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Book ROTATING SHAKE TEST AND MODAL ANALYSIS OF A MODEL HELICOPTER ROTOR BLADE NASA TM 4760 SEP 16 1997

Download or read book ROTATING SHAKE TEST AND MODAL ANALYSIS OF A MODEL HELICOPTER ROTOR BLADE NASA TM 4760 SEP 16 1997 written by United States. National Aeronautics and Space Administration and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Rotating Beam Problem in Helicopter Dynamics

Download or read book The Rotating Beam Problem in Helicopter Dynamics written by Ranjan Ganguli and published by Springer. This book was released on 2017-10-14 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book addresses computational methods for solving the problem of vibration, response, loads and stability of a helicopter rotor blade modeled as a rotating beam with flap or out-of-plane bending. The focus is on explaining the implementation of the finite element method in the space and time domain for the free vibration, aeroelastic response and stability problems. The use of Floquet analysis for the aeroelastic stability analysis of rotor blades is also shown. The contents of the book will be useful to researchers in aerodynamics and applied mechanics, and will also serve well professionals working in the aerospace industry.

Book Performance Data from a Wind tunnel Test of Two Main rotor Blade Designs for a Utility class Helicopter

Download or read book Performance Data from a Wind tunnel Test of Two Main rotor Blade Designs for a Utility class Helicopter written by Jeffrey D. Singleton and published by DIANE Publishing. This book was released on 1990 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Estimation of Helicopter Rotor Loads from Blade Structural Response

Download or read book Estimation of Helicopter Rotor Loads from Blade Structural Response written by Daiju Uehara and published by . This book was released on 2019 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measuring the load distribution along a helicopter rotor blade has been one of the most challenging tasks in experimental aeromechanics. Conventional loads measurements with on-blade instrumentation, such as pressure transducers for airloads and strain gages for structural loads, require the experimentalist to overcome a large number of technical barriers; for example, sensor integration to the rotor blade structure, sensor failure due to strong centrifugal forces, and influence of sensor installation on rotor blade dynamics. The goal of this dissertation is to develop a new, combined experimental and theoretical methodology to estimate helicopter rotor loads without using these conventional on-blade sensors. The rotor loads estimation methodology begins with the measurement of blade structural deformation measurements using non-contact, optical, time-resolved Digital Image Correlation (DIC). The time-resolved DIC technique successfully showed its capability of measuring the three-dimensional deformation time history of a rotating blade for both a small- and a large-scale rotor in hover. The modal properties (natural frequencies, mode shapes, damping ratios, and modal coordinates) of the blade in the rotating-frame were then extracted from the deformation time history using Natural Excitation Technique - Eigensystem Realization Algorithm (NExT-ERA) and Complexity Pursuit (CP), which are operational modal analysis (OMA) algorithms. The first three modes were identified by the OMA algorithms and well correlated with a numerical model. Rotor loads were then finally estimated based on the measured deformations and blade modal characteristics. Having validated the present approach incrementally with measurements performed on rotors at different scales, configurations, and operating conditions, the current study estimated the spanwise lift distribution and integrated thrust at the hub for a 2 m-diameter, two-bladed, isolated single rotor in hover. Due to a lack of participating modes (only the first and second flap modes), the estimated sectional lift distribution did not capture the lift loss typically observed at regions of the blade tip and induced by trailing tip vortices. Nevertheless, the mean value of the estimated thrust at the rotor hub was within 5% of the measured value for all the operating conditions

Book Sensitivity Analysis of Torsional Vibration Characteristics of Helicopter Rotor Blades Part 1 Structural Dynamics Analysis

Download or read book Sensitivity Analysis of Torsional Vibration Characteristics of Helicopter Rotor Blades Part 1 Structural Dynamics Analysis written by and published by . This book was released on 1974 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical investigation of structural vibration characteristics of rotor blades was carried out. Coupled equations of motion for flapwise bending and torsion were formulated for rotor blades with noncollinear elastic and mass axes. The finite element method was applied for a detailed representation of blade structural properties. Coupled structural mass and stiffness coefficients were evaluated. The range of validity of a set of coupled equations of motion linearized with respect to eccentricity between elastic and mass axes was investigated. The sensitivity of blade vibration characteristics to torsion were evaluated by varying blade geometric properties, boundary conditions, and eccentricities between mass and elastic axes.

Book Determination of Rotating Mode Shapes and Natural Frequencies of a Helicopter Rotor Blade Using the Non rotating Mode Shapes as Generalized Coordinates

Download or read book Determination of Rotating Mode Shapes and Natural Frequencies of a Helicopter Rotor Blade Using the Non rotating Mode Shapes as Generalized Coordinates written by Randall F. Smith and published by . This book was released on 1985 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Helicopter Blade Dynamic Loads Measured During Performance Testing of Two Scaled Rotors

Download or read book Helicopter Blade Dynamic Loads Measured During Performance Testing of Two Scaled Rotors written by John D. Berry and published by . This book was released on 1987 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: A test to determine the performance differences between the 27-percent-scale models of two rotors for the U.S. Army AH-64 helicopter was conducted in the Langley 14- by 22-Foot Subsonic Tunnel. One rotor, referred to as the baseline rotor, simulated the geometry and dynamic characteristics of the production baseline rotor, and the other rotor, referred to as the advanced rotor, was designed to have improved hover performance. During the performance test, the dynamic pitch-link forces and blade bending and torsion moments were also measured. Dynamic data from the forward flight investigation have been reduced and are presented herein. The advanced blade set was designed to have dynamic characteristics similar to those of the baseline rotor so that test conditions would not be limited by potential rotor instability and blade resonances and so that the measured performance increments could be considered to be due purely to aerodynamic causes. Data show consistent trends with advance ratio for both blade sets with generally higher oscillatory loads occurring for the advanced blade set when compared with the baseline blade set.

Book Helicopter Rotor Blade Design for Minimum Vibration

Download or read book Helicopter Rotor Blade Design for Minimum Vibration written by Robert B. Taylor and published by . This book was released on 1984 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Loads and Performance Data from a Wind Tunnel Test of Generic Model Helicopter Rotor Blades

Download or read book Loads and Performance Data from a Wind Tunnel Test of Generic Model Helicopter Rotor Blades written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation was conducted in the NASA Langley Transonic Dynamics Tunnel to acquire data for use in assessing the ability of current and future comprehensive analyses to predict helicopter rotating-system and fixed-system vibratory loads. The investigation was conducted with a generic model helicopter rotor system using blades with rectangular planform, no built-in twist, uniform radial distribution of mass and stiffnesses, and a NACA 0012 airfoil section. Rotor performance data, as well as mean and vibratory components of blade bending and torsion moments, fixed-system forces and moments, and pitch link loads were obtained at advance ratios up to 0.35 for various combinations of rotor shaft angle-of-attack and collective pitch. The data are presented without analysis. Yeager, William T., Jr. and Wilbur, Matthew L. Langley Research Center 23-065-40-30...

Book Vibratory Loads Data from a Wind Tunnel Test of Structurally Tailored Model Helicopter Rotors

Download or read book Vibratory Loads Data from a Wind Tunnel Test of Structurally Tailored Model Helicopter Rotors written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-23 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was conducted in the Langley Transonic Dynamics Tunnel to investigate the use of a Bell Helicopter Textron (BHT) rotor structural tailoring concept, known as rotor nodalization, in conjunction with advanced blade aerodynamics as well as to evaluate rotor blade aerodynamic design methodologies. A 1/5-size, four-bladed bearingless hub, three sets of Mach-scaled model rotor blades were tested in forward flight from transition up to an advance ratio of 0.35. The data presented pertain only to the evaluation of the structural tailoring concept and consist of fixed-system and rotating system vibratory loads. These data will be useful for evaluating the effects of tailoring blade structural properties on fixed-system vibratory loads, as well as validating analyses used in the design of advanced rotor systems. Yeager, William T., Jr. and Hamouda, M-Nabil H. and Idol, Robert F. and Mirick, Paul H. and Singleton, Jeffrey D. and Wilbur, Matthew L. Langley Research Center BELL AIRCRAFT; DYNAMIC STRUCTURAL ANALYSIS; HELICOPTER DESIGN; HELICOPTERS; ROTARY WINGS; ROTOR AERODYNAMICS; ROTOR BLADES; VIBRATORY LOADS; AIRCRAFT MODELS; HORIZONTAL FLIGHT; SCALE MODELS; TRANSONIC WIND TUNNELS; WIND TUNNEL TESTS...