Aerospace Engineering Commons^™

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 …

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 …

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 …

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 …

The Evolution And Testing Of An Aerovalve Pulsejet Engine, Gregory V. Meholic

Master's Theses - Daytona Beach

The goal of this project was to develop and test a self-aspirating aerovalve pulsejet and measure its operating characteristics. An investigation of pulsejets developed by previous experimenters revealed design trends associated with the engine geometry. These trends were followed in the development of an aerovalve pulsejet engine entitled the Astra. The engine employed variable fuel injection methods, ignition location and exhaust pipe length to show that certain combinations of geometry relations and fuel injection methods were more conducive to pulse combustion. Even though the engine pulsed with forced inlet air, the Astra did not self-aspirate as did the engines …

A Direct Synthesis Method For The Conceptual Design Of Transport Aircraft, Pierre Andre Fruytier

Master's Theses - Daytona Beach

The problem of synthesizing a transport aircraft at the conceptual design level is considered. A direct sizing algorithm that does not require iteration is developed. Such direct synthesis methods can be used as important building blocks in an aircraft optimization process. New statistical equations based on current aircraft are derived for approximating the widths and lengths of the cabin and fuselage. A more accurate static thrust over gross weight, which is based on the equations of motion specified by the FAR part 25 climb requirements, is presented. A cruise at constant altitude with optional step-climb is taken into account. The …

Dynamic Simulation Of General Aviation Cabin Environments And Occupant Restraint Systems, Mark A. Shilladay

Master's Theses - Daytona Beach

After a five year study of General Aviation (GA) accidents, the National Transportation Safety Board (NTSB) has concluded that aircraft cabin environments place the occupant at high risk of suffering severe injuries in an emergency crash situation. Studies of Federal Aviation Administration (FAA) seat tests were used to form the basis of a computer analysis to address dynamic cabin environments. In this effort a simplified system of masses, springs, and dampers are used to simulate the more complex configuration of cabin structure, seat, pilot, and restraints on a personal computer. The primary objective of this study is to accurately simulate …

An Experimental Study Of Transient Flows In Pulse Combustors, Michael P. Femandes

Master's Theses - Daytona Beach

The purpose of this investigation was to experimentally characterize a pulse combustor with respect to ambient conditions, pressure amplitudes, wall temperature, combustor geometry and type of centerbody used. The wall temperatures were recorded and the pressure variation was obtained using a sampling rate of 10,000 readings per second. These parameters were recorded for two different tailpipe lengths and centerbodies, and for different ambient conditions. Power spectrums were then obtained from the pressure variations. These spectrums displayed the peak amplitudes and the frequencies at which they occurred. The experiment showed distinct repeatability. It was concluded that combustor displayed the steady, pulsing …

Classification Of Acoustic Emission Signals From An Aluminum Pressure Vessel Using A Self-Organizing Map, Weldon Paul Thornton

Master's Theses - Daytona Beach

Acoustic emission nondestructive testing has been used for real-time monitoring of complex structures. All of the structures were made of materials at least 0.070 inch thick. The purpose of this research was to demonstrate the feasibility of using neural networks to classify acoustic emission signals gathered from a pressure vessel made of 2024-T3 aluminum 0.040 inches thick, i.e. thin aluminum sheet. AE waveforms were recorded during fatigue cycling of one pressure vessel using a wide band transducer and a digital oscilloscope connected to a computer. The source for each signal was determined using two narrow band transducers and a LOCAN-AT …

Numerical Investigation Of Second-Order Effects In A Supersonic Boundary-Layer, Timothy R. Membrino

Master's Theses - Daytona Beach

Historically, the study of boundary-layer flows has centered on the analysis of the first-order boundary-layer equations and their application to physical flow problems. However, selected “real-world” boundary-layer flows exhibit significant second-order effects which are neglected by the first-order equations. Full Navier-Stokes solutions are often not merited or desired for these flows. Therefore, the second-order boundary-layer equations provide a compromise.

Few validating comparisons have been attempted between second-order boundary-layer theory and experimental or numerical solutions of compressible viscous flows. Experimental simulations to capture second-order effects are difficult since the desired effects are small and can exist simultaneously, resulting in a neutralizing …

Nonlinear Analysis Of Composite Beams Under Random Excitations, Snorri Gudmundsson

Master's Theses - Daytona Beach

The vibration responses of three unsymmetrically laminated beams, that are excited with a Gaussian random forcing function, are studied in this thesis. The beams are analyzed nonlinearly and compared to linear results, indicating some important corrections. The solution procedure begins with the derivation of the general equation of motion using Galerkin's method. Then, two approaches are taken in the solution. First, the equation of motion is attacked directly employing a real time Runge-Kutta numerical analysis. Second, the method of equivalent linearization is used. The thesis finds the results from the two approaches to be in a close agreement, although some …

The Professional Air Traffic Controllers Strike: A Retrospective Analysis, Steven E. Durnin

Master's Theses - Daytona Beach

The purpose of this study was to assess the opinions, beliefs, and perspectives of former air traffic controllers who were terminated from employment with the Federal Aviation Administration for participating in the Professional Air Traffic Controllers Organization (PATCO) strike of 1981. The study examines the perceptions of the former controllers to determine their feelings toward the justification for going on strike over 13 years ago. This is relevant in light of recent events including the lifting of the ban against rehiring PATCO controllers by the Clinton Administration.

The data collected for this study were obtained with an opinionnaire mailed via …

Numerical Analysis Of The Viscous Flow In A Supersonic Diffuser, Sa'ed A'Rafat

Master's Theses - Daytona Beach

The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one …

Nonlinear Finite Element Analysis Of Laminated Composite Beams Subjected To Harmonic Excitations Using A 20 Dof Beam Element, Mansour Nosrati Kenareh

Master's Theses - Daytona Beach

The purpose of this thesis is to study the nonlinear analysis of antisymmetrically laminated composite beams including shear deformation subjected to harmonic excitation, using a 20-degree of freedom finite element beam. The beam has 10 degrees of freedom at each node: The axial displacements, the transverse deflection due to bending and transverse shear, the twisting angle, the in-plane shear rotation, and their derivatives along the axial direction. In this study, the effect of different parameters such as damping, shear deformation and different edge conditions on the steady-state frequency-responce will be investigated. The analysis was based on the use of finite …

Nonlinear Forced Vibration Of An Unsymmetrically Laminated Composite Beam, Marie Helene Pompei

Master's Theses - Daytona Beach

The purpose of this thesis is to study the nonlinear forced vibration of an unsymmetrically laminated composite beam. Two cases are considered: unsymmetrical angle-ply and unsymmetrical cross-ply composite beams. The nonlinear governing partial differential equations of motion are obtained by taking into account the von-Karman geometrical nonlinearity. These equations are transformed into nonlinear ODE (Ordinary Differential Equations) by means of the Galerkin method. For both cases the forced Duffing equation was obtained. It is to be noted that only for the unsymmetrical cross-ply laminate simply-supported case are both quadratic and cubic nonlinearities present. The resulting equations for both cases are …

Neural Network Detection Of Fatigue Crack Growth In Riveted Joints Using Acoustic Emission, Adriano F. De Almeida

Master's Theses - Daytona Beach

The purpose of this research was to demonstrate the capability of neural networks to discriminate between individual acoustic emission (AE) signals originating from crack growth and rivet rubbing (fretting) in aluminum lap joints. AE waveforms were recorded during tensile fatigue cycling of six notched and riveted 7075-T6 specimens using a broadband piezoelectric transducer and a computer interfaced oscilloscope. The source of 1,311 signals was identified based on triggering logic, amplitude relationships, and time of arrival data collected from the broad-band transducer and three additional 300 Hz resonant transducers bonded to the specimens. The power spectrum of each waveform was calculated …

Comparison Of Air Traffic Control Candidate Ability With Simulator-Based Training Measures, Lawrence A. Tomaskovic

Master's Theses - Daytona Beach

The purpose of this study was to determine if the utilization of an experimental computer-based selection test battery would aid in the prediction of a candidate's performance when using an air traffic control computer-based simulation program. Each candidate completed the selection test battery, and then received air traffic control instruction using the air traffic control simulation program incorporated in the TRACON/Pro™ simulator system. The selection test battery results were correlated with the subsequent simulator scoring results.

The Effect Of Active And Passive Control On Air Traffic Controller Dynamic Memory, Esa M. Rantanen

Master's Theses - Daytona Beach

The purpose of this study was to investigate the effect of automated and passive control on air traffic controller dynamic memory. The study consisted of two experiments, each involving a realistic ATC scenario for radar approach control with a mix of arriving and departing traffic. In Experiment I, the subjects performed manual control of the traffic while, in Experiment II, the scenario was highly automated and the subjects were tasked with only monitoring the situation. The dynamic memory performance was measured by interrupting the scenario and having the subjects recall the traffic situation at the moment of simulation interruption. The …

Incorporation Of Traffic Collision Alert System (Tcas) Advisories On Heads-Up Displays: Enhanced Pilot Response, Hamadeh A. Nureddine

Master's Theses - Daytona Beach

This study evaluated the effects that heads-up mounted TCAS displays had on pilot response and workload. Pilot response was evaluated by: (a) response time to a traffic advisory, and (b) number of missed traffic alerts. Workload assessment was accomplished in accordance with NASA's Task Load Index (TLX). Subjects were all licensed pilots with a minimum of a private pilot license and an instrument rating. A total of 32 subjects were randomly assigned to experimental and control groups utilizing HUD-mounted, and conventional, TCAS displays respectively. Performance data was collected during computer-simulated flights, while subjective workload levels were reported at the end. …

Low Reynolds Number Laminar Separation Bubble Control Using A Backward Facing Step, Dominique Rothan

Master's Theses - Daytona Beach

The problem of a laminar separation bubble on the upper surface of a 9.5% thick airfoil operated at low Reynolds number (R_N = 380,000) was investigated experimentally.

An unmodified LRN-010 airfoil and a modified LRN-010 airfoil with a backward facing step on its upper surface were built and tested in the ERAU wind tunnel in order to obtain pressure distributions and drag for different angles of attack.

Results were found to be in good agreement with the results obtained from the XFOIL CFD code. It was concluded that the step cutout modification improves the airfoil’s lift-to-drag ratio at low …

Utilizing Instructional Design Constructs To Enhance Computer-Based Instruction In Air Traffic Controller Training, Theodore Scott Rhoads

Master's Theses - Daytona Beach

This study demonstrates that a computer-based instructional design format is appropriate for novice air traffic control (ATC) training. The computer presents the student with small amounts of information in tutorial and drill and practice sequences that necessitate student interactivity. The student is then periodically audit tested to ascertain mastery of the subject matter. The result of these mid-lesson evaluations serve as a self-check so that the student can assess his/her progress in the learning cycle. The systematic design of instruction and interactive approach to learning, enhances student motivation, improves learning and retention, while placing the responsibility of achieving specific learning …

Thermally Induced Vibration Of A Cross-Ply Laminated Plate With Hygrothermal Effects (Exact Solution), Stephen Jerry Maerz

Master's Theses - Daytona Beach

Of increasing importance in structural design is the use of fiber-reinforced polymeric composite material, notably in advanced aircraft and projectiles. These applications expose the materials to varied environmental conditions, therefore the material performance under these conditions is of great interest. One aspect of this is the solution of the dynamic response of a composite structure under elevated temperature and moisture conditions. An exact solution is formulated which describes the hygrothermal effects due to heating and moisture diffusion on one surface of a symmetric cross-ply plate made of AS/3501 graphite epoxy with simply-supported boundary conditions.

Isolating Failure Mechanisms In A Fiberglass/Epoxy Tensile Test Specimen Using Acoustic Emission Signal Parameters, Michael Kouvarakos

Master's Theses - Daytona Beach

This study used acoustic emission (AE) signal parameters to isolate the failure mechanisms in a 0° unidirectional, fiberglass/epoxy tensile test specimen. Since several failure mechanisms were known to be present, the lack of any distinctly identifiable bands in the original amplitude distribution indicated that there was considerable overlap between the AE signals of the various failure mechanisms. In order to separate the amplitude bands associated with each mechanism, it was necessary to sort on the duration of the AE signal. Two additional plots, counts versus amplitude and hits versus counts, were used to verify that the amplitude distributions were comprised …

Thermal Post-Buckling And Vibration Analysis Of Thermally Buckled Antisymmetrically Laminated Beams Using A 20 Dof Finite Element, Misao Mizuno

Master's Theses - Daytona Beach

The purpose of this study is to use the finite element method to analyze thermal buckling, post-buckling, and vibrations of thermally buckled composite beams including shear deformation. The beam element used has ten degrees of freedom at each node: axial displacement, transverse displacement due to bending and shear, twisting angle, inplane shear rotation and their derivatives with respect to x. Hermitian polynomials and Lagrange's equation were used to derive the equations of motion. The equations of motion were divided into static and dynamic parts. For buckling analysis, the eigenvalue problem was solved for the critical temperature. The scaled first mode …

Determination Of The Parameter Limits For Artificial Non-Random Microwave Signal Detection, Irvin Lee Burough

Master's Theses - Daytona Beach

The Doppler shift of small bandwidth (several Hertz) microwave signals makes identification of spectral features difficult; the Doppler individual bandwidth shift can be a factor of hundreds or thousands of times greater than the bandwidth. A computer model supplied by the National Aeronautics and Space Administration's (NASA) Search for Extra-Terrestrial Intelligence (SETI) project, which can simulate radio frequency interference (RFI) and a buried ETI signal, will determine the limits of the signal-to-noise ratio (SNR) and false alarm threshold for identification of the signal after Doppler shifting. By running the model on a MicroVAX II computer, it will be possible to …

An Investigation Of The Floor Attachment Assembly Of A Large Transport Aircraft Seat Subjected To Crash Dynamic Loadings, Mark William Creager

Master's Theses - Daytona Beach

Accident investigations by the National Transportation Safety Board concluded that the passenger seat and restraint systems found in today's aircraft used by the airlines are inadequate to protect the occupant in airplane crashes. Computer models were developed of the seat-track assembly and finite element analyses were performed subjected to crash dynamic loadings. The seat-track interface was modeled with gap elements to accurately model the geometric interaction between the track and seat-track fittings. Results showed large deformations and stresses above yielding in both the seat and track when subjected to accelerations prescribed for certification under the Federal Aviation Administration (FAA) regulations.