Aerospace Engineering Commons^™

Slipstream Measurements Of Small-Scale Propellers At Low Reynolds Numbers, Robert W. Deters, Gavin K. Ananda, Michael S. Selig

Publications

The continuing growth in the use of small UAVs has required the need to more fully understand the propellers that power them. Part of this understanding is the behavior of the propeller slipstream. Using a 7-hole probe, the slipstreams of several small-scale propellers (diameters of 4.2, 5, and 9 in) were measured in both static (V∞ = 0) and advancing-flow (V∞ > 0) conditions at several locations downstream. For static conditions, as the slipstream expanded downstream, the maximum values of the axial and swirl velocities decreased. The general shape of the static slipstream was also found to be nearly the same …

The “Stratospheric Cricket Keeper” – Developing A Simple“Life-Support” Payload For High-Altitude Balloon Missions, Lucas Kramer, Chad Serba, James Flaten

2017 Academic High Altitude Conference

Exposure to the environmental conditions of “near-space” (AKA the stratosphere) is quickly fatal to nearly all forms of animal life. It is even challenging to build a sealable enclosure that can keep insects (crickets) alive through the dramatic and simultaneous pressure and temperature drops experienced during a high-altitude balloon mission. This poster describes the development of a rugged “cricket keeper” in which we were able to fly crickets to the stratosphere and, quoting the words of JFK, “return (them) safely to the earth!” This “life-support” payload had large windows (for the view!) and included Arduino-logged temperature and pressure sensors, an …

Using Tank Pressure To Determine The Lift Of A Balloon, Sarah M. Biver

2017 Academic High Altitude Conference

An important aspect of high altitude ballooning is accuracy regarding the calculation of helium inflation in the balloon. If the balloon is over-filled it will increase rapidly in velocity and burst too quickly to record data. If the balloon is under-filled the rate of ascension will be too slow or not at all. This paper highlights the importance of accuracy in helium inflation by examining a method that uses pressure to control the inflation of a high altitude balloon. On every helium tank there is a pressure gauge, which can be used to monitor the change in pressure. Using that …

Parafoil Recovery Of A High Altitude Balloon Payload, Chelsea Velasquez, Zachariah Benedict

2017 Academic High Altitude Conference

The Recovery Guidance System is a subproject of Iowa State Universities’ High Altitude Ballooning Experiments in Technology (HABET) group. The system is designed to avoid common hazards during descent including large area objects such as populated areas and roadways, as well as smaller objects such as trees in a field, with an accuracy within tens of meters. RGS provides guidance for the payload using a two servo system aboard the payload in conjunction with GPS and radio communication. Navigation will be handled by a mixture of GPS and video analysis. For guidance, only longitudinal and directional dynamics of the payload-parafoil …

Autonomous Altitude Control Device For Latex Hab, John W. Siepierski

2017 Academic High Altitude Conference

The advent of latex High Altitude Balloons has dramatically reduced the costs associated with conducting research at altitudes reaching the stratosphere. Latex balloons are less expansive than zero-pressure and super-pressure alternatives, but they have an important disadvantage: while zero-pressure and super-pressure balloons can float at a desired altitude for long periods of time, latex balloons ascend continuously, flying only around two hours before reaching a bursting altitude (usually around 100,000 ft) and falling back to earth. Enabling latex High Altitude Balloons to float at a constant altitude for extended (and specifically defined) periods of time could make them significantly more …

A Methodology For The Optimization Of Disaggregated Space System Conceptual Designs, Robert E. Thompson

Theses and Dissertations

Optimal design techniques have proven to be an effective systems engineering tool. Using systems architecture as the foundation, this research explores the use of mixed variable optimization models for synthesizing and evaluating disaggregated space system concepts. Model-based conceptual design techniques are used to identify and assess system architectures based upon estimated system cost, performance trades, and cost risk. The Disaggregated Integral System Concept Optimization (DISCO) methodology is introduced, and then applied to representative space-based missions. Several results are obtained that indicate significant cost effectiveness gains from the optimization of multi-orbit and multi-function/multi-orbit disaggregated space systems. The general methodology has broad …

Simulation Of Metal Particulates In High Energetic Materials, Eduardo Nieto

Theses and Dissertations

This research focused on analyzing the effects of aluminum in high explosives such as PBX9501 using the MPEXS computational simulation code for a wide range of metalized explosive cases. The varying parameters are aluminum particle diameter and mass fraction of aluminum. The addition of metal particulates in explosive mixtures increases the density of the shock wave, causing a higher pressure in the shock. It was concluded that pressure and density steadily increases as the Al particle diameter increases, and pressure and density decreases when Al mass fraction increases. The concentrated pressures will dissipate quickly due to the high density, providing …

Creep Of Sylramic-Ibn Fiber Tows At Elevated Temperature In Air And In Silicic Acid-Saturated Steam, Kevin B. Sprinkle

Theses and Dissertations

Stressed oxidation experiments on Sylramic-iBN fiber tows were performed to evaluate the novel fiber's mechanical performance, creep behavior, and creep mechanisms. This research effort investigated creep response of Sylramic-iBN fiber tows at elevated temperatures in both air and in silicic acid-saturated steam environments. Creep experiments were conducted at creep stresses ranging from 127 to 762 MPa at 400°C and 500°C in order to examine the mechanical behavior of the Sylramic-iBN fiber tows at temperatures below and above the melting point of boria (450°C). Sylramic-iBN fibers are known to have excellent creep resistance, better than most other non-oxide fibers and significantly …

Topology Optimization Of An Aircraft Wing, David L. Walker

Theses and Dissertations

A Topology Optimization (TO) was conducted on an aircraft wing in order to mathematically determine an ideal structural case for future aircraft. TO generally involves iteratively reducing individual elemental density until the desired mass or volume constraint is met. Two different TO styles where approached: a global three-dimensional concept and a more traditional two-dimensional rib and spar optimization which more closely mimics the baseline model. All optimizations were compared against a baseline wing for von-Mises stress, displacement, and buckling. The objective of this research was to develop a design procedure maintaining the baseline structural integrity of the wing while reducing …

Exhaust Composition In A Small Internal Combustion Engine Using Ftir Spectroscopy, Kevin P. Horn

Theses and Dissertations

The mission-specific needs of small, remotely piloted aircraft demand lighter, more efficient engines with increased performance for their propulsion systems. A wide range of experimental efforts were undertaken to further the ability to obtain performance data on small engines as well as to develop understanding of their operation. Data were collected to quantify friction losses present in the dynamometer drivetrain on the small engine research bench. A correction and calibration model was developed for brake power collected by the dynamometer. Mechanical efficiencies for 28 cm3, 55 cm3 and 85 cm3 engines were 92.4%, 91.3% and 89.7%, respectively. Maximum fuel conversion …

Modal Characterization Of A Piezoelectric Shaker Table, Randall J. Hodkin

Theses and Dissertations

Piezoelectric actuated shaker tables are often used for high frequency fatigue testing. Since natural frequencies can appear in the operating range of these shaker tables, it is necessary to conduct modal characterization of the system before testing. This thesis describes the design and experimental validation of a mechanical model used for modal analysis of a piezoelectric shaker table. A commercially available three-dimensional scanning device was used to produce a point cloud model of the surface geometry, which was converted to a solid model and imported into a Finite Element Analysis (FEA) package for modal analysis. Using a laser vibrometer to …

Orbit Estimation Of Non-Cooperative Maneuvering Spacecraft, Gary M. Goff

Theses and Dissertations

Due to the ever increasing congestion of the space environment, there is an increased demand for real-time situation awareness of all objects in space. An unknown spacecraft maneuver changes the predicted orbit, complicates tracking, and degrades estimate accuracies. Traditional orbit estimation routines are implemented, tested, and compared to a multiple model format that adaptively handles unknown maneuvers. Multiple Model Adaptive Estimation is implemented in an original way to track a non-cooperative satellite by covariance inflation and filtering-through a maneuver. Parameters for successful instantaneous maneuver reconstruction are analyzed. Variable State Dimension estimation of a continuously maneuvering spacecraft is investigated. A requirements …

Effect Of Prior Exposure At Elevated Temperatures On Tensile Properties And Stress-Strain Behavior Of Four Non-Oxide Ceramic Matrix Composites, Sarah M. Wallentine

Theses and Dissertations

Thermal stability of four non-oxide ceramic matrix composites was studied. The materials studied were commercially available composites: SiC/SiNC; C/SiC; C/SiC-B4C (C/HYPR-SiC^TM); and SiC/SiC-B4C (SiC/HYPR-SiC^TM). COI Ceramics manufactured the SiC/SiNC and C/SiC composites using polymer infiltration and pyrolysis (PIP). The C/HYPR-SiC^TM and SiC/HYPR-SiC^TM CMCs were manufactured by Hyper-Therm High-Temperature Composites using chemical vapor infiltration (CVI). All four composites rely on a dense matrix for strength, stiffness, and oxidation protection. Fiber coating provides a fiber-matrix interface that allows fiber-matrix debonding and fiber pullout to occur, imparting fracture toughness to the CMC. The SiC/SiNC, C/SiC, and C/HYPR-SiC …

Brief Look At The Environment Of Space, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Brief Look at the Environment of Space" from June 17, 2015.

Cooperative 3-D Map Generation Using Multiple Uavs, Andrew Erik Lawson

University Scholar Projects

This report aims to demonstrate the feasibility of building a global 3-D map from multiple UAV robots in a GPS-denied, indoor environment. Presented are the design of each robot and the reasoning behind choosing its hardware and software components, the process in which a single robot obtains a individual 3-D map entirely onboard, and lastly how the mapping concept is extended to multiple robotic agents to form a global 3-D map using a centralized server. In the latter section, this report focuses on two algorithms, Online Mapping and Map Fusion, developed to facilitate the cooperative approach. A limited selection …

Tuning And Measuring Trap Shape For Cold Atom Sensors, James A. Stickney

Space Dynamics Laboratory Publications

Table of Contents

1. Tuneable atom chip
2. Cloud sloshing in a weakly non-harmonic trap
3. Data

Automatic Building Change Detection In Wide Area Surveillance, Paheding Sidike, Almabrok Essa, Fatema Albalooshi, Vijayan K. Asari, Varun Santhaseelan

Electrical and Computer Engineering Faculty Publications

We present an automated mechanism that can detect and characterize the building changes by analyzing airborne or satellite imagery.

The proposed framework can be categorized into three stages: building detection, boundary extraction and change identification. To detect the buildings, we utilize local phase and local amplitude from monogenic signal to extract building features for addressing issues of varying illumination. Then a support vector machine with Radial basis kernel is used for classification. In the boundary extraction stage, a level-set function with self-organizing map based segmentation method is used to find the building boundary and compute physical area of the building …

Effect Of Time Delay Between Etching And Adhesive Bonding (“Outlife” Time) On Lap-Shear Strength Of Aluminum Alloys Using Environmentally-Friendly P2 Etch, Josh Barkhimer, Matthew Erich, Gokul Nair

Materials Engineering

Raytheon Company currently uses a Forest Products Laboratory (FPL) paste etchant for preparing aluminum surfaces for adhesive bonding, and FPL is a source of hazardous hexavalent chromium. The goal of this study was to evaluate a less-toxic P2 paste etchant as a possible replacement. Coupons of 2024-T3, 6061-T6, and 7075-T6 grades of aluminum alloy were solvent-degreased, abrasively cleaned, and etched at room temperature using P2 paste following a strict protocol adopted from Raytheon. Coupons were then left exposed to air for assigned time intervals (or “outlife” times) of 0, 1, 4, 8, 16, and 63 or 72 hours. The aluminum …

Characterization Of Laser Deposited Ti-6al-4v To Nb Gradient Alloys, Clincy Cheung

Materials Engineering

An alloy was fabricated with Ti-6Al-4V and Nb powder using laser deposition (LD) to form a compositional gradient. The gradient was deposited, starting with Ti-6Al-4V powder, onto a forged Ti-6Al-4V substrate in an Argon environment. Niobium (Nb) composition increased by 4-at.% with each layer deposited until the composition reached 100-at.% Nb. This process yielded steep thermal gradients and affected the microstructure and mechanical properties across the compositional gradient. To observe the microstructural changes in the alloy, an etched gradient was viewed with optical microscopy at 1000x, where the grain structure was observed to be an acicular α phase at 100-at.% …

A Customer Value Assessment Process (Cvap) For Ballistic Missile Defense, Alex Hernandez

Master's Theses

A systematic customer value assessment process (CVAP) was developed to give system engineering teams the capability to qualitatively and quantitatively assess customer values. It also provides processes and techniques used to create and identify alternatives, evaluate alternatives in terms of effectiveness, cost, and risk. The ultimate goal is to provide customers (or decision makers) with objective and traceable procurement recommendations. The creation of CVAP was driven by an industry need to provide ballistic missile defense (BMD) customers with a value proposition of contractors’ BMD systems. The information that outputs from CVAP can be used to guide BMD contractors in formulating …