Download or read book Aerodynamic Analysis of the Joiined wing Configuration of a High altitude Long endurance hale Aircraft written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The three-dimensional, unsteady, flow is simulated over the joined-wing section of a HALE (High-Altitude Long Endurance) aircraft based on the Sensorcraft configuration. This is the first step in the high-fidelity, nonlinear aeroelastic analysis of the HALE aircraft. These vehicles operate in a high-altitude, low-density, low-Reynolds number (Re) environment. Also, the sensor Equipment housed within the wings requires the sections to be thick. In order to produce the necessary lift, the wings of these aircraft are made extremely long compared to the average chord of the wing section, leading to aspect ratios typically around 25. The fluid loads experienced by the structure result in these high-aspect ratio wings undergoing large deflections. These can cause appreciable change in the geometry, and hence, in the corresponding flow, and necessitate an aeroelastic analysis. The flow solution is obtained by solving the Reynolds-Averaged Navier-Stokes (RANS) governing equations, using the Spalart-Allmaras turbulence model, or by using Detached Eddy Simulation (DES). The flow solver, COBALT60 is a finite-volume, cell-centered, second-order accurate in space and time, unstructured-grid flow solver. With successful completion of the validation cases, simulations were performed at the lower and upper limits (M = 0.4-0.6, [alpha] = 0-12ʻ) of the operating regime of the Sensorcraft. Inviscid simulations were also considered as a computationally efficient alternative to viscous simulations for the computation of the surface pressure loads to be applied on the structure, particularly at low angle of attack ([alpha] = 0ʻ). This is verified by performing inviscid simulations, and comparing the resulting pressure with the corresponding viscous results at the Mach number of 0.6. The surface pressure comparison is satisfactory for this low angle of attack (? = 0ʻ), whereas at? = 12ʻ, the presence of flow separation in the joint region, and a mild oblique shock at the trailing edge of the aft wing in the joint region results in significant viscous effects. A procedure has been set up for the preliminary process of load transfer to the joined-wing structure. The study serves as the foundation to provide an integrated aerodynamic and structural analyses software using a Multi-Disciplinary Computing Environment (MDICE) to predict the aeroelastic behavior of lifting bodies.

Download or read book Structural Modeling and Optimization of a Joined wing Configuration of a High altiude i e Altitude Long endurance HALE Aircraft written by Valentina B. Kaloyanova and published by . This book was released on 2009 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent research trends have indicated an interest in High-Altitude, Long-Endurance (HALE) aircraft as a low-cost alternative to certain space missions, such as telecommunication relay, environmental sensing and military reconnaissance. HALE missions require a light vehicle flying at low speed in the stratosphere at altitudes of 60,000-80,000 ft, with a continuous loiter time of up to several days. To provide high lift and low drag at these high altitudes, where the air density is low, the wing area should be increased, i.e., high-aspect-ratio wings are necessary. Due to its large span and lightweight, the wing structure is very flexible. To reduce the structural deformation, and increase the total lift in a long-spanned wing, a sensorcraft model with a joined-wing configuration, proposed by AFRL, is employed. The joined-wing encompasses a forward wing, which is swept back with a positive dihedral angle, and connected with an aft wing, which is swept forward. The joined-wing design combines structural strength, high aerodynamic performance and efficiency. The results of the simulation of the complex, three-dimensional flow past the joined-wing of a HALE aircraft are used as an input for the structural analysis. The Reynolds-Averaged Navier-Stokes (RANS)-based flow solver, COBALT, provided detailed flow results for altitudes 30,000 ft and 60,000 ft for the cases with M=0.4 and [alpha] = 0°, M = 0.6 and [alpha] = 0°, and M = 0.6 and [alpha] = 12°. The surface static pressure from the flow analyses comprises the load transferred to the structural models developed in this study. To date in the existing studies, only simplified structural models have been examined. In the present work, a semi-monocoque structural model is developed. All stringers, skin panels, ribs and spars are represented by appropriate elements in a finite-element model. Also, the model accounts for the fuel weight and sensorcraft antennae housed within the wings. Linear and nonlinear static analyses under the aerodynamic load are performed. Design optimization is performed to achieve a fully stressed design. The shell elements thickness and stringers cross-sectional area are properly resized to obtain a structure that meets the allowable stress in each element and is minimum weight. In addition to the stress constraints, deflection constraints are also imposed in the design optimization. As the joined-wing structure is prone to buckling, after the design optimization is complete linear and nonlinear bucking analyses are performed to study the global joined-wing structural instability, the load magnitude at which it is expected to occur, and the buckling mode. As this design and analysis study is aimed towards developing a realistic structural representation of the innovative joined-wing configuration, in addition to the global, or upper-level optimization, a local level design optimization is performed as well. At the lower (local) level detailed models of wing structural panels are used to compute more complex failure modes and to design details not included in the upper (global) level model. Proper coordination between local skin-stringer panel models and the global joined-wing model prevents inconsistency between the global and local level models.

Download or read book Structural Analysis of an Equivalent Box wing Representation of Sensorcraft Joined wing Configuration for High Altitude Long Endurance HALE Aircraft written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The current research focuses on studying the modal response of a joined wing aircraft based on the Sensorcraft configuration. Sensorcraft, a class of High-Altitude, Long-Endurance (HALE) aircraft, is an Unmanned Air Vehicle (UAV), and is being studied by the AFRL for applications involving telecommunication relay, environmental sensing and military reconnaissance. The Sensorcraft is designed to operate at high altitudes (60,000 ft) with low speed and for long durations of time (60 to 80 hours). At these operating conditions, the density, and hence, the Reynolds number, is low. These conditions require the Sensorcraft to operate with high lift and low drag with high-aspect ratio wings. Moreover, the vehicle must be lightweight and strong, and offer high aerodynamic performance and efficiency. The AFRL has identified a diamond shape joined wing configuration for Sensorcraft due to the primary structural advantage of strength as each wing braces the other against lift loads. The University of Cincinnati (UC), along with its partners, AFRL and Ohio State University are working together to study the complete nonlinear aeroelastic behavior of the joined-wing model. At UC, four different structural modeling approaches were adopted for analysis. The current research focuses on the analysis of an in-house Sensorcraft joined wing model developed by the AFRL. This model is an equivalent representation of the actual 3-D joined wing model. The wing is idealized as a box structure consisting of shells, rods, beams, shear panels and concentrated masses. This box wing structure has the advantage of being computationally inexpensive over the full 3-D model, and has been optimized to minimize the deflections of the antennae equipment in the control surface of the wing. The fluid loads applied on the box-wing structure are obtained from a concurrent aerodynamic analysis for different mach numbers and angles of attack performed at UC. A modal representation is obtained for different operating boundary conditions as the first step in the overall aeroelastic analysis of the joined wing. AFRL has obtained the modal representation for the Sensorcraft model using NASTRAN, and as part of the DAGSI project requirement, the structural analyses at UC are performed using ANSYS. The results are compared with those from NASTRAN and the correctness of the methodology is verified. Prior to the NASTRAN box-wing model translation into ANSYS, a number of validation tests are performed to test the consistency between the functionalities of the ANSYS elements and NASTRAN elements. Once the results of the validation test cases are found to be satisfactory, the actual analysis of the joined wing is performed for clamped, rigid and symmetry boundary conditions at the wing roots. The frequencies were found to be different between the two codes for each of these boundary conditions. In order to trace the issue causing the differences in the results, a number of simpler joined wing models are analyzed. Finally, the problem is traced down to differences in the formulation between the constraint equations in ANSYS and RBE1 elements in NASTRAN. Due to the assumption of small deflections, linear static analysis is performed and considered sufficient for predicting the displacement response. However, a nonlinear analysis is also performed to validate the assumptions of linearity that have been used in the modeling of the wing. The tip deflection from linear is estimated to be 5.3 % of the span of the wing. For higher angles of attack, the pressure difference between the upper and lower surfaces of the wing is higher, and consequently the lift forces are greater in magnitude. This could cause larger deformation in the main wing that could potentially lead to buckling of the aft wing. Hence, an eigenvalue buckling analysis is performed which show that the wing is stable and not prone to buckling for the loads employed for the linear static analysis. A procedure is also established to determine the structural response under time varying aerodynamic loads from the CFD analysis. This analysis serves as a starting point for future complete aeroelastic analysis of the joined wing.

Download or read book Aerodynamic Analysis of the Joined wing Configuration of a HALE Aircraft written by Rangarajan Sivaji and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Prediction of Structural Behavior of Joined wing Configuration of High altitude Long endurance HALE Aircraft written by Soujanya Marisarla and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flexible Twist for Pitch Control in a High Altitude Long Endurance Aircraft with Nonlinear Response written by Vanessa L. Bond and published by . This book was released on 2008 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Anm rkninger til Statsregnskabet for Finansaaret 1915 16 1918 19 written by and published by . This book was released on 1950 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book The Aerodynamic Design of Wings with Cambered Span Having Minimum Induced Drag written by Clarence D. Cone (Jr.) and published by . This book was released on 1963 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The basic aerodynamic relations needed for the design of wings with cambered span having a minimum induced drag at specified flight conditions are developed for wings of arbitrary spanwise camber. Procedures are also developed for determining the physical wing form required to obtain the maximum value of lift-drag ratio at cruise, when the wing spanwise camber-line and section profiles are specified, by optimizing the wing chord and twist distributions with respect to both profile and induced drags. The application of the design procedure is illustrated by determining the physical wing form for a circular-arc spanwise camber line. The efficiency of this cambered wing is compared with that of an equal-span, flat wing of elliptical planform which satisfies the same set of fright operating conditions as does the cambered wing. The wing pitching- moment equations for optimally loaded cambered-span wings at design flight conditions are also developed for use in trim analyses on complete aircraft designs."--Page 1.

Download or read book Fifth International Conference on Mathematical Problems in Engineering and Aerospace Sciences written by S. Sivasundaram and published by . This book was released on 2005 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Fifth International Conference on Mathematical Problems in Engineering and Aerospace Sciences was held at the West University of Timisoara on June 2-4, 2004"--Preface.

Download or read book Aircraft Performance and Sizing Volume I written by Timothy Takahashi and published by Momentum Press. This book was released on 2017-12-15 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a concise practical treatise for the student or experienced professional aircraft designer. This volume comprises key fundamental subjects for aerodynamic performance analysis: the basics of flight mechanics bridging both engineering and piloting perspectives, propulsion system performance attributes, practical drag prediction methods, aircraft “up and away” flight performance and aircraft mission performance. This book may serve as a textbook for an undergraduate aircraft performance course or as a reference for the classically trained practicing engineer.

Download or read book Aerodynamics of Tandem Wing Aircraft written by Illia Kryvokhatko and published by Springer Nature. This book was released on 2023-03-02 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains extensive data about tandem wing aircraft. It includes a review of modern flying vehicles with four fixed wings, a review of analytical, numerical and experimental methods; results of the studies about aerodynamics; dependencies between geometrical parameters and aerodynamic characteristics, practical recommendations in development and optimizing of tandem wing aircraft to provide high lift-to-drag ratio, stability, and controllability. This is an ideal book for graduate students, researchers, and engineers working in fields of aerodynamics and conceptual design of the aircraft especially UAVs, ground-effect vehicles, and convertiplanes.

Download or read book Flight Performance of Fixed and Rotary Wing Aircraft written by Antonio Filippone and published by Elsevier. This book was released on 2006-05-10 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Calculation and optimisation of flight performance is required to design or select new aircraft, efficiently operate existing aircraft, and upgrade aircraft. It provides critical data for aircraft certification, accident investigation, fleet management, flight regulations and safety. This book presents an unrivalled range of advanced flight performance models for both transport and military aircraft, including the unconventional ends of the envelopes. Topics covered include the numerical solution of supersonic acceleration, transient roll, optimal climb of propeller aircraft, propeller performance, long-range flight with en-route stop, fuel planning, zero-gravity flight in the atmosphere, VSTOL operations, ski jump from aircraft carrier, optimal flight paths at subsonic and supersonic speed, range-payload analysis of fixed- and rotary wing aircraft, performance of tandem helicopters, lower-bound noise estimation, sonic boom, and more.This book will be a valuable text for undergraduate and post-graduate level students of aerospace engineering. It will also be an essential reference and resource for practicing aircraft engineers, aircraft operations managers and organizations handling air traffic control, flight and flying regulations, standards, safety, environment, and the complex financial aspects of flying aircraft. - Unique coverage of fixed and rotary wing aircraft in a unified manner, including optimisation, emissions control and regulation. - Ideal for students, aeronautical engineering capstone projects, and for widespread professional reference in the aerospace industry. - Comprehensive coverage of computer-based solution of aerospace engineering problems; the critical analysis of performance data; and case studies from real world engineering experience. - Supported by end of chapter exercises

Download or read book Analysis of Linked Aircraft Aerodynamics and Flight Dynamics written by Edgar Adrian Cuji and published by . This book was released on 2011 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research, I have analyzed different aircrafts with nonconventional wings. The analyses have included aerodynamic modeling, flight dynamics and trajectory optimization. Two different nonconventional aircrafts are analyzed, a V-shape morphing wings and a Linked UAV system. A modern adaptation of Prandtl's liftingline method is utilized to analyze the aerodynamics of both systems. This method can compute the aerodynamic forces for a system of lifting surfaces with arbitrary camber, sweep, dihedral, position and orientation. The V-shape morphing wings consist of a wing configuration that has two panels, an out-of-plane dihedral section and a horizontal section. An analysis of the aircraft turning dynamics shows that by manipulating the dihedral angles, of the V-shape wings, either by symmetric or asymmetric wing shape changes, can affect the turning capabilities of an aircraft to perform a variety of different missions depending on the importance of each of the turning performance measurements. A linked UAV concept, where individual UAVs link at high altitude, creates an aerodynamically efficient system of aircraft which has long endurance capabilities and can cruise for extended periods with significantly reduced power loads. This dissertation presents an analysis of close proximity aerodynamics and aircraft dynamics of two Linked UAVs. As the UAVs approach each other for wingtip docking there are strong aerodynamic coupling between their wings tips. An aerodynamic disturbance intensity field has been generated, utilizing both simulation and wind tunnel data, to determine a trajectory for the two UAVs to approach each other for midair docking. Finally, two optimal trajectories, a 2-D and 3-D docking trajectories are generated and compared. Dynamic wind tunnel test are performed to compare different midair wingtip docking trajectories. The results of the optimization concludes that a trajectory with a span-wise approach is more desirable since it goes through the least aerodynamic disturbances and requires less control effort to perform the midair docking maneuver.

Download or read book Aircraft Design Projects written by Lloyd R. Jenkinson and published by Elsevier. This book was released on 2003-04-28 with total page 393 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written with students of aerospace or aeronautical engineering firmly in mind, this is a practical and wide-ranging book that draws together the various theoretical elements of aircraft design - structures, aerodynamics, propulsion, control and others - and guides the reader in applying them in practice. Based on a range of detailed real-life aircraft design projects, including military training, commercial and concept aircraft, the experienced UK and US based authors present engineering students with an essential toolkit and reference to support their own project work.All aircraft projects are unique and it is impossible to provide a template for the work involved in the design process. However, with the knowledge of the steps in the initial design process and of previous experience from similar projects, students will be freer to concentrate on the innovative and analytical aspects of their course project. The authors bring a unique combination of perspectives and experience to this text. It reflects both British and American academic practices in teaching aircraft design. Lloyd Jenkinson has taught aircraft design at both Loughborough and Southampton universities in the UK and Jim Marchman has taught both aircraft and spacecraft design at Virginia Tech in the US.* Demonstrates how basic aircraft design processes can be successfully applied in reality* Case studies allow both student and instructor to examine particular design challenges * Covers commercial and successful student design projects, and includes over 200 high quality illustrations

Download or read book An Experimental Investigation of a Joined Wing Aircraft Configuration Using Flexible Reduced Scale Flight Test Vehicles written by Jenner Richards and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The United States Air Force has specified a need for the next generation, High Altitude, Long Endurance aircraft capable of carrying advanced sensor arrays over very large distances and at extreme altitudes. These extensive set of requirements has required a radical shift away from the conventional wing & tube configurations with a new focus placed on extremely light weight and unconventional structural and aerodynamic configurations. One such example is the Boeing Joined wing SensorCraft Concept. The Joined wing concept has potential structural and sensor carrying benefits, but along with these potential benefits come several challenges. One of the primary concerns is the aeroelastic response of the aft wing, with potential adverse behaviours such as flutter and highly nonlinear structural behaviour of the aft wing under gust conditions. While nonlinear computation models have been developed to predict these responses, there exists a lack of experimental ground and flight test data for this unique joined wing configuration with which to benchmark the analytical predictions. The goal of this work is to develop a 5m, scaled version of the Boeing Joined Wing configuration and collect data, through a series of ground and flight based tests, which will allow designers to better understand the unique structural response of the configuration. A computational framework was developed that is capable of linearly scaling the aeroelastic response of the full scale aircraft and optimize a reduced scale aircraft to exhibit equivalent scaled behaviour. A series of reduced complexity models was developed to further investigate the flying characteristics of the configuration, test avionics and instrumentation systems and the develop flight control laws to adequately control the marginally stable aircraft. Lessons learned were then applied the 5m flight test article that was designed and constructed by the author.In the final stage of the project, the decision was made to relax the aeroelastically scaled constraint in order to allow additional softening of the structure to further investigate the nonlinear behaviour of the aircraft. Due to the added risk and complexity of flying this highly flexible aircraft the decision was made to produce the final aeroelastically scaled article at the 1.85m scale. This model was designed, developed and ground tested in the lead up to a follow on project which will see additional flight testing performed in conjunction with Boeing Inc.

Download or read book New Developments in Computational Fluid Dynamics written by Kozo Fujii and published by Springer Science & Business Media. This book was released on 2006-01-05 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contains 20 papers presented at the Sixth International Nobeyama Workshop on the New Century of Computational Fluid Dynamics, Nobeyama, Japan, April 21-24, 2003. These papers cover computational electromagnetics, astrophysical topics, CFD research and applications in general, large-eddy simulation, mesh generation topics, visualization, and more.