Aerospace Engineering Commons^™

Cold Flow Performance Of A Ramjet Engine, Harrison G. Sykes

Master's Theses

The design process and construction of the initial modular ramjet attachment to the Cal Poly supersonic wind tunnel is presented. The design of a modular inlet, combustor, and nozzle are studied in depth with the intentions of testing in the modular ramjet. The efforts undertaken to characterize the Cal Poly supersonic wind tunnel and the individual component testing of this attachment are also discussed. The data gathered will be used as a base model for future expansion of the ramjet facility and eventual hot fire testing of the initial components. Modularity of the inlet, combustion chamber, and nozzle will allow …

A Pareto-Frontier Analysis Of Performance Trends For Small Regional Coverage Leo Constellation Systems, Christopher Alan Hinds

Master's Theses

As satellites become smaller, cheaper, and quicker to manufacture, constellation systems will be an increasingly attractive means of meeting mission objectives. Optimizing satellite constellation geometries is therefore a topic of considerable interest. As constellation systems become more achievable, providing coverage to specific regions of the Earth will become more common place. Small countries or companies that are currently unable to afford large and expensive constellation systems will now, or in the near future, be able to afford their own constellation systems to meet their individual requirements for small coverage regions.

The focus of this thesis was to optimize constellation geometries …

Experiment And Simulation Of The Acoustic Signature Of Fatigued-Cracked Gears In A Two-Stage Gearbox, Matthew James Ostiguy

Master's Theses

This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy …

Improving And Expanding The Capabilities Of The Poly-Picosatellite Orbital Deployer, David Pignatelli

Master's Theses

The Poly-Picosatellite Orbital Deployer (P-POD) has undergone a series of revisions over the years. The latest revision, described in this Master’s Thesis, incorporates new capabilities like EMI shielding, an inert gas purge system, and an electrical interface to the CubeSats after they are integrated into the P-POD. Additionally, some mass reduction modifications are made to the P-POD, while its overall strength is increased. The P-POD inert gas purge system successfully flew, on a previous revision P-POD. The P-POD components are analyzed to a set of dynamic loads for qualification, and successfully undergoes random vibration qualification testing. The P-POD encounters some …

Control Of A Spacecraft Using Mixed Momentum Exchange Devices, Blake J. Currie

Master's Theses

Hardware configurations, a control law, and a steering law are developed for a mixed hardware spacecraft that uses both control moment gyros and reaction wheels. Replacing one or more gyros in a spacecraft with a reaction wheel has potential for cost savings while still achieving much greater performance than using reaction wheels alone. Several simulated tests are run to compare the performance to a traditional all reaction wheel or all control moment gyro spacecraft, including analysis of failure modes and singular configurations. The mixed system performed similarly to all gyro systems, responding within 6% of the gyro system’s time for …

Effects Of Low Velocity Impact On The Flexural Strength Of Composite Sandwich Structures, Jeffrey Scott Carter

Master's Theses

The use of composite sandwich structures is rapidly increasing in the aerospace industry because of their increased strength-to-weight and stiffness-to-weight characteristics. The effects of low velocity impacts on these structures, however, are the main weakness that hinders further use of them in the industry because the damages from these loadings can often be catastrophic. Impact behavior of composite materials in general is a crucial consideration for a designer but can be difficult to describe theoretically. Because of this, experimental analysis is typically used to attempt to describe the behavior of composite sandwiches under impact loads. Experimental testing can still be …

Effect Of Adaptive Tabs On Drag Of A Square-Base Bluff Body, Brian W. Barker

Master's Theses

This thesis involves the experimental wind tunnel testing of a 0.127m by 0.127m square-base bluff body to test the effectiveness of trailing edge tabulations to reduce drag in the Cal Poly 0.912m by 1.219 m low-speed wind tunnel. To accomplish this, the boundary layer was first measured on the trailing edge of the model for the three speeds at 10, 20, and 30 m/s, with Re = 8.3e4, 1.6e5 and 2.5e5 respectively, without the tabs. Three different tests were performed to determine the effectiveness of the tabs. These tests included base pressure measurements, total drag force measurements and hotwire velocity …

Experimental Investigation Of Active Wingtip Vortex Control Using Synthetic Jet Actuators, Peter J. Sudak

Master's Theses

An experiment was performed in the Cal Poly Mechanical Engineering 2x2 ft wind tunnel to quantify the effect of spanwise synthetic jet actuation (SJA) on the drag of a NACA 0015 semispan wing. The wing, which was designed and manufactured for this experiment, has an aspect ratio of 4.20, a span of 0.427 m (16.813”), and is built around an internal array of piezoelectric actuators, which work in series to create a synthetic jet that emanates from the wingtip in the spanwise direction. Direct lift and drag measurements were taken at a Reynolds Number of 100,000 and 200,000 using a …

Influence Of Grain Size And Widmanstätten Colonies On Variability Of Tensile Properties Of Forged Ti-6al-4v, Blake T. Gaspar

Master's Theses

When testing forgings for specifications, it was found that some parts did not meet the requirements for mechanical properties. This triggered an investigation into two of the parts from the lot that did not meet specification. The ultimate reason for failure was due to lower than necessary yield strength and ultimate tensile strength values, as well as unwanted variability between regions of the part. Therefore, samples of the regions were tensile tested to determine the differences that existed in yield strength, ultimate tensile strength, and elongation. After tensile testing, quantitative metallography and fractography were conducted to identify aspects of the …

An Investigation Into The Properties And Fabrication Methods Of Thermoplastic Composites, Ann E. Livingston-Peters

Master's Theses

As applications for thermoplastic composites increase, the understanding of their properties become more important. Fabrication methods for thermoplastic composites continually improve to match designs specifications. These advanced thermoplastics have begun to show an improvement in mechanical properties over those found in thermoset composites commonly used in industry. Polyaryletherketones (PEK) have high service temperatures, good mechanical properties, and improved processing capabilities compared to thermoplastics used in the past making them important to the aerospace industry. The wide range of types of PEK make them suitable for a variety of applications, but selection of specific chemistries, processing parameters, and composite stack-ups determine …

A Study On The Vibrational Performance Characteristics Of An E22 Isolator After Outgassing And Bake-Out, Alma Melendez

Master's Theses

The launch environment experiences many vibration, shock, and acoustic loads. A great concern is the high random vibration levels that can damage components and spacecraft structures, which can cause a mission failure. An effective method of reducing high frequency energy is using isolators. Overall, the need for vibration isolation has been increasing because there has been an increase in the use of mechanisms in which vibrations are prevalent. In addition, there has not been extensive research on the effects of isolators that are outgassed and cured. Therefore, it is important to investigate and understand the vibrational effects on isolators. It …

Flight Testing Small Uavs For Aerodynamic Parameter Estimation, Adam Thomas Chase

Master's Theses

A flight data acquisition system was developed to aid unmanned vehicle designers in verifying the vehicle's design performance. The system is reconfigurable and allows the designer to choose the correct combination of complexity, risk, and cost for a given flight test. The designer can also reconfigure the system to meet packaging and integration requirements. System functionality, repeatbility, and accuracy was validated by collecting data during multiple flights of a radio-controlled aircraft. Future work includes sensor fusion, thrust prediction methods, stability and control derivative estimation, and growing Cal Poly's small-scale component aerodynamic database.

Reduced-Order Reference Models For Adaptive Control Of Space Structures, Alexander I. Scherling

Master's Theses

In addition to serving as a brief overview of aspects relevant to reduced-order modeling (in particular balanced-state and modal techniques) as applied to structural finite element models, this work produced tools for visualizing the relationship between the modes of a model and the states of its balanced representation.

Specifically, error contour and mean error plots were developed that provide a designer with frequency response information absent from a typical analysis of a balanced model via its Hankel singular values. The plots were then used to analyze the controllability and observability aspects of finite element models of an illustrative system from …

Modification Of The Cal Poly Spacecraft Simulator System For Robust Control Law Verification, Tomoyuki Kato

Master's Theses

The Cal Poly Spacecraft Dynamics Simulator, also known as the Pyramidal Reaction Wheel Platform (PRWP), is an air-bearing four reaction wheel spacecraft simulator designed to simulate the low-gravity, frictionless condition of the space environment and to test and validate spacecraft attitude control hardware and control laws through real-time motion tests. The PRWP system was modified to the new Mk.III configuration, which adopted the MATLAB xPC kernel for better real-time hardware control. Also the Litton LN-200 IMU was integrated onto the PRWP and replaced the previous attitude sensor. Through the comparison of various control laws through motion tests the Mk.III configuration …

Dual High-Voltage Power Supply For Use On Board A Cubesat, Nicholas Weiser

Master's Theses

Since their conception in 1999, CubeSats have come and gone a long way. The first few that went into space were more of a “proof of concept,” and were more focused on sending simple data and photographs back to Earth. Since then, vast improvements have been made by over 40 universities and private firms, and now CubeSats are beginning to look towards interplanetary travel. These small satellites could provide a cost effective means of exploring the galaxy, using off the shelf components and piggy-backing on other launch vehicles with more expensive payloads. However, CubeSats are traditionally launched into Low Earth …

Addition Of A Stanton Gauge To The Boundary Layer Data System, Brittany Reanne Kinkade

Master's Theses

The Stanton gauge technique provides an indirect method for measurement of skin friction on a smooth aerodynamic surface in which a pressure tap is available. This thesis presents the design and evaluation of a new type of skin friction measurement gauge based on the Stanton gauge concept but not requiring a surface pressure tap. This new skin friction measurement gauge, called a "Flow Tab", can therefore be used on an aerodynamic model or aircraft surface without alteration of the surface. The Flow Tab is thus particularly well-suited to use with Cal Poly's Boundary Layer Data System (BLDS), a small, self-contained …

Analysis Of Environmentally Friendly Marking Ink For Military Equipment And Electronics, Liang Li

Master's Theses

Recent advancements in corrosion-resistance coating technology has reduce the use of environmentally harmful compounds such as Hexavalent Chromium by replacing Hexavalent Chromium in primers and topcoat. However, marking inks were neglected in the process. Products such as Enthone 50 series are still widely used, which contain compounds such as lead, hexavalent chromium, bisphenol A (BPA), Cadmium Sulfide, and more. Excluding catalyst compositions in Enthone, the chemicals in the ink alone contained three reproductive toxicant and numerous carcinogens. Therefore, it was essential to search and validate the performance of potential marking ink that would meet the standards in military applications.

Eleven …

Autonomous Close Formation Flight Of Small Uavs Using Vision-Based Localization, Michael B. Darling

Master's Theses

As Unmanned Aerial Vehicles (UAVs) are integrated into the national airspace to comply with the 2012 Federal Aviation Administration Reauthorization Act, new civilian uses for robotic aircraft will come about in addition to the more obvious military applications. One particular area of interest for UAV development is the autonomous cooperative control of multiple UAVs. In this thesis, a decentralized leader-follower control strategy is designed, implemented, and tested from the follower’s perspective using vision-based localization.

The tasks of localization and control were carried out with separate processing hardware dedicated to each task. First, software was written to estimate the relative state …

Applied Mass Properties Identification Method To The Cal Poly's Spacecraft Simulator, Long H. Dam

Master's Theses

The Cal Poly Spacecraft Simulator is currently being developed for future testing and verifying theoretical control applications. This paper details the effort to balance the platform and remove undesired external torque from the system using System Identification technique developed by Patrick Healy. Since the relationship between the input and output of the system is linear, the least square method is proposed to identify the mass properties and location of center of mass of the system. The tests use four sine wave generators that are out of phase with different amplitudes as the inputs to excite various structural modes of the …

On The Growth Rate Of Turbulent Mixing Layers: A New Parametric Model, Jeffrey L. Freeman

Master's Theses

A new parametric model for the growth rate of turbulent mixing layers is proposed. A database of experimental and numerical mixing layer studies was extracted from the literature to support this effort. The domain of the model was limited to planar, spatial, nonreacting, free shear layers that were not affected by artificial mixing enhancement techniques. The model is split into two parts which were each tuned to optimally fit the database; equations for an incompressible growth rate were derived from the error function velocity profile, and a function for a compressibility factor was generalized from existing theory on the convective …

Flight And Stability Of A Laser Inertial Fusion Energy Target In The Drift Region Between Injection And The Reaction Chamber With Computational Fluid Dynamics, Tiffany Leilani Mitori

Master's Theses

A Laser Inertial Fusion Energy (LIFE) target’s flight through a low Reynolds number and high Mach number regime was analyzed with computational fluid dynamics software. This regime consisted of xenon gas at 1,050 K and approximately 6,670 Pa. Simulations with similar flow conditions were performed over a sphere and compared with experimental data and published correlations for validation purposes. Transient considerations of the developing flow around the target were explored. Simulations of the target at different velocities were used to determine correlations for the drag coefficient and Nusselt number as functions of the Reynolds number. Simulations with different target angles …

Development Of Safety Standards For Cubesat Propulsion Systems, Liam Jon Cheney

Master's Theses

The CubeSat community has begun to develop and implement propulsion systems. This movement represents a new capability which may satisfy mission needs such as orbital and constellation maintenance, formation flight, de-orbit, and even interplanetary travel. With the freedom and capability granted by propulsion systems, CubeSat providers must accept new responsibilities in proportion to the potential hazards that propulsion systems may present.

The Cal Poly CubeSat program publishes and maintains the CubeSat Design Specification (CDS). They wish to help the CubeSat community to safety and responsibly expand its capabilities to include propulsive designs. For this reason, the author embarked on the …

Study The Effects Of Core Orientation And Different Face Thicknesses On Mechanical Behavior Of Honeycomb Sandwich Structures Under Three Point Bending, Joshua M. Lister

Master's Theses

This study will present the Experimental, numerical and analytical characterizations of composite sandwich structures needed to optimize structure design. In this study, the effects of varying honeycomb core ribbon orientation and varying face sheet thickness’s have on the flexural behavior of honeycomb sandwich structures was investigated. Honeycomb sandwich panels were constructed using Hexcel 6367 A250-5H carbon fiber face sheets and Hexcel Nomex HRH-10-1/8-5 honeycomb cores. The mechanical properties of the constituent materials were discovered experimentally using ASTM standards and theoretical models using honeycomb mechanics and classical beam and plate theory are described. A failure mode map for loading under three …

Investigation Into The Mitigation Of The Effects Of Uncertain Optical Degradation On An Interplanetary Solar Sail Mission Using A Single Model Update, Jordan Smiroldo

Master's Theses

The renewed academic interest in using solar sails as a source of spacecraft propulsion has been accompanied by a recent fervor of investigations into non-ideal and off-nominal sail performance considerations. One of the most influential considerations, uncertain optical degradation, has been shown to present significant trajectory design difficulties. This paper investigates the potential of using a mid-course degradation model update to mitigate the risk of missing the target destination in a sample 300 day Earth-Venus trajectory. Using a range of potential degradation profiles, it is shown that correcting in the first half of the mission is highly likely to result …

Analysis Of An Inflatable Gossamer Device To Efficiently De-Orbit Cubesats, Robert A. Hawkins Jr.

Master's Theses

There is an increased need for spacecraft to quickly and efficiently de-orbit themselves as the amount of debris in orbit around Earth grows. Defunct spacecraft pose a significant threat to the LEO environment due to their risk of fragmentation. If these spacecraft are de-orbited at the end of their useful life their risk to future spacecraft is greatly lessened. A proposed method of efficiently de-orbiting spacecraft is to use an inflatable thin-film envelope to increase the body's area to mass ratio and thusly shortening its orbital lifetime. The system and analysis presented in this project is sized for use on …

Adaptive Control Techniques For Transition-To-Hover Flight Of Fixed-Wing Uavs, Brian Decimo Marchini

Master's Theses

Fixed-wing unmanned aerial vehicles (UAVs) with the ability to hover combine the speed and endurance of traditional fixed-wing fight with the stable hovering and vertical takeoff and landing (VTOL) capabilities of helicopters and quadrotors. This combination of abilities can provide strategic advantages for UAV operators, especially when operating in urban environments where the airspace may be crowded with obstacles. Traditionally, fixed-wing UAVs with hovering capabilities had to be custom designed for specific payloads and missions, often requiring custom autopilots and unconventional airframe configurations. With recent government spending cuts, UAV operators like the military and law enforcement agencies have been urging …

Hollow Plume Mitigation Of A High-Efficiency Multistage Plasma Thruster, Scott Alan Mcgrail

Master's Theses

Since 2000, a relatively new electric thruster concept has been in research, development, and production at Thales Electron Devices in Germany. This High Efficiency Multistage Plasma Thruster, or HEMPT, has promising lifetime capabilities due to its plasma confinement system. However, the permanent magnet system that offers this and other benefits also creates a hollow plume, where ions are accelerated at angles rather than up the thruster centerline, causing a dip in ion current along the centerline. A laboratory model, built at JPL, was run at Cal Poly to characterize this plume shape and implement a shield to restore a conical …

Numerical Flow Field Analysis Of An Air Augmented Rocket Using The Axisymmetric Method Of Characteristics, Jeffrey Massman

Master's Theses

An Axisymmetric Rocket Ejector Simulation (ARES) was developed to numerically analyze various configurations of an air augmented rocket. Primary and secondary flow field visualizations are presented and performance predictions are tabulated. A parametric study on ejector geometry is obtained following a validation of the flow fields and performance values.

The primary flow is calculated using a quasi-2D, irrotational Method of Characteristics and the secondary flow is found using isentropic relations. Primary calculations begin at the throat and extend through the nozzle to the location of the first Mach Disk. Combustion properties are tabulated before analysis to allow for propellant property …

Mode I Fracture Toughness Of Eight-Harness-Satin Carbon Cloth Weaves For Co-Cured And Post-Bonded Laminates, Josh E. Smith

Master's Theses

Mode I interlaminar fracture of 3k 8-Harness-Satin Carbon cloth, with identical fill and weft yarns, pre-impregnated with Newport 307 resin was investigated through the DCB test (ASTM D5528). Crack propagations along both the fill and weft yarns were considered for both post-bonded (co-bonded) and co-cured laminates. A patent-pending delamination insertion method was compared to the standard Teflon film option to assess its applicability to mode I fracture testing. The Modified Beam Theory, Compliance Calibration method, and Modified Compliance Calibration method were used for comparative purposes for these investigations and to evaluate the validity of the proposed Equivalent Stiffness (EQS) method. …

Computational And Experimental Comparison Of A Powered Lift, Upper Surface Blowing Configuration, Jay M. Marcos

Master's Theses

In the past, 2D CFD analysis of Circulation Control technology have shown poor comparison with experimental results. In Circulation Control experiments, typical results show a relationship between lift coefficient, CL, vs blowing momentum coefficient, Cμ. CFD analysis tend to over-predict values of CL due to gridding issues and/or turbulence model selection. This thesis attempted to address both issues by performing Richardson’s Extrpolation method to determine an acceptable mesh size and by using FLUENT’s 2-equation turbulence models. The experimental results and CAD geometry were obtained from Georgia Tech Research Institute for comparison with the CFD analysis.

The study showed that 3D …