Engineering Commons^™

The Symposium Proceedings Of The 1998 Air Transport Research Group (Atrg), Volume 2, Aisling Reynolds-Feighan, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 98-4

The Symposium Proceedings Of The 1998 Air Transport Research Group (Atrg), Volume 1, Aisling Reynolds-Feighan, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 98-3

The Symposium Proceedings Of The 1998 Air Transport Research Group (Atrg), Volume 3, Aisling Reynolds-Feighan, Brent D. Bowen, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 98-5

Emerald: Where We Are And Where We Are Going, Freddy Pranajaya, Bryan Palmintier

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Freddy Pranajaya and Bryan Palmintier titled "EMERALD: Where We Are and Where We Are Going" from October 29, 1998.

Fatigue Life Prediction Of Edge-Welded Metal Bellows Using Neural Networks And Multiple Linear Regression, David L.W. Ballard

Master's Theses - Daytona Beach

Edge-welded metal bellows present an ongoing challenge: the prediction of an accurate cycle life. Current methods rely on physical leak detection to determine a bellow's cycle life to failure. It is known, however, that crack initiation begins many cycles before a leak path is present. Bellows manufacturers require a method for detection of fatigue cracks when they initiate but before they result in leak rates large enough to contaminate a process. Acoustic emission (AE) testing is one method which can meet this need and is a proven, reliable technique for detecting crack initiation and monitoring fatigue crack growth.

Four sets …

A Comparison Of Pseudo 3-Dimensional Collision Avoidance-Predictor Displays For Free Flight, Steve Kertesz Jr.

Master's Theses - Daytona Beach

This study was the second of two studies to evaluate the use of a pseudo three-dimensional display to present information about future possible conflicts. The purpose of this study was to evaluate variations of a cockpit screen display that transfers relevant data to the pilot in a manner which is easy to interpret and to facilitate the possible stressful situations that may be encountered due to the proposed free flight environment. In the first phase, three display concepts, using three different screen designs were compared. In this study, three different displays, all of which used using the space-time predictor concept …

Skin-Stiffener Separation In Buckled Composite Plates And Shallow Shells, Mark Edward Robeson

Mechanical & Aerospace Engineering Theses & Dissertations

The development of an approximate analysis for predicting stresses in the skin-stiffener interface region of composite plates and shallow shells is presented. The analysis determines interlaminar normal stress and transverse shear stresses in the direction of the stiffener axial coordinate and the direction of the inplane coordinate perpendicular to the stiffener axis. The analysis accounts for skin-stiffener interfaces with nonzero thickness and for curvature in the skin and stiffener. The interlaminar normal stress and transverse shear stresses at the interface are applied to the lower face of the skin and the upper face of the stiffener flange as unknown functions, …

Saturation Control For Reduction Of Rotor Blade Lag Vibration, Sayam Saguanrum

Mechanical & Aerospace Engineering Theses & Dissertations

Within the context of this research, the performance of saturation control for reduction in the vibratory lag motion of helicopter rotor blades is investigated. The single-degree-of-freedom plant, which consists of a spring and damper attached to the rotor blade, is perturbed by an aerodynamic force, and produces the unwanted vibration. To restrict this vibration, the second-order controller is provided to couple with the blade system. It works adaptively, when the system is excited and the controller frequency is set at half of the blade lag frequency in accordance with the relationship of both natural frequencies. The nonlinear terms from the …

Emerald: The Next Squirt, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "EMERALD: The Next Squirt" from October of 1998.

Design Optimization Of Magnetic Bearings And Magnetic Suspension Systems, V. Dale Bloodgood Jr.

Mechanical & Aerospace Engineering Theses & Dissertations

Magnetic suspension systems were first demonstrated as practical by Holmes and Beams in the 1930's. Since then, numerous academic researchers have worked with various types of these systems. Commercial applications have largely been limited to magnetic bearings for rotating machinery. Other applications that have held considerable promise include wind tunnel model suspensions, space payload pointing and vibration isolation systems, satellite momentum storage and control devices and electromagnetic launch systems. However, none of these have progressed significantly beyond the prototype stage. Maglev trains have not reached serious commercial service but are being aggressively developed in Germany and Japan.

Design methods for …

Cooling Saber With A Miniature Pulse Tube Refrigerator, Scott M. Jensen, J. Clair Batty, William A. Roettker, Matthew J. Felt

Space Dynamics Laboratory Publications

Utah State University/Space Dynamics Laboratory (USU/SDL), teaming with NASA Langley Research Center, is currently building the Sounding of the Atmosphere using Broadband Emission Radiometry(SABER) instrument. Stringent mass and power constraints, together with a greater than two year mission life, led to the selection of a TRW miniature pulse tube refrigerator to cool SABER's infrared detectors to the required temperature of 75 K.

This paper provides an overview of the SABER thermal management plan and the challenges encountered in matching the refrigerator characteristics with instrument performance requirements under the broadly variant space environments expected for this mission. Innovative technologies were developed …

Orion: A Microsatellite Testbed For Formation Flying, Robert J. Twiggs, Jonathan How

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs and Jonathan How titled "ORION: A Microsatellite Testbed for Formation Flying" from September 3, 1998.

Navier-Stokes Analysis Of Lift-Enhancing Tabs On Multi-Element Airfoils, Paul G. Carrannanto, Bruce L. Storms, James C. Ross, Russell M. Cummings

Aerospace Engineering

The flow over multi-element airfoils with flat-plate lift-enhancing tabs was numerically investigated. Tabs ranging in height from 0.25 to 1.25% of the reference airfoil chord were studied near the trailing edge of the main element. The two-dimensional numerical simulation employed an incompressible Navier–Stokes solver using a structured, embedded grid topology. The effects of various tabs were studied at a constant Reynolds number on a two-element airfoil with a slotted flap. Both computed and measured results indicated that a tab in the main-element cove improved the maximum lift and lift-to-drag ratio relative to the baseline airfoil without a tab. Computed streamlines …

Electro-Mechanical Fatigue Behavior Of A Quasi-Isotropic Laminate With An Embedded Piezoelectric Actuator, Tse Lin Hsu

Theses and Dissertations

This study primarily investigated the electro-mechanical fatigue behavior of the embedded piezoelectric actuators in graphite/epoxy laminate with a lay-up of 0 | ± 45 | 90s. A secondary focus was the investigation of the mechanical fatigue effects of the 0 | 0 | ± 45 | 0 | 0 | 90s laminate with embedded PZT under tensile loading. All the fatigue tests were conducted with a triangular loading waveform which had a frequency of 10 Hz and with R=0. 1. In the electro-mechanical testing, the embedded actuator was excited by a -10 V to -100 V or a 10 V …

A Small/Micro-/Pico-Satellite Programfor Investigating Thunderstorm-Related Atmospheric Phenomena, Christopher Kitts

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Christopher Kitts titled "A Small/Micro-/Pico-Satellite Programfor Investigating Thunderstorm-Related Atmospheric Phenomena" from Septemebr of 1998.

Design Methodology For Low Speed High Altitude Long Endurance Unmanned Aerial Vehicles, Aaron Altman

Mechanical and Aerospace Engineering Faculty Publications

High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV's) are increasingly being considered to perform a wide range of tasks. Recent years have seen greater value of UAV's in the military reconnaissance arena, first in the Persian Gulf war, with the use of small UAV's, and more recently over Bosnia with medium sized UAV's.

The NASA ERAST program uses HALE UAV's for environmental sensing and monitoring. The military has investigated using HALE UAV's for Theater Ballistic Missile defense, as well as general battlefield reconnaissance. Proposals have been made to use HALE UAV's for communications relay, long term surveillance (with a …

In-Flight Fatigue Crack Monitoring Of An Aircraft Engine Cowling, Samuel Gordon Vaughn Iii

Master's Theses - Daytona Beach

This research investigates the feasibility of implementing an in-flight fatigue crack monitoring system in an airplane to identify fatigue crack growth. An acoustic emission data acquisition system coupled with a Kohonen self organizing map neural network were used to perform the analysis.

Fatigue cracking was responsible for ripping the top of a fuselage off an Aloha Airlines Boeing 737-200 as it carried passengers over the Pacific Ocean, killing some aboard. This tragedy is perhaps a precursor of problems to come, as our nation’s aircraft age. These planes experience fatigue as they perform their daily routine of ferrying passengers from location …

Chemical Kinetics And Heat Transfer In Polyurethane Foam And Resin Composites, Yumi Morisaki

Master's Theses - Daytona Beach

A development of the composite materials parts require knowledge of the theoretical model that describes the physics, the chemical kinetics, and the heat-transfer properties of the materials.

For this work, the chemical kinetics of the polyurethane foam and the fiberglass-reinforced resin is investigated individually. An adiabatic method, which is commonly used by many investigators, is used for the polyurethane foam, while an isothermal degree and the rate of cure relationship is applied for the resin. A heat transfer effect during the curing process of both polyurethane foam and the resin is also investigated. A common approximate method for the heat-conduction …

Nonlinear Stability And Control Of Three-Dimensional Boundary Layers, Erik Janke

Mechanical & Aerospace Engineering Theses & Dissertations

The linear and nonlinear evolution of steady and traveling disturbances in three-dimensional incompressible boundary layer flows is studied using Parabolized Stability Equations (PSE). Extensive primary stability analyses for the model problems of Swept Hiemenz flow and the DLR Transition experiment on a swept flat plate are performed first. Second, and building upon these results, detailed secondary instability studies based on both the classical Floquet Theory and a novel approach that uses the nonlinear PSE are conducted. The investigations reveal a connection of unstable secondary eigenvalues to both the linear eigenvalue spectrum of the undisturbed mean flow and the continuous spectrum, …

Vortex Wake And Exhaust Plume Interaction, Including Ground Effect, Ihab Gaber Adam

Mechanical & Aerospace Engineering Theses & Dissertations

Computational modeling and studies of the near-field wake-vortex turbulent flows, far-field turbulent wake-vortex/exhaust-plume interaction for subsonic and High Speed Civil Transport (HSCT) airplane, and wake-vortex/exhaust-plume interaction with the ground are carried out. The three-dimensional, compressible Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The turbulence models of Baldwin and Lomax, one-equation model of Spalart and Allmaras and two-equation shear stress transport model of Menter are implemented with the RANS solver for turbulent-flow modeling.

For the near-field study, computations are carried out on a fine grid for a rectangular wing with a NACA-0012 airfoil section and …

Development And Experimental Validation Of An Underwater Manipulator Hydrodynamic Model, Timothy W. Mclain, Stephen M. Rock

Faculty Publications

Hydrodynamic forces can be large and hence have a significant effect on the dynamic performance of underwater manipulation systems. this paper investigates these forces for a cylindrical single-link arm undergoing motions that are characteristics of a robotic manipulator. Based on flow visualization, theoretical analysis, and experimental measurements, a new model is developed that describes these forces. This model differs from previous models in that the drag and added-mass coefficients are state-dependent functions that depend on the distance traveled by the arm. A factor of four improvement in accuracy is demonstrated over standard constant-coefficient models.

Approximate Analytical Relationships For Linear Optimal Aeroelastic Flight Control Laws, Ayman Hamdy Kassem

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation introduces new methods to uncover functional relationships between design parameters of a contemporary control design technique and the resulting closed-loop properties. Three new methods are developed for generating such relationships through analytical expressions: the Direct Eigen-Based Technique, the Order of Magnitude Technique, and the Cost Function Imbedding Technique. Efforts concentrated on the linear-quadratic state-feedback control-design technique applied to an aeroelastic flight control task. For this specific application, simple and accurate analytical expressions for the closed-loop eigenvalues and zeros in terms of basic parameters such as stability and control derivatives, structural vibration damping and natural frequency, and cost function …

Wind Tunnel Testing For Drag Reduction Of An Aircraft Laser Turret, Christopher H. Snyder

Theses and Dissertations

This study investigated the use of aft-mounted fairings and splitter plates to reduce the drag of a half-scale aircraft laser turret. Forces, moments, and pressure distributions were measured in the AFIT 1.5-m (5-ft) wind tunnel at Reynolds numbers between 3x10⁵ and 9x10⁵ based on the turret diameter. Oil traces indicated the nature of the flow near the surface of the unmodified turret and the surrounding area. Tufts placed on the turret, fairings, and splitter plates showed changes in separation regions when configurations were changed. The flow around the turret was characterized by dominant vortices shedding from the top …

Numerical Investigation Of An Airfoil With A Gurney Flap, Cory S. Jang, James C. Ross, Russell M. Cummings

Aerospace Engineering

A two-dimensional numerical investigation was performed to determine the effect of a Gurney flap on a NACA 4412 airfoil. A Gurney flap is a flat plate on the order of 1–3% of the airfoil chord in length, oriented perpendicular to the chord line and located on the airfoil windward side at the trailing edge. The flowfield around the airfoil was numerically predicted using INS2D, an incompressible Navier–Stokes solver, and the one-equation turbulence model of Baldwin and Barth. Gurney flap sizes of 0.5%, 1.0%, 1.25%, 1.5%, 2.0%, and 3.0% of the airfoil chord were studied. Computational results were compared with available …

Singularity Avoidance Strategies For Satellite Mounted Manipulators Using Attitude Control, Nathan A. Titus

Theses and Dissertations

Control concepts for satellite mounted manipulators (SMM) are examined. The primary focus is on base actuated concepts, which eliminate singularity problems associated with free floating SMMs. A new form of the equations of motion for an n-link SMM is developed using a quasi coordinate form of Lagrange's Equation. Alternative free floating SMM designs are presented which eliminate dynamic singularities, but still experience difficulties due to the unactuated base. A new generic SMM controller is developed as a framework for various control concepts with and without base actuation. Momentum constrained Jacobians are shown to produce better SMM tracking than fixed base …

The Effect Of Nonvertical Shear On Turbulence In A Stably Stratified Medium, Frank G. Jacobitz, Sutanu Sarkar

School of Engineering: Faculty Scholarship

Direct numerical simulations were performed in order to investigate the evolution of turbulence in a stably stratified fluid forced by nonvertical shear. Past research has been focused on vertical shear flow, and the present work is the first systematic study with vertical and horizontal components of shear. The primary objective of this work was to study the effects of a variation of the angle θ between the direction of stratification and the gradient of the mean streamwise velocity from θ=0, corresponding to the well-studied case of purely vertical shear, to θ=π/2,corresponding to purely horizontal shear. It was observed that the …

Three-Bladed Propeller Design For The Reduction Of General Aviation Radiated Noise Characteristics, Ronald W. Finn

Master's Theses - Daytona Beach

The purpose of this study was to design a quiet 3-Bladed propeller for general aviation aircraft. A combination of design technique and analytical predictions using the NASA Aircraft Noise Prediction Program - Propeller Analysis System (ANOPP-PAS) was used to achieve this goal. The propellers were designed for an engine power of 200 hp, a rotational speed of 2,400 RPM and a free-stream speed of 160 kts. A straight 76 in. diameter 2-bladed propeller was designed as a reference for the 64 in. diameter 3-bladed propeller. The ANOPP-PAS computer code was used for predicting the aerodynamic performance and radiated noise characteristics …

Research And Design Of A High L/D Aircraft, Blake Ashby, Gregory Nielson

Undergraduate Honors Capstone Projects

This senior design team, consisting of Blake Ashby, Shelly Barlow, Greg Nielson, Deryl Snyder, and Chris Wright, designed, built, and flew an airplane that met the requirements of the Cessna/ONR Student Design/Build/Fly Competition sponsored by AIAA. This radio-controlled airplane was designed to fly the most laps around a course in seven minutes using only 2.5 pounds of NiCad batteries. A total of three senior design teams from Utah State University designed separate airplanes. Though all three teams designed, built, and tested complete airplanes, each emphasized a different aspect of a successful entry. This team emphasized theoretical and numerical analysis in …

Hydrogen On-Orbit Storage And Supply: A Spacecraft Bus Design, Roy Gladden

Undergraduate Honors Capstone Projects

Spacecraft designers have two options when developing spacecraft for a particular mission. The bus, which is the primary structure and support system for the spacecraft, can be designed from an existing layout or a new design may be developed to meet specific mission needs. In recent years, the trend in small satellite design has been to employ a previously designed spacecraft bus in order to reduce cost and development time. However, these structures sometimes provide greater capability than is required for smaller, simple missions at a higher price. Therefore, it may be preferable to custom design a bus to meet …

Design Of The Guidance, Navigation, And Control Subsystem For The Proposed Firebird Spacecraft, Erin Robinson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Firebird spacecraft is a space mission to gather scientific and physical data on the effects of atmospheric deceleration, commonly called aerobraking. The objective of the Firebird mission is to measure specified aerobraking parameters over a range of reentry velocities to provide a database sufficient to construct and validate mathematical models of such aerobraking mission maneuvers. The Firebird senior design team designed the first spacecraft in the mission series to look at aerobraking at an altitude of 160 kilometers above the surface of the Earth. This paper looks specifically at the design of the subsystem that provides the guidance, navigation, …