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Topics On Flexible Airplane Dynamics Part Iii Coupling Of The Rigid And Elastic Degrees Of Freedom Of An Airframe
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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 Topics on Flexible Airplane Dynamics. Part Iii. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe by : H. R. Pass
Download or read book Topics on Flexible Airplane Dynamics. Part Iii. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe written by H. R. Pass and published by . This book was released on 1963 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic coupling of rigid and elastic de grees of freedom of an airplane are described by two methods. In the first, coupling is de scribed by the changes in airframe character istic equation roots caused by the introduc tion of coupling terms to the equations of mo tion. The second method employs modal response coeffients to compare the relative amplitudes of rigid and elastic degrees of freedom at each coupled mode frequency. Simple literal expres sions are obtained for each of these descrip tors and physical interpretations given. Time vector diagrams are also used to show the major parameters affecting coupling. (Author).
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 Topics on Flexible Airplane Dynamics: Residual stiffness effects in truncated modal analysis by :
Download or read book Topics on Flexible Airplane Dynamics: Residual stiffness effects in truncated modal analysis written by and published by . This book was released on 1963 with total page 42 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 Topics on Flexible Airplane Dynamics. Pt. 3. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe by : H.R. Pass
Download or read book Topics on Flexible Airplane Dynamics. Pt. 3. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe written by H.R. Pass and published by . This book was released on 1963 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Topics on Flexible Airplane Dynamics: The application of flexible airframe transfer function approximations and the sensitivity of airframe transfer functions to elastic mode shapes by :
Download or read book Topics on Flexible Airplane Dynamics: The application of flexible airframe transfer function approximations and the sensitivity of airframe transfer functions to elastic mode shapes written by and published by . This book was released on 1963 with total page 62 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 Topics on Flexible Airplane Dynamics. Part Iv. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe - Autopilot System by : H. R. Pass
Download or read book Topics on Flexible Airplane Dynamics. Part Iv. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe - Autopilot System written by H. R. Pass and published by . This book was released on 1963 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the use of the sensitivity techniques of ASD-TDR-62-1014 for locating a single sensor on an elastic airframe-autopilot system. The sensor is located such that closed loop coupling does not interfere with good closed-loop operation of the airframe. Such coupling can physically be interpreted as the generation of undesired command inputs to the autopilot caused by the detection of elastic motion by the sensor. A reasonable first loca tion for the sensor is decided by engineering judgment and the sensitivity of the closed-loop roots to sensor location is found by employing the aforementioned sensitivity techniques. Prediction of the most desirable sensor loca tion can then be made without many tedious iterations. (Author).
Book Synopsis Topics on Flexible Airplane Dynamics. Pt. 4. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe-autopilot System by : H.R. Pass
Download or read book Topics on Flexible Airplane Dynamics. Pt. 4. Coupling of the Rigid and Elastic Degrees of Freedom of an Airframe-autopilot System written by H.R. Pass and published by . This book was released on 1963 with total page 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 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explore the interface between aeroelasticity, flight dynamics and control in this fresh, multidisciplinary approach. New insights into the interaction between these fields, rarely separately considered in most modern aircraft, are fully illustrated in this one-of-a-kind book. The comprehensive, systematic coverage will enable the reader to analyse and design next-generation aircraft. Presenting basic concepts in a rigorous yet accessible way, the book builds up to state-of-the-art models through an intuitive step-by-step approach. Both linear and non-linear attributes are covered, and by revisiting classical solutions using modern analysis methods this book provides a unique, modern 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 Topics on Flexible Airplane Dynamics. Part I. Residual Stiffness Effects in Truncated Modal Analysis by : B. F. Pearce
Download or read book Topics on Flexible Airplane Dynamics. Part I. Residual Stiffness Effects in Truncated Modal Analysis written by B. F. Pearce and published by . This book was released on 1963 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flexible airframe equations of motion are derived with an arbitrary number of elastic de grees of freedom included. The number of equa tions is reduced to include only those necessary for adequate dynammic representation of the air frame, and the effects of the excluded modes are shown. The result is that a matrix X sub in finity must be calculated which is a function of the flexibility represented by the excluded modes. The calculation of this matrix is com plicated by the fact that it is, in explicit form, a function of the mode shapes for the ex cluded elastic degrees of freedom. Usually only a few of these higher order mode shapes can be found withh any accuracy. The problem is resolved by identifying two quantities, X sub f and X sub f infinity, which are ssuperposable to give the complete effects of structural static deflections, X sub infinity. This physi cally satisfying result is implemented by re lating X sub f infinity and X sub f to basic geometrical, inertial, and stiffness properties. The solution is completely general and applies to all elastic systems. (Author).
Book Synopsis Topics on Flexible Airplane Dynamics. Part Ii. the Application of Flexible Airframe Transfer Function Approximations and the Sensitivity of Airframe Transfer Functions to Elastic Mode Shapes by : B. F. Pearce
Download or read book Topics on Flexible Airplane Dynamics. Part Ii. the Application of Flexible Airframe Transfer Function Approximations and the Sensitivity of Airframe Transfer Functions to Elastic Mode Shapes written by B. F. Pearce and published by . This book was released on 1963 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The generality of the airframe transfer function factor approximation formulas presented in ASD TDR-279 is tested by applying them to three dif ferent aircraft. The equations of motion for the test cases are presented and the exact and approximat1actors have been tabulated. The approximation formulas are then utilized to cal culate the sensitivity of the flexible airframe transfer function factors to mode shape. The formulas are given in terms of airplane stability derivatives which in turn are functions of the elastic mode deflections. Then, using the re sults of ASD-TDR-62-279, the desired sensitivity is readily calculable. Many of the transfer function factors are shown to be relatively in sensitive to mode shape, thus allowing effective approximation. A review of the literature per taining to approximate methods for calculating elastic mode shapes is presented in the form of an annotated bibliography. (Author).
Book Synopsis Elementary Flight Dynamics with an Introduction to Bifurcation and Continuation Methods by : Nandan K. Sinha
Download or read book Elementary Flight Dynamics with an Introduction to Bifurcation and Continuation Methods written by Nandan K. Sinha and published by CRC Press. This book was released on 2016-04-19 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many textbooks are unable to step outside the classroom and connect with industrial practice, and most describe difficult-to-rationalize ad hoc derivations of the modal parameters. In contrast, Elementary Flight Dynamics with an Introduction to Bifurcation and Continuation Methods uses an optimal mix of physical insight and mathematical presentatio
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 Dynamics and Identification on Flexible Aircraft by : William R. Wells
Download or read book Dynamics and Identification on Flexible Aircraft written by William R. Wells and published by . This book was released on 1976 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Dynamics and Identification of Flexible Aircraft by : William R. Wells
Download or read book Dynamics and Identification of Flexible Aircraft written by William R. Wells and published by . This book was released on 1976 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Topics on Flexible Airplane Dynamics. Pt. 2. The Application of Flexible Airframe Transfer Function Approximations and the Sensitivity of Airframe Transfer Functions to Elastic Mode Shapes by : B.F. Pearce
Download or read book Topics on Flexible Airplane Dynamics. Pt. 2. The Application of Flexible Airframe Transfer Function Approximations and the Sensitivity of Airframe Transfer Functions to Elastic Mode Shapes written by B.F. Pearce and published by . This book was released on 1963 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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: