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Publication Metadata only Effect of pressure loss devices on the performance of hybrid rocket systems(International Astronautical Federation (IAF), 2018) N/A; Department of Mechanical Engineering; Karabeyoğlu, Mustafa Arif; Faculty Member; Department of Mechanical Engineering; College of Engineering; 114595Internal ballistic devices that are used to trip the gas flow such as blades, steps, diaphragms or screens are commonly implemented in hybrid rocket motors to improve the mixing in the system. Enhanced mixing typically leads to an improvement in the regression rates and combustion efficiencies. The major issues with the use of these elements are 1) the pressure drop associated with the gas flow over these obstacles, 2) additional weight and 3) additional system complexity and cost. Even though a total pressure drop leads to a reduction in the thrust specific fuel consumption for air breathing propulsion systems, rockets do not suffer a direct hit on their specific impulse. The objective of this paper is to outline a theoretical proof that any pressure drop encountered along the motor axis does not lead to a reduction in the thrust or specific impulse performance of the rocket system. The primary adverse effect of the pressure loss is on the structural mass fraction of the rocket system. Assuming that the pressure at the nozzle entrance does not change, pressure drop requires higher head end pressures leading to increased injector manifold and feed system pressures. Using some example cases, we have estimated the combustion efficiency improvement required to balance the structural mass fraction increase caused by the flow trip devices. Such analysis needs to be conducted to justify the use of pressure drop elements for each design. Even though these arguments were developed for hybrid rockets, the analysis and conclusions are valid for all other chemical rocket types as well (i.e. solids and liquids).Publication Metadata only Electric propulsion optimization of microsatellite moon missions preliminary design application on CubeSats and Turkish small satellite field(International Astronautical Federation (IAF), 2014) N/A; N/A; Department of Mechanical Engineering; Kara, Ozan; Karabeyoğlu, Mustafa Arif; PhD Student; Faculty Member; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 114595Subsystems miniaturization of spacecraft is making scientific microsatellite missions feasible. Specifically interplanetary space exploration mission can be provided by onboard micro propulsion systems. Due to the low requirements, Moon is a feasible destination for a preliminary space mission that universities, companies and governments can perform. This paper addresses the optimization of an electric propulsion system for a potential microsatellite lunar mission. Optimization takes the thrust level as a free variable to find the minimum initial mass along with the associated total burn time. The initial thrust range is chosen between 0.5-6mN. For a given thrust value, corresponding specific impulse, thruster power and thruster mass are determined based on curve fittings. As the next step, the input thrust level is extended up to 42mN to observe optimization over a broader thruster size. A feasible low thrust continuous orbit transfer to the Moon requires a high ΔV which is over 7,000 m/s. Edelbaum's analysis with optimal control theory is utilized to estimate the ΔV value. Edelbaum presents an approach for two non-coplanar circular orbits without any perturbations and shadowing effects. Furthermore, the optimization approach is applied for the preliminary design of a CubeSat Moon Mission. The spacecraft is determined to have an initial mass of 12 kg and requires a total power up to 100W. The particular mission selected for the study starts at 700km LEO and finishes at 200 km LLO. In addition, preliminary mission design presents (1) mass and power budgets, (2) thermal analysis, (3) ADCS selection, (4) structure and array mechanisms, and (5) cost estimation. In this paper, previous and planned small satellite researches in Turkey have also been reviewed. Small satellite projects which are performed by government, universities and industries show that Turkey has a small but growing small satellite activity.Publication Metadata only Findings from IAC 2013 Young Professional Workshop: tools and project organization methodologies that can be implemented into the space sector from other industries(International Astronautical Federation (IAF), 2014) Stube, Kevin; Wood, Danielle; Svoboda, Jan; Li, Rui; Fuse, Tetsuhito; Kukhta, Andrii; N/A; Kara, Ozan; PhD Student; Graduate School of Sciences and Engineering; N/AApplied technologies in space sector are performing complicated and challenging projects in comparison other industries. This complexity in the space sector requires new alternatives for business management and project development. Therefore, management strategies in an organization directly affect the project achievements. Project applications, improvement of economic earnings, relations among people in an organization, mentorships, motivation factors and international activities are other significant issues which are really crucial for space sector. To discuss these important issues, we were one of five groups at International Astronautical Congress, Young Professional Workshop in Beijing, 20th September 2013. Our relevant group topic was "What tools and project organization methodologies have been and can be implemented into the space sector from other industries and the YPs' experience (e.g. software, automotive)?". As a group we have met several times prior to the workshop. Many ideas are emerged in consequence of meetings. Pre-meeting report helped us to prepare individual materials as members thru the workshop. These different reflections were: (1) agile software and engineering issues, (2) process improvement techniques and learning from manufacturing by multiple copies of the same space platform, (3) social activities of organizations for the internal motivation, (4) TRL improvement, (5) project management and system engineering certification the examples from NASA APPEL and Aerospace Corporation, (6) technology transfer among sectors just as military-space and biology-space, (7) Experience assessment of JAXA, (8) software tools that are being used across industries. During the workshop, we simplified these findings and made the final presentation. In addition, preliminary survey questions are listed and determined after the workshop. Finally, common grounds in our final report are summarized as (1) Software development tools, (2) Process improvement techniques, (3) Project management, system engineering education and certification, (4) Company organization structures and (5) Social Activities to improve sector interest. In the final report, group recommendations are given for the each topic and presented to the IAF YP Committee.Publication Open Access Gravitational Higgs mechanism and resulting observational effects(American Physical Society (APS), 2020) Krall, Verena; Kokkotas, Kostas D.; Department of Physics; Coates, Andrew; Researcher; Department of Physics; College of SciencesRecently, a toy model was introduced to demonstrate that screening mechanisms in alternative theories of gravitation can hide additional effects. In this model a scalar field is charged under a U(1) symmetry. In sufficiently compact objects the scalar field spontaneously grows, i.e., the object scalarizes, spontaneously breaking the U(1) symmetry. Exactly as in the U(1) Higgs mechanism this leads to the emergence of a mass for the gauge field. The aim of this paper is to provide an example of the physical consequences if we consider this toy model as a prototype of Weak Equivalence Principle (WEP) violations. We model neutron stars with a dipolar magnetic field to compare the magnetic field behavior of stars in Einstein-Maxwell theory on the one hand and in scalar-tensor theory with the, so-called, gravitational Higgs mechanism on the other hand.Publication Metadata only Systems advantages of electric pump fed upper stage hybrid rocket(International Astronautical Federation (IAF), 2018) N/A; Department of Mechanical Engineering; N/A; Gegeoğlu, Kaan; Karabeyoğlu, Mustafa Arif; Kara, Ozan; Master Student; Faculty Member; PhD Student; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; N/A; 114595; N/APropellant feed systems in liquid rocket engines deliver fuel and oxidizer from tanks to the combustion chamber at required flow rate and pressure. In hybrid rockets, only the liquid propellant is fed into the combustion chamber where solid propellant resides. The feed system has also a critical role for performance especially at upper stages of launch vehicles. There are two conventional feed system architectures that are mostly used. One employs a turbo pump while the other uses tank pressure to feed propellants. Briefly, propellant pumps are used in high pressure and high performance applications; however using turbo pumps makes design more complex and heavy. In contrast, the pressure fed system has simpler design although it is limited to low chamber pressures since high-pressure requirements make propellant tanks heavy. In addition there is a constant need for making elements such as tanks, valves, feed lines and pressurization devices lighter, simpler and more efficient. With advancing technologies in electric motor and batteries, electric pump feed system as an alternative to conventional feed system types has started to emerge. Most of the hybrid rocket applications evade turbo pumps since it requires carrying at least one another liquid propellant to drive turbines. Therefore, the performance of electric pump fed system over traditional pressure fed system is analyzed in this research on an upper stage of hybrid rocket engine. For this purpose, an optimization procedure has been applied on both systems and ∆V values as performance parameter are compared. on missions utilizing electric pump fed system, a noticeable improve of ∆V by 6.6% is reported. Optimization showed that longer burn times are also in the favor of electric pump fed systems.Publication Metadata only The micro-broadband receiver (MU BBR) on the very-low-frequency propagation mapper cubesat(American Geophysical Union, 2021) Marshall, Robert A.; Sousa, Austin; Reid, Riley; Wilson, Gordon; Starks, Michael; Ramos, Daniel; Ballenthin, John; Quigley, Steven; Kay, Ron; Patton, James; Coombs, Joseph; Fennelly, Judy; Linscott, Ivan; Department of Electrical and Electronics Engineering; İnan, Umran Savaş; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; 177880The very low frequency (VLF) propagation mapper (VPM) is a 6U CubeSat designed to measure VLF radio waves in Low-Earth Orbit. The science goals of the VPM mission are to measure VLF signals broadcast by the DSX mission, and to study natural and anthropogenic signals (from lightning and VLF transmitters) in the near-Earth space environment. The primary payload consists of an electric field dipole antenna deployed to 2 meters in length, and a magnetic search coil deployed 50 cm from the spacecraft. Signals from these two sensors are conditioned by analog electronics, sampled, and then processed digitally into downloadable data products. The VPM mission was launched in January 2020; science operations began in March 2020 and continued through September, when contact with the spacecraft was lost. This paper describes the mission goals and instrument designs in detail, as well as some examples of the VPM data se