Aerospace Engineering Commons^™

Six Degrees Of Freedom From Six Degrees Of Separation: The History Of Flight Simulators, David Keck, Morgan Lopez

Publications

Some of today's advanced flight simulators have the capacity to provide pilots with experiences of six degrees of freedom: forward/backward, up/down, or left/right (or pitching, rolling, or yawing in either direction). These incredible devices are the product of over 100 years of design developments that come from a series of technological discoveries and historical events.

Design Of Variable Stiffness Composite Panels For Maximum Strength, Joel P. Hurley

Doctoral Dissertations and Master's Theses

The purpose of this research is to explore the design of variable stiffness composites and develop an automated framework to model, analyze and optimize these structures. Variable stiffness composites have been shown to exhibit increased strength and stiffness over traditional constant stiffness composites by tailoring fiber orientations for specific load conditions. This is achieved by allowing the fiber orientation to vary spatially across the design domain. Motivation for new design methods is driven by the recent advancements in composite additive manufacturing, such as automated fiber placement machines, which allow fiber reinforcements to be placed along prescribed trajectories during manufacturing. Through …

Numerical Study Of Mixing Of A Supercritical Jet In A Supercritical Environment, Neil Sullivan

Doctoral Dissertations and Master's Theses

A numerical simulation campaign is conducted to better elucidate flow physics and modeling requirements of a supercritical (SC) nitrogen jet injected into a tank of quiescent SC nitrogen. The goals of this work are twofold: to inform the design of injectors and combustion chambers for use in the direct-fired supercritical CO2 (s-CO2) power generation cycle and cryogenic liquid propellant rockets, and to investigate the extent to which meaningful flow characterization can be achieved with computationally expedient methods, using commercial software. Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) approaches are used in STAR-CCM+ versions 10.06.010 and 12.02.011. Jet disintegration is …

Investigation, Modeling And Validation Of Digital Bridge For A New Generation Hot-Wire Anemometer, Karthik Kamalakar Joshi

Mechanical & Aerospace Engineering Theses & Dissertations

The Digital Bridge Thermal Anemometer (DBTA) is a new generation anemometer that uses advanced electronics and a modified half-Wheatstone bridge configuration, specifically a sensor and a shunt resistor in series. This allows the miniaturization of the anemometer and the communication between host computer and anemometer is carried out using serial or ethernet which eliminates the noise due to the use of long cables in conventional anemometer and the digital data sent to host computer is immune to electrical noise. In the new configuration the potential drop across a shunt resistor is used to control the bridge.

This thesis is confined …

Improved Ballistic Wind Prediction Using Projectile Tracking Data, William Arthur Kenney

Computational Modeling & Simulation Engineering Theses & Dissertations

The United States Air Force AC-130 gunships have been in operation since the Vietnam War and have seen frequent use during recent conflicts. They are able to employ gun weapon systems from above a target in a way that maximizes possible time on target. When firing, the gun operators must deal with miss distances caused by winds acting on the projectile in flight. Operators currently perform a “tweak” to predict a ballistic wind affecting fired rounds which is then used in the fire-control to correct for the real winds and bring shots onto target. This correction, a single-point wind prediction, …

A Decentralized Adaptive Control Architecture For Large-Scale Active-Passive Modular Systems, Benjamin C. Gruenwald, Ehsan Arabi, Tansel Yucelen, Animesh Chakravarthy, Drew Mcneely

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Decentralized control of large-scale active-passive modular systems is considered. These systems consist of physically interconnected and generally heterogeneous modules, where local control signals can be only applied to a subset of these modules (i.e., active modules) and the rest are not subject to any control signals (i.e., passive modules). Using a set-theoretic adaptive control approach predicated on restricted potential functions, we design decentralized command following control architectures for each active module such that they can effectively perform their tasks with strict performance guarantees in the presence of unknown physical interconnections between modules and module-level system uncertainties. The efficacy of the …

An Algorithm For Enlarging The Region Of Attraction Using Trajectory Reversing, Nilay Kant, Dhrubajit Chowdhury, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Trajectory reversing is a method commonly used for estimating the region of attraction of stabilized equilibria. Using a discrete set of points obtained by trajectory reversing, this paper presents an algorithm for estimation and mathematical representation of the region of attraction using convex hulls. Several two-dimensional examples are presented to illustrate the usefulness of the algorithm. The method provides larger estimates compared to that obtained by existing algorithms, but its main advantage lies in its applicability to higher-order systems. The mathematical representation of the region of attraction is useful in applying the Impulse Manifold Method, which was developed for stabilization …

Enlarging The Region Of Attraction Of Equilibria Of Underactuated Systems Using Sum Of Squares And Impulse Manifold Method, Dhrubajit Chowdhury, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents an algorithm to enlarge the estimate of the Region of Attraction of stable equilibria of underactuated systems. To achieve this, we use a combination of the Sum of Squares (SOS) method and the Impulse Manifold Method (IMM). Initially, the SOS method is used to optimize the control input u(x) in order to obtain an enlarged Region of Attraction. The IMM is then applied on enlarged Region of Attraction obtained using SOS to further enlarge it. The IMM is implemented using high gain feedback and to demonstrate the efficacy of our algorithm, we present simulation results where an …

Validation Of Adaptive Control Laws Using Optimization And Trajectory Sensitivity, Mario Luca Fravolini, Antonio Ficola, Fabio Radicioni, Tansel Yucelen, Ehsan Arabi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper it is proposed an easy-to-use verification and validation method for adaptive control laws that relies on time domain simulations. The problem is set as a trajectory falsification problem that is the search of closed loop trajectories that, starting from a set of admissible initial conditions, reach a set of unsafe states. The falsification is placed as a nonlinear optimization problem whose decision variables are the initial condition of the states and the uncertain parameters of the system. The falsification is performed iteratively using the local gradient of the sensitivity function derived from a linearized model of the …

Swing-Up Of The Inertia Wheel Pendulum Using Impulsive Torques, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The swing-up control problem of the inertia wheel pendulum is revisited in this paper. As different from existing methods, purely impulsive control inputs are used for swing-up. A mathematical formulation of the problem indicates that swing-up can be achieved using impulsive inputs applied at two discrete time instants. Two different swing-up schemes are presented and validated using numerical simulations where the impulsive inputs are approximated by high-gain feedback. The results of numerical simulations establish a direct link between high wheel velocities during swing-up and control strategies that take the pendulum directly to the upright configuration. They also indicate that the …

Cruise Missile Integrated Air Defense System Penetration: Modeling The S-400 System, Michael Pelosi, Amie K. Honeycutt

International Journal of Aviation, Aeronautics, and Aerospace

This research determines improved flight-path routes that make maximum utilization of terrain-masking opportunities, and defending radar and missile system equipment performance and launch timing constraints, in order to avoid radar detection and tracking, and to mitigate subsequent missile shoot-down risks. The problem is formulated as one of constrained optimization in three dimensions. Advantageous solutions are identified using the A* Algorithm in conjunction with detailed equipment performance and constraint calculations and high-resolution digital terrain elevation maps. Topographical features in digital terrain are exploited by the algorithm to avoid radar detection and tracking. The model includes provisions for all-aspect/all-frequency radar cross section …

Identifying Design Parameters Controlling Damage Behaviors Of Continuous Fiber-Reinforced Thermoplastic Composites Using Micromechanics As A Virtual Testing Tool, Ditho Pulungan, Gilles Lubineau, Arief Yudhanto, Recep Yaldiz, Warden Schijve

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, we propose a micromechanical approach to predict damage mechanisms and their interactions in glass fibers/polypropylene thermoplastic composites. First, a representative volume element (RVE) of such materials was rigorously determined using a geometrical two-point probability function and the eigenvalue stabilization of homogenized elastic tensor obtained by Hill–Mandel kinematic homogenization. Next, the 3D finite element models of the RVE were developed accordingly. The fibers were modeled with an isotropic linear elastic material. The matrix was modeled with an isotropic linear elastic, rate-independent hyperbolic Drucker–Prager plasticity coupled with a ductile damage model that is able to show pressure dependency of …

Analysis Of An Experimental Space Debris Removal Mission, Krista L. L. Roth

Theses and Dissertations

Encountering space debris is an ever-increasing problem in space exploration and exploitation, especially in Low Earth Orbit. While many space-faring governing bodies have attempted to control the orbital lifetime post mission completion of satellites and rocker bodies, objects already in orbit pose a danger to future mission planning. Currently, governments and academic institutions are working to develop missions to remove space debris; however, the proposed missions are typically costly primary missions. This research proposes an alternative to use an upper stage rocket, to be called a chaser, already launching a primary mission near the desired debris as a host for …

Static Testing Of Propulsion Elements For Small Multirotor Unmanned Aerial Vehicles, Robert W. Deters, S.C. Kleinke, Michael S. Selig

Publications

The growing use of small multirotor aircraft has increased the interest in having better performance results especially with the propulsion system. The size of the propellers used on these aircraft operate at low Reynolds numbers that are typically less than 200,000. Static performance testing of ten propeller pairs (tractor and pusher) were completed and is the beginning of a systematic test of propellers used on multirotor systems. The propellers chosen for this initial set of tests were selected from four popular quadrotors. Besides testing the propellers provided with the aircraft, propellers that are sold as replacements from third-party companies were …

Jfs Turbine Engine For Cal Poly Mechanical Engineering Department, Dorian Capps, Zoe Kai Tuggle

Mechanical Engineering

This project concerns the development of a gas turbine engine laboratory activity for use in one of Cal Poly’s technical elective courses in the Mechanical Engineering Department, ME 444: Combustion Engine Design. The class is taught by Dr. Patrick Lemieux, who is also in charge of the on-campus engines lab where the turbine engine will be installed. The engine itself is a JFS-100-13A turboshaft engine that will be coupled to an electric dynamometer inside of the dyno test cell. Students taking the ME 444 class, likely starting in Winter Quarter of 2018, will be able to perform hands-on experiments using …

Mass Estimation Through Fusion Of Astrometric And Photometric Data Collection With Application To High Area-To-Mass Ratio Objects, Matthew Richardson

Master's Theses

This thesis work presents the formulation for a tool developed in MATLAB to determine the mass of a space object from the fusion of astrometric and photometric data. The application for such a tool is to better model the mass estimation method used for high area-to-mass ratio objects found in high altitude orbit regimes. Typically, the effect of solar radiation pressure is examined with angles observations to deduce area-to-mass ratio calculations for space objects since the area-to-mass ratio can greatly affect its orbital dynamics. On the other hand, photometric data is not sensitive to mass but is a function of …

Wing Deflection Analysis Of 3d Printed Wind Tunnel Models, Matthew G. Paul

Master's Theses

This work investigates the feasibility of producing small scale, low aerodynamic loading wind tunnel models, using FDM 3D printing methods, that are both structurally and aerodynamically representative in the wind tunnel. To verify the applicability of this approach, a 2.07% scale model of the NASA CRM was produced, whose wings were manufacturing using a Finite Deposition Modeling 3D printer. Experimental data was compared to numerical simulations to determine percent difference in wake distribution and wingtip deflection for multiple configurations.

Numerical simulation data taken in the form of CFD and FEA was used to validate data taken in the wind tunnel …

Optimum Design Of Composite Wing Spar Subjected To Fatigue Loadings, Juan Reuben Lazarin

Master's Theses

Composites are now being incorporated into aircraft designs because of their high strength to weight ratio compared to traditional metal materials. Due to the complexity of the material, composite parts are presently being over designed to satisfy static and fatigue requirements. A greater understanding of composite fatigue behavior will allow for even greater weight savings leading to increased fuel economy. A critical part of an aircraft that is subjected to fatigue bending loads are its wings. The forces acting on the wings include its lift distribution, powerplant, and fuel which can be carried in the wing body. When in flight …

Invariant-Based Method For Improving Efficiency Of Mechanical Testing In Aerospace Certification Of Carbon Fiber-Epoxy Composites, Alyssa Rina Gruezo, Erika Gabrielle Hansen

Materials Engineering

The current challenge with qualification of carbon fiber composites in the aerospace industry would be the low efficiency of testing hundreds of samples. The Trace Theory strives to streamline the qualification process by utilizing a material’s Trace to predict properties of composites using Excel programs and basis data. To test this theory, predicted properties from the program, QuickLam, were compared to experimental data. Unidirectional 0° (T1), unidirectional 90° (T2), quasi-isotropic (T3), and hard quasi-isotropic (T4) laminates were made using HexTowR carbon fiber and TC250 resin provided by TenCate Advanced Composites. Tensile and compression tests were done according to ASTM D3039 …

Activsense Sidestick: A Force Sensing And Force Feedback Joystick, Kobbe Farwick

Electrical Engineering

As aircraft systems continue to become more integrated and fully electronic, hence fly-by-wire, the pilot is slowly losing the physical cues that were once relied upon for the safe operation of the aircraft. Many commercial airliners, such as Airbus, use passive sidesticks that integrate with the electronic flight controls system. These sidesticks move much like a gaming joystick which results in the pilot not having any “feel” for the aerodynamic forces present on the control surfaces. Without the force feedback of a mechanically linked control system the pilot could inadvertently stall the aircraft or place it into an unstable flight …