The AE Brown Bag Lecture Series is a Daniel Guggenheim School tradition: select AE undergrads and grad students share their research before an audience that includes their peers and academic advisors. If you would like to present a Brown Bag, speak with your advisor or contact faculty coordinator, Michelle Hall to schedule.
COVID-19 Programming Adjustment
Most Fridays during the Spring 2021 Semester, we will host 2 Brown Bag presentations, beginning at 12:30 p.m. EST. They will be viewable from your laptop via BlueJeans. If you are not able to attend, you may view a video recording of the presentation by clicking on the presentation title, below.
"Electrical Topology for eVTOL Concept"
The primary focus of this presentation is the development of the electrical topology for a multi-rotor eVTOL aircraft. Motor and battery type and number were already chosen based on powertrain needs. Given the powertrain, the electrical topology is designed to enable safety and low weight. The first important consideration for safety is isolation of motors from one another such that if any component of the powertrain (battery, motor, or inverter) fails, only the opposite motor is potentially affected, preventing failure propagation. Another important safety consideration is ensuring that, in the event of a failure in a circuit, the aircraft continues to maintain full flight control. This is achieved through servos capable of accepting redundant power drawing from two isolated circuits. In addition, servos with redundant motors allow for maintaining control if a servo motor fails. In order to reduce the weight of the circuitry, the power to the ailerons and flaps is carried by the same wires as the power to the motors until near the actuators, where the wires are branched and a DC/DC converter drops the voltage from the motor voltage to the actuator voltage. For actuators that are distant from any motors, such as actuators for tail control surfaces, the DC/DC converter drops the voltage near the batteries, minimizing the wire gauge required to carry power to the actuator.
"SAE Aero Design: Developing a Highly Competitive System of Systems"
For the past 6 years, Georgia Tech has taken first place at the annual SAE Aero Design Advanced Class competition. The competition objectives are inspired by a Mars colonization mission and tasks teams with prototyping and flying an aircraft capable of accurately dropping water bottles, Nerf Aero Howlers, and autonomous gliders into a 50’ target. The aircraft is subjected to a 11’ maximum wingspan and a 750W power limit. Each glider must carry as many “colonists” (represented by table tennis balls) as possible, glide to and land autonomously within the target zone, and weigh less than 9 oz. Score is determined by payload quantity as well as an optimum ratio between the three types of payload delivered.
The iterative design process includes but is not limited to aircraft sizing, aerodynamics analysis, structural analysis, propulsion system selection, and systems testing. The analysis, modeling, manufacturing, and testing methods refined over multiple years have contributed to overall success. Constant flight testing and a history of learning from failure leads not only to a reliable aircraft system but also to a body of adept students that can compete with confidence. Lastly, a constant cycle of peer student-to-student mentoring ensures continued improvement of the team’s ability to design, build, and fly aircraft rapidly.
"2D Automatic Table Generation"
Having multiple parameters and being able to get a solution for an unknown in real time is crucial in fields where this information can be used to make split second decisions. The automatic generation of a 2D table allows for adaptive updates to take place throughout the entire procedure/mission. These computations happen in a continuous manner where the table is updated rather than recomputed. This presentation highlights the iterative methods used to generate the table.
"Development of a Cold-Gas Thruster Component Testbed"
The volumetric constraints of small-satellites, specifically CubeSats, limit the availability of propulsion systems for small-satellite missions. The Lightsey Research Group in the GT Space Systems Design Lab develops custom cold gas thrusters for small-satellite missions, making use of additive manufacturing to integrate the main tank, plenum tank, nozzles, and tubing into one monolithic structure that optimally uses the available volume. However, the compact design significantly limits the ability to test individual components, particularly the solenoid valves and their electronic controller. A scaled-up model of the cold-gas system would allow for simple testing of components along with measurement of pressure and temperature at intermediate points in the flow path. This presentation will discuss the design, development, and upcoming testing of an expanded cold-gas thruster component testbed.
Current Mars entry missions use a rigid thermal protection system, which is limited in diameter by the payload fairing of the launch vehicle. To account for the larger payload masses and decelerator surface areas required for future surface missions, NASA has conducted studies into Hypersonic Inflatable Aerodynamic Decelerators (HIADs), which allow large decelerators to be packaged into small volumes. However, HIADs require a flexible thermal protection system (FTPS), which is currently at a low TRL and requires high-fidelity modeling prior to full-scale system testing. This presentation includes the Martian atmospheric entry trajectory modeling for HIAD use cases, stagnation point heat flux calculation for a given trajectory, and the preliminary modeling of FTPS layups to determine the necessary material thicknesses for a given entry trajectory.
Interest in small satellites, specifically CubeSats, has surged in recent years as they offer opportunities to conduct scientific investigations and technology demonstrations in space in such a way that is cost-effective, timely and relatively easy to accomplish. GT-1 is a student-led 1-U CubeSat mission being developed in the Space Systems Design Laboratory with a goal of developing a fully functioning and robust spacecraft bus to be implemented on future GT series CubeSat missions designed to operate in Low Earth Orbit. A critical feature of the spacecraft bus is the UHF antenna and solar panel deployment mechanisms. The small form factor of the 1-U CubeSat (10cm×10cm×10cm) imposes several constraints on such deployment mechanisms and therefore require unique solutions to meet the mission requirements. This presentation aims to explain the development and decision-making process involved in designing, manufacturing, testing, and integrating the deployment mechanisms including the problems encountered and the lessons learned throughout the past year
Isaac Del Valle
Tensegrity, a term derived from tensional integrity, refers to a specific class of structures composed of rigid bars and cables. When these bars and cables are connected to each other, they form a lattice-type structure which is capable of undergoing severe deformation due to the buckling of its bars. Utilizing the ability to deform or compress, a tensegrity lattice demonstrates advantageous characteristics as a rover for micro or low gravity environments, including being robust to failure, impact tolerant, and capable of energy efficient modes of locomotion. This presentation highlights the manufacturing processes used to build tensegrity structures, as well as the methods that have been employed to provide locomotion to a tensegrity lattice for future planetary exploration.
One of the recent areas of focus in aerospace has been the use of Model-Based Systems Engineering approaches to aid in the system engineering process. This talk will give an overview of the application, benefits, and limitations of MBSE to modeling aspects of an unmanned mars mission system using SysML in MagicDraw. This includes modeling aspects such as requirements, system structure and hierarchy, and parametric analysis. Additionally, this talk will also briefly discuss the aerodynamic and trajectory analysis code developed for planetary entry as well as the current limitations of MATLAB integration within MagicDraw.
"Conceptual Design and Data Visualizations for Georgia Tech Interuniversity Mission Operations Control Center (GTMOCC) for Cubesat Missions"
As Georgia Tech expands its space systems capabilities with current and planned future Cubesat Missions, it requires a strong foundation for mission operations to be able to send commands and downlink telemetry from these systems. GT-1 and TARGIT are scheduled to be the first customers of the MOCC, however this system will be designed for versatility to accommodate multiple future missions including GT-2+, and formation flying mission like SWARM-EX and VISORS. This presentation aims to provide a proposed layout of how data received from the satellites will be processed to generate mission critical visualizations, and describe the different MOCC operating modes. Integrating AGI Systems Tool Kit along with MATLAB will provide the functionality to propagate estimated orbits for the satellites and calculate access data regarding when estimated next passes occur in order to aid the operations team in changing operating modes.
Utilizing hydrocarbon fuels for rocket engines is beneficial in terms of cost, reliability, and environmental friendliness. To enable more informed and cost-effective designs of rocket engines, it is key to understand the combustion processes involved in the combustion chamber; one approach to do so is through numerical simulations. Numerical simulations facilitate deeper exploration of the physics involved in comparison to experiments. In this study, the numerical simulation of a 7-injector, GCH4/GOX, experimental rocket engine (developed at the Technical University of Munich) is performed with an in-house LES CFD solver. The numerical methodology adopted is based on the well-established, second-order accurate (in both space and time) finite-volume solver for the unsteady Favre-filtered multi-species compressible Navier-Stokes equations. A hybrid scheme, which switches between a second-order-accurate central scheme and a third-order-accurate MUSCL (Monotone Upstream-centered Schemes for Conservation Laws) scheme is employed. The reacting flow and flame features/characteristics are studied from the simulation results.
"Finite Element Model Characterization of a Regeneratively Cooled Nozzle"
Regeneratively cooled nozzles often circulate cryogenic compressed fuel through a nozzle composed of hundreds of tubes. This process cools and helps maintain the strength of the metal components during rocket engine operation. Engine designers use a simplified engine system finite element model to determine loads for component design. A two-dimensional shell mesh can be used for the nozzle in this load analysis model. Beam theory can be leveraged to compute approximate orthotropic material properties such that the shell elements will exhibit the same behavior as the nozzle tubes. A “truth model” can be made using cyclic symmetry. The mode shapes and frequencies of the shell model can be tuned to this truth model using Attune by adjusting the shell orthotropic material properties.
The AIAA undergraduate engine design competition committee has requested proposals for a new engine design for their Mach 2.1 business jet entering into service in the year 2030. The YJ-2030 is Georgia Tech’s response to the AIAA Request For Proposal (RFP). The engine is an afterburning mixed flow turbofan that allows the aircraft to cross the Atlantic in under 5 hours, while still offering extended range at subsonic cruise. This presentation will cover the requirement definition, cycle design, component design and the material and weight analysis of the YJ-2030 engine.
Adrian Vincente La Lande
“3-Dimensional B-Field Profile of a Hall-Effect Thruster”
Like many forms of electric propulsion, Hall Effect thrusters rely on the interaction of electro-static forces. One of the most important physical features is the magnetic field that is distributed both axially and radially inside the discharge channel and allows the thruster to create its characteristic Hall current. This is a critical function of the thruster, as the Hall current sustained by this magnetic field is necessary for creating the plasma ultimately used to produce thrust. Understanding the magnetic field topology of Hall effect thrusters is critical for improving their performance. Despite this, we do not have many ways of spatially characterizing said magnetic fields in our lab. To enhance the diagnostic capabilities of the High-Power Electric Propulsion Lab (HPEPL), a B-Field Mapper (BFM) tool was developed to allow users the ability to accurately and 3-dimensionally map the magnetic field flux of a thruster. This presentation covers the development, application, and performance of the BFM, as well as the magnetic-field topography it measured from a T-220 Hall-effect thruster.
"Developing Preliminary Sizing Optimization and Safety Analysis Tool for Wing Substructure"
Early design decisions made during the conceptual and preliminary design phases of a development program are largely influential to the final weight, design, and cost of the aircraft. This presentation discusses the development and integration of a tool designed to optimize the weights of primary substructure groups within a user-defined wingbox. The optimization process is constrained to ensure all relevant structural margins of safety are satisfied under various shear and bending loads experienced during flight. The resulting optimal weights are summed to return to the user an evaluation of the ideal weight of the analyzed wingbox. This allows for fast and accurate sizing considerations early in the design process.
"Optimal Control for In-Host Virus Models"
Mathematical virus models bear a close resemblance to dynamical systems common in aerospace engineering. This similarity enables the use of optimal control methods to determine improved treatment regimes. The talk will give an overview of ordinary differential equation and continuous time markov chain models (a type of jump process) for viral in-host infections. Control emerges by interrupting infection of new cells with medication. The cost function encodes minimizing amount of medication, and thus side effects, while still eliminating the viral population. Differential dynamic programming will be discussed for the ordinary case and model predictive path integral for the stochastic case.
"Modelling and Analysis of Satellite Megaconstellations"
Much of the anxiety surrounding the deployment of constellations of hundreds or thousands of satellites stems from a position of concern as to the potential interference impact such constellations will have on communications infrastructure. By making use of the capabilities found in STK, especially those related to communications, it was determined that certain types of ground receivers, under the right conditions, are more exposed to interference from the downlink satellites of these megaconstellations. The project also developed a workflow procedure to efficiently and accurately model megaconstellations by using generating two line element files for the individual assets of the constellation.
Since the proposed constellations have not yet been deployed as of this project, certain assumptions had to be made to generate a realistic notional constellation, including altitude, RAAN, and inclination of the orbital shells. A custom-made python script was used to iterate through values in the TLE to generate evenly distributed networks of satellites in each shell based on input altitude, planes per shell, and satellites per plane. A notional constellation of 12,000 satellites distributed among three different shells was created. Deck Access was then used to determine which of these fictional spacecraft would fall within the field-of-view of the ground-site within the analysis period.
"Initial Prototyping and Testing of a Modular Delivery Drone"
Delivery companies are looking to drones as a method for delivering packages quickly and reliably to consumer doorsteps. However, the development of a universal delivery vehicle leads to a tradeoff between payload capacity and flight efficiency. One solution is to build a modular drone such that smaller loads would be carried by a single drone while larger loads would be carried by, for example, four drones together. One such prototype was developed as a series of quadrotors organized in an X-pattern. After a single quadrotor was built and flown, a lightweight aluminum frame was constructed to interlock four drones and a single flight controller.
Flight testing was accomplished by tethering all drones to the ground, enabling a controllable flight radius ranging from three to thirty feet. The drone was able to be piloted directly with full directional control, but with noticeable flight instability. In an attempt to solve this, GPS systems were added to the drone to enable autopilot functionality. However, the drone was unable to maintain a constant position and altitude. Most recently, a single drone was flown with a suspended load using both direct and remote control with great success. As such, it was determined that flight controller redesign in the form of PID gain manipulation would allow for stable flight of the modular drone system