Aerospace Engineering Commons^™

Designed Reduction Of Radiated Noise Characteristics From Two-Bladed General Aviation Propellers, Chandra K. Stich

Master's Theses - Daytona Beach

In recent years increased public awareness has made the reduction of environmental noise pollution a top priority for the aviation industry. Utilizing current technology, this study examines the reduction of noise generated by two bladed general aviation propellers, through design. The Aircraft Noise Prediction Program - Propeller Analysis System (ANOPP-PAS) is used to predict the noise and performance characteristics for an industry typical reference propeller as well as for the final quiet and efficient design.

This investigation is based on the use of a 200 hp engine rotating a 76 inch propeller. Typically, such a propeller would be rotated at …

Optimization Of A Vortex Generator Configuration For A 1/4-Scale Piper Cherokee Wing, Kerri A. Raykowski

Master's Theses - Daytona Beach

Several sets of wind tunnel tests were performed to determine an optimum vortex generator configuration for a 1/4-scale model of the Piper Cherokee wing. Several variables were incorporated into this experiment in an effort to determine their influence on vortex generator performance enhancement (or degradation). Vane type vortex generators were used with 3 different leading edge sweeps: zero (rectangular planform), 20, and 45 degrees. Three different vortex generator heights were tested (0.05”, 0.1”, and 0.2”) to find the optimal vortex generator height relative to the local boundary layer thickness. The vortex generator angle of incidence relative to the freestream was …

Reduction Of Helmet Buffeting In Open Cockpit, Single Seat Race Cars, Mark Vallon

Master's Theses - Daytona Beach

At speeds approaching 240 mph, drivers of open cockpit race cars frequently experience large aerodynamic forces which act on the helmet. These forces, specifically the aerodynamic buffeting of the helmet, reach levels which are very fatiguing and distracting to the driver, and are therefore unacceptable. Little investigation has been done in this area, because normal wind tunnel tests do not isolate the helmet from the rest of the car. During this project, measurements of aerodynamic forces acting on a helmet inside a race car cockpit were made to determine the cause of the buffeting, and to determine possible improvements.

Tests …

Effect Of Multiple Range Rings Vs. A Single Range Ring On Pilot Perception Of Vertical Separation On A Cockpit Display Of Traffic Information, Daniel B. Rizzardi

Master's Theses - Daytona Beach

The purpose of this study was to determine the effectiveness of both a two and four mile range ring versus a single three mile range ring on pilot's perception of future vertical separation as viewed on a cockpit display of traffic information. The subjects consisted of 30 volunteer pilots from Embry-Riddle Aeronautical University and the surrounding Daytona Beach, Florida area.

The simulation of a cockpit display of traffic information was generated using SuperCard® Version 1.6 software and a Macintosh IIx® personal computer. Eighty unique scenarios were monitored by the pilots in which they determined, as early as possible, what the …

Classification Of In-Flight Fatigue Cracks In Aircraft Structures Using Acoustic Emission And Neural Networks, Christopher Lee Rovik

Master's Theses - Daytona Beach

The research encompassed within this paper deals with the analysis and classification of fatigue cracks in aircraft structures. The particular structure that was examined was the vertical tail section of a Cessna T-303 Crusader aircraft. The analysis was performed using the nondestructive evaluation technique known as acoustic emission (AE), as well as the artificial intelligence of neural networks. Data were taken in a controlled laboratory environment as well as in a flying testbed aboard the aircraft.

The first part of the research involved the analysis of a typical aircraft structure in a controlled laboratory environment. This support structure was fabricated …

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 …

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 …

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 …

A Study Of The Volume Of Fluid Method For Moving Boundary Problems, Marianne Francois

Master's Theses - Daytona Beach

Moving boundary problems are often encountered in engineering and science. One of the methods to solve such problems numerically is the volume of fluid (VOF) method. The VOF method uses an additional field variable/to track the interface using the Eulerian fixed grid. In this work, the VOF method is combined with the Continuum surface force model. The governing flow equations for Newtonian fluids in incompressible flow in two dimensions are solved using the pressure-based algorithm. A linear interface reconstruction algorithm is developed and improved by interpolations. In order to validate the code, the problem of the convection of a two-fluid …

A Model For Calculating Acoustic Gravity Wave Energy And Momentum Flux In The Mesosphere From Oh Airglow, Gary R. Swenson, Alan Z. Liu

Physical Sciences - Daytona Beach

Acoustic gravity and tidal waves propagating in the mesosphere/lower thermosphere (80-110 km) perturb the airglow layer intensities. The OH airglow has recently been modeled to determine the relationship between the relative perturbed atmospheric density and temperature (ρ’/ ρ, T’/T) to the OH intensity ( I’_OH/I_OH ) at the OH emission altitudes [Swenson and Gardner, 1997]. A model is presented here which relates wave perturbed OH airglow to the wave energy and momentum flux as they propagate through the emission layer. The model is dependent on the wave horizontal and vertical wavelengths (or phase speed as related through …

An Analysis Of Current Interruption Upon The Behavior Of Light Bulb Filament During Initial Aircraft Impact In Support Of Aircraft Accident Investigations, Daniel J. Larow

Master's Theses - Daytona Beach

The purpose of analyzing annunciator panels, warning, and indicator lamps is to determine the state ("on" or "off") of each light bulb immediately before the impact. Determination of the state of lamps may help investigators determine the probable cause of the accident. The information gained from the lamp's filaments may be used to infer the aircraft's operational parameters prior to impact and to a qualitative appreciation of the severity of the accident. It is generally agreed that upon impact the filament of an unlit bulb will fracture without deformation and the filament of a lit bulb will display plastic deformation …

Trends. The Cassini Mission To Saturn: Plutonium As Propaganda, Ibpp Editor

International Bulletin of Political Psychology

The author discusses the plutonium-carrying Cassini mission to Saturn.

Application Of Active Noise Control To Reduce Cabin Noise In Single Engine General Aviation Aircraft, Jeroen Hendrik Dolmans

Master's Theses - Daytona Beach

The application of active noise control to reduce cabin noise in single engine, general aviation aircraft is investigated through the use of the 'filtered x' least mean square algorithm and a simple acoustic feedforward method to generate a reference signal is tested. The system is designed to utilize one reference signal and up to two feedback signals and two audio speakers. The feedforward system consists of a microphone placed in close proximity to the front windshield and isolated from the cabin noise. Cabin noise and reference signals are recorded during flight in a Cessna 172 Skyhawk, a Piper Cherokee 140 …

Aerospace And Foreign Policy, Ibpp Editor

International Bulletin of Political Psychology

The author discusses developing and implementing foreign policy towards the Peoples Republic of China regarding the market for aircraft and aerospace technology.

Development And Initial Evaluation Of An Acoustic Apparatus Used For Testing Of Farfield Noise Emitted By A Propeller In A Short Duct, R. Duane Oleson

Master's Theses - Daytona Beach

The purpose of this thesis was to design, construct and evaluate an apparatus which was used for testing of acoustic emissions by a propeller in a short duct. An apparatus was designed based on a combination of acoustic principles and a desire to be able apply the knowledge gained to a practical application such as an ultralight aircraft in an effort to reduce the overall noise levels emitted. The apparatus consisted of a 35 horsepower ultralight engine, a four bladed ultralight propeller, and a duct constructed of a foam core covered with fiberglass. Initial evaluations compared noise levels from the …

The Design And Experimental Optimization Of A Wingtip Vortex Turbine For General Aviation Use, Andrew Roberts

Master's Theses - Daytona Beach

A wingtip vortex turbine (WVT) is an induced drag reduction device that straightens the vortex flow (reducing induced drag and wake turbulence) and also produces a thrust force component. The WVT also has the advantage of extracting the rotational energy of the vortex to turn a generator, which could be used to power onboard applications during normal or emergency flight operations. A 1/4-scale model of a thrust-producing WVT has been designed and tested in a wind tunnel for optimal drag reduction and power generation for general aviation aircraft — specifically, a Piper Cherokee — in both a stationary and a …

Cooperative Power-Limited Optimal Rendezvous Between Many Spacecraft, Virginie Guerre

Master's Theses - Daytona Beach

The minimum fuel rendezvous problem between several power-limited low-thrust spacecraft neighboring either a circular or an elliptic orbit is investigated. Both cooperative and non cooperative maneuvers are studied. The maximum principle of Pontryagin is applied to the optimal control rendezvous problem of several spacecraft. The gravitational field models investigated are the Clohessy-Wiltshire field and the inverse-square gravity field. Numerical solutions using a shooting method and the finite difference method are used in order to determine the trajectories of the spacecraft. Unlike previous investigations, this work is not restricted to a rendezvous of two spacecraft around a circular orbit, but a …

An Investigation Of The Hydrodynamic Effects Of Enteromorpha Clathrata Fouling On Hydrofoils, Brian J. Collino

Master's Theses - Daytona Beach

The purpose of this investigation was to determine the effects of biological fouling on hydrofoils. NACA 4412 and 4415 hydrofoil models with 6 inch chord and 8 inch span were used in this study. A water tunnel facility was designed and constructed to perform the tests, and the results were verified using computational fluid dynamic modeling. The CFD software package Fluent was used to create a two dimensional model of the water tunnel test section and hydrofoil. The model was meshed using a Laplacian grid smoothing technique that forced the structured grid lines to follow the same approximate contour as …

Burst Pressure Prediction Of Filament Wound Composite Pressure Vessels Using Acoustic Emission, Marcus Elwood Fisher

Master's Theses - Daytona Beach

This research demonstrates how acoustic emission (AE) data from flaw growth activity can be used to predict burst pressures in filament wound composite pressure vessels. Acoustic emission data were taken during hydroproof testing for a set of eleven ASTM standard 5.75 inch diameter fiberglass/epoxy bottles. Amplitude distributions were created using only the AE data up to 25% of the expected burst pressure to simulate low level proof loadings (thereby avoiding damage to the bottles). The bottles were tested at three different temperatures -- 32°F, 70°F, and 110°F - and hydroproofed using two different pressurization schemes and two transducer configurations. Moreover, …

Detection Of Fatigue Crack Growth In A Simulated Aircraft Fuselage, Michael Lee Marsden

Master's Theses - Daytona Beach

Acoustic emission (AE) nondestructive testing can detect fatigue cracks as they occur in complex structures. One use for AE has been in-flight detection of fatigue cracks in aircraft. The KC-135 aircraft were successfully monitored as early as 1979. The main problem with this and subsequent applications was an unfavorable signal to noise ratio, the key being to separate the small amplitude crack signals from the large amplitude ambient noise. This was accomplished here through the use of a Kohonen self-organizing map (SOM) neural network.

In order to simulate a fuselage undergoing fatigue, a pressure vessel was constructed from a 0.040 …

A Methodology For The Prediction Of The Empennage In-Flight Loads Of A General Aviation Aircraft Using Backpropagation Neural Networks, Maciej Marciniak

Master's Theses - Daytona Beach

Backpropagation neural networks have been used to predict strain resulting from the maneuver in-flight loads in the empennage structure of a Cessna 172P. The purpose of this research was to develop a methodology for the prediction of strain in the tail section of a general aviation aircraft and to determine the minimum set of sensors necessary to adequately train the neural networks. Linear accelerometer, angular accelerometer, rate gyro, and strain gage signals were collected in flight using DAQBook portable data acquisition system for dutch-roll, roll, sideslip left, sideslip right, stabilized g turn left, stabilized g turn right, and push-pull maneuvers …

Behavior Of A Hypersonic Nozzle Using Finite Rate Chemistry, Guillermo Jose Hernandez Paul

Master's Theses - Daytona Beach

This study is concerned with the investigation of the behavior of a hypersonic nozzle with finite rate chemistry. First, equations describing steady one dimensional flow through a nozzle are presented. Solution methodologies for frozen, equilibrium and detailed chemistry flow are then discussed. A hydrogen-air chemical reaction mechanism, which is made up of fourteen different chemical species, and forty nine chemical reactions is used in this investigation for obtaining detailed chemistry flow solutions. The investigation also performs a sensitivity analysis on the reaction mechanism. Results from this may be used to eliminate a particular reaction from the chemical reaction mechanism that …

An Investigation Of The Relationships Between The Angle Of Mental Rotation Required For Spatial Orientation, Response Times, And Accuracy, Ronald D. Archer

Master's Theses - Daytona Beach

The purpose of this study is to investigate the relationship between the angles of mental rotation when attempting to spatially orientate and the resulting response times and levels of accuracy. By means of a computer program, participants were presented with 64 mental rotational trials. The mental rotational trials consisted of a triangle placed in the center of the screen with a standard stick symbol of an aircraft appearing at various headings and orientations around the triangle. The participants were required to imagine themselves inside the flight deck of the aircraft, and then respond as quickly and accurately as possible to …

Controlling Chaos In Dynamical Systems Described By Maps, Claire A. Marduel

Master's Theses - Daytona Beach

The purpose of this thesis is to study methods for the control of chaos in dynamical systems described by maps. Two simple model dynamical systems, a one-dimensional map, the logistic map and a two-dimensional map, the prey-predator map are treated first. A feedback control method is introduced, in which an independent parameter of the system is perturbed. The chaotic behavior is successfully suppressed and the maps are stabilized about an unstable fixed point. Next, a more complex two-dimensional map is studied: the dynamics of a marker particle advected by the flow field generated by a blinking vortex. This flow field …

A Comparison Of Two Geo-Centric Attitude Indicators As Aids To Unusual Attitude Recovery: Pictorial Vs. Symbolic Displays, Christopher Cohoes

Master's Theses - Daytona Beach

Aircraft require high cognitive quality aircraft attitude information. Evidence will be presented on aircrew decision-making performance on an unusual attitude recovery task using three different types of attitude displays. Results indicated that among a sample of low-flight time student pilots attending Embry-Riddle Aeronautical University, mean reaction times were significantly faster and error rates significantly lower using an outside-in pictorial display than with either an outside-in symbolic display or an attitude gyro. This is attributed to the pictorial display being a more intuitive display by providing a more natural or realistic representation of aircraft orientation than the other two displays. The …

Evaluation Of A Display With Both Quickened And Status Information For Control Of A Second Order System, Matthew J. Neal

Master's Theses - Daytona Beach

Quickened displays have a severe limitation in that they do not give any indication of status information, and therefore no indication of actual error. It was hypothesized in this study that a display with both quickened and status information would enable the operator to make more effective control responses than either a status alone display, or a quickened alone display.

A horizontal axis pursuit tracking task was developed and controlled by eighteen participants with three display types: (1) a status alone display; (2) a quickened alone display; and (3) a status and quickened combined display.

The primary hypothesis was only …

The Design, Fabrication, And Evaluation Of A Low-Speed, Low-Turbulence, Anechoic Wind Tunnel, Brian J. Kaplan

Master's Theses - Daytona Beach

In order to provide a means for testing noise reduction techniques in propellers and fans, a low-speed, low-turbulence, anechoic wind tunnel was designed, fabricated and evaluated at Embry-Riddle Aeronautical University.

This open circuit wind tunnel was designed using several other existing wind tunnels as a guide and incorporated an open jet test section. The tunnel, which was built almost entirely out of wood and fiberglass, is powered by a 15 hp centrifugal fan.

Tufts of yarn, a pitot-static tube, and a hot film anemoter were used to determine the flow characteristics in the test section of this wind tunnel. From …

Compressible Flow Analysis Of Thrust Augmenting Ejectors, Mohamed Moujahid

Master's Theses - Daytona Beach

The present work was initiated due to the need for a method to understand and predict the thrust augmenting characteristics of jet ejectors. The mixing process in ejectors can be analyzed using either the control volume approach, or detailed models based on the Navier -Stokes Equations and the theory of turbulent jets. The control volume approach uses integrated forms of the conservation equations of mass, momentum and energy. It is chosen in the first part of the study since it affords the best vehicle for the parametric studies required to understand the potential of ejectors for a given application. Compressibility …