpm for thrust coefficients (CT/sigma) between 0.0 and 0.12. At constant rotor thrust, a minimum in rotor inplane damping was measured at 400 rpm. Good agreement is shown between experimental performance data and predicted performance. The influence of different aerodynamic inflow models on predicting damping levels is also shown. The best correlation with experimental stability data was obtained when a dynamic inflow model was used instead of static or quasistatic inflow models. Comparison with other full scale, hingeless rotor data in hover is presented. The hingeless rotor data and data from a full scale, bearingless main rotor test performed on the same general purpose test apparatus were compared. Although the bearingless rotor was more highly damped at design tip speed and 1-g thrust operation, greater sensitivity to operating conditions is shown. At low thrust levels the bearingless main rotor is less damped than the hingeless rotor. Warmbrodt, W. and Peterson, R. L. Ames Research Center NASA-TM-85990, A-9827, NAS 1.15:85990 RTOP 532-06-11
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ISBN 13 :
Total Pages : 128 pages
Book Rating : 4.:/5 (317 download)
Download or read book Aeroelastic Stability of a Full-Scale Hingeless Rotor written by and published by . This book was released on 1996 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : David L. Sharpe
Publisher :
ISBN 13 :
Total Pages : 92 pages
Book Rating : 4.:/5 (317 download)
Download or read book An Experimental Investigation of the Flap-lag-torsion Aeroelastic Stability of a Small-scale Hingeless Helicopter Rotor in Hover written by David L. Sharpe and published by . This book was released on 1986 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: A small scale, 1.92 m diam torsionally soft, hingeless helicopter rotor was investigated in hover to determine isolated rotor stability characteristics. The two-bladed, untwisted rotor was tested on a rigid test stand at tip speeds up to 101 m/sec. The rotor mode of interest in this investigation was the lightly damped lead-lag mode. The dimensionless lead-lag frequency of the mode is approximately 1.5 at the highest tip speed. The hub was designed to allow variation in precone, blade droop, pitch control stiffness, and blade pitch angle. Measurements of modal frequency and damping were obtained for several combinations of these hub parameters at several values of rotor speed. Steady blade bending moments were also measured. The lead-lag damping measurements were found to agree well with theoretical predictions for low values of blade pitch angle. The test data confirmed the predicted effects of precone, droop, and pitch control stiffness parameters on lead-lag damping. The correlation between theory and experiment was found to be poor for the mid-to-high range of pitch angles where the theory substantially overpredicted the experimental lead-lag damping. The poor correlation in the mid-to-high blade pitch angle range is attributed to low Reynolds number nonlinear aerodynamics effects not included in the theory. The experimental results also revealed an asymmetry in lead-lag damping between positive and negative thrust conditions. Investigations of the rotor induced velocity field suggest that the asymmetry in lead-lag damping is not caused by the aerodynamic inflow but more likely from the influence of blade weight on the equilibrium blade deflection.
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ISBN 13 :
Total Pages : 32 pages
Book Rating : 4.:/5 (317 download)
Download or read book Analysis of Small-scale Rotor Hover Performance Data written by and published by . This book was released on 1990 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 356 pages
Book Rating : 4.:/5 (317 download)
Download or read book Performance and Loads Data from a Wind Tunnel Test of a Full-scale, Coaxial, Hingeless Rotor Helicopter written by and published by . This book was released on 1981 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: A test of a full-scale XH-59A Advancing Blade Concept Helicopter was conducted in Ames Research Center's 40- by 80-Foot Wind Tunnel. The helicopter was tested with the rotor on and off, rotor hub fairings on and off, inter-rotor shaft fairing on and off, rotor instrumentation module on and off, and auxiliary propulsion thrust on and off. The investigation was accomplished over an advance ratio range of 0.25 and 0.45 with the rotor on and from 60 to 180 knots with the rotor off. This report presents data on aerodynamic forces and moments, rotor loads, rotor control positions and vibration for the XH-59A as well as the aerodynamic performance of the isolated rotor. (author).
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ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (317 download)
Download or read book Aeromechanical Stability of a Hingeless Rotor in Hover and Forward Flight: Analysis and Wind Tunnel Tests written by and published by . This book was released on 1983 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research effort of analysis and testing has been conducted in the NASA-Langley Transonic Dynamics Tunnel to investigate the ground resonance phenomenon of a soft in-plane hingeless rotor. Experimental data were obtained using a 9 ft. (2.74 m) diameter model rotor in hover and forward flight. Eight model rotor configurations were investigated. Configuration parameters included pitch-flap coupling, blade sweep and droop, and precone of the blade feathering axis. An analysis based on a comprehensive analytical model of rotorcraft aerodynamics and dynamics was used for this study. The moving-block method was used to experimentally determine the regressing lead-lag mode damping. Good agreement has been obtained between the analysis and test. Both analysis and experiment indicated ground resonance instability in hover. The paper presents an outline of the analysis, a description of the experimental model and procedures, and comparison of the analytical and experimental data. (Author).
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ISBN 13 :
Total Pages : 380 pages
Book Rating : 4.X/5 (4 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author : James P. Shivers
Publisher :
ISBN 13 :
Total Pages : 32 pages
Book Rating : 4.:/5 (31 download)
Download or read book Hovering Characteristics of a Rotor Having an Airfoil Section Designed for a Utility Type of Helicopter written by James P. Shivers and published by . This book was released on 1962 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781722087562
Total Pages : 30 pages
Book Rating : 4.0/5 (875 download)
Download or read book Analysis of Small-Scale Rotor Hover Performance Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-30 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotor hover-performance data from a 1/6-scale helicopter rotor are analyzed and the data sets compared for the effects of ambient wind, test stand configuration, differing test facilities, and scaling. The data are also compared to full scale hover data. The data exhibited high scatter, not entirely due to ambient wind conditions. Effects of download on the test stand proved to be the most significant influence on the measured data. Small-scale data correlated resonably well with full scale data; the correlation did not improve with Reynolds number corrections. Kitaplioglu, Cahit Ames Research Center RTOP 505-61-51...
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ISBN 13 :
Total Pages : 94 pages
Book Rating : 4.:/5 (317 download)
Download or read book Rotorcraft Research Testing in the National Full-Scale Aerodynamics Complex at NASA Ames Research Center written by and published by . This book was released on 1985 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Aeromechanical Stability of a Hingeless Rotor in Hover and Forward Flight written by and published by . This book was released on 1987 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 22 pages
Book Rating : 4.:/5 (317 download)
Download or read book Aeroelastic Model Helicopter Rotor Testing in the Langley TDT written by and published by . This book was released on 1985 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
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ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (317 download)
Download or read book An Experimental Investigation of the Aeromechanical Stability of a Hingeless Rotor in Hover and Forward Flight written by and published by . This book was released on 1987 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis and testing were conducted in the Langley Transonic Dynamics Tunnel to investigate the aeromechanical stability of a soft inplane hingeless rotor model. Rotor stability data were obtained in hover and in forward flight up to an advanced ratio of 0.35. Model rotor parameters evaluated were blade sweep and droop, pre-cone of the blade feathering axis, and blade pitch-flap coupling. Data obtained during these tests are presented without analysis. Keywords: Hovering; Hingeless helicopter rotor dynamics; Helicopter rotor blades; Ground resonance.
Author : Martin D. Maisel
Publisher :
ISBN 13 :
Total Pages : 222 pages
Book Rating : 4.:/5 (31 download)
Download or read book The History of the XV-15 Tilt Rotor Research Aircraft written by Martin D. Maisel and published by . This book was released on 2000 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : James A. Staley
Publisher :
ISBN 13 :
Total Pages : 179 pages
Book Rating : 4.:/5 (227 download)
Download or read book Validation of Rotorcraft Flight Simulation Program Through Correlation with Flight Data for Soft-in-Plane Hingeless Rotors written by James A. Staley and published by . This book was released on 1976 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to evaluate the 300,000-byte version of the C- 81 AGAJ74 helicopter simulation program's capability for prediction of performance, rotor dynamic loads, and stability for soft-in-plane hingeless rotor helicopters. Available test data were compiled for the BO-105 single-rotor helicopter to provide a basis for evaluation of computer program analytical results. Results indicated good correlation for trim and performance, and reasonable correlation for main rotor alternating flap bending moments. Poorer correlation was obtained for main rotor chord and shaft bending moments. Poor agreement was obtained for response to control inputs in hover and at 100 knots; this may have been due to selection of too large a numerical integration interval. Approximately the same damping was indicated by test and analysis for aeroelastic stability. Attempts to compare C-81 results for control power and stability derivatives with analytical results from Boeing Vertol's Y-92 computer program were not sucessful. Significant differences were attributed to restraint of blade flapping in C-81 during these computations.
Author : W. Z. Stepniewski
Publisher : Courier Corporation
ISBN 13 : 0486318516
Total Pages : 640 pages
Book Rating : 4.4/5 (863 download)
Download or read book Rotary-Wing Aerodynamics written by W. Z. Stepniewski and published by Courier Corporation. This book was released on 2013-04-22 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: DIVClear, concise text covers aerodynamic phenomena of the rotor and offers guidelines for helicopter performance evaluation. Originally prepared for NASA. Prefaces. New Indexes. 10 black-and-white photos. 537 figures. /div
