Aerospace Engineering Commons^™

First-Year Project Experience In Aerospace: Apogee Determination Of Model Rockets With Explicit Consideration Of Drag Effect, Hüseyin Sarper, Drew Landman, Linda Vahala

Electrical & Computer Engineering Faculty Publications

This paper describes a student team project using model rockets and engines to learn engineering solution methods for determining the apogee of model rocket when the drag effect is considered explicitly instead of estimating its effect later. Model rocketry is a powerful tool for instructors who wish to incorporate science, engineering, and mathematics into a fun, engaging, and challenging activity for the students. The apogee can be determined using a number of distinct methods: trigonometry, onboard altimeters, analytical calculations, and simulation. This paper emphasizes numerical analytical solution using spreadsheet programming instead of a full analytical solution that requires higher mathematics. …

Quantitative Assessment Of Secondary Flows Of Single-Phase Fluid Through Pipe Bends, Z. Kaldy, O. Ayala

Engineering Technology Faculty Publications

Single-phase fluid flow was simulated passing through various three dimensional pipe elbows. The simulations varied by Reynolds number, curvature ratios, and sweep angles and were all conducted using the k-e model available in COMSOL Multiphysics 5.1. The intent of this research was to qualitatively assess the flow characteristics under several different conditions. Many similarities were seen especially when comparing curvature ratios, the vorticity location for the turbulent cases show near identical behavior at the elbow midsection. One of the variables quantified in this paper is the maximum secondary velocity module which shows increasing values until the midsection of the elbow.

Thrust Prediction For A Rotor Operating In A Ship Airwake, Mathew Thomas

Mechanical & Aerospace Engineering Theses & Dissertations

This report details work performed at Old Dominion University focused on developing a thrust prediction capability for a rotor operating in a ship airwake. The study has built upon previous experimental work utilizing particle image velocimetry-based velocity field measurements to quantify the degree of coupling in a simplified rotor/ship airwake experiment. Using the velocity field data of the previous study, a database was built representing the volume over the landing deck. Rotor thrust was computed using blade element methods and compared to direct load cell measurements and to a superposed velocity field. Results show that the blade element method has …

Flight Dynamics Nonlinearity Assessment Across A New Aerodynamic Attitude Flight Envelope, Ayman Muhammad Abdallah

Mechanical & Aerospace Engineering Theses & Dissertations

A new asymmetric level aerodynamic attitude flight envelope is introduced in this dissertation. The aerodynamic attitude envelope is an angle of attack vs. sideslip angle region which describes the extent of where an aircraft can sustain a steady slipping horizontal flight condition. The new envelope is thus an extension of the more common speed-altitude symmetric level flight envelope. This new envelope can be used for design requirements, dynamic analysis, control synthesis, or performance comparison. Moreover, this envelope provides enhanced insight into trimability-controllability limitations within the aircraft design model. The aerodynamic attitude flight envelope is constructed for a six degree of …

Nano Scale Mechanical Analysis Of Biomaterials Using Atomic Force Microscopy, Diganta Dutta

Mechanical & Aerospace Engineering Theses & Dissertations

The atomic force microscope (AFM) is a probe-based microscope that uses nanoscale and structural imaging where high resolution is desired. AFM has also been used in mechanical, electrical, and thermal engineering applications. This unique technique provides vital local material properties like the modulus of elasticity, hardness, surface potential, Hamaker constant, and the surface charge density from force versus displacement curve. Therefore, AFM was used to measure both the diameter and mechanical properties of the collagen nanostraws in human costal cartilage. Human costal cartilage forms a bridge between the sternum and bony ribs. The chest wall of some humans is deformed …

Morris Leroy Spearman

Virginia Journal of Science

Obituary for Morris Leroy Spearman

Performance Characteristics Of Fluidic-Based Thrust Augmentation Using A Slot Jet For Unmanned Aerial Vehicle Propulsion, Brendan A. Wiedow

Mechanical & Aerospace Engineering Theses & Dissertations

Currently most small vertical takeoff and landing Unmanned Aerial Vehicles (UA V's) use a quadcopter design by utilizing four exposed blades rotating at high RPMs around a central array of components. The research performed in this thesis is focused on understanding the underlying fluid dynamics of a slot jet through the use of flow entrainment for thrust augmentation with the application to be integrated into a novel UAV system with no external moving parts. Current publicly available quadcopter rotor design type aircraft were used as a basis for the design target weight and power to estimate the amount of thrust …

Guidance And Navigation For A Spinning Projectile Using A Strapdown Seeker, Timothy J. Josey

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis describes the derivation and implementation of an Extended Kalman Filter for the purpose of estimating the line of sight rates between a non-thrusting, guided projectile and a ground target. Line of sight rates are required signals to implement the proportional navigation guidance scheme. Using low-cost strapdown sensors, the line of sight rate is not directly measurable but is observable as shown in this thesis. The line of sight signal generated by strapdown seekers inherently includes projectile body motion, but with the use of a global positioning system and a strapdown inertial sensor suite, the seeker signal is transformed …

Modeling, Dynamics And Control Of Spacecraft Relative Motion In A Perturbed Keplerian Orbit, Mohamed Okasha, Brett Newman

Mechanical & Aerospace Engineering Faculty Publications

The dynamics of relative motion in a perturbed orbital environment are exploited based on Gauss' and Cowell's variational equations. The inertial coordinate frame and relative coordinate frame (Hill frame) are used, and a linear high fidelity model is developed to describe the relative motion. This model takes into account the primary gravitational and atmospheric drag perturbations. Then, this model is used in the design of a navigation, guidance, and control system of a chaser vehicle to approach towards and to depart from a target vehicle in proximity operations. Relative navigation uses an extended Kalman filter based on this relative model …

Correlation Of Csk2sb Photocathode Lifetime With Antimony Thickness, M. A. Mamun, C. Hernandez-Garcia, M. Poelker, A. A. Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

CsK₂Sb photocathodes with quantum efficiency on the order of 10% at 532 nm, and lifetime greater than 90 days at low voltage, were successfully manufactured via co-deposition of alkali species emanating from an effusion source. Photocathodes were characterized as a function of antimony layer thickness and alkali consumption, inside a vacuum chamber that was initially baked, but frequently vented without re-baking. Photocathode lifetime measured at low voltage is correlated with the antimony layer thickness. Photocathodes manufactured with comparatively thick antimony layers exhibited the best lifetime. We speculate that the antimony layer serves as a reservoir, or sponge, for …

Adaptive Double Chain Quantum Genetic Algorithm For Constrained Optimization Problems, Kong Haipeng, Li Ni, Yuzhong Shen

Computational Modeling & Simulation Engineering Faculty Publications

Optimization problems are often highly constrained and evolutionary algorithms (EAs) are effective methods to tackle this kind of problems. To further improve search efficiency and convergence rate of EAs, this paper presents an adaptive double chain quantum genetic algorithm (ADCQGA) for solving constrained optimization problems. ADCQGA makes use of double-individuals to represent solutions that are classified as feasible and infeasible solutions. Fitness (or evaluation) functions are defined for both types of solutions. Based on the fitness function, three types of step evolution (SE) are defined and utilized for judging evolutionary individuals. An adaptive rotation is proposed and used to facilitate …

The Space Infrastructure Vulnerability Cadastre: Orbital Debris Critical Loads, Adrian V. Gheorghe, Daniel E. Yuchnovicz

Engineering Management & Systems Engineering Faculty Publications

Orbital debris from over 50 years of human activity in space are threatening the operations of existing and future satellites and the sustainability of high-value satellite orbits. This technical memorandum calls for the development of a cadastre that depicts the vulnerability of critical satellite orbits to accumulating orbital debris. A space infrastructure vulnerability cadastre could serve as a governance tool for use by developers and operators of critical space infrastructures to better communicate the current and future vulnerability of high-value orbits to the accumulation of orbital debris. These high-value orbits are susceptible to "loss" for decades or centuries if generation …

Uncertainty Estimates And Prediction Interval Development For Internal Strain Gage Balance Calibration Systems, Kenneth G. Toro

Mechanical & Aerospace Engineering Theses & Dissertations

Currently, there is a lack of the use of mathematically rigorous methods to evaluate the performance of multivariate force measurement systems. The specific problem addressed in the research stems from the practical issues faced by test engineers when wind tunnel models with internal strain gage balances are readied for test. Check loads are applied and the question that needs to be answered is whether or not the balance is reading within acceptable limits. These systems tend to be difficult to characterize uncertainty, primarily due to their multivariate nature, but also due to the desire for an estimate on the explanatory …

Use Of Single Stage Model Rockets To Teach Some Engineering Principles And Practices To First Year Engineering And Engineering Technology Students, Hüseyin Sarper, Linda Vahala

Electrical & Computer Engineering Faculty Publications

Model rocketry has been called miniature astronautics; a technology in miniature, a hobby, a sport, a technological recreation, an educational tool, and it is all of these things. This paper will describe student projects using model rockets and engines to learn engineering principles for launching rockets and determining the apogee. Model rocketry is a powerful tool for instructors who wish to incorporate science, technology, engineering, and mathematics into a fun, engaging, and challenging activity for first year engineering students. The apogee can be determined using four distinct methods: trigonometry using hand held angle measuring tools, onboard altimeter devices, analytical calculations …

Laminar Deflagrated Flame Interaction With A Fluidic Jet Flow For Deflagration-To-Detonation Flame Acceleration, Joseph P. Mcgarry

Mechanical & Aerospace Engineering Theses & Dissertations

The concept of the Pulse Detonation Engine (PDE) has been of interest for centuries. The issue was originally studied to understand flame propagation in mine shafts after explosions due to methane buildup. The flames would travel down the shafts, transitioning to turbulent flames due to the roughness of the shaft walls, and accelerate to detonation, delivering powerful, destructive forces. The potential for efficient energy production was noticed, and the theory behind flame propagation was later applied to developing propulsion systems. Recently, researchers have begun to understand the full potential of PDEs to efficiently produce an immense amount of thrust due …

Methods For Initial Relative Orbit Determination Using Angles-Only Observations, Ethan M. Pratt

Mechanical & Aerospace Engineering Theses & Dissertations

An approximate second order nonlinear closed-form solution for three-dimensional relative motion assuming Keplerian dynamics and a circular reference track are applied to the relative initial orbit determination problem. A series of azimuth-elevation angular measurements locating a deputy satellite with respect to a chief satellite are coupled through the observation geometry with the nonlinear dynamics model for the relative motion in terms of linear, quadratic, and bilinear combinations of the deputy initial conditions and chief orbital elements. The resulting set of nonlinear measurement equations are analyzed, formulated, and solved using three separate non-iterative methods. By using a nonlinear dynamics model with …

Design Improvements For A Reusable Horizontal Takeoff And Landing Aircraft For Use On Mars, Brian A. Skoog

Mechanical & Aerospace Engineering Theses & Dissertations

Unmanned aerial vehicle capabilities are required for expanded exploration of the Martian surface. These vehicles can not only gather data at an altitude otherwise unreachable by rovers and satellites, but also deliver small payloads and retrieve samples from distant off-site locations. Previous multi-purpose reusable Mars aircraft studies have been unable to achieve the flight ranges required for expanded exploration. This study has focused on increasing the range of prototype aircraft designs. Assuming that large precision cargo delivery capabilities have been developed and much of the infrastructure associated with a fixed Mars base is in place, the challenge of linking dispersed …

The Study Of Electrostatic And Magnetostatic Active Space Radiation Shielding For Deep Space Missions, Leroy A. Fung

Electrical & Computer Engineering Theses & Dissertations

A goal of the National Aeronautics and Space Administration (NASA) has been to develop technologies that will enable deep space explorations. Such missions include a prolonged stay on the Moon and the ability to sustain a long duration of travel time to Mars and beyond. Long-term human exposures to radiation are a crucial concern. Recent research has taken focus on active and passive shielding methods as a way of eliminating the hazard posed by radiation particles. Passive shielding involves the use of materials that has the ability to withstand radiation particles and reduce the dose by stopping or slowing the …

Time-Based Collision Risk Modeling For Air Traffic Management, Alan E. Bell

Engineering Management & Systems Engineering Theses & Dissertations

Since the emergence of commercial aviation in the early part of last century, economic forces have driven a steadily increasing demand for air transportation. Increasing density of aircraft operating in a finite volume of airspace is accompanied by a corresponding increase in the risk of collision, and in response to a growing number of incidents and accidents involving collisions between aircraft, governments worldwide have developed air traffic control systems and procedures to mitigate this risk. The objective of any collision risk management system is to project conflicts and provide operators with sufficient opportunity to recognize potential collisions and take necessary …

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 …

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 …

The Relationship Among Hfacs Levels And Analysis Of Human Factors In Unmanned And Manned Air Vehicles, Veysel Yesilbas

Engineering Management & Systems Engineering Theses & Dissertations

This dissertation analyzes the structural relationships among the Human Factors Accident Classification System levels for unmanned air vehicle and manned air vehicle accidents and the common relationships between unmanned air vehicle and manned air vehicle accident causes. The study acquired DOD HFACS accident classification data from 347 United States Air Force Class A accident reports for the years between 2000 and 2013.

The dissertation utilized a set of analysis that is considered to contribute substantially to the respective domain of the study. The correlations found among categorical levels were applied to HFACS taxonomy based on the Reason Model via path …

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 …

Relative Motion Guidance, Navigation And Control For Autonomous Orbital Rendezvous, Mohamed Okasha, Brett Newman

Mechanical & Aerospace Engineering Faculty Publications

In this paper, the dynamics of the relative motion problem in a perturbed orbital environment are exploited based on Gauss’ variational equations. The relative coordinate frame (Hill frame) is studied to describe the relative motion. A linear high fidelity model is developed to describe the relative motion. This model takes into account primary gravitational and atmospheric drag perturbations. In addition, this model is used in the design of a control, guidance, and navigation system of a chaser vehicle to approach towards and to depart from a target vehicle in proximity operations. Relative navigation uses an extended Kalman flter based on …

Intelligent Sensing Based On Low Cost Unmanned Aerial Vehicles (Uav) For Bridge Condition Assessment, Theodore Teates, Austin Boyd, Chung-Hao Chen

Electrical & Computer Engineering Faculty Publications

The eventual completion of this project envisions the use of an Unmanned Aerial Vehicle (UAV) to inspect bridge infrastructure. This project may also be expanded to encompass general object detection and inspection in order to unburden this technology so that it may reach its fullest potential. The project requires research and development in three distinct areas of image processing, control structures, and integration of systems. Initial undergraduate research sets the base knowledge for the overall project, explores the areas of concentration that are desired to expand upon in the future project, and provides a base UAV model that new researchers …

Identifiability Of Additive Actuator And Sensor Faults By State Augmentation, Suresh M. Joshi, Oscar R. Gonzalez, Jason M. Upchurch

Electrical & Computer Engineering Faculty Publications

A class of FDI (fault detection and identification) methods for bias-type actuator and sensor faults was explored from the point of view of fault identifiability. The methods use banks of Kalman-Bucy filters (KBFs) to detect faults, determine the fault pattern, and estimate the fault values. A complete characterization of conditions for identifiability of bias-type actuator faults, sensor faults, and simultaneous actuator and sensor faults was presented. It was shown that FDI of simultaneous actuator and sensor faults is not possible using these methods when all sensors have unknown biases. The fault identifiability conditions were demonstrated via numerical examples. The analytical …

Role Of Surface Chemistry In Nanoscale Electrokinetic Transport, Secuk Atalay

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation work presents the efforts to study the electrofluidics phenomena, with a focus on surface charge properties in nanoscale systems with the potential applications in imaging, energy conversion, ultrafiltration, DNA analysis/sequencing, DNA and protein transport, drug delivery, biological/chemical agent detection and micro/nano chip sensors.

Since the ion or molecular or particle transport and also liquid confinement in nano-structures are strongly dominated by the surface charge properties, in regards of the fundamental understanding of electrofluidics at nanoscale, we have used surface charge chemistry properties based on 2-pK charging mechanism. Using this mechanism, we theoretically and analytically showed the surface charge …

New Test Capabilities For The 0.3-Meter Transonic Cryogenic Wind Tunnel, Ben D. Phillips

Mechanical & Aerospace Engineering Theses & Dissertations

The small-scale, cryogenic, and high pressure characteristics of the 0.3-Meter Transonic Cryogenic Tunnel provide a unique, high-Reynolds number research capability. However, the facility is currently restricted by its reliance on a two-dimensional adaptive wall test section coupled with an inadequate facility control system. Access to the test section is restricted, the walls require excess time for convergence and are mechanically constrained by a wall jacking system that degrades under cyclic cryogenic operations, and the tunnel requires excessive time to reach the set point, particularly at low Mach numbers. As a result, productivity and operational efficiency are limited, leading to expensive …