Aerospace Engineering Commons^™

Fatigue Behavior Of An Advanced Melt-Infiltrated Sic/Sic Composite With Environmental Barrier Coating At 1200°C In Air And In Steam, Thaddeus M. Williams

Theses and Dissertations

Advanced aerospace applications such as aircraft turbine engine components, hypersonic flight vehicles, and spacecraft reentry thermal protection systems require structural materials that have superior long-term mechanical properties under high temperature, high pressure, and varying environmental factors, such as moisture. Because of their low density, high strength and fracture toughness at high temperatures SiC fiber-reinforced SiC matrix composites are being evaluated for aircraft engine hot-section components. In these applications the composites will be subjected to various types of mechanical loadings at elevated temperatures in oxidizing environments. Because their constituents are intrinsically oxidation-prone, the most significant problem hindering SiC/SiC composites is oxidation …

A Reference Architecture For Cubesat Development, Luke J. Farrell

Theses and Dissertations

Developing a space vehicle is a complex and detailed process, and while CubeSats are smaller and more accessible than traditional satellites the design process is relatively unchanged. Creating a viable space vehicle design requires detailed analysis of a set of mission needs in order to define the mission, with this need set used to then create the specific mission requirements. These requirements are used to formulate a concept of operations, and then move into developing a physical system for executing the mission. The successful production of CubeSats within an organization is contingent upon the accurate execution of the general CubeSat …

Evaluation Framework For Cislunar Space Domain Awareness (Sda) Systems, Simon R. Knister

Theses and Dissertations

Modern space missions are increasingly transiting cislunar space, requiring expansion of existing Space Traffic Management (STM) functions. Legacy Space Domain Awareness (SDA) systems were not purpose-built to detect and track cislunar objects, which could require acquisition of a new system of systems. There are numerous parameters that could be varied for each system, as well as the type and location of systems across the architecture. This research attempts to solve this problem by applying a model-based systems engineering (MBSE) approach to assess the performance and financial burden of a given system of systems. Fitness metrics are developed based upon the …

The Impact Of Changing The Size Of Aircraft Radar Displays On Visual Search In The Cockpit, Justin R. Marsh

Theses and Dissertations

Advances in sensor technology have enabled our fighter aircraft to find, fix, track, target, engage (F2T2E) at greater distances, providing the operator with more data within the battlefield. Modern aircraft are designed with larger displays while our legacy aircraft are being retrofitted with larger cockpit displays to enable display of the increased data. While this modification has been shown to enable improvements in human performance of many cockpit tasks, this effect is often not measured nor fully understood at a more generalizable level. This research outlines an approach to comparing human performance across two display sizes in future F-16 cockpits. …

Development, Test And Evaluation Of Autonomous Unmanned Aerial Systems In A Simulated Wide Area Search Scenario: An Implementation Of The Autonomous Systems Reference Architecture, Katherine E. Cheney, David D. King

Theses and Dissertations

The implementation and testing of autonomous and cooperative unmanned systems is challenging due to the inherent design complexity, infinite test spaces, and lack of autonomy specific measures. These challenges are limiting the USAF's ability to deploy and take advantage of tactical and strategic advantages offered by these systems. This research instantiates an Autonomous System Reference Architecture (ASRA) on a Wide Area Search (WAS) scenario as a test bed for rapid prototyping and evaluation of autonomous and cooperative systems. This research aims to pro- vide a framework to evaluate the system’s ability to achieve mission and autonomy objectives, develop reusable autonomous …

Improving Aeromagnetic Calibration Using Artificial Neural Networks, Mitchell C. Hezel

Theses and Dissertations

The Global Positioning System (GPS) has proven itself to be the single most accurate positioning system available, and no navigation suite is found without a GPS receiver. Even basic GPS receivers found in most smartphones can easily provide high quality positioning information at any time. Even with its superb performance, GPS is prone to jamming and spoofing, and many platforms requiring accurate positioning information are in dire need of other navigation solutions to compensate in the event of an outage, be the cause hostile or natural. Indeed, there has been a large push to achieve an alternative navigation capability which …

Cyber Risk Assessment And Scoring Model For Small Unmanned Aerial Vehicles, Dillon M. Pettit

Theses and Dissertations

The commercial-off-the-shelf small Unmanned Aerial Vehicle (UAV) market is expanding rapidly in response to interest from hobbyists, commercial businesses, and military operators. The core commercial mission set directly relates to many current military requirements and strategies, with a priority on short range, low cost, real time aerial imaging, and limited modular payloads. These small vehicles present small radar cross sections, low heat signatures, and carry a variety of sensors and payloads. As with many new technologies, security seems secondary to the goal of reaching the market as soon as innovation is viable. Research indicates a growth in exploits and vulnerabilities …

An Analytic Study Of Pursuit Strategies, Mark E. Vlassakis

Theses and Dissertations

The Two-on-One pursuit-evasion differential game is revisited where the holonomic players have equal speed, and the two pursuers are endowed with a circular capture range ℓ > 0. Then, the case where the pursuers' capture ranges are unequal, ℓ₁ > ℓ₂ ≥ 0, is analyzed. In both cases, the state space region where capture is guaranteed is delineated and the optimal feedback strategies are synthesized. Next, pure pursuit is considered whereupon the terminal separation between a pursuer and an equal-speed evader less than the pursuer's capture range ℓ > 0. The case with two pursuers employing pure pursuit is considered, and …

Semantic Segmentation Of Aerial Imagery Using U-Nets, Terence J. Yi

Theses and Dissertations

In situations where global positioning systems are unavailable, alternative methods of localization must be implemented. A potential step to achieving this is semantic segmentation, or the ability for a model to output class labels by pixel. This research aims to utilize datasets of varying spatial resolutions and locations to train a fully convolutional neural network architecture called the U-Net to perform segmentations of aerial images. Variations of the U-Net architecture are implemented and compared to other existing models in order to determine the best in detecting buildings and roads. A final dataset will also be created combining two datasets to …

Analysis Of Additively Manufactured Rings Under Compression Loading For Use In A Vacuum Lighter Than Air Vehicle Structure, Kevin D. Greenoe

Theses and Dissertations

A Vacuum Lighter Than Air Vehicle (VLTAV) utilizes a lightweight structure paired with an internal vacuum to achieve buoyancy; this allows it to float through-out a given atmosphere. The pressure differential between the internal vacuum andexternal atmosphere places the vehicle under intense loading. A specific structure under investigation is the celestial icosahedron, which features nine intersecting rings that have an outer diameter of 0.2032m and circular cross-sectionalthickness of 5.08mm.The celestials rings are positioned in three different orientations and are analyzed both experimentally and analytically.

Linear Regression Models Applied To Imperfect Information Spacecraft Pursuit-Evasion Differential Games, Dax Linville

Theses and Dissertations

Within satellite rendezvous and proximity operations lies pursuit-evasion differential games between two spacecraft. The extent of possible outcomes can be mathematically bounded by differential games where each player employs optimal strategies. A linear regression model is developed from a large data set of optimal control solutions. The model is shown to map pursuer relative starting positions to final capture positions and estimate capture time. The model is 3.8 times faster than the indirect heuristic method for arbitrary pursuer starting positions on an initial relative orbit about the evader. The linear regression model is shown to be well suited for on-board …

Experimental Measurements Of Hypseronic Instabilities Over Ogive-Cylinders At Mach 6, Jonathan Luke Hill

Theses and Dissertations

Hypersonic boundary layer transition experiments were performed in the Air Force Research Lab (AFRL) Mach 6 Ludwieg tube over a meter long ogive-cylinder model with interchangeable nose tip angles and bluntnesses. Measurements of instabilities were captured via focused laser differential interferometry (FLDI), surface mounted pressure sensors, and high speed Schlieren imagery at nominal unit Reynolds numbers ranging from 4.0*10⁶/m to 1.4*10⁷/m. This study attempts to isolate the effects of increasing tip angle and spherical bluntness on instabilities measured downstream over the cylindrical body of the model.

Distributed Adaptive State Estimation And Tracking By Using Active-Passive Sensor Networks, Akhilesh Raj, Sarangapani Jagannathan, Tansel Yucelen

Electrical and Computer Engineering Faculty Research & Creative Works

Heterogeneous sensor networks (HSN) find a wide range of applications in the field of military and civilian environments, where sensor nodes are utilized to estimate the position of a target with both dynamics and control input being unknown for the purposes of tracking. In the HSN, nodes are considered active depending upon their ability to sense the target output while the others are taken passive. Accurate estimation requires local information exchange among the spatially located sensor nodes, so that the active nodes as well as the passive nodes converge simultaneously to the same value. The local information exchange among the …

Verifying And Improving A Flight Reference System's Performance, Loren E. Myers

Theses and Dissertations

The 746th Test Squadron (746 TS) at Holloman AFB, NM operates the Ultra High Accuracy Reference System (UHARS) as part of its mission positioning and navigation test. This research presents a method for verifying the performance of a flight reference system using a Delta-Position velocity derived from radio navigation positioning measurements. The algorithm presented may utilize Global Positioning System (GPS) or the Locata ground based positioning system. In the latter case, Locata provides a velocity truth independent from GPS. The accuracy of Locata and GPS are assessed and UHARS velocity measurements are characterized both in nominal and GPS denied applications.

Comparison Of Signaling Profiles In The Low Dose Range Following Low And High Let Radiation, Deepa M. Sridharan, Lung-Chang Chien, Francis A. Cucinotta, Janice M. Pluth

Environmental & Global Health Faculty Research

During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82–6, was exposed to a range of lower doses (0.05–0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si …

Angular Correlation Using Rogers-Szego-Chaos, Christine Schmid, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Polynomial chaos expresses a probability density function (pdf) as a linear combination of basis polynomials. If the density and basis polynomials are over the same field, any set of basis polynomials can describe the pdf; however, the most logical choice of polynomials is the family that is orthogonal with respect to the pdf. This problem is well-studied over the field of real numbers and has been shown to be valid for the complex unit circle in one dimension. The current framework for circular polynomial chaos is extended to multiple angular dimensions with the inclusion of correlation terms. Uncertainty propagation of …

Dislocation-Oxide Interaction In Y2o3 Embedded Fe: A Molecular Dynamics Simulation Study, M. Mustafa Azeem, Qingyu Wang, Zhongyu Li, Yue Zhang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Oxide dispersed strengthened (ODS) steel is an important candidate for Gen-IV reactors. Oxide embedded in Fe can help to trap irradiation defects and enhances the strength of steel. It was observed in this study that the size of oxide has a profound impact on the depinning mechanism. For smaller sizes, the oxide acts as a void; thus, letting the dislocation bypass without any shear. On the other hand, oxides larger than 2 nm generate new dislocation segments around themselves. The depinning is similar to that of Orowan mechanism and the strengthening effect is likely to be greater for larger oxides. …

Ground And In-Flight Calibration Of The Osiris-Rex Camera Suite, D. R. Golish, C. Drouet D'Aubigny, B. Rizk, D. N. Dellagiustina, P. H. Smith, K. Becker, N. Shultz, T. Stone, M. K. Barker, E. Mazarico, E. Tatsumi, R. W. Gaskell, L. Harrison, C. Merrill, C. Fellows, B. Williams, S. O'Dougherty, Michael Whitely, Jed Hancock, B. E. Clark, C. W. Hergenrother, D. S. Lauretta

Space Dynamics Laboratory Publications

The OSIRIS-REx Camera Suite (OCAMS) onboard the OSIRIS-REx spacecraft is used to study the shape and surface of the mission’s target, asteroid (101955) Bennu, in support of the selection of a sampling site. We present calibration methods and results for the three OCAMS cameras—MapCam, PolyCam, and SamCam—using data from pre-flight and in-flight calibration campaigns. Pre-flight calibrations established a baseline for a variety of camera properties, including bias and dark behavior, flat fields, stray light, and radiometric calibration. In-flight activities updated these calibrations where possible, allowing us to confidently measure Bennu’s surface. Accurate calibration is critical not only for establishing a …

Differential Vector Phase Locked Loop Gps Reception Method, James Brewer, John F. Raquet

AFIT Patents

A method for enhancing GPS location accuracy includes providing a base station receiver having a known surveyed location, and a roving receiver at a location distinct from the base station receiver. The method further includes receiving single-frequency code and carrier-phase measurements from the base station, and translating the single-frequency code and carrier-phase measurements to a Kalman filter-predicted location of the roving receiver. The translated single frequency code and carrier phase measurements are used to generate a local replica of the Kalman filter-predicted location signals for each channel of the roving receiver. The method further includes correlating the local replicas with …

Congressional Committee Resources On Space Policy During The 115th Congress (2017-2018): Providing Context And Insight Into U.S. Government Space Policy, Bert Chapman

Libraries Faculty and Staff Scholarship and Research

Article 1 of the US Constitution assigns the US Congress numerous responsibilities. These include creating new laws, revising existing laws, funding government programs, and conducting oversight of these programs' performance. Oversight of US Government agency space policy programs is executed by various congressional space policy committees, including the House and Senate Science Committees, Armed Services, and Appropriations Committees. These committees conduct many public hearings on space policy which invite witnesses to testify on US space policy programs and feature debate on the strengths and weaknesses of these programs. Documentation produced by these committees is widely available to the public, except …

Characterization Of Inertial Particles In The Turbulent Wake Of A Porous Disk, Kristin Nichole Travis

Dissertations and Theses

This study presents the findings of a wind tunnel experiment investigating the behaviour of micrometric inertial particles in the turbulent wake of a stationary porous disk. Various concentrations [Φ_v ∈ (2.95 x 10^-6 - 1.22 x 10^-5)] of polydisperse water droplets (diameter 13-41 µm) are compared to sub-inertial tracer particles. Hot-wire anemometry, phase Doppler interferometry and particle image velocimetry were implemented in the near and far wake regions to study the complex dynamics of the particles. Turbulence statistics and particle size distributions are presented and used to explore the particle wake interaction.

Near-Field Pressure Signature Splicing For Low-Fidelity Design Space Exploration Of Supersonic Aircraft, Christian R. Bolander, Douglas F. Hunsaker

Mechanical and Aerospace Engineering Student Publications and Presentations

As interest in supersonic overland flight intensifies, new ways to meet government restrictions on sonic boom loudness must be implemented. Low-fidelity aerodynamic tools, such as PANAIR, can estimate the near-field pressure signature that ultimately determines the loudness of the sonic boom at the ground. These tools can greatly benefit the exploration of large design spaces due to their computational efficiency. One of the limitations of low-fidelity tools is the accuracy of the solution produced, which is dependent on the fundamental physical assumptions made in the development of the governing equations. If flow patterns are produced that severely violate these fundamental …

Close Formation Flight Missions Using Vision-Based Position Detection System, Ashok Sarath Chandra Reddy Irigireddy

Doctoral Dissertations and Master's Theses

In this thesis, a formation flight architecture is described along with the implementation and evaluation of a state-of-the-art vision-based algorithm for solving the problem of estimating and tracking a leader vehicle within a close-formation configuration. A vision-based algorithm that uses Darknet architecture and a formation flight control law to track and follow a leader with desired clearance in forward, lateral directions are developed and implemented. The architecture is run on a flight computer that handles the process in real-time while integrating navigation sensors and a stereo camera. Numerical simulations along with indoor and outdoor actual flight tests demonstrate the capabilities …

Carbon Fiber Composite Recycling, Wolfe Dennis

All Undergraduate Projects

During construction of Boeing’s aircrafts, carbon fiber reinforced composites are used as the primary material for the wings of the aircraft. Excess material during the manufacturing process is trimmed and discarded as waste. Although there is no viable process thus far, these trimmings have the potential to be recycled and reclaimed to be used in various other manufactured products. The trimmings of carbon fiber composite are approximately 10-12 layers of material bonded together. This project focuses on delaminating the trimmings into individual layers so that the carbon can be pyrolyzed from the bonding resin. In order to separate the layers …

Test Article, Test Author

Documentation

Description

Tangle-Free Exploration With A Tethered Mobile Robot, Danylo Shapovalov, Guilherme Pereira

Faculty & Staff Scholarship

Exploration and remote sensing with mobile robots is a well known field of research, but current solutions cannot be directly applied for tethered robots. In some applications, tethers may be very important to provide power or allow communication with the robot. This paper presents an exploration algorithm that guarantees complete exploration of arbitrary environments within the length constraint of the tether, while keeping the tether tangle-free at all times. While we also propose a generalized algorithm that can be used with several exploration strategies, our implementation uses a modified frontier-based exploration approach, where the robot chooses its next goal in …

Mechanical And Aerospace Engineering, 2019-2020, College Of Engineering And Applied Sciences

Mechanical and Aerospace Engineering News

• Letter from the Chair
• The MAE Staff
• Dr. Zachary Asher
• Alumni Excellence Academy Inductees
• From Sunway University to Success in America
• Student Experience at the Oshkosh Airventure
• Parker-Hannifin Donates New Hydraulic Trainers
• Electric Ducted Fan Lab for the Aircraft Propulsion Course
• MAE Faculty

Drone Payload Storage & Release System (Dpsrs), Joseph E. Key

All Undergraduate Projects

The retail giant Amazon has become a household name synonymous with nearly instantaneous online shopping. What previously took weeks to deliver at exorbitant shipping fees can now arrive at your doorstep within two days—and all for free. This huge buyer incentive has skyrocketed the demand for online shopping, making Amazon the most valuable brand in the world. To meet this demand, Amazon and its distributors have proposed using drones to make deliveries. However, due to issues with cost and complexity, this has not yet materialized. As such, this project’s objective was to create a cheap and lightweight package-delivery system that …

Composite Ruddervator Replacement, Kelson Mills

All Undergraduate Projects

The Beechcraft V-tail Bonanza is a popular general aviation aircraft. Over 10,000 were built, but with the weakness of magnesium skinned control surfaces. Control surfaces on aircraft must be light, and precisely balanced. The V-tail Bonanza uses a unique “ruddervator” system, which combines the rudder and elevator into one surface to reduce drag, controlling the pitch and yaw of the aircraft. Magnesium was chosen by the designers for its lightweight properties, but corrodes badly and is becoming difficult to source for replacement parts. Aerodynamic flutter, from flexibility in the lightly built surface, and corrosion can cause breakup in flight, and …

A Generalized Low Order Model For Vortex Shedding From A Tandem Cylinder Arrangement Using Delay Coupled Van Der Pol Oscillators, Michael Soroka

Honors Undergraduate Theses

A generalized low order model (LOM) for the fluctuating lift coefficient caused by vortex shedding from a tandem cylinder pair is proposed to expand upon models from previous authors. This model could provide a reduced computational time method for collecting qualitative and quantitive data from a tandem shedding pair. A delay coupled system with sufficient bifurcation characteristics is developed to account for the different flow regimes (extended-body, reattachment, and co-shedding) which occur as cylinder spacing is varied. Coefficient and parameter fitting is performed to fit experimental data. Finally, results and physical interpretations of the interactions in the model are discussed. …