Aerospace Engineering Commons^™

Control Design And Implementation For An Autonomous Surface Vehicle Using Azimuth Thrusters, Stanton James Coffey

Mechanical & Aerospace Engineering Theses & Dissertations

Autonomous Surface Vehicle research for water applications is inspired by a technological push to create more automated robotics that can perform functions too menial for a human to spend time on as well as too complex, difficult, or dangerous for a person to perform. The development objective is to construct, program, and test an autonomous surface vehicle that can perform precision hold maneuvers independent of human control. This capability would be useful in many situations where it is desirable to freeze the current position of the boat in order to perform some duty task. To conduct the research for this …

Microphone-Based Pressure Diagnostics For Boundary Layer Transition, Spencer Everett Lillywhite

Master's Theses

An experimental investigation of the use low-cost microphones for unsteady total pressure measurement to detect transition from laminar to turbulent boundary layer flow has been conducted. Two small electret condenser microphones, the Knowles FG-23629 and the FG-23742, were used to measure the pressure fluctuations and considered for possible integration with an autonomous boundary layer measurement system. Procedures to determine the microphones’ maximum sound pressure levels and frequency response using an acoustic source provided by a speaker and a reference microphone. These studies showed that both microphones possess a very flat frequency response and that the max SPL of the FG-23629 …

Use Of A Rolling Road System In Crosswind Conditions, Mau-Kuo Chen

Mechanical & Aerospace Engineering Theses & Dissertations

Wind tunnel testing continues to play an important role in vehicle aerodynamic development. Accurate results are strongly associated with whether the wind tunnel can closely simulate the on-road conditions, including the Reynolds number and all boundary conditions. Rolling road systems (or moving belts) have been a successful tool for many auto makers and racing teams to simulate the relative motion between the stationary vehicle model and the floor in the test section. The mechanism of the rolling road system is simple, but how it affects the adjacent flow field and how this flow interacts with the flow underneath the vehicle …

Active-Twist Rotor Blades Design, Analysis, And Testing, Andrew Randall Kreshock

Mechanical & Aerospace Engineering Theses & Dissertations

The subject of this thesis is the design, analysis, and experimental assessment of active-twist rotors. These active rotors use piezoelectric actuators embedded in the skins to twist the blade to reduce vibratory loads in the fixed system. First, the design and optimization of the twist response within the geometric and structural constraints of a rotor blade is presented. A parametric analysis is conducted varying the airfoil thickness, active-material placement, and structural plies to determine the maximum static twist response. A Macro-Fiber Composite (MFC), which is a fibrous piezoelectric device is used as the active material. Analyses of the cross-section are …

Conceptual Design Of A Reusable Mars Aircraft, Bryce L. Horvath

Mechanical & Aerospace Engineering Theses & Dissertations

This study assumes that the launch vehicles and precision Mars entry descent and landing systems, required for eventual crewed missions to the surface, have been developed, motivating the rapid build-up of a fixed surface base to enable extended human stays. During the time interval between the first successful placement of a heavy (between 20 and 80 metric ton) payload and completion of the baseline human-rated Mars outpost, it will be possible to utilize this large payload delivery capability to accelerate robotic exploration of the surface from the fixed base location.

One element of such an expanded robotic exploration program will …

Creating Exact Bezier Representations Of Cst Shapes, David D. Marshall

Aerospace Engineering

The paper presents a method of expressing CST shapes pioneered by Kulfan into standard Bezier curves and surfaces. Out of the seven standard shape classes identified by Kulfan as representable using CST curves, four of them, including airfoils, can be represented as Bezier curves exactly. For the other three, a convergent series expansion proves insufficient to achieve any practical accuracy, however these three classes are not the most commonly used of the CST classes. With the ability to express most common CST curves and surfaces as generic Bezier curves and surfaces, CST shapes can be used in CAD, solid modeling, …

Crack Initiation And Growth Behavior At Corrosion Pit In 7075-T6 High Strength Aluminum Alloy, Eric M. Hunt

Theses and Dissertations

Research on fatigue crack formation from two types corrosion pits tangent to a circular hole in a 7075-T6 aluminum alloy subjected to uni-axial loads (R = 0.5, lambda = 0) in both an air and saltwater environment provides a method for exploring crack initiation and initial growth rates. This work focuses on a fracture mechanics approach to explore the transition from corrosion pit to crack growth. Specimens with a cylinder shaped through-pit tangent to a circular hole have a closed form solution to predict this delta K that closely resembles the finite element solutions. Specimens with a semi-circular corner-pit tangent …

Design Of A Lighter Than Air Vehicle That Achieves Positive Buoyancy In Air Using A Vacuum, Trent T. Metlen

Theses and Dissertations

Three designs for a Lighter Than Air (LTA) structure that achieve positive buoyancy using a vacuum in place of a lifting gas were proposed and evaluated. The ratio of structure weight to the weight of displaced air was termed Weight/Buoyant Force (W/B) where a W/B1 corresponds to positive buoyancy. Two methods of geometrically stiffening a sphere were investigated and their W/B evaluated. A thin shelled sphere of beryllium stiffened with an isogrid of blade type stiffeners using Ultra High Modulus (UHM) carbon epoxy was predicted to give a W/B= 0.79. A geodesic sphere composed of a frame of cylindrical, UHM, …

Kysat-2 Electrical Power System Design And Analysis, Brandon L. Molton

Morehead State Theses and Dissertations

A Thesis Presented to the Faculty of the College of Science & Technology Morehead State University in Partial Fulfillment of the Requirements for the Degree Master of Science by Brandon L. Molton on June 4, 2013.

Control System Infrastructure For The Cal Poly Human Powered Helicopter: Upturn Ii, Douglas A. Thornber, Samuel J. Wahyou

Aerospace Engineering

The Upturn was donated to Cal Poly in October 2012 by Neal Saiki from NTS. Our project was to replicate the old system to decrease the turn-around time in case of a crash during a test flight. The control system for the Upturn II was designed with the same considerations that were used for the Upturn. The result we got was inconclusive for the sensor selection, the new control system is heavier than the old system, and we couldn’t validate the system without doing a flight test. For the next iteration if some of the replication requirements are relaxed the …

Ramjet Combustion Chamber, Paul Cameron Stone

Aerospace Engineering

A ramjet combustion chamber is designed and some initial assembly fabrication and test completed as a component of a ramjet graduate project for California Polytechnic State University, San Luis Obispo Supersonic Wind Tunnel. The combustor design is driven by a theoretical model created by a Cal Poly graduate student, Harrison Sykes. Temperature, pressure, and fuel flow will be measured.

The Effects Of Fabrication Methods And Cure Cycle On The Mechanical Properties Of Carbon Fiber Laminate In Tensile And 3-Point Bend Testing, Adriano Agostino

Aerospace Engineering

This project was completed at the California Polytechnic State University, San Luis Obispo Aerospace Engineering Structures and Composites Lab during Spring Quarter 2013. The purpose of this project was to research and to gain insight into the effects of fabrication methods and of modifying cure cycles for Newport NB-301 12l 2x2 Twill Weave Carbon Fiber material properties. The two fabrication methods used were autoclave and heat press (compression molding) methods. Each fabrication method used two cure cycles, a recommended cure cycle of 275°F for 1 hour and a modified cure cycle of 250°F for 1.5 hours. The exact product data …

Design And Fabrication Of A Ramjet Engine, Clinton C. Humphrey

Aerospace Engineering

In this report, the design and fabrication of the inlet to a ramjet engine is described. The inlet utilizes a single ramp and single sided three shock internal compression to slow the airflow from supersonic to subsonic speeds while providing maximum stagnation pressure to the combustor. The optimum angle for the inlet ramp is calculated to be 10° and it decelerates the airflow from Mach 3.3019 to Mach 0.5438. The stagnation pressure increases from 150 psi to 4.67 ksi. The material of the inlet is composed primarily of low carbon mild steel to accommodate the high pressure of the inlet.

Feasibility Of Cubesat Formation Flight Using Rotation To Achieve Differential Drag, Skyler M. Shuford

Aerospace Engineering

This paper presents the results of a study conducted to understand the feasibility of CubeSat formation flight. The mechanism for separation and formation studied was differential drag, achieved by rotating the CubeSats to give them different cross-sectional areas. Intuitively, lower altitude orbits provide much higher separation effects. Although the most influential orbital effects occur with maximum and minimum cross-sectional areas, an attitude-controlled and a tumbling CubeSat may provide enough differential drag to meet separation requirements of a mission. Formation flight is possible, but due to the non-linearity of the system, gain scheduling may be the most effective method of long …

Proof Of Concept For Propeller Performance Testing In The Cal Poly Wind Tunnel, Alex N. May, Clayton R. Green, Clinton J. Kirsop, Jason A. Schupp

Aerospace Engineering

The goal of this experiment was to execute a proof of concept for a potential propulsion systems laboratory. During the course of this experiment, a data acquisition system was designed, built, and tested in order to collect data from the Cal Poly 3x4 ft draw-down wind tunnel. By operating a brushless outrunner motor and propeller on the sting mount, data was collected for thrust, torque, RPM, current, voltage, and tunnel velocity. By obtaining data for each of these performance metrics, trends were analyzed to confirm the concept and apparatus was functional. The results of the experiment revealed that the concept …

Nozzle Design For The Supersonic Wind Tunnel Ramjet Attachment, Andrew Michael Carter

Aerospace Engineering

This document outlines the concept, design, and manufacturing stages of the nozzle section to the Ramjet Attachment. This project is a subsidiary of the thesis, Baseline Performance of Ramjet Engine”, developed by Harrison Sykes. The nozzle geometry is based off of theoretical calculations using Isentropic and Rayleigh line flow relations for a two-dimensional cross section. The nozzle sees an inlet temperature of 953 degrees Fahrenheit, pressure of 28 psi, and a Mach number of 0.356 after the combustion chamber. The nozzle section is a two foot long converging diverging nozzle to choke and accelerate the flow to achieve an exit …

Redesigned Aerospace Control System Platform For Laboratory Re-Purposing, Ryan W. Moskaluk

Aerospace Engineering

This senior project encompasses using an aircraft model in conjunction with the 3' by 4' low speed wind tunnel at Cal Poly San Luis Obispo. The aircraft model is controlled through piezoelectric actuators embedded inside the flexible tail structure via a PID controller. The objective for this project is to demonstrate the effect of tuning the individual PID controller gains with the aircraft model inside the low speed wind tunnel and to create an easy to use graphical user interface for doing so.

Coupled Flow Field Simulations Of Charring Ablators With Nonequilibrium Surface Chemistry, Hicham Alkandry, Iain D. Boyd, Alexandre Martin

Mechanical Engineering Faculty Publications

This paper describes the coupling of a Navier-Stokes solver to a material response code to simulate nonequilibrium gas-surface interactions. The Navier-Stokes solver used in this study is LeMANS, which is a three-dimensional computational fluid dynamics code that can simulate hypersonic reacting flows including thermo-chemical nonequilibrium effects. The material response code employed in this study is MOPAR, which uses the one-dimensional control volume nite-element method to model heat conduction and pyrolysis gas behavior. This coupling is demonstrated using a test case based on the Stardust sample return capsule. Coupled simulations are performed at three different trajectory conditions. The effects of the …

A New Approach To Light-Weight Ablators Analysis: From Micro-Tomography Measurements To Statistical Analysis And Modeling, Nagi N. Mansour, Francesco Panerai, Alexandre Martin, Dilworth Y. Parkinson, Alastair A. Macdowell, Abdelmoula Haboub, Timothy A. Sandstrom, Tony Fast, Gerard L. Vignoles, Jean Lachaud

Mechanical Engineering Faculty Publications

The morphology characteristics and ablation behavior of a highly porous carbon fiber preform are studied using a combined experimental/numerical approach. Morphological characterization of the three-dimensional structure of the material is performed by hard X-rays synchrotron micro-tomography at the Advanced Light Source of Lawrence Berkeley National Laboratory. The resulting micro-tomography voxels are used to compute geometrical properties of the carbon preform, like porosity, specific surface area and tortuosity, that are otherwise indirectly measured through experimental techniques. The reconstructed volumes are used to build a computational grid for numerical simulations of the fibers' ablation. By modeling the diffusion of oxygen through the …

Volume Averaged Modeling Of The Oxidation Of Porous Carbon Fiber Material, Alexandre Martin

Mechanical Engineering Faculty Publications

Charring ablators remain the premium choice for space exploration missions that involve atmospheric re-entry. This type of ablative material is composed of a carbon matrix, usually made of fibers, which is then impregnated with a resin. During re-entry, the high heat flux produced by convective heating causes the material to chemically react. First, the resin pyrolyzes, and is vaporized into a gas that travels through the material, and is eventually ejected at the surface. Then, as the temperature rises, the surface of the porous matrix recess through ablative processes. For re-entry conditions typical of space exploration missions, this is mainly …