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Book Aerothermoelastic Considerations for a Control Surface on an Air breathing Hypersonic Vehicle

Download or read book Aerothermoelastic Considerations for a Control Surface on an Air breathing Hypersonic Vehicle written by Benjamin R. Szpak and published by . This book was released on 2009 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Air-breathing hypersonic vehicles have risen to the forefront of the aerospace research community in reaction to the requirements of NASA and the US Air Force. NASA has interest in developing a next generation Reusable Launch Vehicle and the US Air Force is interested in an unmanned hypersonic vehicle. Recent research has focused on developing comprehensive models in order to successfully design a vehicle capable of operating in the severe hypersonic environment. Due to the layout of this class of vehicle, where the propulsion system is fully integrated into the lifting body fuselage, a tight coupling exists between the airframe, propulsion system, control system, and aerodynamics. This characteristic necessitates a multi-disciplinary approach to modeling for control design. To achieve this, a simplified model of each subsystem is needed to efficiently perform a multi-disciplinary analysis. Two important and challenging areas for multi-disciplinary modeling are the incorporation of complex aerodynamic and aerothermoelastic phenomena. The focus of this research is on the development of a model for the control surface. Specifically an aerothermoelastic model, based on a plate representation, has been developed for the vehicle control surface. This model was adapted from a previous model, developed at the Air Force Research Laboratory, to incorporate important characteristics such as taper and sweep of the control surface. Thus, the model more realistically represents the geometry of a control surface for a hypersonic vehicle. The structural model developed was then verified using finite element analysis to compare the free vibration frequencies and modeshapes. Since the structural dynamic characteristics of a solid plate are not compatible to those of a shell structured wing, the structural properties were modified to match the first two frequencies of a representative wing, namely the F-104 Lockheed Starfighter wing. As the temperature of a plate increases, the first two frequencies begin to coalesce. This coalescence of frequencies leads to a phenomena known as flutter. As the temperature of the plate was increased the aerothermoelastic response was computed at a constant Mach number until the onset of flutter. By implementing a flexible control surface model, the response of the wing to control inputs and fuselage deformations could also be investigated. Both of these effects are modeled as base motion of the cantilevered plate. Second order piston theory, a commonly used model for hypersonic aerodynamics, was used to calculate the aerodynamic forces on the plate. Results presented provide insight into the importance of aerothermoelastic effects for control oriented modeling, as well as the effect of plate sweep and taper compared to a simple square plate representation.

Book Control oriented Analysis of Aerothermoelastic Effects for a Hypersonic Vehicle

Download or read book Control oriented Analysis of Aerothermoelastic Effects for a Hypersonic Vehicle written by Sanketh Bhat and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Hypersonic flight is seen as a feasible solution to make space travel faster, safer and more affordable. The design of the Air-breathing hypersonic vehicle is such that there is coupling between the structure and the propulsion system. Therefore, the aerodynamic, propulsion and the structural effects must be accounted to effectively model the vehicle. The vibrations from the structure affect the performance of the vehicle. Hence, vibration attenuation is a critical requirement for hypersonic vehicles. The problems of vibration are compounded by variations in heating during flight. Structural variations resulting from the tremendous heating incurred during hypersonic flight is mitigated by a thermal protection system (TPS); however, such mitigation is accompanied by an increase in weight that can be prohibitive. The actual design of a thermal protection system can be chosen to vary the level of heating reduction, and associated weight, across the structure.

Book Structural Dynamic and Aeroelastic Considerations for Hypersonic Vehicles

Download or read book Structural Dynamic and Aeroelastic Considerations for Hypersonic Vehicles written by and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Selected Aerothermodynamic Design Problems of Hypersonic Flight Vehicles

Download or read book Selected Aerothermodynamic Design Problems of Hypersonic Flight Vehicles written by Ernst Heinrich Hirschel and published by Springer Science & Business Media. This book was released on 2009-11-26 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book selected aerothermodynamic design problems in hypersonic vehicles are treated. Where applicable, it emphasizes the fact that outer surfaces of hypersonic vehicles primarily are radiation-cooled, an interdisciplinary topic with many implications.

Book Modeling Analysis and Control of a Hypersonic Vehicle with Significant Aero thermo elastic propulsion Interactions

Download or read book Modeling Analysis and Control of a Hypersonic Vehicle with Significant Aero thermo elastic propulsion Interactions written by Jaidev Khatri and published by . This book was released on 2011 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines themodeling, analysis, and control system design issues for scramjet powered hypersonic vehicles. A nonlinear three degrees of freedom longitudinal model which includes aero-propulsion-elasticity effects was used for all analyses. This model is based upon classical compressible flow and Euler-Bernouli structural concepts. Higher fidelity computational fluid dynamics and finite element methods are needed for more precise intermediate and final evaluations. The methods presented within this thesis were shown to be useful for guiding initial control relevant design. The model was used to examine the vehicle's static and dynamic characteristics over the vehicle's trimmable region. The vehicle has significant longitudinal coupling between the fuel equivalency ratio (FER) and the flight path angle (FPA). For control system design, a two-input two-output plant (FER - elevator to speed-FPA) with 11 states (including 3 flexible modes) was used. Velocity, FPA, and pitch were assumed to be available for feedback. Aerodynamic heat modeling and design for the assumed TPS was incorporated to original Bolender's model to study the change in static and dynamic properties. De-centralized control stability, feasibility and limitations issues were dealt with the change in TPS elasticity, mass and physical dimension. The impact of elasticity due to TPS mass, TPS physical dimension as well as prolonged heating was also analyzed to understand performance limitations of de-centralized control designed for nominal model.

Book Geometry Modeling and Adaptive Control of Air breathing Hypersonic Vehicles

Download or read book Geometry Modeling and Adaptive Control of Air breathing Hypersonic Vehicles written by Tyler J. Vick and published by . This book was released on 2014 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air-breathing hypersonic vehicles have the potential to provide global reach and affordable access to space. Recent technological advancements have made scramjet-powered flight achievable, as evidenced by the successes of the X-43A and X-51A flight test programs over the last decade. Air-breathing hypersonic vehicles present unique modeling and control challenges in large part due to the fact that scramjet propulsion systems are highly integrated into the airframe, resulting in strongly coupled and often unstable dynamics. Additionally, the extreme flight conditions and inability to test fully integrated vehicle systems larger than X-51 before flight leads to inherent uncertainty in hypersonic flight. This thesis presents a means to design vehicle geometries, simulate vehicle dynamics, and develop and analyze control systems for hypersonic vehicles. First, a software tool for generating three-dimensional watertight vehicle surface meshes from simple design parameters is developed. These surface meshes are compatible with existing vehicle analysis tools, with which databases of aerodynamic and propulsive forces and moments can be constructed. A six-degree-of-freedom nonlinear dynamics simulation model which incorporates this data is presented. Inner-loop longitudinal and lateral control systems are designed and analyzed utilizing the simulation model. The first is an output feedback proportional-integral linear controller designed using linear quadratic regulator techniques. The second is a model reference adaptive controller (MRAC) which augments this baseline linear controller with an adaptive element. The performance and robustness of each controller are analyzed through simulated time responses to angle-of-attack and bank angle commands, while various uncertainties are introduced. The MRAC architecture enables the controller to adapt in a nonlinear fashion to deviations from the desired response, allowing for improved tracking performance, stability, and robustness.

Book Output Feedback Control and Sensor Placement for a Hypersonic Vehicle Model

Download or read book Output Feedback Control and Sensor Placement for a Hypersonic Vehicle Model written by Pete Jankovsky and published by . This book was released on 2006 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper addresses issues related to output feedback control, including sensor placement, for a model of an air-breathing hypersonic vehicle. The model presents a number of control challenges, in particular because of strong couplings between the propulsive and aerodynamic forces. Because of the vehicle's low weight, slenderness, and length, the vehicle's flexibility has a large impact on stability and control of the vehicle. Two output feedback control methods are developed. One applies reconstruction of the flexible body system states, toward applications of state feedback control. The other uses a robust design that does not rely on an observer to ensure stabilization and performance throughout a given flight envelope. A rate gyroscope and an accelerometer have been modeled, incorporating the flexible effects, and strategies for sensor placement have been developed for the hypersonic vehicle model to enhance observability or to preserve certain system structures that are favorable for robust control design. Simulation results are provided to demonstrate the sensor placement strategies and output feedback control performances.

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Control Relevant Design of Scramjet powered Hypersonic Vehicles with Aero thermo elastic propulsive Effects and Uncertainty

Download or read book Control Relevant Design of Scramjet powered Hypersonic Vehicles with Aero thermo elastic propulsive Effects and Uncertainty written by Srikanth Sridharan and published by . This book was released on 2010 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Air breathing Hypersonic Vehicle Design and Analysis Methods

Download or read book Air breathing Hypersonic Vehicle Design and Analysis Methods written by Mary K. Lockwood and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Output Feedback Control and Sensor Placement for a Hypersonic Vehicle Model

Download or read book Output Feedback Control and Sensor Placement for a Hypersonic Vehicle Model written by Pete Jankovsky and published by . This book was released on 2007 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis addresses issues related to output feedback control, including sensor placement, for a model of an air-breathing hypersonic vehicle. The model presents a number of control challenges because of unique characteristics of the hypersonic vehicle, particularly the strong coupling between propulsive and aerodynamic forces. Because of the vehicle's low weight, slenderness, and length, the vehicle's flexibility has a large impact on stability and control of the vehicle. A control oriented model is first developed to meet the control and performance objectives for tracking vehicle velocity and flight path angle trajectories. A linear state feedback controller is designed assuming full state information. Concurrently, a rate gyroscope and an accelerometer have been modeled. Incorporating the flexible effects into the measured outputs which provides insight into sensor placement effects on system observability. This leads to the development of sensor placement strategies for the hypersonic vehicle model designed to either enhance observability or to preserve certain system structures that are favorable for robust control design. Our results for the hypersonic vehicle follow traditional sensor placement work for flight vehicles based on observability. Observer based output feedback of the hypersonic vehicle model is dependent on selecting a good placement for time output sensors and is successfully demonstrated for limited conditions near the trim condition and nominal fuel condition. These limitations are addressed with an output feedback controller based on robust control methods. Building on sensor modeling and sensor placement, the robust controller performs over a much larger range of trim conditions and fuel conditions. Simulation results are provided to demonstrate the sensor placement strategies and output feedback control performances.

Book Aerothermoelastic Modeling of Hypersonic Vehicles

Download or read book Aerothermoelastic Modeling of Hypersonic Vehicles written by Ryan Dale Jamison and published by . This book was released on 2008 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: