Aerospace Engineering Commons^™

Flight Dynamic Response Of Hale Aircraft To Kc-135 Flowfield, Amanda J. Devuono

Theses and Dissertations

This research effort examines the static effects of a KC-135 flowfield on a flexible winged Sensorcraft model. The KC-135 flowfield data is generated by a vortex lattice code and integrated into Sensorcraft model for analysis. Building on previous research, a refueling situation was modeled to note the effects of the Sensorcraft at varying locations within the flowfield. The Sensorcraft model was analyzed for both rigid and flexible wings as a means of comparision. Flowfield locations of interest were determined and trimmed conditions were computed for each flowfield location. Utilizing the trimmed condition and flowfield locations, the nonlinear set of EOM's …

Radar Orbit Analsis Tool Using Least Squares Estimator, Sandra M. Rashash

Theses and Dissertations

Most objects tracked in space follow a regular Keplerian orbit; unfortunately, non-Keplerian objects such as maneuvering satellites, tethered systems, and thrusting ballistic missiles are becoming more common. It is important to be able to distinguish between Keplerian and non-Keplerian objects due to the potential risk of a tethered satellite being mistaken for an object on re-entry. This research focused on creating a computer model that can detect the non-gravitational acceleration present in non-Keplerian orbits. A 3rd order Taylor series expansion was used to model the dynamics and to produce simulated radar data. Linear least squares estimation was used to estimate …

Where Do We Get The Next Generations Of Space Engineers & Scientists?, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Where do we get the Next Generations Of Space Engineers & Scientists?" from August 13, 2007.

Asmo American Student Moon Orbiter, Robert J. Twiggs, Yvonne Clearwater

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professors Bob Twiggs and Yvonne Clearwater  titled "ASMO American Student Moon Orbiter" from August 11, 2007.

Response To "Comment On 'Adhesion-Delamination Mechanics Of A Presented Rectangular Film Adhered Onto A Rigid Substrate' [J. Appl. Phys. 101, 024903 (2007)]", Kai-Tak Wan, Gang Duan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Complete Stress Analysis For Two Dimensional Inclusion Problem Using Complex Variables, Rohan Arun Patil

Mechanical and Aerospace Engineering Theses - Archive

This thesis addresses the problem of finding stresses and displacements in an infinite plate with a two dimensional circular inclusion with different material properties using complex variable method with biaxial loading acting on it. The complex variable method is used so that the continuity equations of traction force and displacement field are satisfied at the interface .All the complex equations are solved using software Mathematica.

Stress Analysis Of An Ellipsoidal Inclusion, Mahesh Kailas

Mechanical and Aerospace Engineering Theses - Archive

The focus of the present thesis is to develop a mathematical model to calculate the stresses inside an ellipsoidal inclusion present in an infinitely extended matrix region and to validate the mathematically derived model by the Finite Element Method. To this end, a theoretical model has been developed to predict the stress inside an ellipsoidal inclusion. This model is based on equivalent inclusion method used to evaluate the stress distribution theoretically. Though there have been many theories to predict the stress distribution inside an ellipsoidal inclusion, its numerical validation is new despite its importance. A finite element model of a …

Exploratory Studies Of Convective Flows Due To Arc Tracking, Richard R. Mitchell

Mechanical and Aerospace Engineering Theses - Archive

The objective of the research was to develop an understanding of how a flame propagates through an electronic enclosure. FLUENT®, a Navier-Stokes solver, was chosen due to its widespread commercial use, the availability of turbulence models and its ability to handle combustion. The relevance of this study with respect to the aerospace and domestic appliance industry was shown through case reports. Initial observations were made on arc discharges, chemical compounds and their relevance to establishing the flame. Experimental bench tests highlighted the instigating factors for flame ignition. The first round of bench testing revealed that solder node separation played an …

Space Suit Concepts And Vehicle Interfaces For The Constellation Program, D. M. Klaus, J. Metts, R. Kobrick, M. Mesloh, T. Monk, Et Al.

Publications

In carrying out NASA’s Vision for Space Exploration, a number of different environments will be encountered that will require the crew to wear a protective space suit. Specifically, four suited mission phases are identified as Launch, Entry & Abort profiles, Contingency 0g (orbital) Extravehicular Activity (EVA), Lunar Surface EVA and Martian Surface EVA. This study presents conceptual design solutions based on a previous architecture assessment that defined space suit operational requirements for four proposed space suit configuration options. In addition, a subset of vehicle interface requirements are defined for enabling umbilical and physical connections between the suits and the various …

The Effects Of Foreign Accent And Language On Reaction Time And Accuracy In An Air Traffic Control Task, Rosabelle Suarez

Master's Theses - Daytona Beach

The present study examines the effect of foreign accent interference with the ability to execute commands presented in speech format. The objective of this study was to demonstrate that a foreign accent influences performance. Participants were between 18 and 40 years of age. Half of the participants were native speakers of Spanish who began learning English as a second language via the classroom setting. The other half were native English-speaking with little or no exposure to the Spanish language. The experimental design was similar to an aviation scenario where participants listened to simulated ATC procedural commands and execute them on …

Reinforcement Learning Based Output-Feedback Control Of Nonlinear Nonstrict Feedback Discrete-Time Systems With Application To Engines, Peter Shih, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning based output-adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to track a desired trajectory for a class of complex nonlinear discrete-time systems in the presence of bounded and unknown disturbances. The controller includes an observer for estimating states and the outputs, critic, and two action NNs for generating virtual, and actual control inputs. The critic approximates certain strategic utility function and the action NNs are used to minimize both the strategic utility function and their outputs. All NN weights adapt online towards minimization of a performance index, utilizing gradient-descent based rule. …

Rotorcraft Smoothing Via Linear Time Periodic Methods, Christopher S. Schulz

Theses and Dissertations

This research presents the development of an on line linear time periodic rotor vibration controller. The Cramer-Rao bound is developed for a linear time periodic system in order to identify the quality of identified system parameters, which are used in system models for controller development. The methods developed in this work allow model parameters can be verified for accuracy and likewise adjusted to improve controller accuracy.

Cooperative Uav Formation Flying With Obstacle/Collision Avoidance, Xiaohua Wang, Vivek Yadav, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Navigation problems of unmanned air vehicles (UAVs) flying in a formation in a free and an obstacle-laden environment are investigated in this brief. when static obstacles popup during the flight, the UAVs are required to steer around them and also avoid collisions between each other. In order to achieve these goals, a new dual-mode control strategy is proposed: a “safe mode” is defined as an operation in an obstacle-free environment and a “danger mode” is activated when there is a chance of collision or when there are obstacles in the path. Safe mode achieves global optimization because the dynamics of …

Microthruster Experimental Analysis, Amy Denise Richards

Master's Theses - Daytona Beach

The purpose of this study was to design an experimental apparatus that could accurately test and measure the thrust efficiency of conical shaped microthrusters with varying divergence half angles. The experimental apparatus measured the thrust of micronozzles for various feed pressures in vacuum (to duplicate in space operation) as well as ambient. Calibration experiments confirmed the force measurement accuracy of the setup while gas thrust experiments were used to help determine the most efficient divergence half angle. Thrust results were compared to findings from two separate scientific studies that sought to optimize microthruster nozzles using CFD software.

Numerical Modeling Of Gas Flows In Micronozzles, Orner San

Mechanical & Aerospace Engineering Theses & Dissertations

Since many microfluidic devices are operated in the continuum-transition regimes, the understanding of heat transfer behavior and fluid flow characteristics in this regime becomes important. The conventional Navier-Stokes model may become less accurate because of its first order constitutive relations. A direct simulation Monte Carlo method can be considered a more accurate numerical simulation for higher Knudsen numbers. However, the large number of required simulated molecules can easily make it prohibitively expensive in terms of computational time. Therefore, the Burnett equations, with their higher order constitutive relations for viscous stress and heat fluxes, are used in modeling flow characteristics in …

A Design Of Experiments Approach To Deck Flow Characterization On An Aircraft Carrier, Yugapriya Sivanesan Wing

Mechanical & Aerospace Engineering Theses & Dissertations

A wind tunnel model of an aircraft carrier was used to make air wake measurements. Particle image velocimetry measurements of turbulence intensity were made on a center plane intersecting the angled deck of the aircraft carrier. The factors of interest for the study were model pitch, yaw, island location, and island type. Two island types were used, a representative shape of current designs and an ideal streamlined airfoil shape. Each factor was studied at two levels in order to provide linear models using a Design of Experiments factorial design. From the data for each experimental combination, regression models for turbulence …

Old Dominion University Space Systems Engineering Competency Development To Accommodate Orbital Flight Projects, Ersin Ancel

Mechanical & Aerospace Engineering Theses & Dissertations

Undergraduate engineering students in Old Dominion University's Batten College of Engineering and Technology have been engaged in the design, development, testing and flight of scientific sounding rocket payloads since 2004. During that time, two payloads have flown and a third payload has nearly achieved flight-ready status. The sophistication achieved by the flight-ready payload has resulted from the evolution of a rather rigorous space system design process that requires student involvement over periods of time that are much longer than those typically associated with an -undergraduate design course sequence.

In order to acquire the expected level of definition and reliability for …

Linear And Nonlinear Responses Of Isotropic Beams Under Concentrated Random Loads Unsynchronized In Time, Ravi Putrevu

Mechanical & Aerospace Engineering Theses & Dissertations

Large-amplitude random response of slender isotropic beams is studied using finite element analysis. The random load is assumed to be a stationary ergodic random Gaussian excitation with white noise characteristics. The loading is considered for three cases, namely synchronized, anti-synchronized, and unsynchronized in time. The linear response of beams is studied for the simply-supported and clamped-simply support conditions at the two ends. The non-linear response is, however, limited only to the simply-supported condition. There are no analytical solutions to the linear and non-linear responses of beams under concentrated random loads unsynchronized in time. The deflections due to unsynchronized loads are …

Using Student Space Assets For Atmospheric Science Research: Cedr Small Satellite Workshop, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Using Student Space Assets For Atmospheric Science Research: CEDR Small Satellite Workshop" from June 27, 2007.

High Resolution Simulation Of Full Aircraft Control At Flight Reynolds Numbers, Scott A. Morton, James R. Forsythe, David R. Mcdaniel, Keith Bergeron, Russell M. Cummings, Stefan Goertz, Jurgen Seidel, Kyle D. Squires

Aerospace Engineering

This paper documents interim results of a three year project to develop a computational method for accurately determining static and dynamic stability and control characteristics of fighter and transport aircraft with various store configurations, as well as the aircraft response to pilot input. In this second year of the project computational data is gathered for a rigid F-16C with no control surface movement in forced motion that approximates flight test maneuvers. "Computational maneuvers" designed to efficiently gather three axes of motion data to build a comprehensive reduced order model are also developed. The data is then post- processed to determine …

Performing Particle Image Velocimetry In A Supersonic Wind Tunnel Using Carbon Dioxide As The Seed Material, Donald W. Peltier Iii

Theses and Dissertations

Particle image velocimetry (PIV) was performed utilizing clean seed particles generated by injecting liquid carbon dioxide (CO₂) directly into an open-circuit blowdown Mach 2.9 supersonic wind tunnel. Rapid atomization and cooling of the liquid CO₂ created a preponderance of nearly uniform and well dispersed microscopic dry ice particles which were illuminated using a frequency double Nd:YAG laser. Ample light was scattered from the flow tracers, which provided a strong signal to noise ratio. The particles completely sublimed into an innocuous gas downstream of the test section causing no side effects or problems with wind tunnel operation. A …

Internet Enabled Remote Driving Of A Combat Hybrid Electric Power System For Duty Cycle Measurement, Jarrett Goodell, Marc Compere, Wilford Smith, Mark Brudnak, Mike Pozolo, Et Al.

Publications

This paper describes a human-in-the-loop motion-based simulator interfaced to hybrid-electric power system hardware, both of which were used to measure the duty cycle of a combat vehicle in a virtual simulation environment. The project discussed is a greatly expanded follow-on to the experiment published in [1,7]. This paper is written in the context of [1,7] and therefore highlights the enhancements. The most prominent of these enhancements is the integration (in real-time) of the Power & Energy System Integration Lab (P&E SIL) with a motion base simulator by means of a “long haul” connection over the Internet (a geographical distance of …

Structural Optimization Of A Distributed Actuation System In A Flexible In-Plane Morphing Wing, James T. Westfall

Theses and Dissertations

Structural weight and efficiency are hurdles for morphing aircraft being realizable on the full-scale level. The optimal distribution and orientation of actuators throughout an in-plane flexible morphing wing structure is investigated. The drive to minimize structural weight causes a wing to be more flexible and the location and orientation of the actuators become more critical as the structure becomes more flexible. NextGen's N-MAS morphing wing is used as a case study. The wing is modeled as a number of unit cells assembled in a scissor-like structure, each comprised of four linkages pinned together and an actuator. The flexible skin of …

Cfd Analysis Of A T-38 Wing Fence, Daniel A. Solfelt

Theses and Dissertations

A computational study of the effects of a wing fence on the T-38 Talon was performed. RANS simulations were conducted using the CFD solver AVUS to examine the flow around the T-38 and the fence at a Reynolds number of 10 million. The T-38 was modeled as a half aircraft with a symmetry plane down the center line and did not include the empennage. The engine inlet and exhaust were modeled as sink and source boundary conditions using mass flow and pressure specifications. Two fence geometries placed 26" from the wing tip were tested. The first fence, called a simple …

A Systems Engineering Approach To Analyzing Weather Input Sensitivities Of The Joint Precision Air Drop System, David L. Gemas

Theses and Dissertations

The United States Air Force is partnering with the United States Army as well as allied nations to develop a revolutionary advance in logistical support known as the Joint Precision Air Drop System (JPADS). The focus of this study is to develop a process to quantitatively analyze system sensitivities to various types of weather inputs and the corresponding effect on system accuracy. Weather balloons were used to provide representative "truth" to which forecast weather could be compared. Each data type was fed into the JPADS Mission Planner to produce navigation points which could then be compared statistically. The process was …

Real-Time Gps-Alternative Navigation Using Commodity Hardware, Jordon L. Fletcher

Theses and Dissertations

Modern navigation systems can use the Global Positioning System (GPS) to accurately determine position with precision in some cases bordering on millimeters. Unfortunately, GPS technology is susceptible to jamming, interception, and unavailability indoors or underground. There are several navigation techniques that can be used to navigate during times of GPS unavailability, but there are very few that result in GPS-level precision. One method of achieving high precision navigation without GPS is to fuse data obtained from multiple sensors. This thesis explores the fusion of imaging and inertial sensors and implements them in a real-time system that mimics human navigation. In …

Real-Time On-Line Space Research Laboratory Environment Monitoring With Off-Line Trend And Prediction Analysis, Kenol Jules, Paul P. Lin

Mechanical Engineering Faculty Publications

With the International Space Station currently operational, a significant amount of acceleration data is being down-linked, processed and analyzed daily on the ground on a continuous basis for the space station reduced gravity environment characterization, the vehicle design requirements verification and science data collection. To help understand the impact of the unique spacecraft environment on the science data, an artificial intelligence monitoring system was developed, which detects in near real time any change in the reduced gravity environment susceptible to affect the on-going experiments. Using a dynamic graphical display, the monitoring system allows science teams, at any time and any …

Controller Design For Accurate Antenna Pointing Onboard A Spacecraft, Victor M. Barba

Theses and Dissertations

Controller design for a spacecraft mounted flexible antenna is considered. The antenna plant model has a certain degree of uncertainty. Additionally, disturbances from the host spacecraft are transmitted to the antenna and need to be attenuated. The design concept explored herein entails feedforward control to slew the antenna. Feedback control is then used to compensate for plant uncertainty and to reject the disturbance signals. A tight control loop is designed to meet performance specifications while minimizing the control gains. Simulations are conducted to show that the integration of feedforward control action and feedback compensation produces better responses than the implementation …

Structural Stability Of A Joined-Wing Sensorcraft, Brandon J. Adams

Theses and Dissertations

This thesis employed a multi-disciplinary design approach to determine the structural stability of the Boeing Joined-Wing SensorCraft. Specifically, this thesis sought to characterize the free vibration modes, ensure a buckling safe design and determine the influence of the geometric and aeroelastic nonlinearities associated with this joined-wing design. The clamped free vibration modes were developed for a wind tunnel model and were compared to the free-free vibration modes, several differences were found. Linear static analyses were performed on numerous maneuver loads and gust conditions to determine the critical loading condition. The SensorCraft was then redesigned for the critical load case to …

Development Of Cursor-On-Target Control For Semi-Autonomous Unmanned Aircraft Systems, Joshua D. Crouse

Theses and Dissertations

The research presented in this thesis focuses on developing, demonstrating, and evaluating the concept of a Cursor-on-Target control system for semi-autonomous unmanned aircraft systems. The Department of Defense has mapped out a strategy in which unmanned aircraft systems will increasingly replace piloted aircraft. During most phases of flight autonomous unmanned aircraft control reduces operator workload, however, real-time information exchange often requires an operator to relay decision changes to the unmanned aircraft. The goal of this research is to develop a preliminary Cursor-on-Target control system to enable the operator to guide the unmanned aircraft with minimal workload during high task phases …