Aerospace Engineering Commons^™

Active Control Of Aerial Refueling Drogue, Taeseung Kuk

Dissertations

An active stabilization method for an aerial refueling drogue used in probe-drogue refueling system is presented in this study. The present refueling drogue exhibits an unstable motion due to various turbulent natures, which results in high failure rates and sometimes catastrophic accidents. Although it is considered a routine procedure for human pilot, the workload for mid-air refueling is highly demanding and autonomous operation is by no means a simple task. With rapidly growing use of unmanned aerial vehicles, autonomous aerial refueling is identified as one of essential technologies in future aviation. The present research is a pioneering work in active …

System Identification Of An Autonomous Surface Vehicle, Christopher John Cook

Mechanical & Aerospace Engineering Theses & Dissertations

The modeling and system identification of a small pontoon based marine craft, without rudder control, in a controlled environment. Old Dominion University's autonomous surface vehicle was modeled using the Observer/Kalman System Identification method. The experimental position data was collected using a laser positioning system along with Arduino based sensors on board the boat to collect the motor speeds of the dual outboard motors. The data was then compiled using the System/ Observer/Controller Identification Toolbox to derive a dynamic model that is capable of providing path estimation and prediction information to the autonomous robotic system.

Design And Construction Of A Reconfigurable Pilot-In-The-Loop Aircraft Simulation Workstation, John J. Miller

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis presents and explains the methodology used to design and construct an aircraft dynamics simulation workstation. Beginning from an outdated Navy T-34 training simulator, a gift to the school by the Naval Aerospace Medical Research Laboratory via a previous student, a new system was created to allow an engineer and/or pilot to manually control and evaluate vehicle characteristics for the purposes of research, development, and testing. Retaining only the superstructure of the original T-34 trainer, the entire system was re-engineered to provide a functional, immersive, and expandable simulation environment, complete with a five-screen visual system covering 97.5 deg of …

Design And Implementation Of An Aircraft Human-In-The-Loop Engineering Simulator, Joshua Reed

Mechanical & Aerospace Engineering Theses & Dissertations

Simulation is a powerful tool for examining a dynamic system or process, but ensuring the model represents the real world sufficiently well for a given objective is difficult. This thesis will present and explain the methodology used to design a Human-In-The-Loop Engineering Aircraft Simulator. For aircraft simulation, numerical methods must be employed to perform the calculations required. The number of required calculations per second is computationally and resource expensive. Some existing aircraft simulations trade off mathematical accuracy of the model so available computing power can be used to run a human interface. Conversely, another simulator may have a very poor …

Modeling The Thermosphere As A Driven-Dissipative Thermodynamic System, William R. Frey, C. S. Lin, Matthew B. Garvin, Ariel O. Acebal

Faculty Publications

Thermospheric density impacts satellite position and lifetime through atmospheric drag. More accurate specification of thermospheric temperature, a key input to current models such as the High Accuracy Satellite Drag Model, can decrease model density errors. This paper improves the model of Burke et al. (2009) to model thermospheric temperatures using the magnetospheric convective electric field as a driver. In better alignment with Air Force satellite tracking operations, we model the arithmetic mean temperature, T _1/2, defined by the Jacchia (1977) model as the mean of the daytime maximum and nighttime minimum exospheric temperatures occurring in opposite hemispheres at a …

Flow Separation Control Using Synthetic Jets On A Flat Plate, Karunakaran Saambavi

Doctoral Dissertations and Master's Theses

The primary goal of this thesis is to assess the effect of synthetic jets on flow separation. CFD simulation is conducted for laminar flow over a flat plate using the commercial software ANSYS FLUENT. The oscillating zero mass jet flow is simulated by imposing a harmonically varying boundary condition on the wall surface.

In this work, the effect of synthetic jets for different angles of attack and different frequencies ranging from 200 Hz to 800 Hz was assessed. The application of the synthetic jet actuators is based in their ability to energize the boundary layer, thereby providing significant increase in …

Slosh Damping With Floating Magnetoactive Micro-Baffles, Vijay Santhanam

Doctoral Dissertations and Master's Theses

Liquid sloshing within propellant tanks of launch vehicles and other major vehicles has been a major concern. Various methods have been utilized for the damping of slosh through Propellant Management Devices (PMD) accomplishing a wide range of results. Exploratory research conducted at the Embry-Riddle Aeronautical University Fuel Slosh Test Facility in development of an innovative PMD is presented. Embedding floating micro-baffles with a magnetoactive material such that the baffle can be manipulated when exposed to a magnetic field preserves the benefits of both floating and static baffle designs. Activated micro-baffles form a rigid layer at the free surface and provide …

3d Aerodynamic Optimization Of Nrel Vi Wind Turbine Blade For Increased Power Output And Visualization Of Flow Characteristics, Tsewang Rabga Shrestha

Doctoral Dissertations and Master's Theses

The thesis focuses on the aspect of optimization of NREL VI wind turbine blade for increased power output using commercial solver ANSYS 14.5. The power curve obtained from BEMT, Baseline NREL VI CFD Simulations and Optimized Blade Simulations are compared with experimental results. Over prediction is observed in the theoretical result while computational analysis under predicts power produced at post stall region. Parameter correlation and sensitivity analysis study relates the effectiveness of design parameters on the objective outcome. Scatter plots and Determination Matrix indicate the problem setup as non-linear quadratic. Adaptive Single Objective Optimization algorithm is used for the optimization …

Evaluation Of Mixing-Limited Quasi-Global Wind-Us Model For Hifire 2 Flowpath, Michael R. Borghi Jr.

Doctoral Dissertations and Master's Theses

A Reynolds-averaged Navier-Stokes computational model featuring a mixing-limited, quasi-global chemical kinetics approach for an ethylene-methane fuel mixture is described and used in a validation effort against the Hypersonic International Flight Research Experimentation (HIFiRE) Direct Connect Rig experimental data for flight Mach numbers of 5.84, 6.5, and 8.0. An average error level between the numerical predictions and corresponding experimental measurements for static pressure along the engine flowpath is found to be within approximately 10%, for the two lowest Mach number cases, without calibration. Key features of the numerical flowfield development are identified, including regions within the combustor found to be significantly …

Assessment Of The Thermal Advantages Of Biased Supersonic Cooling, Michael J. Carkin

Doctoral Dissertations and Master's Theses

The following work investigates an alternative supersonic film cooling method for hydrogen-fueled, gas-generator cycle rocket engines. The research is intended to serve as an initial proof-of-concept for a biased supersonic film cooling method envisioned for nozzle extension thermal management. The proposed method utilizes a dual-stream injection process that leverages the high heat capacity of the fuel-rich gas-generator gases. By comparing the proposed cooling strategy to the conventional mixed injection process, the research numerically validates the biased supersonic film cooling scheme for low supersonic slot Mach numbers. The average film cooling effectiveness was improved 5%-8% with increases as high as 12%. …

Integrating Mammalian Hazards With Management At U.S. Civil Airports: A Case Study., Kristin M. Biondi, Jerrold L. Belant, James A. Martin, Travis L. Devault, Guiming Wang

United States Department of Agriculture Wildlife Services: Staff Publications

Wildlife incidents with U.S. civil aircraft cost an estimated $1.4 billion from 1990 to 2010, with mammals 5 times more likely to cause damage than other wildlife. We surveyed 2 general aviation (GA) airports and 6 Part-139 certificated (i.e., certified) airports to assess efficacy of management practices for mammalian species hazardous to aircraft. We obtained information on mammalian species present on airport grounds, types and estimated effectiveness of management techniques, and effort spent on wildlife management. We evaluated management techniques relative to aircraft–wildlife collisions (i.e., incident) frequencies taken from Federal Aviation Administration’s (FAA) National Wildlife Strike Database and species hazard …

State Variable Model For Unsteady Two Dimensional Axial Vortex Flow With Pressure Relaxation, Mazin Mohammed Elbakri Abuharaz

Mechanical & Aerospace Engineering Theses & Dissertations

This research has utilized a state variable model for unsteady two dimensional axial vortex flows experiencing non-equilibrium pressure gradient forces. The model was developed successfully using perturbed radial and azimuthal momentum equations and a pressure Poisson's equations. Three main regions of the axial vortex flow were highlighted in this study including: a laminar core region, a non-equilibrium pressure envelope, and an outer potential vortex.

Linear stability theory was utilized to formulate the model and the perturbation functions were assumed to be of the Fourier type. The flow parameters considered were the Reynolds numbers, ranging between 6,000 and 14,000, and a …

Fluid-Structure Interaction Modeling Of A F/A-18 Twin-Tail Buffet Using Non-Linear Eddy Viscosity Models, Ahmed M. Nagib M. Elmekawy

Mechanical & Aerospace Engineering Theses & Dissertations

When turbulent flow generates unsteady differential pressure over an aircraft's structure, this may generate buffeting, a random oscillation of the structure. The buffet phenomenon is observed on a wide range of fighter aircraft, especially fighters with twin-tail. More research is needed to better understand the physics behind the vortical flow over a delta wing and the subsequent tail buffet.

This dissertation reports the modeling and simulation of a steady-state one-way fluid-structure interaction for the tail buffet problem observed on a F/A-18 fighter. The time-averaged computational results are compared to available experimental data. Next, computations are extended to simulate an unsteady …

White Paper On Tuition Based Ab Initio Training Programs For Air Traffic Controllers, Tim Brady, Gregory Mcguirk

Publications

Embry-Riddle Aeronautical University is proposing an evaluation to transform the legacy method for hiring and training air traffic controllers. This evaluation will examine a transition to a prospective employee-funded, tuition-based model, while reinvesting savings to create a state-of-the-art air traffic training center at the FAA Academy in Oklahoma City.

Eps Simulator, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on the "EPS Similator" on March 24, 2014.

Gps Multipath Reduction With Correlator Beamforming, Jason M. Barhorst

Theses and Dissertations

This research effort investigates the feasibility of beamforming using a single Global Positioning System (GPS) front end. Traditional methods of beamforming use multiple front ends, typically one per antenna element. By enabling a receiver to sample a switched antenna array, the hardware cost of implementing a GPS antenna array can be significantly reduced. Similar techniques of reducing the number of receivers have been used by Locata Corporation in the design of their non-GPS positioning systems. However, Locata Corporation's local transmitters provide a signal strength much higher than GPS's signal strength. For this reason, the inclusion of low-noise amplifiers into the …

Image-Aided Navigation Using Cooperative Binocular Stereopsis, Justin T. Soeder

Theses and Dissertations

This thesis proposes a novel method for cooperatively estimating the positions of two vehicles in a global reference frame based on synchronized image and inertial information. The proposed technique - cooperative binocular stereopsis - leverages the ability of one vehicle to reliably localize itself relative to the other vehicle using image data which enables motion estimation from tracking the three dimensional positions of common features. Unlike popular simultaneous localization and mapping (SLAM) techniques, the method proposed in this work does not require that the positions of features be carried forward in memory. Instead, the optimal vehicle motion over a single …

Radio Frequency Emitter Geolocation Using Cubesats, Andrew J. Small

Theses and Dissertations

The ability to locate an RF transmitter is a topic of growing interest for civilian and military users alike. Geolocation can provide critical information for the intelligence community, search and rescue operators, and the warfighter. The technology required for geolocation has steadily improved over the past several decades, allowing better performance at longer baseline distances between transmitter and receiver. The expansion of geolocation missions from aircraft to spacecraft has necessitated research into how emerging geolocation methods perform as baseline distances are increased beyond what was previously considered. The CubeSat architecture is a relatively new satellite form which could enable small-scale, …

Thermal Characterization Of The Air Force Institute Of Technology Solar Simulation Thermal Vacuum Chamber, Daniel M. Hatzung

Theses and Dissertations

Although predictive thermal modeling on CubeSats has previously been accomplished, a method to validate these predictive models with terrestrial experiments is essential for developing confidence in the model. As a part of this effort, AFIT has acquired a new Solar Simulation Thermal Vacuum Chamber. This research analyzed the thermal environment to which a test article is exposed within the AFIT Solar Simulation Thermal Vacuum Chamber. A computational model of the thermal environment in the chamber was created and then validated using an experimental buildup approach through thermal balance testing of the empty chamber and an aluminum plate. First, the modeled …

Feasibilty Of Very Large Sparse Aperture Depolyable Antennas, Jason C. Heller

Theses and Dissertations

The objective of this research is to explore the technical soundness of a very large, cross-shaped, parabolic, sparse aperture antenna extending 75 m from the bus. Specifically, describing the environment of the satellite, the effect of fabrication error on the structure and the remaining error budget for the system. The methodology involves creation of an ideal truss structure, to which all others are compared. A uniform distribution of proportional errors up to 1e-5 is introduced into the truss members' lengths and the models are subjected to a static Finite Element Analysis. A solution for the surface normal error is addressed …

Optimal Uav Path Planning For Tracking A Moving Ground Vehicle With A Gimbaled Camera, Riley A. Livermore

Theses and Dissertations

This research develops a path planning algorithm that autonomously controls a UAV to provide convoy overwatch. The optimization algorithm determines the best path to y through developing a cost function that minimizes the control effort of the UAV and the deviation from a desired slant range. A heuristic-based algorithm was developed and implemented on the autopilot to approximate the optimal solution. In flight test, the UAV successfully tracked a moving ground vehicle by continually placing the UAV's loiter point directly above the ground vehicle's current location. This method was called the \follow-me mode and provided the baseline for real-world UAV …

Influence Of Mach Number And Dynamic Pressure On Cavity Tones And Freedrop Trajectories, Justin D. Merrick

Theses and Dissertations

Weapons release at supersonic speeds from an internal weapons bay is a highly desirable capability. To ensure a successful release at multiple Mach numbers, the aerodynamic environment must be well-understood and repeatable, with a robust system for safe testing of store separation. For this reason, experimental methods were used to investigate the characteristics of a scaled WICS bay with a length-to-depth ratio of 4.5 at multiple Mach numbers and stagnation pressures. Three new nozzles were designed, manufactured, and characterized for the AFIT small supersonic tunnel, yielding freestream Mach numbers of 2.22, 1.84, and 1.43. In addition, a control valve was …

Thermal Loss Determination For A Small Internal Combustion Engine, Joshua A. Rittenhouse

Theses and Dissertations

Three analysis techniques were used to measure the heat rejection of a 55 cc air-cooled two-stroke engine. This study was performed as part of a larger effort aimed at extending range and endurance limitations of Group 1 & 2 Remotely Piloted Aircraft (RPA). The engine selected for the study was a 55 cc gasoline-fueled, carbureted, spark-ignition engine made by 3W-Modellmotoren and is representative of RPA engines in these groups. With a surface area to volume ratio of 1.48 ¹/_cm, the engine is in a size region where thermal losses begin to dominate engine efficiency and thermal efficiencies …

Ceramic Matrix Characterization Under A Gas Turbine Combustion And Loading Environment, Dustin J. Bertrand

Theses and Dissertations

The fatigue behavior of Hyper-Therm High Temperature Composites (HTC) Sylramic-iBN/BN/CVI SiC material was investigated while being subjected to a unique high temperature environment. The specimens used in this research were subjected to a high temperature combustion environment intended to simulate the conditions this material would see in turbine engine applications. Results show that the effects of the combustion environment on the materials fatigue behavior are significant with increasing temperature.

Operational Characteristics Of An Ultra Compact Combustor, Christopher J. Damele

Theses and Dissertations

Ultra Compact Combustors offer unique solutions to minimize engine size and weight. They accomplish this by reducing the number of components in the engine core and perform the combustion in a circumferential cavity that encircles the core flow. Within this cavity, the fuel is injected rich. Burning continues to occur in the vane passage beneath the circumferential cavity which must be completed in a controlled manner prior to the inlet plane of the turbine rotor. Furthermore, the temperature distribution at the exit of the vane passage must be controlled to generate high work extraction from the turbine. The primary metrics …

Design And Analysis Of An Attitude Determination And Control Subsystem (Adcs) For Afit's 6u Standard Bus, Erin R. Dannemeyer

Theses and Dissertations

The design and testing of AFIT's 6U Attitude Determination and Control Subsystem (ADCS) are explored to establish 3-axis attitude control. The development of AFIT's 6U CubeSat standard bus is an on-going research effort designed to create in-house CubeSat bus components and software. The 6U chassis measures approximately 11 x 24 x 37 cm³ and can have a mass up to 12 kg. The larger bus size (as compared to the more common 3U CubeSat) allows for increased power capabilities and potential to host multiple or larger payloads. Individual ADCS hardware components were either commercially purchased or built in-house and …

The Use Of An Ultra-Compact Combustor As An Inter-Turbine Burner For Improved Engine Performance, Jose L. Miranda

Theses and Dissertations

An Inter-Turbine Burner (ITB) represents a novel mechanism for generating additional work from a gas turbine engine in applications where an afterburner would typically be used. An ITB can achieve higher thermal efficiencies over a typical afterburner while also generating shaft work versus only additional thrust. In an effort to investigate the potential applications for the ITB, a numerical engine cycle comparison was made between the ITB cycle and a conventional afterburning cycle using the Numerical Propulsion System Simulation (NPSS). In the case of thrust augmentation, the ITB model outperformed the afterburning model when Thrust Specific Fuel Consumption (TSFC) is …

Investigation Of The Potential For Ftir As A Nondestructive Inspection Technique For Aircraft Coating Degradation, Hans G. Korth

Theses and Dissertations

Polyurethane-based aircraft coating degradation was examined using Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFTs). Two sample sets were aged in an autoclave; each containing four samples. Sample set A contained two as-cured samples and two samples treated to a level of visual degradation. Sample set B contained one sample left as-cured and three samples of differing degradation. DRIFTs spectra were collected on sample set B and singular value decomposition (SVD) was used to reveal trends between the degradation levels. Linear discriminant analysis (LDA) was then applied to the SVD coefficients to determine the most accurate spectral band for classification of …

Comm-Using Decibels - Loose Slides, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Comm-Using Decibles - Loose Slides" from March 13. 2014.

Post-Fracture Capacity Of Railroad Flat Car Bridges, Teresa L. Washeleski

Purdue Road School

Railroad flatcars (RRFCs) are a convenient option to replace existing deteriorating bridge structures on low-volume roads. They are typically used as the bridge superstructure by placing two or more flatcars side-by-side to achieve the desired bridge width. Utilizing RRFCs as a bridge allows for rapid construction and greater cost savings compared to traditional practices. These benefits make them an attractive solution for rural communities in Indiana, as well as other states.

Uncertainty remains about the response under higher loads than could be easily achieved in the field and the level of redundancy of railroad flatcar bridges. Using RRFCs as bridges …