A Study of Helicopter Rotor Dynamics and Modeling Methods

A Study of Helicopter Rotor Dynamics and Modeling Methods

Author: Daniel S. Hiatt

Publisher:

Published: 1995

Total Pages: 117

ISBN-13:

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The rotor system is the primary source of vibratory forces on a helicopter. Vibratory forces result from the rotor system response to dynamic and aerodynamic loading. This thesis discusses sources of excitation, and investigates rotor system modeling methods. Computer models based on finite element and Mykiestad methods are developed and compared for the free and forced vibration cases of a nniform rotor blade. The modeling assumptions and the effects of non-iniform physical parameters are discussed. The Myklestad based computer model is expanded to include coupling effects isherent in modern rotor blades. This rotor modeling program is incorporated into the Dynamics section of the Joint Army/Navy Rotorcraft Analysis and Design (JANRAD) program currenfly used by the Naval Postgraduate School?s helicopter design course (AA43O6) for preliminary helicopter design and analysis. Computer programs are developed as tools to investigate the stabffity of a rotor system for the specfflc cases of rotor flapping and ground/air resonance. A rotor flapping stability model, based upon Floquet theory, provides a means of analyzing the effect of increasing advance ratio on the flapping stability of a rotor system. The ground/air resonance model uses a constant coefficient approximation of the rotor system to allow analysis of the effects of coupling between rotor lag motion and airframe motion.


Fundamentals of Helicopter Dynamics

Fundamentals of Helicopter Dynamics

Author: C. Venkatesan

Publisher: CRC Press

Published: 2014-08-19

Total Pages: 342

ISBN-13: 1466566345

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Helicopter Dynamics Introduced in an Organized and Systematic Manner A result of lecture notes for a graduate-level introductory course as well as the culmination of a series of lectures given to designers, engineers, operators, users, and researchers, Fundamentals of Helicopter Dynamics provides a fundamental understanding and a thorough overview of helicopter dynamics and aerodynamics. Written at a basic level, this text starts from first principles and moves fluidly onward from simple to more complex systems. Gain Valuable Insight on Helicopter Theory Divided into 11 chapters, this text covers historical development, hovering and vertical flight, simplified rotor blade model in flap mode, and forward flight. It devotes two chapters to the aeroelastic response and stability analysis of isolated rotor blade in uncoupled and coupled modes. Three chapters address the modeling of coupled rotor–fuselage dynamics and the associated flight dynamic stability, and provide a simplified analysis of the ground resonance aeromechanical stability of a helicopter. Explains equations derived from first principles and approximations Contains a complete set of equations which can be used for preliminary studies Requires a basic first–level course in dynamics, as well as a basic first–level course in aerodynamics Useful for any student who wants to learn the complexities of dynamics in a flying vehicle, Fundamentals of Helicopter Dynamics is an ideal resource for aerospace/aeronautical, helicopter, and mechanical/control engineers, as well as air force schools and helicopter/rotorcraft manufacturers.


Modeling Helicopter Blade Dynamics Using a Modified Myklestad-Prohl Transfer Matrix Method

Modeling Helicopter Blade Dynamics Using a Modified Myklestad-Prohl Transfer Matrix Method

Author: Juan D. Cuesta

Publisher:

Published: 1994

Total Pages: 65

ISBN-13:

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Rotor Blade vibratory stresses are of utmost importance in helicopter design. A modified Myklestad-Prohl method for rotating beams has been coded to assist in preliminary helicopter rotor blade design. The rotor blade dynamics program is part of the Joint Army/Navy Rotorcraft Analysis and Design (JANRAD) program which was developed to aid in the preliminary design and analysis of helicopter rotor performance, stability and control, and rotor dynamics. JANRAD is an interactive, user friendly program written in MATLAB version 4.0 programming language and has been used extensively in the Naval Postgraduate School's capstone helicopter design course (AA 4306). A sample case is run and results are discussed.


Helicopter Flight Dynamics

Helicopter Flight Dynamics

Author: Gareth D. Padfield, CEng, PhD, FRAeS

Publisher: Wiley-Blackwell

Published: 2008-04-15

Total Pages: 680

ISBN-13: 0470691166

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The behaviour of helicopters is so complex that understanding the physical mechanisms at work in trim, stability and response, and thus the prediction of Flying Qualities, requires a framework of analytical and numerical modelling and simulation. Good Flying Qualities are vital for ensuring that mission performance is achievable with safety and, in the first edition of Helicopter Flight Dynamics, a comprehensive treatment of design criteria was presented. In this second edition, the author complements this with a new Chapter on Degraded Flying Qualities, drawing examples from flight in poor visibility, failure of control functions and encounters with severe atmospheric disturbances. Fully embracing the consequences of Degraded Flying Qualities during the design phase will contribute positively to safety. The accurate prediction and assessment of Flying Qualities draws on the modelling and simulation discipline on the one hand and testing methodologies on the other. Checking predictions in flight requires clearly defined ‘mission-task-elements’, derived from missions with realistic performance requirements. High fidelity simulations also form the basis for the design of stability and control augmentation systems, essential for conferring Level 1 Flying Qualities. The integrated description of flight dynamic modelling, simulation and flying qualities forms the subject of this book, which will be of interest to engineers in research laboratories and manufacturing industry, test pilots and flight test engineers, and as a reference for graduate and postgraduate students in aerospace engineering. The Author Gareth Padfield, a Fellow of the Royal Aeronautical Society, is the Bibby Professor of Aerospace Engineering at the University of Liverpool. He is an aeronautical engineer by training and has spent his career to date researching the theory and practice of flight for both fixed-wing aeroplanes and rotorcraft. During his years with the UK’s Royal Aircraft Establishment and Defence Evaluation and Research Agency, he conducted research into rotorcraft dynamics, handling qualities and flight control. His work has involved a mix of flight testing, creating and testing simulation models and developing analytic approximations to describe flight behaviour and handling qualities. Much of his research has been conducted in the context of international collaboration – with the Technical Co-operation Programme, AGARD and GARTEUR as well as more informal collaborations with industry, universities and research centres worldwide. He is very aware that many accomplishments, including this book, could not have been achieved without the global networking that aerospace research affords. During the last 8 years as an academic, the author has continued to develop his knowledge and understanding in flight dynamics, not only through research, but also through teaching the subject at undergraduate level; an experience that affords a new and deeper kind of learning that, hopefully, readers of this book will benefit from.


Modeling, Control and Coordination of Helicopter Systems

Modeling, Control and Coordination of Helicopter Systems

Author: Beibei Ren

Publisher: Springer Science & Business Media

Published: 2012-02-02

Total Pages: 243

ISBN-13: 1461415632

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Modeling, Control and Coordination of Helicopter Systems provides a comprehensive treatment of helicopter systems, ranging from related nonlinear flight dynamic modeling and stability analysis to advanced control design for single helicopter systems, and also covers issues related to the coordination and formation control of multiple helicopter systems to achieve high performance tasks. Ensuring stability in helicopter flight is a challenging problem for nonlinear control design and development. This book is a valuable reference on modeling, control and coordination of helicopter systems,providing readers with practical solutions for the problems that still plague helicopter system design and implementation. Readers will gain a complete picture of helicopters at the systems level, as well as a better understanding of the technical intricacies involved.


Nonlinear Dynamics in the Modeling of Helicopter Rotor Blade Lead/Lag Motion

Nonlinear Dynamics in the Modeling of Helicopter Rotor Blade Lead/Lag Motion

Author: Robert L. King

Publisher:

Published: 1999-06-01

Total Pages: 176

ISBN-13: 9781423543527

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Until recently, computer simulations of helicopter rotor dynamics have employed equations of motion that have been linearized or simplified. These modified equations of motion did not allow for the evaluation of nonlinear material properties in the rotor since higher order terms in the dynamics had been modified in the simplification process. With recent advances in both computer simulation hardware and symbolic mathematic manipulation software, the full nonlinear equations of motion may be utilized in helicopter rotor simulations. This dissertation reports on the use of the full nonlinear equations of motion in the analysis of rotor blade lead/lag motion and its effect on rotor hub and rigid body fulselage motion. Nonlinear modeling methods are implemented using Maple symbolic mathematic manipulation software and Matlab and Simulink computer simulation environments. Results are compared to the RAH- 66 Comanche Froude scale wind tunnel article and new methodologies evaluated in the search for a damperless rotor system that is free of ground and air resonance mechanical instabilities.


Helicopter Flight Dynamics

Helicopter Flight Dynamics

Author: G. D. Padfield

Publisher: AIAA (American Institute of Aeronautics & Astronautics)

Published: 1996

Total Pages: 552

ISBN-13:

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This volume provides a comprehensive treatment of the theoretical background to the dynamics of helicopter flight, the development of handling criteria, and new flight-test techniques. Flying quality is described from both objective and subjective perspectives, and test results are presented from a variety of different sources.


The Rotating Beam Problem in Helicopter Dynamics

The Rotating Beam Problem in Helicopter Dynamics

Author: Ranjan Ganguli

Publisher: Springer

Published: 2017-10-14

Total Pages: 109

ISBN-13: 9811060983

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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.