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Coupled Nonlinear Flight Dynamics Aeroelasticity And Control Of Very Flexible Aircraft
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Book Synopsis Coupled Nonlinear Flight Dynamics, Aeroelasticity, and Control of Very Flexible Aircraft by : Christopher Mark Shearer
Download or read book Coupled Nonlinear Flight Dynamics, Aeroelasticity, and Control of Very Flexible Aircraft written by Christopher Mark Shearer and published by . This book was released on 2006 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamics of Flexible Aircraft by : Rafael Palacios
Download or read book Dynamics of Flexible Aircraft written by Rafael Palacios and published by Cambridge University Press. This book was released on 2023-06-30 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore the connections among aeroelasticity, flight dynamics, and control with an up-to-date multidisciplinary approach. New insights into the interaction between these fields, which is a distinctive feature of many modern aircraft designed for very high aerodynamic efficiency, are fully illustrated in this one-of-a-kind book. Presenting basic concepts in a systematic and rigorous, yet accessible way, this book builds up to state-of-the-art models through an intuitive step-by-step approach. Both linear and nonlinear attributes are covered and, by revisiting classical solutions using modern analysis methods, this book provides a unique perspective to bridge the gap between disciplines. Numerous original numerical examples, including online source codes, help to build intuition through hands-on activities. This book will empower the reader to design better and more environmentally friendly aircraft, and is an ideal resource for graduate students, researchers, and aerospace engineers.
Book Synopsis Flight Dynamics, Simulation, and Control by : Ranjan Vepa
Download or read book Flight Dynamics, Simulation, and Control written by Ranjan Vepa and published by CRC Press. This book was released on 2014-08-18 with total page 694 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore Key Concepts and Techniques Associated with Control Configured Elastic Aircraft A rapid rise in air travel in the past decade is driving the development of newer, more energy-efficient, and malleable aircraft. Typically lighter and more flexible than the traditional rigid body, this new ideal calls for adaptations to some conventional concepts. Flight Dynamics, Simulation, and Control: For Rigid and Flexible Aircraft addresses the intricacies involved in the dynamic modelling, simulation, and control of a selection of aircraft. This book covers the conventional dynamics of rigid aircraft, explores key concepts associated with control configured elastic aircraft, and examines the use of linear and non-linear model-based techniques and their applications to flight control. In addition, it reveals how the principles of modeling and control can be applied to both traditional rigid and modern flexible aircraft. Understand the Basic Principles Governing Aerodynamic Flows This text consists of ten chapters outlining a range of topics relevant to the understanding of flight dynamics, regulation, and control. The book material describes the basics of flight simulation and control, the basics of nonlinear aircraft dynamics, and the principles of control configured aircraft design. It explains how elasticity of the wings/fuselage can be included in the dynamics and simulation, and highlights the principles of nonlinear stability analysis of both rigid and flexible aircraft. The reader can explore the mechanics of equilibrium flight and static equilibrium, trimmed steady level flight, the analysis of the static stability of an aircraft, static margins, stick-fixed and stick-free, modeling of control surface hinge-moments, and the estimation of the elevator for trim. Introduces case studies of practical control laws for several modern aircraft Explores the evaluation of aircraft dynamic response Applies MATLAB®/Simulink® in determining the aircraft’s response to typical control inputs Explains the methods of modeling both rigid and flexible aircraft for controller design application Written with aerospace engineering faculty and students, engineers, and researchers in mind, Flight Dynamics, Simulation, and Control: For Rigid and Flexible Aircraft serves as a useful resource for the exploration and study of simulation of flight dynamics.
Book Synopsis Introduction to Nonlinear Aeroelasticity by : Grigorios Dimitriadis
Download or read book Introduction to Nonlinear Aeroelasticity written by Grigorios Dimitriadis and published by John Wiley & Sons. This book was released on 2017-03-10 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Nonlinear Aeroelasticity Introduces the latest developments and technologies in the area of nonlinear aeroelasticity Nonlinear aeroelasticity has become an increasingly popular research area in recent years. There have been many driving forces behind this development, increasingly flexible structures, nonlinear control laws, materials with nonlinear characteristics and so on. Introduction to Nonlinear Aeroelasticity covers the theoretical basics in nonlinear aeroelasticity and applies the theory to practical problems. As nonlinear aeroelasticity is a combined topic, necessitating expertise from different areas, the book introduces methodologies from a variety of disciplines such as nonlinear dynamics, bifurcation analysis, unsteady aerodynamics, non-smooth systems and others. The emphasis throughout is on the practical application of the theories and methods, so as to enable the reader to apply their newly acquired knowledge Key features: Covers the major topics in nonlinear aeroelasticity, from the galloping of cables to supersonic panel flutter Discusses nonlinear dynamics, bifurcation analysis, numerical continuation, unsteady aerodynamics and non-smooth systems Considers the practical application of the theories and methods Covers nonlinear dynamics, bifurcation analysis and numerical methods Accompanied by a website hosting Matlab code Introduction to Nonlinear Aeroelasticity is a comprehensive reference for researchers and workers in industry and is also a useful introduction to the subject for graduate and undergraduate students across engineering disciplines.
Book Synopsis Computational and Experimental Simulations in Engineering by : Hiroshi Okada
Download or read book Computational and Experimental Simulations in Engineering written by Hiroshi Okada and published by Springer Nature. This book was released on 2019-11-16 with total page 1278 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers the latest advances, innovations, and applications in the field of computational engineering, as presented by leading international researchers and engineers at the 24th International Conference on Computational & Experimental Engineering and Sciences (ICCES), held in Tokyo, Japan on March 25-28, 2019. ICCES covers all aspects of applied sciences and engineering: theoretical, analytical, computational, and experimental studies and solutions of problems in the physical, chemical, biological, mechanical, electrical, and mathematical sciences. As such, the book discusses highly diverse topics, including composites; bioengineering & biomechanics; geotechnical engineering; offshore & arctic engineering; multi-scale & multi-physics fluid engineering; structural integrity & longevity; materials design & simulation; and computer modeling methods in engineering. The contributions, which were selected by means of a rigorous international peer-review process, highlight numerous exciting ideas that will spur novel research directions and foster multidisciplinary collaborations.
Book Synopsis Flexible Aircraft Dynamics with a Geometrically-nonlinear Description of the Unsteady Aerodynamics by : Joseba Murua
Download or read book Flexible Aircraft Dynamics with a Geometrically-nonlinear Description of the Unsteady Aerodynamics written by Joseba Murua and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Unsteady Vortex-Lattice Method provides a medium-fidelity tool for the prediction of non-stationary aerodynamic loads in low-speed, but high-Reynolds-number, attached flow. Despite a proven track record in applications where free-wake modelling is critical, other models based on potential-flow theory, such as the Doublet Lattice and thin-aerofoil approximation, have been favoured in fixed-wing aircraft aeroelasticity and flight dynamics. This dissertation presents how the Unsteady Vortex-Lattice Method can be re-engineered as an enhanced alternative to those techniques for diverse situations that arise in flexible-aircraft dynamics. A historical review of the methodology is included, with latest developments and practical applications. Different formulations of the aerodynamic equations are outlined, and they are integrated with a nonlinear beam model for the full description of the dynamics of a free-flying flexible vehicle, which furnishes a geometrically-nonlinear description of both structure and aerodynamics. Nonlinear time-marching captures large wing excursions and wake roll-up, and the linearisation of the equations lends itself to a seamless, monolithic state-space assembly, particularly convenient for stability analysis. The aerodynamic model and the unified framework for the simulation of high-aspect-ratio planes are exhaustively verified by comparing them to lower- and higher-fidelity approaches. Numerical studies emphasising scenarios where the Unsteady Vortex-Lattice Method can provide an advantage over other state-of-the-art tools are presented. Examples of this comprise unsteady aerodynamics in vehicles with coupled aeroelasticity and flight dynamics, and in lifting surfaces undergoing complex kinematics, large deformations, or in-plane motions. Geometric nonlinearities are shown to play an instrumental, and often counter-intuitive, role in the aircraft dynamics. The Unsteady Vortex-Lattice Method is unveiled as a remarkable tool that can successfully incorporate them in the unsteady aerodynamics modelling.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781720600879 Total Pages :76 pages Book Rating :4.6/5 (8 download)
Book Synopsis Integrated Approach to the Dynamics and Control of Maneuvering Flexible Aircraft by : National Aeronautics and Space Administration (NASA)
Download or read book Integrated Approach to the Dynamics and Control of Maneuvering Flexible Aircraft written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work uses a fundamental approach to the problem of simulating the flight of flexible aircraft. To this end, it integrates into a single formulation the pertinent disciplines, namely, analytical dynamics, structural dynamics, aerodynamics, and controls. It considers both the rigid body motions of the aircraft, three translations (forward motion, sideslip and plunge) and three rotations (roll, pitch and yaw), and the elastic deformations of every point of the aircraft, as well as the aerodynamic, propulsion, gravity and control forces. The equations of motion are expressed in a form ideally suited for computer processing. A perturbation approach yields a flight dynamics problem for the motions of a quasi-rigid aircraft and an 'extended aeroelasticity' problem for the elastic deformations and perturbations in the rigid body motions, with the solution of the first problem entering as an input into the second problem. The control forces for the flight dynamics problem are obtained by an 'inverse' process and the feedback controls for the extended aeroservoelasticity problem are determined by the LQG theory. A numerical example presents time simulations of rigid body perturbations and elastic deformations about 1) a steady level flight and 2) a level steady turn maneuver.Waszak, Martin R. (Technical Monitor) and Meirovitch, Leonard and Tuzcu, IlhanLangley Research CenterAEROSERVOELASTICITY; AERODYNAMICS; FLEXIBLE WINGS; AIRCRAFT MANEUVERS; FLIGHT SIMULATION; AIRCRAFT CONTROL; ROLL; SIDESLIP; YAW; ELASTIC DEFORMATION; EQUATIONS OF MOTION; LINEAR QUADRATIC GAUSSIAN CONTROL; FEEDBACK CONTROL
Book Synopsis Topics on Flexible Airplane Dynamics: Coupling of the rigid and elastic degrees of freedom of an airframe by :
Download or read book Topics on Flexible Airplane Dynamics: Coupling of the rigid and elastic degrees of freedom of an airframe written by and published by . This book was released on 1963 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: pt.3: The dynamic coupling of rigid and elastic degrees of freedom of an airplane are described by two methods. In the first, coupling is described by the changes in airframe characteristic equation roots caused by the introduction of coupling terms to the equations of motion. The second method employs modal response coefficients to compare the relative amplitudes of rigid and elastic degrees of freedom at each coupled mode frequency. Simple literal expressions are obtained for each of these descriptors and physical interpretations given. Time vector diagrams are also used to show the major parameters affecting coupling. (Author).
Book Synopsis Flight Dynamics by : Robert F. Stengel
Download or read book Flight Dynamics written by Robert F. Stengel and published by Princeton University Press. This book was released on 2022-11-01 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: An updated and expanded new edition of an authoritative book on flight dynamics and control system design for all types of current and future fixed-wing aircraft Since it was first published, Flight Dynamics has offered a new approach to the science and mathematics of aircraft flight, unifying principles of aeronautics with contemporary systems analysis. Now updated and expanded, this authoritative book by award-winning aeronautics engineer Robert Stengel presents traditional material in the context of modern computational tools and multivariable methods. Special attention is devoted to models and techniques for analysis, simulation, evaluation of flying qualities, and robust control system design. Using common notation and not assuming a strong background in aeronautics, Flight Dynamics will engage a wide variety of readers, including aircraft designers, flight test engineers, researchers, instructors, and students. It introduces principles, derivations, and equations of flight dynamics as well as methods of flight control design with frequent reference to MATLAB functions and examples. Topics include aerodynamics, propulsion, structures, flying qualities, flight control, and the atmospheric and gravitational environment. The second edition of Flight Dynamics features up-to-date examples; a new chapter on control law design for digital fly-by-wire systems; new material on propulsion, aerodynamics of control surfaces, and aeroelastic control; many more illustrations; and text boxes that introduce general mathematical concepts. Features a fluid, progressive presentation that aids informal and self-directed study Provides a clear, consistent notation that supports understanding, from elementary to complicated concepts Offers a comprehensive blend of aerodynamics, dynamics, and control Presents a unified introduction of control system design, from basics to complex methods Includes links to online MATLAB software written by the author that supports the material covered in the book
Book Synopsis Integrated Approach to the Dynamics and Control of Maneuvering Flexible Aircraft by :
Download or read book Integrated Approach to the Dynamics and Control of Maneuvering Flexible Aircraft written by and published by . This book was released on 2003 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling Flexible Aircraft for Flight Control Design by : E. C. Bekir
Download or read book Modeling Flexible Aircraft for Flight Control Design written by E. C. Bekir and published by . This book was released on 1989 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: Trends to lower structural fraction of aircraft increase flexibility effects. Higher bandwidth control systems combined with these more flexible structures cause more aeroservoelastic interactions. Active, closed-loop control systems allow greater flexibility. To take advantage of this design possibility, an integrated ASE model is needed for conceptual and preliminary design stages of aircraft. This report seeks to define the equations of motion of a flexible aircraft from first principles to aid future discussions between experts in the specialties which make up ASE: aerodynamics, controls, and structures. This theoretical report documents the development of the equations, and states under what conditions the assumptions and approximations are accurate. It consists of 5 sections on different technical areas and a summary section: 1) Linearization of flexible aircraft hybrid-coordinate dynamic equations and inclusion of aerodynamic and gravitational loads; 2) Derivation of equations of motion and stability derivatives for a flexible aircraft vehicle; 3) Aerodynamics for aeroservoelasticity; 4) Model-order reduction for linear systems; and 5) Hydraulic actuator equations for aeroservoelastic modeling. Flight control systems; Servomechanisms. (edc).
Book Synopsis Trajectory Control for Very Flexible Aircraft by :
Download or read book Trajectory Control for Very Flexible Aircraft written by and published by . This book was released on 2006 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper focuses on trajectory control of the 6-DOF body fixed reference frame located on a very flexible aircraft. The 6-DOF equations of motion of a reference point on the aircraft are coupled with the aeroelastic equations that govern the geometrically nonlinear structural response of the vehicle. A low-order strain-based nonlinear structural analysis coupled with unsteady finitestate potential flow aerodynamics form the basis for the aeroelastic model. The nonlinear beam finite element structural model assumes constant strain over an element in extension, twist, and in/out of plane bending. The geometrically nonlinear structural formulation, the finite state aerodynamic model, and the nonlinear rigid body equations together provide a low-order complete nonlinear aircraft analysis tool. Due to the inherent flexibility of the aircraft modeling, the low order structural fre quencies are of the same order as the rigid body modes. This creates a coupling which cannot be separated by previous control schemes. The flexibility must be accounted for directly in the controller development. To accomplish this a heuristic approach based upon pilot behavior is developed. This approach separates the problem into two parts: a fast inner-loop and a slower outer-loop. Dominant kinematic nonlinearities are handled in the outer-loop while the inner-loop is further separated into a lateral and longitudinal motion. Control of the inner-loop lateral motion is accomplished using a standard Linear Quadratic Regulator. For the longitudinal motion Dynamic Inversion is utilized. Differences between the desired and actual trajectories are handled in the nonlinear outer-loop using traditional proportional-integral-derivative design guidelines. The closed loop time integration is accomplished using an implicit modified Newmark method. Numerical simulations are presented highlighting the strengths and weaknesses of the method.
Book Synopsis Flight mechanics and flight control for a multibody aircraft by : Köthe, Alexander
Download or read book Flight mechanics and flight control for a multibody aircraft written by Köthe, Alexander and published by Universitätsverlag der TU Berlin. This book was released on 2019-06-26 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft operating as so-called High Altitude Platform Systems (HAPS) have been considered as a complementary technology to satellites since several years. These aircraft can be used for similar communication and monitoring tasks while operating at a fraction of the cost. Such concepts have been successfully tested. Those include the AeroVironment Helios and the Airbus Zephyr, with an endurance of nearly 624 hours (26 days). All these HAPS aircraft have a high-aspect-ratio wing using lightweight construction. In gusty atmosphere, this results in high bending moments and high structural loads, which can lead to overloads. Aircraft crashes, for example from Google’s Solara 50 or Facebook’s Aquila give proof of that fact. Especially in the troposphere, where the active weather takes place, gust loads occur, which can lead to the destruction of the structure. The Airbus Zephyr, the only HAPS aircraft without flight accidents, provides only a very small payload. Thus it does not fully comply with the requirements for future HAPS aircraft. To overcome the shortcomings of such single-wing aircraft, so-called multibody aircraft are considered to be an alternative. The concept assumes multiple aircraft connected to each other at their wingtips. It goes back to the German engineer Dr. Vogt. In the United States, shortly after the end of World War II, he experimented with the coupling of manned aircraft. This resulted in a high-aspect-ratio wing for the aircraft formation. The range of the formation could be increased correspondingly. The engineer Geoffrey S. Sommer took up Vogt’s idea and patented an aircraft configuration consisting of several unmanned aerial vehicles coupled at their wingtips. However, the patent does not provide any insight into the flight performance, the flight mechanical modeling or the control of such an aircraft. Single publications exist that deal with the performance of coupled aircraft. A profound, complete analysis, however, is missing so far. This is where the present work starts. For the first time, a flying vehicle based on the concept of the multibody aircraft will be analyzed in terms of flight mechanics and flight control. In a performance analysis, the aircraft concept is analyzed in detail and the benefits in terms of bending moments and flight performance are clearly highlighted. Limits for operation in flight are shown considering aerodynamic optimal points. The joints at the wingtips allow a roll and pitch motion of the individual aircraft. This results in additional degrees of freedom for the design through the implementation of different relative pitch and bank angles. For example, using individual pitch angles for individual aircraft further decreases the induced drag and increases flight performance. Because the lift is distributed symmetrically, but not homogenously along the wingspan, a lateral trim of the individual aircraft in formation flight becomes necessary. The thesis presents a new method to implement this trim by moving the battery mass along half the wingspan, which avoids additional parasite drag. Further, a complete flight dynamics model is provided and analyzed for aircraft that are mechanically connected at their wingtips. To study this model in detail, a hypothetical torsional and bending spring between the aircraft is introduced. If the spring constants are very high, the flight dynamics model has properties similar to those of an elastic aircraft. Rigid-body and formation eigenmotions can be clearly distinguished. If the spring constants are reduced towards zero, which represents the case of the multibody aircraft, classical flight mechanics eigenmotions and modes resulting from the additional degrees of freedom are coupled. This affects the eigenstructure of the aircraft. Hence, normal motions with respect to the inertial space as known from a rigid aircraft cannot be observed anymore. The plant also reveals unstable behavior. Using the non-linear flight dynamics model, flight controllers are designed to stabilize the plant and provide the aircraft with an eigenstructure similar to conventional aircraft. Different controller design methods are used. The flight controller shall further maintain a determined shape of the flight formation, it shall control flight, bank and pitch angles, and it shall suppress disturbances. Flight control theories in the time domain (Eigenstructure assignment) and in the frequency domain (H-infinity loop-shaping) are considered. The resulting inner-control loops yield a multibody aircraft behavior that is similar to the one of a rigid aircraft. For the outer-control loops, classical autopilot concepts are applied. Overall, the flight trajectory of the multibody aircraft above ground is controlled and, thus, an actual operation as HAPS is possible. In the last step, the flight controller is successfully validated in non-linear simulations with complete flight dynamics. Flugzeuge in der Form von sogenannten Höhenplattformen (engl. High-Altitude Platform Systems, HAPS) werden seit einigen Jahren als kostengünstige Ergänzung zu teuren Satelliten betrachtet. Diese Flugzeuge können für ähnliche Kommunikations- und überwachungsaufgaben eingesetzt werden. Zu den gegenwärtigen Konzepten solcher Fluggeräte, die bereits erfolgreich im Flugversuch eingesetzt wurden, zählen der Helios von AeroVironment und der Airbus Zephyr, der eine Flugdauer von fast 624 Stunden (26 Tagen) erreicht hat. Alle diese HAPS-Flugzeuge besitzen einen Flügel langer Streckung, der in Leichtbauweise konstruiert ist. Hieraus resultieren in böiger Atmosphäre hohe Biegemomente und starke strukturelle Belastungen, die zu überbelastungen führen können. Flugunfälle beispielsweise von Googles Solara 50 oder Facebooks Aquila belegen dies. Insbesondere in der Troposphäre, in der das aktive Wetter stattfindet, treten Böenlasten auf, die die Struktur zerstören können. Der Airbus Zephyr, der bisher als einziges HAPS-Flugzeug frei von Flugunfällen ist, besitzt nur eine sehr geringe Nutzlast. Daher kann er die Anforderungen an zukünftige HAPS-Flugzeuge nicht vollständig erfüllen. Um die Schwachstellen solcher Ein-Flügel-Konzepte zu überwinden, wird in dieser Arbeit ein alternatives Flugzeugkonzept betrachtet, das als Mehrkörperflugzeug bezeichnet wird. Das Konzept geht von mehreren, an den Flügelspitzen miteinander verbundenen Flugzeugen aus und beruht auf Ideen des deutschen Ingenieurs Dr. Vogt. Dieser hatte in den USA kurz nach Ende des Zweiten Weltkrieges bemannte Flugzeuge aneinanderkoppeln lassen. Hierdurch ergab sich ein Flugzeugverbund mit einem Flügel langer Streckung. Damit konnte die Reichweite des Verbundes gesteigert werden. Geoffrey S. Sommer griff die Idee von Vogt auf und lies sich eine Flugzeugkonfiguration patentieren, die aus mehreren, unbemannten Flugzeugen besteht, die an den Enden der Tragflächen miteinander gekoppelt sind. Die Patentschrift gibt jedoch keinen Einblick in die Flugleistungen, die flugmechanische Modellierung oder die Regelung eines solchen Fluggerätes. Vereinzelt existieren Veröffentlichungen, die sich mit den Flugleistungen von gekoppelten Luftfahrzeugen beschäftigen. Eine tiefgreifende, vollständige flugmechanische Analyse fehlt jedoch bisher. Hier setzt die vorliegende Arbeit an. Ein Fluggerät basierend auf dem Konzept des Mehrkörperflug-zeugs wird erstmalig hinsichtlich der Flugmechanik und Flugregelung untersucht. In einer Flugleistungsbetrachtung wird das Flugzeugkonzept genau analysiert und die Vorteile hinsichtlich der Biegemomente und der Flugleistungen klar herausgestellt. Die Grenzen des Einsatzes im Flugbetrieb werden mithilfe aerodynamischer Optimalpunkte aufgezeigt. über die Lager an den Flügelspitzen, die eine relative Roll- und Nickbewegung der Flugzeuge untereinander ermöglichen, ergeben sich durch die Einstellung unterschiedlicher Längslage- und Hängewinkel zusätzliche Freiheitsgerade im Entwurf. Die Verwendung unterschiedlicher Nicklagewinkel der einzelnen Flugzeuge reduziert beispielsweise den induzierten Widerstand weiter und steigert die Flugleistung. Durch die symmetrische, entlang der Spannweite jedoch nicht homogene Auftriebsverteilung ist auch eine laterale Trimmung der einzelnen Flugzeuge in der Formation notwendig. Hier stellt die Arbeit eine neuartige Möglichkeit vor, um diese Trimmung ohne zusätzlichen parasitären Widerstand mittels Verschiebung der Batteriemasse entlang der Halbspannweite umzusetzen. Weiterhin wird ein vollständiges flugdynamisches Modell für über mechanische Lager verbundene Luftfahrzeuge aufgestellt und analysiert. Für diese Analyse wird eine hypothetische Torsions- und Biegefeder zwischen den Flugzeugen modelliert. Sind die Federsteifigkeiten hinreichend hoch, besitzt das flugdynamische Modell Eigenschaften, die einem elastischen Flugzeug entsprechen. Starrkörper- und elastische Eigenbewegungsformen sind in diesem Fall klar separiert. Bei immer weiterer Reduzierung, bis auf eine Federsteifigkeit von Null, kommt es zu Kopplungen zwischen den klassischen, flugmechanischen Eigenbewegungsformen und den Moden aus den zusätzlichen Freiheitsgraden. Dies stellt den Auslegungsfall für das Mehrkörperflugzeug dar. Hierbei verändert sich die Eigenstruktur (engl. eigenstructure) des Flugzeugs und normale, bei einem starren Flugzeug beobachtbare Bewegungen gegenüber dem inertialen Raum sind nicht mehr erkennbar. Zusätzlich zeigt die Strecke instabiles Verhalten. Basierend auf dem nichtlinearen, flugdynamischen Modell werden mit verschiedenen Methoden Regler entworfen, die die Regelstrecke stabilisieren und dem Flugzeug eine Streckenstruktur zuweisen, die derjenigen klassischer Flugzeuge ähnelt. Zudem soll durch die Regler eine vorgegebene Form des Flugzeugverbundes beibehalten werden, die Fahrt, der Längs- und Rolllagewinkel sollen geregelt und Störungen unterdrückt werden. Als Auslegungsverfahren werden Theorien der Zustandsregelungen im Zeitbereich (Eigenstrukturvorgabe) und Frequenzbereich (H-infinity loop-shaping) verwendet. Hierdurch wird durch die inneren Regelschleifen ein Verhalten des Mehrkörperflugzeugs erzielt, das dem eines starren Flugzeugs entspricht. Für die äußeren Regelschleifen werden anschließend klassische Konzepte von Autopiloten verwendet. Im Ergebnis ist eine Regelung des Flugweges über Grund des Mehrkörperflugzeugs und somit ein tatsächlicher Betrieb als HAPS möglich. Die Funktionalität des Reglers wird abschließend in nichtlinearen Simulationen mit vollständiger Flugdynamik verifiziert.
Book Synopsis Topics on Flexible Airplane Dynamics by :
Download or read book Topics on Flexible Airplane Dynamics written by and published by . This book was released on 1963 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: pt.3: The dynamic coupling of rigid and elastic degrees of freedom of an airplane are described by two methods. In the first, coupling is described by the changes in airframe characteristic equation roots caused by the introduction of coupling terms to the equations of motion. The second method employs modal response coefficients to compare the relative amplitudes of rigid and elastic degrees of freedom at each coupled mode frequency. Simple literal expressions are obtained for each of these descriptors and physical interpretations given. Time vector diagrams are also used to show the major parameters affecting coupling. (Author).
Book Synopsis Introduction to Aircraft Aeroelasticity and Loads by : Jan R. Wright
Download or read book Introduction to Aircraft Aeroelasticity and Loads written by Jan R. Wright and published by John Wiley & Sons. This book was released on 2014-12-16 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Aircraft Aeroelasticity and Loads, SecondEdition is an updated new edition offering comprehensivecoverage of the main principles of aircraft aeroelasticity andloads. For ease of reference, the book is divided into three partsand begins by reviewing the underlying disciplines of vibrations,aerodynamics, loads and control, and then goes on to describesimplified models to illustrate aeroelastic behaviour and aircraftresponse and loads for the flexible aircraft before introducingsome more advanced methodologies. Finally, it explains howindustrial certification requirements for aeroelasticity and loadsmay be met and relates these to the earlier theoretical approachesused. Key features of this new edition include: Uses a unified simple aeroelastic model throughout thebook Major revisions to chapters on aeroelasticity Updates and reorganisation of chapters involving FiniteElements Some reorganisation of loads material Updates on certification requirements Accompanied by a website containing a solutions manual, andMATLAB® and SIMULINK® programs that relate to the modelsused For instructors who recommend this textbook, a series oflecture slides are also available Introduction to Aircraft Aeroelasticity and Loads, SecondEdition is a must-have reference for researchers andpractitioners working in the aeroelasticity and loads fields, andis also an excellent textbook for senior undergraduate and graduatestudents in aerospace engineering.
Book Synopsis Flight Dynamics by : Robert F. Stengel
Download or read book Flight Dynamics written by Robert F. Stengel and published by Princeton University Press. This book was released on 2022-11-01 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt: An updated and expanded new edition of an authoritative book on flight dynamics and control system design for all types of current and future fixed-wing aircraft Since it was first published, Flight Dynamics has offered a new approach to the science and mathematics of aircraft flight, unifying principles of aeronautics with contemporary systems analysis. Now updated and expanded, this authoritative book by award-winning aeronautics engineer Robert Stengel presents traditional material in the context of modern computational tools and multivariable methods. Special attention is devoted to models and techniques for analysis, simulation, evaluation of flying qualities, and robust control system design. Using common notation and not assuming a strong background in aeronautics, Flight Dynamics will engage a wide variety of readers, including aircraft designers, flight test engineers, researchers, instructors, and students. It introduces principles, derivations, and equations of flight dynamics as well as methods of flight control design with frequent reference to MATLAB functions and examples. Topics include aerodynamics, propulsion, structures, flying qualities, flight control, and the atmospheric and gravitational environment. The second edition of Flight Dynamics features up-to-date examples; a new chapter on control law design for digital fly-by-wire systems; new material on propulsion, aerodynamics of control surfaces, and aeroelastic control; many more illustrations; and text boxes that introduce general mathematical concepts. Features a fluid, progressive presentation that aids informal and self-directed study Provides a clear, consistent notation that supports understanding, from elementary to complicated concepts Offers a comprehensive blend of aerodynamics, dynamics, and control Presents a unified introduction of control system design, from basics to complex methods Includes links to online MATLAB software written by the author that supports the material covered in the book
Book Synopsis Advanced Flight Dynamics with Elements of Flight Control by : Nandan K. Sinha
Download or read book Advanced Flight Dynamics with Elements of Flight Control written by Nandan K. Sinha and published by CRC Press. This book was released on 2017-06-27 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Flight Dynamics aim to integrate the subjects of aircraft performance, trim and stability/control in a seamless manner. Advanced Flight Dynamics highlights three key and unique viewpoints. Firstly, it follows the revised and corrected aerodynamic modeling presented previously in recent textbook on Elementary Flight Dynamics. Secondly, it uses bifurcation and continuation theory, especially the Extended Bifurcation Analysis (EBA) procedure devised by the authors, to blend the subjects of aircraft performance, trim and stability, and flight control into a unified whole. Thirdly, rather than select one control design tool or another, it uses the generalized Nonlinear Dynamic Inversion (NDI) methodology to illustrate the fundamental principles of flight control. Advanced Flight Dynamics covers all the standard airplane maneuvers, various types of instabilities normally encountered in flight dynamics and illustrates them with real-life airplane data and examples, thus bridging the gap between the teaching of flight dynamics/ control theory in the university and its practice in airplane design bureaus. The expected reader group for this book would ideally be senior undergraduate and graduate students, practicing aerospace/flight simulation engineers/scientists from industry as well as researchers in various organizations. Key Features: Focus on unified nonlinear approach, with nonlinear analysis tools. Provides an up-to-date, corrected, and unified presentation of aircraft trim, stability and control analysis including nonlinear phenomena and closed-loop stability analysis. Contains a computational tool and real-life example carried through the chapters. Includes complementary nonlinear dynamic inversion control approach, with relevant aircraft examples. Fills the gap in the market for a text including non-linear flight dynamics and continuation methods.