Aerospace Engineering Commons^™

Linear Covariance Analysis For Gimbaled Pointing Systems, Randall S. Christensen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Linear covariance analysis has been utilized in a wide variety of applications. Historically, the theory has made significant contributions to navigation system design and analysis. More recently, the theory has been extended to capture the combined effect of navigation errors and closed-loop control on the performance of the system. These advancements have made possible rapid analysis and comprehensive trade studies of complicated systems ranging from autonomous rendezvous to vehicle ascent trajectory analysis. Comprehensive trade studies are also needed in the area of gimbaled pointing systems where the information needs are different from previous applications. It is therefore the objective of …

Design Practice, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Design Practice" on July 30, 2013.

Power Storage & Control, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Power Storage & Control" on July 30, 2013.

Overview Of Eps, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on an "Overview of EPS" on July 30, 2013.

Power Sources, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Power Sources" on July 30, 2013.

Computing Radiation Exchange, Jonathan L. Nutzati Fontaine

Doctoral Dissertations and Master's Theses

A computational tool to simulate thermal radiation between surfaces is developed. The output is verified against cases for which the analytical solutions are available. The tool can be used as a stand-alone program, or as an interactive module for CFD. In such an application the module would augment other heat transfer boundary conditions. The tool is demonstrated by post-processing surface temperature field data from a supersonic CFD calculation. The result is a net thermal radiation surface data field - the black body radiative effluxes as functions of temperature, less the integrated influxes multiplied by their geometric view factors from other …

More Effective Human Spaceflight Programs And Their International Security Implications, Bert Chapman, Sarag J. Saikia

Libraries Faculty and Staff Scholarship and Research

NASA can more effectively perform its missions by transferring its aeronautic responsibilities to the Federal Aviation Administration and be renamed the National Space Agency. The U.S. must also recognize that space is an emerging arena of international competition and conflict and militarily protect its space assets from China which seeks to use space to restrict the U.S.' ability to defend its strategic interests in regions such as the Western Pacific.

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 …

Simulations Of Ion Thruster Plume Contamination With A Whole Grid Sputtered Mo Source Model, Daoru Frank Han, Joseph J. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A particle simulation based source model is developed to calculate the density distribution of the sputtered Mo atoms for a whole ion optics grid. The source model is used in PIC simulation of ion thruster plume contamination for 3-grid and 2-grid ion thrusters. The results show that the commonly used point-source approximation for sputtered Mo atoms is oversimplified and would lead to over-prediction of contamination deposition.

Improving Affordability: Separating Research From Development And From Design In Complex Programs, Bohdan W. Oppenheim

Systems Engineering Faculty Works

This paper presents arguments for why defense programs creating physical systems should clearly separate three developmental phases from each other: research, development and design. Research is to be performed first by small teams of scientists addressing the "unknown unknowns" and maturing fundamental science from TRL of 1 to about 3. Next, development of physical modules is to be performed by small and highly specialized engineers. Finally, the system-level design should focus on efficient trading off the module locations, sizes and shapes versus system performance, mass, power requirements, etc. The design with all modules mature and available is equivalent to a …

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 …

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 …

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 …

Design Advantages Of Skin Friction Drag Reduction Using Riblets, John Michael Gregory

Mechanical & Aerospace Engineering Theses & Dissertations

The research reported here has examined the potential improvements in overall aircraft performance that can result from integrating skin friction reduction technology, such as riblets, early in the aircraft design cycle. This study has shown that riblets can improve the payload capacity, increase the range, and improve performance of transport aircraft. If recent advances in fabrication techniques make it possible to create aluminum wing surfaces with integral riblet geometries, the applications could be widespread and the gains significant.

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 …

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 …