Download or read book Flight Control Design for Rotorcraft with Variable Rotor Speed written by Wei Guo and published by . This book was released on 2009 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flight control design issues for rotorcraft with variable rotor speed are investigated, and new design methodologies are developed to deal with the challenges of variable rotor speed. The benefits of using variable rotor speed for rotorcraft are explored with a rotor speed optimization study using a modified GENHEL model of UH-60A Blackhawk. The optimization results recommend to use the optimal rotor speed in each flight condition to improve the helicopter performance. The efforts are made to accommodate the optimal rotor speed schedule into the flight control system design and also address the stability issues due to the rotor speed variation. The rotor speed optimization results show significant performance improvements can be achieved with moderate reductions in rotor speed. The objective of the control design is to accommodate these rotor speed variations, while achieving desired flying qualities and maneuver performance. A gain scheduled model following/model inversion controller is used to control the roll, pitch, yaw, heave, and rotor speed degrees of freedom. Rotor speed is treated as a redundant control effector for the heave axis, and different control allocation schemes are investigated. The controllers are evaluated based on step responses and the ADS-33E height response requirement. Results show that dynamic variation in rotor speed can improve maximum climb rate and flying qualities for moderate to large commands in vertical speed, but that non-linear effects present significant challenges when integrating control of the aircraft and the engine. The effects of reduced rotor speeds on stability margins, torque required, and stability issues are also studied. A power command system in the vertical axis is designed to incorporate variable rotor speed while handling torque limits and other constraints. The vertical axis controller uses a fixed nonlinear mapping to find the combination of collective pitch and rotor speed to optimize performance in level flight, climbing/descending flight, and steady turns. In this scheme, the controller is open-loop, making it an inexpensive and reliable solution. The mapping is designed to produce a desired power level for a given pilot input. Thus the mapping can take into account the performance limits associated with the vertical axis such as power limits, torque limits, and maximum rate of descent. A model following controller is implemented for the pitch, roll, and yaw axes. The piloted simulation was performed to evaluate the controller. The impact of variable rotor speed on closed loop stability of rotorcraft is discussed. The model following controller can provide high bandwidth control and improve performance using variable rotor speed. However, reduction of rotor speed can result in rotor body coupling and even instability. A rotor state feedback control law can be designed independently and easily integrated into the baseline model following control architecture. Simulations were performed to verify the effectiveness of RSF control to stabilize the rotorcraft dynamics or improve the command tracking performance in the presence of reduced rotor RPM.

Download or read book Integrated Flight propulsion Control with Variable Rotor Speed Command for Rotorcraft written by Stanford University. Department of Aeronautics and Astronautics and published by . This book was released on 1996 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances In Aircraft Flight Control written by MB Tischler and published by Routledge. This book was released on 2018-04-24 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a single comprehensive resource that reviews many of the current aircraft flight control programmes from the perspective of experienced practitioners directly involved in the projects. Each chapter discusses a specific aircraft flight programme covering the control system design considerations, control law architecture, simulation and analysis, flight test optimization and handling qualities evaluations. The programmes described have widely exploited modern interdisciplinary tools and techniques and the discussions include extensive flight test results. Many important `lessons learned' are included from the experience gained when design methods and requirements were tested and optimized in actual flight demonstration.

Download or read book Aircraft Control and Simulation written by Brian L. Stevens and published by John Wiley & Sons. This book was released on 2015-10-05 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt: Get a complete understanding of aircraft control and simulation Aircraft Control and Simulation: Dynamics, Controls Design, and Autonomous Systems, Third Edition is a comprehensive guide to aircraft control and simulation. This updated text covers flight control systems, flight dynamics, aircraft modeling, and flight simulation from both classical design and modern perspectives, as well as two new chapters on the modeling, simulation, and adaptive control of unmanned aerial vehicles. With detailed examples, including relevant MATLAB calculations and FORTRAN codes, this approachable yet detailed reference also provides access to supplementary materials, including chapter problems and an instructor's solution manual. Aircraft control, as a subject area, combines an understanding of aerodynamics with knowledge of the physical systems of an aircraft. The ability to analyze the performance of an aircraft both in the real world and in computer-simulated flight is essential to maintaining proper control and function of the aircraft. Keeping up with the skills necessary to perform this analysis is critical for you to thrive in the aircraft control field. Explore a steadily progressing list of topics, including equations of motion and aerodynamics, classical controls, and more advanced control methods Consider detailed control design examples using computer numerical tools and simulation examples Understand control design methods as they are applied to aircraft nonlinear math models Access updated content about unmanned aircraft (UAVs) Aircraft Control and Simulation: Dynamics, Controls Design, and Autonomous Systems, Third Edition is an essential reference for engineers and designers involved in the development of aircraft and aerospace systems and computer-based flight simulations, as well as upper-level undergraduate and graduate students studying mechanical and aerospace engineering.

Download or read book Lecture Notes in Rotorcraft Engineering written by Antonio Filippone and published by Springer Nature. This book was released on 2023-01-27 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a multi-disciplinary compendium that includes several aspects of rotorcraft technology. It introduces the reader to the aerodynamic aspects of rotary wings and presents experimental techniques for aerodynamics. The chapters also cover rotorcraft engines and rotorcraft steady-state flight performance and stability. It explores several aspects of the tiltrotor configuration and lists challenges in their design, modelling and simulation. The reader will also find an introductory overview of flight control systems for rotorcraft, as well as the conceptual and preliminary design concepts for a conventional helicopter. This textbook contains video recordings of computer simulations that can be used alongside the main text.

Download or read book Rotorcraft Flight propulsion Control Integration written by James R. Mihaloew and published by . This book was released on 1988 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Robust Flight Control of Rotorcraft written by Adam Daniel Pechner and published by . This book was released on 2010 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotorcraft Flight propulsion Control Integration written by James R. Mihaloew and published by . This book was released on 1988 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotorcraft Flight Control Design with Alleviation of Unsteady Rotor Loads written by Umberto Saetti and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this research effort is to develop rotorcraft flight control laws that minimize unsteady rotor loads by acting solely through the primary flight controls (first harmonic swashplate control). As opposed to Higher-Harmonic Control, this strategy does not affect stationary (periodic trim) loads, and is therefore effective only in maneuvering flight. However, such system could be readily integrated with existing or future Automatic Flight Control Systems (AFCS). The study considers control designs for both conventional and compound configurations.Starting from a non-linear simulation model of the rotorcraft developed in FLIGHTLAB, which includes sufficient fidelity to simulate rotor loads and vibrations, Linear Time-Periodic models (LTP) are derived via linearization. Next, the Harmonic Decomposition methodology is used to approximate the LTP systems with higher-order Linear Time-Invariant (LTI) systems. Reduced-order systems are subsequently obtained by using singular perturbation theory. By retaining the higher-harmonics of the rotor loads in the output, the reduced-order models are shown to accurately predicted the influence of the zeroth harmonics of the rigid-body and rotor flapping states on the higher-harmonics of the rotor loads. This way, previous limitations such as the reliance on non-physics-based models and curve fits to approximate rotor loads are lifted. Next, model following flight control laws are developed based on the reduced-order models. Parametric studies are performed to provide insights on how both the feed-forward and feedback paths of the model following control laws can be used to alleviate the rotor loads. Also, the impact of load alleviation on handling qualities is studied. It is shown that, for a standard helicopter configuration, load alleviation comes at the cost of a degradation in handling qualities. However, for the case of a compound rotorcraft, allocation of the control signal to the redundant control surfaces provides load alleviation without degradation in the handling qualities. The flight control laws are subsequently optimized using CONDUIT to meet a comprehensive set of stability, handling qualities, and performance specifications for specific mission task elements while minimizing the unsteady rotor loads. Finally, since industry will not only rely on LTP systems obtained from simulation models, a novel methodology is developed to identify LTP systems from flight test data. The methodology is successfully applied to JUH-60A Black Hawk flight test data using CIFER. The identified LTP systems capture the Nb/rev component of the rotorcraft dynamics. Further, it is shown how the higher-harmonics of the rotor states contribute to the overall rotorcraft dynamics for up to a 7%. On the other hand, the rigid-body states contribute to the overall rotorcraft dynamics almost entirely through their zeroth harmonic. Flight control design based on LTP systems identified from flight-test data could benefit the Future Vertical Lift (FVL) program. FVL is a plan to develop a new generation of military helicopters for the U.S. Army with increased capabilities in speed, range, and payload, and reduced maintenance and operational cost. Because these rotorcraft would operate at significantly higher speeds than the current helicopters, alleviation of the higher harmonic rotor loads and flight envelope protection are key elements to reduced maintenance cost. These rotorcraft are also likely to employ redundant control surfaces which, in connection with LTP-based flight control design, demonstrated outstanding effectiveness towards the alleviation of unsteady rotor loads.

Download or read book Technology Needs for High Speed Rotorcraft 2 written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-04 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical study was conducted to identify rotorcraft concepts best capable of combining a cruise speed of 350 to 450 knots with helicopter-like low speed attributes, and to define the technology advancements needed to make them viable by the year 2000. A systematic approach was used to compare the relative attributes and mission gross weights for a wide range of concepts, resulting in a downselect to the most promising concept/mission pairs. For transport missions, tilt-wing and variable diameter tilt-rotor (VDTR) concepts were found to be superior. For a military scout/attack role, the VDTR was best, although a shrouded rotor concept could provide a highly agile, low observable alternative if its weight empty fraction could be reduced. A design speed of 375 to 425 knots was found to be the maximum desirable for transport missions, with higher speed producing rapidly diminishing benefits in productivity. The key technologies that require advancement to make the tilt-wing and VDTR concepts viable are in the areas of wing and proprotor aerodynamics, efficient structural design, flight controls, refinement of the geared flap pitch control system, expansion of the speed/descent envelope, and the structural and aerodynamic tradeoffs of wing thickness and forward sweep. For the shrouded rotor, weight reduction is essential, particularly with respect to the mechanism for covering the rotor in cruise. Scott, Mark W. Unspecified Center NASA-CR-177590, A-91215, NAS 1.26:177590 NAS2-13058...

Download or read book Robust Multivariable Flight Control written by Richard J. Adams and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: Manual flight control system design for fighter aircraft is one of the most demanding problems in automatic control. Fighter aircraft dynamics generally have highly coupled uncertain and nonlinear dynamics. Multivariable control design techniques offer a solution to this problem. Robust Multivariable Flight Control provides the background, theory and examples for full envelope manual flight control system design. It gives a versatile framework for the application of advanced multivariable control theory to aircraft control problems. Two design case studies are presented for the manual flight control of lateral/directional axes of the VISTA-F-16 test vehicle and an F-18 trust vectoring system. They demonstrate the interplay between theory and the physical features of the systems.

Download or read book Applications of Flight Control System Methods to an Advanced Combat Rotorcraft written by and published by . This book was released on 1989 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced flight control system design, analysis, and testing methods are applied in an analytical and flight test evaluation of the Advanced Digital Optical Control System (ADOCS) demonstrator. This paper describes the knowledge gained about the implications of digital flight control system design for rotorcraft, and illustrates. The analysis of the resulting handling-qualities in the context of the proposed new handling-qualities specification for rotorcraft. Topics included are digital flight control design and analysis methods, flight testing techniques, ADOCS handling-qualities evaluation results, and correlation of flight test results with analytical models and the proposed handling- qualities specification. Evaluation of the ADOCS demonstrator indicated desirable response characteristics based on equivalent damping and frequency, but undesirably large effective time-delays. Piloted handling-qualities are desirable or adequate for all low, medium, and high pilot gain tasks; but handling-qualities are inadequate for ultra-high gain tasks such as slope and running landings. Correlation of these results with the proposed handling- qualities specification indicates good agreement for the bandwidth boundaries, but suggests the need for more stringent limits on allowable phase-delay. Analytical models based on emulation (s-plane) techniques compare favorably with flight extracted frequency-domain characteristics of the overall (end-to-end) ADOCS responses. Direct digital analysis procedures are necessary to characterize the intersample behavior of the actuator rate response.

Download or read book Practical Methods for Aircraft and Rotorcraft Flight Control Design written by Mark Brian Tischler and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reducing the theoretical methods of flight control to design practice, Practical Methods for Aircraft and Rotorcraft Flight Control Design: An Optimization-Based Approach compiles the authors' extensive experience and lessons learned into a single comprehensive resource for both academics and working flight control engineers.

Download or read book Flight Control Systems written by Roger Pratt and published by IET. This book was released on 2000 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation Bridging the gap between academic research and real-world applications, this reference on modern flight control methods for fixed-wing aircraft deals with fundamentals of flight control systems design, then concentrates on applications based on the modern control methods used in the latest aircraft. The book is written for practicing engineers who are new to the aviation industry, postgraduate students in strategic or applied research, and advanced undergraduates. Some knowledge of classical control is assumed. Pratt is a member of IEEE and is UK Member for AIAA's Technical Committee on Guidance, Navigation and Control. Annotation c. Book News, Inc., Portland, OR (booknews.com)

Download or read book Rotorcraft Flight Control Design Using Quantitative Feedback Theory and Dynamic Crossfeeds written by Rendy P. Cheng and published by . This book was released on 1995 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Automatic Control of Atmospheric and Space Flight Vehicles written by Ashish Tewari and published by Springer Science & Business Media. This book was released on 2011-08-04 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Automatic Control of Atmospheric and Space Flight Vehicles is perhaps the first book on the market to present a unified and straightforward study of the design and analysis of automatic control systems for both atmospheric and space flight vehicles. Covering basic control theory and design concepts, it is meant as a textbook for senior undergraduate and graduate students in modern courses on flight control systems. In addition to the basics of flight control, this book covers a number of upper-level topics and will therefore be of interest not only to advanced students, but also to researchers and practitioners in aeronautical engineering, applied mathematics, and systems/control theory.

Download or read book A Robust Rotorcraft Flight Control System Design Methodology Utilizing Quantitative Feedback Theory written by Peter James Gorder and published by . This book was released on 1993 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: