Download or read book Correlation of Airloads on a Two bladed Helicopter Rotor written by Francisco J. Fernandez and published by . This book was released on 1993 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Correlation of Airloads on a Two Bladed Helicopter Rotor written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Airloads measured on a two-bladed helicopter rotor in flight during the Ames' Tip Aerodynamic and Acoustic Test are compared with calculations from a comprehensive helicopter analysis (CAMRAD/JA), and the pressures compared with calculations from a full-potential rotor code (FPR). The flight-test results cover an advance ratio range of 0.19 to 0.38. The lowest-speed case is characterized by the presence of significant blade-vortex interactions. Good correlation of peak-to-peak vortex-induced loads and the corresponding pressures is obtained. Results of the correlation for this two-bladed rotor are substantially similar to those for three- and four-bladed rotors, including the tip-vortex core size for best correlation, calculation of the peak-to-peak loads on the retreating side, and calculation of vortex iduced loads on inboard radial stations. The higher-speed cases are characterized by the presence of transonic flow on the outboard sections of the blade. Comparison of calculated and measured airloads on the advancing side is not considered appropriate because the presence of shocks makes chordwise integration of the measured data difficult. However, good correlation of the corresponding pressures is obtained. Fernandez, Francisco J. and Johnson, Wayne Ames Research Center RTOP 505-59-36...
Download or read book In flight Measurement and Correlation with Theory of Blade Airloads and Responses on the XH 51A Compound Helicopter Rotor Measurement and data reduction of airloads and structural loads written by and published by . This book was released on 1968 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of a two-phase research program consisting of (1) in-flight measurement of aerodynamic pressures and structural loads on a compound, rigid-rotor helicopter and (2) correlation of these data with theoretical results. Flight test data obtained in Phase I and recorded on an oscillograph were read on an oscillograph reading machine and were processed in an automatic data reduction program. This data processing consisted of integration of the pressure data to obtain the distribution of aerodynamic lift and pitching moments over the rotor blade, as functions of azimuth position. Airload and structural load data were harmonically analyzed. Output of the data reduction program was used in Phase II as input to the correlation program. The measured airloads were used to compute the theoretical bending and torsion responses of the blade. The measured torsion moments were used in the theoretical prediction of the airloads. The results of the applied theories are compared with the flight measurements.
Download or read book In flight Measurement and Correlation with Theory of Blade Airloads and Responses on the XH 51A Compound Helicopter Rotor written by and published by . This book was released on 1968 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of a two-phase research program consisting of (1) in-flight measurement of aerodynamic pressures and structural loads on a compound, rigid-rotor helicopter and (2) correlation of these data with theoretical results. Flight test data obtained in Phase I and recorded on an oscillograph were read on an oscillograph reading machine and were processed in an automatic data reduction program. This data processing consisted of integration of the pressure data to obtain the distribution of aerodynamic lift and pitching moments over the rotor blade, as functions of azimuth position. Airload and structural load data were harmonically analyzed. Output of the data reduction program was used in Phase II as input to the correlation program. The measured airloads were used to compute the theoretical bending and torsion responses of the blade. The measured torsion moments were used in the theoretical prediction of the airloads. The results of the applied theories are compared with the flight measurements.
Download or read book IN FLIGHT MEASUREMENT AND CORRELATION WITH THEORY OF BLADE AIRLOADS AND RESPONSES ON THE XH 51A COMPOUND HELICOPTER ROTOR VOLUME 2 MEASUREMENT AND DATA REDUCTION OF AIRLOADS AND STRUCTURAL LOADS APPENDIXES 5 THROUGH 9 written by and published by . This book was released on 1968 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Differential pressure -- dynamic components; Differential pressure -- static components; Blade loads -- dynamic and static components; Harmonic components of airloads and pitching moments; Harmonic components of structural loads.
Download or read book Theory Test Correlation of Helicopter Rotor Blade Element Airloads in the Blade Stall Regime written by Christopher J. Bobo and published by . This book was released on 1972 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In flight Measurement and Correlation with Theory of Blade Airloads and Responses on the Xh 51a Compound Helicopter Rotor written by E.A. Bartsch and published by . This book was released on 1968 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In flight Measurement and Correlation with Theory of Blade Airloads and Responses on the Xh 51a Compound Helicopter Rotor written by J.E. Sweers and published by . This book was released on 1968 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book IN FLIGHT MEASUREMENT AND CORRELATION WITH THEORY OF BLADE AIRLOADS AND RESPONSES ON THE XH 51A COMPOUND HELICOPTER ROTOR VOLUME I MEASUREMENT AND DATA REDUCTION OF AIRLOADS AND STRUCTURAL LOADS written by and published by . This book was released on 1968 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the results of a two-phase research program consisting of (1) in-flight measurement of aerodynamic pressures and structural loads on a compound, rigid-rotor helicopter and (2) correlation of these data with theoretical results. Flight test data obtained in Phase I and recorded on an oscillograph were read on an oscillograph reading machine and were processed in an automatic data reduction program. This data processing consisted of integration of the pressure data to obtain the distribution of aerodynamic lift and pitching moments over the rotor blade, as functions of azimuth position. Airload and structural load data were harmonically analyzed. Output of the data reduction program was used in Phase II as input to the correlation program. The measured airloads were used to compute the theoretical bending and torsion responses of the blade. The measured torsion moments were used in the theoretical prediction of the airloads. The results of the applied theories are compared with the flight measurements.
Download or read book Helicopter Rotor Wake Geometry and Its Influence in Forward Flight Volume 1 Generalized Wake Geometry and Wake Effect on Rotor Airloads and Performance written by T. A. Egolf and published by . This book was released on 1983 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytic investigation to generalize wake geometry of a helicopter rotor in steady level forward flight and to demonstrate the influence of wake deformation in the prediction of rotor airloads and performance is described. Volume 1 presents a first level generalized wake model based on theoretically predicted tip vortex geometries for a selected representative blade design. The tip vortex distortions are generalized in equation form as displacements from the classical undistorted tip vortex geometry in terms of vortex age, blade azimuth, rotor advance ratio, thrust coefficient, and number of blades. These equations were programmed to provide distorted wake coordinates at very low cost for use in rotor airflow and airloads prediction analyses. The sensitivity of predicted rotor airloads, performance, and blade bending moments to the modeling of the tip vortex distortion are demonstrated for low to moderately high advance ratios for a representative rotor and the H-34 rotor. Comparisons with H-34 rotor test data demonstrate the effects of the classical, predicted distorted, and the newly developed generalized wake models on airloads and blade bending moments. Use of distorted wake models results in the occurrence of numerous blade-vortex interactions on the forward and lateral sides of the rotor disk. The significance of these interactions is related to the number and degree of proximity to the blades of the tip vortices. The correlation obtained with the distorted wake models (generalized and predicted) is encouraging.
Download or read book In flight Measurement and Correlation with Theory of Blade Airloads and Responses on the XH 51A Compound Helicopter Rotor written by E. A. Bartsch and published by . This book was released on 1968 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Helicopter Rotor Blade Element Airloads on a Model Rotor in the Blade Stall Regime written by and published by . This book was released on 1971 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book V STOL Dynamics and Aeroelastic Rotor Airframe Technology Volume 2 Description and Correlation of New Methodologies written by and published by . This book was released on 1972 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: The blade loads analysis calculates rotor blade flapwise, chordwise, and torsional deflections and loads, together with rotor performance, control system forces, and vibratory hub loads. Articulated and hingeless rotors with 2 to 9 blades and large twist may be analyzed. The analysis considers coupled flapwise-chordwise-torsion deflections of the rotor blades. Boundary conditions for either articulated or hingeless rotors are applied and the solution is obtained by expanding the variables in a 10-harmonic Fourier series. Airload calculations include the effects of airfoil section geometry, compressibility, stall, 3-dimensional flow, unsteady aerodynamics, and nonuniform inflow. In the area of rotor loads, correlation of prop/rotor and helicopter rotor loads test data has been made with the fully coupled rotor loads and steady in-plane hub moments for prop/rotors and for alternating blade loads, pitch link loads, and airloads for helicopters. An unexpected discovery of this study was the sensitivity of the rotor derivatives to blade lead-lag motion when the frequency of this mode is near 1 per rev. This result was subsequently confirmed by test. The impact of the new prediction capabilities and possible refinement or development of design criteria through use of the analysis are discussed. The methods contained in this report are intended to be used by designers to calculate with improved accuracy, the dynamic and aeroelastic response characteristics of rotor powered V/STOL aircraft. The essential new feature of these methods is that the coupled flap-pitch-lag blade deflections are taken into account. These calculations are essential if a high level of confidence is to be had in the results.
Download or read book In flight Measurement and Correlation with Theory of Blade Airloads and Responses on the XH 51A Compound Helicopter Rotor written by J. E. Sweers and published by . This book was released on 1968 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book IN FLIGHT MEASUREMENT AND CORRELATION WITH THEORY OF BLADE AIRLOADS AND RESPONSES ON THE XH 51A COMPOUND HELICOPTER ROTOR VOLUME 3 THEORETICAL PREDICTION OF AIRLOADS AND STRUCTURAL LOADS AND CORRELATION WITH FLIGHT TEST MEASUREMENTS written by and published by . This book was released on 1968 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: In most of the conditions analyzed, the computed bending moments were found to be in good agreement with the measured moments. The agreement between computed and measured torsion moments, however, was poor, indicating that improvements are required in the mathematical model as far as the torsional properties are concerned. (These may include the introduction of the control system degrees of freedom in the model.) Comparison of measurements with airloads obtained with the Cornell program shows good agreement of the variations of the airloads over the azimuth. At the lower forward speeds the rotor wake can be represented by a set of ring vortexes. An urgent need exists for a method for predicting wake deformation and for programming this method. Torsional responses are important in the computation of airloads. A rotor trim procedure included in a rotor loads program has been shown to be useful in the prediction of rotor loads. Based on the results obtained for chordwise bending moments, the relationship between normal force coefficient and chord force coefficient used in Lockheed Program I should be reexamined, particularly in high angle-of-attack areas. Such investigation may result in improved estimates of drag coefficients.
Download or read book Analysis and Correlation of Helicopter Rotor Blade Response in a Variable Inflow Environment written by Raymond G. Carlson and published by . This book was released on 1965 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: The program was conducted to determine the ability to predict Helicopter rotor response with a combined analysis based on the Sikorsky aeroelastic analysis and the Cornell Aeronautical Laboratory variable inflow analysis. The Sikorsky analysis is a fully coupled flatwise-edgewise-torsional dynamic analysis modified to incorporate refinements in rotor trim and airload calculation and to adapt it for use with the variable inflow analysis. Analytical results were compared with available flight data for steady level flight of the H-34 at 41, 70, and 112 knots with a neutral center of gravity (C.G.), and 73 knots with aft C.G., as well as the HU-1A at 113 knots with neutral C.G. Fairly good correlation with test data was obtained. The analysis gave better correlation of blade air loads and bending moments than had been obtained from constant inflow analysis. In particular, more realistic values were obtained for the higher harmonic root-shear forces needed to define airframe response. While further improvement can be obtained by refinement of the variable inflow analysis, the combined analysis developed for the program provides an improved design tool for rotor blade evaluation. (Author).
