Download or read book Influence of Pylon Airloads and Composite Tailoring on Aeroelastic Stability of a Forward Swept Wing written by Jason C. Slaby and published by . This book was released on 2010 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of Pylon Air Loads and Composite Tailoring on Aeroelastic Stability of Folding Tiltrotor Aircraft in Cruise Flight written by Jason C. Slaby and published by . This book was released on 2010 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeroelastic Tailoring with Composites Applied to Forward Swept Wings written by T. J. Hertz and published by . This book was released on 1981 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The application of aeroelastic tailoring with advanced composites has made forward swept wings a viable configuration option for high performance aircraft. Forward swept wings have an inherent tendency to encounter a static aeroelastic instability called divergence. The extreme weight penalty required to avoid this instability in conventional metallic construction has been the basis for the reluctance of designers to incorporate forward sweep in aircraft. Studies performed for the Flight Dynamics Laboratory and by others independently show that, through the use of aeroelastic tailoring (the design process that makes use of the directional properties of fibrous composite materials in wing skins and orients these materials in optimum directions) with advanced composite material, the aeroelastic behavior of a conventional aft swept wing can be controlled and forward swept wings can be constructed with composites that results in an increase in the divergence speed without a prohibitive increase in weight. This report presents the background and evolution of aeroelastic tailoring as applied to forward swept wings together with a summary of work required to establish an aeroelastic data base for forward swept design.

Download or read book Aeroelastic Stability and Performance Characteristics of Aircraft with Advanced Composite Sweptforward Wing Structures written by Terrence A. Weisshaar and published by . This book was released on 1978 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sweptforward metallic wings have not been considered to be a serious design concept for nearly thirty years. The large structural weights necessary to preclude aeroelastic divergence of metallic wing structures are unfavorable when compared to similar sweptback designs, designs that are usually divergence free. The development of fibrous laminated composite materials and the fact that forward swept wings may have superior aerodynamic performance has led to renewed interest in this design. In this report, laminated beam theory, together with aerodynamic strip theory, is used to predict the static aeroelastic divergence characteristics of swept wings. From the results of this theory, it is predicted that, because of elastic coupling between bending and torsional deformation of the wing box, laminated composites may be used to preclude wing divergence for a large range of wing forward sweep angles. Formulas are developed to illustrate the important parameters governing composite wing divergence. Two examples are presented to illustrate the use of these formulas. These examples show that composite forward swept wings have the potential to be feasible, efficient designs.

Download or read book Aeroelastic Behavior of Forward Swept Graphite epoxy Wing Aircraft with Rigid Body Freedoms written by Gun-Shing Chen and published by . This book was released on 1986 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical and experimental investigation was made of the aeroelastic flutter and divergence behavior of a forward swept graphite/epoxy wing aircraft in free flight. Because of the inherent "aeroelastic destiffening" of a forward swept wing and the "aerodynamic stiffening" of the aircraft short period mode, an aeroelastic/flight dynamic interaction becomes possible which can modify the aeroelastic behavior of cantilever wings. A transient aeroelastic analysis, using Rayleigh-Ritz formulation, modified strip theory and measured aircraft aerodynamic derivatives, was developed to predict and interpret the aeroelastic behavior and instability mechanism. The transient aerodynamic representation was obtained by approximating the Theodorsen function in the Laplace domain. With the augmented state variables, stability of the aeroelastic system was determined by linear eigenvalue analysis. A generic, full-span, 30° forward swept wing aircraft model allowing both rigid body pitch and plunge was constructed and tested at MIT's low speed wind tunnel. The effect of aeroelastic tailoring was demonstrated by wings made of different ply layups, namely, [02/90]s' , [152/0]s' , [302/0]s', and [-152/0]s'. These symmetric but unbalanced specimens were chosen to spin a wide range of bending-twisting coupling. Wind tunnel tests on the softly restrained "free flying" models revealed a so-called body freedom flutter, bending-torsion wing flutter, and a tunnel support related dynamic instability which could be eliminated by proper adjustment of the support stiffness. Good agreement with linear theory was found for all the observed instabilities and transient responses. The body freedom flutter boundary was compared with the cantilever wing divergence boundary, and was shown to follow the same aeroelastic tailoring trends, but to be more critical than the wing divergence. Additional tests on the model with rigid body pitch only resulted in a lower body freedom flutter speed, and thereby gave a conservative flutter boundary. The model with [152/0]a wing demonstrated the best tailored aeroelastic behavior for all wings tested.

Download or read book The Aerodynamic Analysis and Aeroelastic Tailoring of a Forward Swept Wing written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of forward-swept wings has aerodynamic benefits at high angles of attack and in supersonic regimes. These consist of reduction in wave drag, profile drag, and increased high angle of attack handling qualities. These increased benefits are often offset due to an increase in structural components, to overcome flutter and wing tip divergence due to high loading of the wing tips at high angles of attack. The use of composite materials and aeroelastic tailoring of the structures eliminates these instabilities without a significant increase in weight. This work presents the design of an aeroelastic wing structure for a highly forward-swept wing, and the verification of the aerodynamic and structural finite element analysis through experimental testing.

Download or read book A Demonstration of the Principle of Aeroelastic Tailoring Applied to Forward Swept Wings written by Van C. Sherrer and published by . This book was released on 1982 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: The principle of aeroelastic tailoring with advanced composite materials to increase the divergence speed of a forward swept wing has been demonstrated through low speed wind tunnel tests. The approach was to perform a low cost, fairly simple wind tunnel test on a variable sweep cantilever wing model. Available analytical methods were used and were shown to accurately predict the divergence speed of both aluminum and composite plate structures in the subsonic speed range. Methods were evaluated for predicting the onset of divergence using subcritical wind tunnel data. Results of the analyses and tests are presented.

Download or read book Aeroelastic Tailoring of a Forward Swept Wing and Comparisons with Three Equivalent Aft Swept Wings written by William E. Triplett and published by . This book was released on 1980 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Aerodynamic Analysis and Aeroelastic Tailoring of a Forward swept Wing written by David William Roberts and published by . This book was released on 2006 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: Aeroelastic, Forward-Swept, Divergence.

Download or read book Development of a Composite Tailoring Technique for Airplane Wing written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of a new composite beam modeling technique to represent the principal load-carrying member in the wing is reported along with the development of a formal design optimization procedure to investigate the effect of composite tailoring on aeroelastic stability and structural characteristics of airplane wings. The developed procedure is used to perform design optimization studies on realistic airplane configurations to investigate the various aeroelastic/structural/dynamic design issues. Chattopadhyay, Aditi and Jha, Ratneshwar Ames Research Center NASA-CR-205326, NAS 1.26:205326 NAG2-908...

Download or read book Experimental Aeroelastic Behavior of Forward Swept Graphite epoxy Wings with Rigid Body Freedoms written by Gun-Shing Chen and published by . This book was released on 1986 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical and experimental investigation was made of the aeroelastic flutter and divergence behavior of graphite/epoxy forward swept wings with rigid body pitch and plunge freedoms present. A complete, two-sided 30-degree forward swept wing aircraft model was constructed and mounted with low friction bearings in a low speed wind tunnel. Four different ply layup wings could be interchanged on the model, namely, [02/90]s', [52 /0]s' , [302 /0]s' , and [-152/0]s' . Wind tunnel tests on the "free" flying models revealed body freedom flutter, bending-torsion flutter, and a support dynamic instability which could be eliminated by proper adjustment of the support stiffness. Good agreement with linear theory was found for all the observed instabilities. Additional tests on the models with rigid body pitch only gave lower critical speeds, while tests on the cantilever wings gave higher speeds. The [152 /0]s wing gave the best tailored aeroelastic behavior.

Download or read book Aeroelastic Stability of a Forward Swept Wing with Wing Tip Stores written by William Gene Steele and published by . This book was released on 1982 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: When studying stability of an aircraft, a quasi-steady aerodynamic model is often used. In this study, the results of a stability analysis of an unrestrained flexible forward swept wing aircraft using an unsteady aerodynamic formulation are compared to results obtained with a similar, but quasi-steady, aerodynamic formulation. In addition, the potential effects of wing tip stores on forward swept wing aircraft stability are explored. (Author).

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1984 with total page 1278 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book On the aeroelastic characteristics of the forward swept wing optimized by aeroelastic tailoring written by and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Forward Swept Wing Static Aeroelasticity written by and published by . This book was released on 1979 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report, laminated beam theory is used to predict the subcritical static aeroelastic behavior of swept wings constructed on laminated composite materials. Aerodynamic strip theory airloads are used to develop meaningful expressions for the flexible-to-rigid lift ratio and spanwise center of pressure movement of a swept wing as functions of wing aeroelastic parameters for a uniform property wing. A simple matrix method analysis approach to wing subcritical static aeroelastic response is detailed.

Download or read book Aeroelastic Behavior of Straight and Forward Swept Graphite epoxy Wings written by Brian Jerome Landsberger and published by . This book was released on 1984 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytical and experimental investigation was made of the aeroelastic deflection, divergence, and flutter behavior of both straight and 30' forward swept rectangular, graphite/epoxy, cantilevered plate type wings, with various amounts' of bending-torsion stiffness coupling. The analytical investigation used a Rayleigh-Ritz formulation together with incompressible 3-dimensional Weissinger L-Method aerodynamics for the divergence, and incompressible 2-dimensional unsteady strip theory for the flutter. Rough attempts were also made to obtain the steady airload deflections of the wing including the nonlinear stall behavior. Experiments on 13 wing configurations showed divergence and bending-torsion flutter at low angles of attack, and torsion stall flutter and bending stall flutter at higher angles of attack. Good agreement with theory was found for the divergence and bending-torsion flutter cases at low angles of attack, and for the nonlinear steady wing deflections at high angles of attack. The +15° ply configuration was efficient in relieving the adverse divergence effect of the forward swept wing.

Download or read book Active Suppression of Aeroelastic Instabilities for Forward Swept Wings written by Thomas Edwin Noll and published by . This book was released on 1983 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analytical studies are conducted to investigate the potential of using active feedback control systems for preventing multiple aeroelastic instabilities (in close proximity) from occurring within the flight envelope of an advanced forward swept wing aircraft. With the addition of wing mounted external stores, the classical bending/torsion flutter instability is driven to lower airspeeds into the vicinity of the aeroelastic instabilities more commonly associated with a forward swept wing (divergence or body freedom flutter). For these studies a typical forward swept wing configuration, adversely mass ballasted to create the dynamic characteristics similar to those caused by adding external stores, is investigated. The goal of this study is to establish concept feasibility so that the technology can be considered for future aircraft application during a design as an alternative or option for preventing aeroelastic instabilities. Analyses are conducted to design active systems for the forward swept wing, cantilevered, free in rigid pitch only, and free in rigid pitch and plunge. They are designed such that both aeroelastic instabilities are suppressed simultaneously to a velocity 20 percent above the unaugmented bending torsion flutter speed with gain margins of at least + or - 6db at this speed conditions. Obtaining large phase margins is also taken into consideration during the design analyses.