Aerospace Engineering Commons^™

Porous Emitter Colloid Thruster Performance Characterization Using Optical Techniques, Eric T. Wolf

Theses and Dissertations

This research focuses on experimentally characterizing the performance parameters of a colloid thruster with porous emitters through optical techniques. Porous emitters are different than traditional needle emitters in how they allow a variation in the number and size of Taylor Cones throughout a range of propellant volumetric flow rate conditions. An algorithm is created to calculate the estimated minimum and maximum number of emitter sites based on magnified images of the porous emitter heads. Theoretical thruster performance parameters are then established from the estimated number of emitter sites. Experimental techniques for measuring the thrust and exhaust exit velocity are proposed. …

Training Maneuver Evaluation For Reduced Order Modeling Of Stability & Control Properties Using Computational Fluid Dynamics, Craig C. Porter

Theses and Dissertations

System identification has long been used as a tool for flight test engineers to characterize systems under test; however, the inputs to these characterization activities have previously been limited to wind tunnel and flight test data. There has been a recent effort to incorporate computational fluid dynamics (CFD) into the system identification process. An integral piece of the process is the simulation of training maneuvers utilizing CFD. Up until now, the suitability of particular training maneuvers has been assessed by comparing the reduced model to known results. This research strives to recommend a set of parameters to be used in …

Effects Of Stereoscopic 3d Digital Radar Displays On Air Traffic Controller Performance, Jason G. Russi

Theses and Dissertations

Air traffic controllers are responsible for directing air traffic based upon decisions made from traffic activity depicted on 2Dimensional (2D) radar displays. Controllers must identify aircraft and detect potential conflicts while simultaneously developing and executing plans of action to ensure safe separation is maintained. With a nearly 100% increase in traffic expected within the next decade (FAA, 2012a), controllers' abilities to rapidly interpret spacing and maintain awareness for longer durations with increased workload will become increasingly imperative to safety. The current display design spatially depicts an aircraft's position relative to the controller's airspace as well as speed, altitude, and direction …

Finite Element Analysis Of A Highly Flexible Flapping Wing, Justin K. Mason

Theses and Dissertations

Small unmanned aerial systems are being designed to emulate the flapping kinematics of insects and birds which show superior control in slow speed regimes compared to fixed wing or rotorcraft aircraft. The flight of flapping wing vehicles is characterized by aeroelastic effects. Most research has been dedicated towards understanding the aerodynamic side of the aeroelastic response with minimal effort spent towards validating the structural response. A finite element model of a wing from a commercial flapping wing vehicle was created to validate the structural response. Vacuum testing allowed the isolation of the inertial response for a direct comparison to the …

High Frequency Magnetic Field Direction Finding Using Mgl-S8a B-Dot Sensors, Michael D. Archer

Theses and Dissertations

Aircraft based direction finding (DF) in the high frequency (HF) band is difficult due to the aircraft's size with respect to wavelength and limited azimuthal resolution. A B-dot sensor is useful for detection of the time varying magnetic field and offers improved integration into an aircraft. What the B-dot sensor gains in integration it gives up in sensitivity because it is designed for frequencies above 5 GHz. Design of an airborne HFDF array using Bdot sensors is based in maximizing the physical extent of the array and eliminating multiple main beams. The goals of this research are to complete a …

Error Characterization Of Vision-Aided Navigation Systems, Daniel A . Marietta

Theses and Dissertations

The goal of this work is to characterize the errors committed by an Image Aided Navigation (IAN) algorithm that has been developed for use as a navigation tool in GPS denied areas. The filter under study was developed by the Air Force Institute of Technology's Advanced Navigation Technology center, and has been the focus of numerous research efforts. Unfortunately, these studies have all been based on single runs or simulations, and such results may not be indicative of the true filter performance. This problem extends to IAN publications in general; no analysis of IAN based upon a sizable real world …

Supplementary Computer Generated Cueing To Enhance Air Traffic Controller Efficiency, Laurienne Cibelle Rodrigues De Assis Santana

Theses and Dissertations

Air traffic controllers are often required to simultaneously communicate with several aircraft over multiple radio frequencies. As a result, during peak loading, it is common for the controller to receive multiple concurrent communications, each from a different aircraft, making it difficult to discern audio messages received from multiple pilots simultaneously. To address this problem, a modified air traffic control (ATC) interface was prototyped with the goal of increasing controller-to-pilot communication efficiency. This prototype included supplementary text cueing which was provided by a hypothetical automated text to speech system in an on-screen text box for controller reference in the event of …

Opto-Mechanical Design Of A Chromotomographic Imager Direct-Vision Prism Element, Timothy E. Coon

Theses and Dissertations

Chromotomographic Imaging (CTI) offers advantages in remote sensing by resolving intensity distribution spatially, spectrally, and temporally. The Chromotomography Experiment (CTEx) at the Air Force Institute of Technology (AFIT) explores the application of CTI as a space-based observer. Previous work in instrument development has revealed many of the intricacies of component fabrication and how they impact the resolving of image data. The proposed CTEx instrument has as its chromatic dispersion element a direct-vision prism (DVP) that is made to rotate in order to achieve multiple projection angles. Analysis of previous research established the need for a more accurate characterization of the …

Application Of Finite Element To Evaluate Material With Small Modulus Of Elasticity, Boyce H. Dauby

Theses and Dissertations

This thesis describes the development of a series of models utilizing the commercial finite element suite ABAQUS specifically to apply towards the study of biological tissue. The end goal is to be able to obtain the material properties of the Manducca Sexta, a biological inspiration for flapping wing micro-air vehicles. Two finite element models were used to analyze the results of two prior studies of other researchers. A flat punch elastic model examined boundary effects and confirmed that the point of indentation was far enough removed from the boundary. The hyperelastic spherical indentation experiment examined the effects of coefficient of …

Comm-Using Decibels, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Comm-Using Decibels" from March 14, 2014.

Towards A “Cloud Curriculum” In Art And Science?, Roger Malina

The Transdisciplinary STEAM+ Journal

Recently an email hit my desk from Paul Thomas in Australia with a proposal to work together on a “Cloud Curriculum for Art and Science”. I immediately agreed to collaborate. I don’t yet have a clue of what a cloud curriculum is, but what I do know is that we are ‘backing into the future’ in educational institutions and we desperately need a ‘cloud curriculum.’ We need to look over the ten year horizon. And in the emerging art-science field I doubt that the usual approach to curriculum development will work.

Design Of A Specimen Fixture For Impact Resistance Testing In An Instron Dynatup 8250 Drop Weight Impact Tester, Daniel Alejandro Barath

Aerospace Engineering

The purpose of this report is to outline the path and methods used to design a specimen fixture for the testing and analysis of fiber reinforced composites subjected to impact loading. This design is done in support of the California Polytechnic State University in San Luis Obispo Structures and Composites Laboratory. The design request was made at the request of Dr. Eltahry Elghandour to support the graduate students Kodi A. Rider and Y. Vanessa Wood in their master’s degree thesis projects.

The design request involved the design of a specimen fixture compatible with the existing impact apparatus located in the …

Influence Of Wing Span On The Aerodynamics Of Wings In Ground Effect, Sammy Diasinos, Tracie J. Barber, Graham Doig

Aerospace Engineering

A computational fluid dynamics study of the influence of wing span has been conducted for an inverted wing with endplates in ground effect. Aerodynamic coefficients were determined for different spans at different ground clearances, highlighting a trend for shorter spans to delay the onset of both separation and resulting loss of negative lift. The vortices at the wing endplates were not observed to change significantly in terms of strength and size; thus, at shorter spans, their influence over a larger percentage of the wing helped the flow stay attached and reduced the severity of the adverse pressure gradient which invokes …

Implementing A Matlab Based Attitude Determination Algorithm In C Within The Polysat Software Architecture, Dominic Bertolino

Computer Engineering

This project focuses on one component within a complete attitude determination and control system (ADCS) for a small satellite. The component consists of porting the algorithm that determines the current attitude of the satellite developed by AERO students / team members. The original algorithm has been developed in MATLAB code. The actual algorithm will be simulated and tested in MATLAB by the AEROs. The porting consisted of integrating the pieces into the custom PolySat software environment in C. Testing was done to verify the ported component corresponded to the original MATLAB component as well as verify its runtime on the …

Senior Project Report - Doctest, Stephen Weessies

Computer Engineering

DocTest is a program that, simply put, allows a programmer or user to document STANAG 4586 (a standard for unmanned aerial vehicle interoperability) messages and test the vehicle system at Lockheed Martin [5]. The program is extensible to allow for further development aiding our software team to do what they do best and not get bogged down in tedious but necessary documentation. DocTest is also used to aid in testing, keeping track of the issues and bugs found and creating a document that captures each issue so an issue is not missed or forgotten. This program was made for use …

Axisymmetric Air Augmented Methanol/Gox Rocket Mixing Duct Experimental Thrust Study, Kyle Jacob Johnson

Master's Theses

A hot-flow axisymmetric Air Augmented Rocket (AAR) test apparatus was constructed to test various mixing duct configurations at static conditions. Primary flow for the AAR was provided through a liquid methanol-gaseous oxygen bipropellant rocket. Experimental thrust measurements were recorded and propellant mass flow rates and chamber conditions were calculated using an iterative solver dependant on recorded propellant line stagnation pressures. Primary rocket flow produced thrust ranging from 14 to 17.9lbf. Primary mass flow rate through testing ranged from 0.071 to 0.085lbm/s with calculated chamber pressures between 298-362psia. Calculated primary flow velocity ranged from 6,600ft/s to 8,000ft/s depending on propellant pressure …

A Gravity Gradient, Momentum-Biased Attitude Control System For A Cubesat, Ryan J. Sellers

Master's Theses

ExoCube is the latest National Science Foundation (NSF) funded space weather CubeSat and is a collaboration between PolySat, Scientific Solutions Inc. (SSI), the University of Wisconsin, NASA Goddard and SRI International. The 3U will carry a mass spectrometer sensor suite, EXOS, in to low earth orbit (LEO) to measure neutral and ionized particles in the exosphere and thermosphere. Measurements of neutral and ion particles are directly impacted by the angle at which they enter EXOS and which leads to pointing requirements. A combination of a gravity gradient system with a momentum bias wheel is proposed to meet pointing requirements while …

Film Cooling In Fuel Rich Environments, Jacob J. Robertson

Theses and Dissertations

The ultra compact combustor is a high performance gas turbine design concept that portends reduced weight for future weapons platforms. A natural outcome of the design is the continual presence of fuel-rich air in the turbine component of the engine. Because modern cooling schemes for hot section turbine blades involve injecting cool, oxygen-rich air adjacent to the surface, the potential arises for reaction with the unconsumed radicals in the mainstream ow and augmented heat transfer to the blade. This outcome is contrary to the purpose of film cooling, and can lead to early life-cycle turbine failure. This study examined the …

Design And Testing Of An H2/O2 Predetonator For A Simulated Rotating Detonation Engine Channel, Stephen J. Miller

Theses and Dissertations

A study is presented on the relationship between a pre-detonator and a detonation channel of an RDE. Testing was conducted on a straight narrow channel made of clear polycarbonate windows connected to an H₂/O₂ pre-detonator to simulate the RDE initiation scheme and allow for flow visualization. A comparison is made on decoupling distance and wave velocities for a range of pre-detonator designs, inclination angles, equivalence ratios and geometries placed within the simulated channel. Regardless of inclination angle or equivalence ratio the detonation wave decoupled within 25 mm from the pre-detonator exit into the channel. A step change …

Ad-Hoc Regional Coverage Constellations Of Cubesats Using Secondary Launches, Guy G. Zohar

Master's Theses

As development of CubeSat based architectures increase, methods of deploying constellations of CubeSats are required to increase functionality of future systems. Given their low cost and quickly increasing launch opportunities, large numbers of CubeSats can easily be developed and deployed in orbit. However, as secondary payloads, CubeSats are severely limited in their options for deployment into appropriate constellation geometries.

This thesis examines the current methods for deploying cubes and proposes new and efficient geometries using secondary launch opportunities. Due to the current deployment hardware architecture, only the use of different launch opportunities, deployment direction, and deployment timing for individual cubes …

Design And Performance Of Circulation Control Geometries, Rory Martin Golden

Master's Theses

With the pursuit of more advanced and environmentally-friendly technologies of today’s society, the airline industry has been pushed further to investigate solutions that will reduce airport noise and congestion, cut down on emissions, and improve the overall performance of aircraft. These items directly influence airport size (runway length), flight patterns in the community surrounding the airport, cruise speed, and many other aircraft design considerations which are setting the requirements for next generation aircraft. Leading the research in this movement is NASA, which has set specific goals for the next generation regional airliners and has categorized the designs that meet the …

Work Ethics For Sse-122: Satellites & Space Systems (Spring 2013), Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

PowerPoint presentation by Professor Bob Twiggs on work ethics for SSE-122: Satellites & Space Systems for the spring 2013 semester, created on February 28, 2013.

Equilibrium And Nonequilibrium Molecular Dynamics Simulations Of Thermal Conductance At Solid-Gas Interfaces, Zhi Liang, William Evans, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Thermal Conductance at Solid-Gas Interfaces with Different Interfacial Bonding Strengths is Calculated through Green-Kubo Equilibrium Molecular Dynamics (EMD) Simulations. Due to the Finite Size of the Simulation System, the Long-Time Integral of the Time Correlation Function of Heat Power Across the Solid-Gas Interface Exhibits an Exponential Decay, Which Contains the Information on Interfacial Thermal Conductance. If an Adsorbed Gas Layer is Formed on the Solid Surface, It is Found that the Solid-Gas Interface Needs to Be Defined at a Plane Outside the Adsorbed Layer So as to Obtain the Correct Result from the Green-Kubo Formula. the EMD Simulation Result …

Vtt Technical Research Centre Of Finland, Vtt Technical Research Centre

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation titled "VTT Technical Research Centre of Finland" from February 14, 2013.

Improvement Of Heat Transfer Efficiency At Solid-Gas Interfaces By Self-Assembled Monolayers, Zhi Liang, William Evans, Tapan Desai, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Molecular Dynamics Simulations, We Demonstrate that the Efficiency of Heat Exchange between a Solid and a Gas Can Be Maximized by Functionalizing Solid Surface with Organic Self-Assembled Monolayers (SAMs). We Observe that for Bare Metal Surfaces, the Thermal Accommodation Coefficient (TAC) Strongly Depends on the Solid-Gas Interaction Strength. for Metal Surfaces Modified with Organic SAMs, the TAC is Close to its Theoretical Maximum and is Essentially Independent from the SAM-Gas Interaction Strength. the Analysis of the Simulation Results Indicates that Softer and Lighter SAMs, Compared to the Bare Metal Surfaces, Are Responsible for the Greatly Enhanced TAC. © 2013 …

Single Network Adaptive Critics Networks-Development, Analysis, And Applications, Jie Ding, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Solving infinite time optimal control problems in an approximate dynamic programing framework with two-network structure has become popular in recent years. In this chapter, an alternative to the two-network structure is provided. We develop single network adaptive critics (SNAC) which eliminate the need to have a separate action network to output control. Two versions of SNAC are presented. The first version, called SNAC outputs the costates and the second version called J-SNAC outputs the cost function values. Special structure called Finite-SNAC to efficiently solve finite time problems is also presented. Illustrative infinite time and finite time problems are considered; numerical …

Smaller Spacecraft For Flying Large Clusters Of Biological Space Experiments, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Smaller spacecraft for flying large clusters of biological space experiments" from February 5, 2013.

Would I Survive In Space?, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Would I survive in Space?" from February 4, 2013.

Smore Revision: Ignition And User Interface, Arash Mehrparvar

Aerospace Engineering

The Static Methanol Oxygen Rocket Engine (SMORE) has undergone several revisions since its inception. This latest revision aimed to increase startup reliability and user safety in the operation of the rocket. The implementation of maintenance procedures, safeguards in the ignition system, as well as construction of a new control box and redesign of the igniter itself have accomplished these goals while keeping costs down and without modifying the current rocket setup. Startup reliability has increased drastically, so long as all other rocket setup procedures are followed properly. 250 subsequent firings of the rocket have proven an igniter reliability of more …

Validation Of Proposed Metrics For Two-Body Abrasion Scratch Test Analysis Standards: In Principle, Any Scratch Can Be Analyzed By This Method, Kenneth W. Street, Ryan L. Kobrick, David M. Klaus

Publications

Abrasion of mechanical components and fabrics by soil on Earth is typically minimized by the effects of atmosphere and water. Potentially abrasive particles lose sharp and pointed geometrical features through erosion. In environments where such erosion does not exist, such as the vacuum of the Moon, particles retain sharp geometries associated with fracturing of their parent particles by micrometeorite impacts. The relationship between hardness of the abrasive and that of the material being abraded is well understood, such that the abrasive ability of a material can be estimated as a function of the ratio of the hardness of the two …