LEE- Uçak ve Uzay Mühendisliği Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/19473

Gözat

Yazar "Aslan, Ali Rüstem" ile LEE- Uçak ve Uzay Mühendisliği Lisansüstü Programı'a göz atma
  • Öge
    Design and optimization of two stage launch vehicles with the same liquid propellant rocket engines in both stages
    (Graduate School, 2022) Özçelik, Kubilay ; Aslan, Ali Rüstem ; 714559 ; Aeronautical and Astronautical Engineering Programme
    Space exploration is an important technological catalyst for humanity. While researching space and its practical uses, it accelerates the development of new technologies. Reaching orbit is a difficult and complex problem. To get the speed required to stay in orbit, launch vehicles need to have very high propellant mass fraction ratios and high performing propulsion systems. Reaching the performance limits to reach orbit needs high technology and expensive materials to be used. Because of this it is very expensive to put payload into orbit. In the recent years private space companies are entering to the launch vehicle market. These privately funded companies try to drop the prices to be able to compete with existing launch service companies to insert payloads into orbit. To do so they try to reuse the same liquid rocket engines in all stages to drop the development and manufacturing costs. Most of the private launch vehicle companies are designing only one rocket engine and are using them in their 1st and 2nd stages. While the 1st stage engines are bundled together using engines that have sea level optimized nozzle. The same engine is used in the 2nd stage with a vacuum optimized nozzle. Doing so, they reduce the development costs, complexity and manufacturing costs of their launch vehicle. Also the new trend is to design the launch vehicle as reusable as possible. This allows for cost reductions that make the launch vehicle more competitive in the market. Some companies that use this approach are SpaceX, RocketLab USA and Relativity Space. In this thesis, a launch vehicle optimization tool is developed specifically for two stage to orbit vehicles that use the same liquid propellant rocket engines for all stages with only minor modifications. In the 1st stage many sea level optimized engines are bundled together and in the 2nd stage a single vacuum optimized engine is used. It can design launch vehicles for different propellant combinations and liquid rocket engine cycles. Most launch vehicle design methods estimate the stage properties and try to distribute the mass of the stages based on estimations. After finding a viable solution it is designed in detail and the assumed performances of the stages cannot be achieved. This causes an iterative design loop that is resource draining. To solve this problem in this thesis the liquid propellant engines and stages are designed in detail. Firstly, the liquid propellant rocket engine is designed in detail and after that the stage is created by adding tanks and pressurization system. The stage design tool is connected and implemented such that it can design stages with bundled engines for the 1st stage and modifies the same engine as vacuum optimized for the 2nd stage to create the desired launch vehicle. The stage design tool is connected to an optimization algorithm and launch vehicle design tool to create the specified launch vehicle design tool necessary for this thesis. One of the most important design parameters for a launch vehicle is the required delta V for the selected mission. But without simulating the launch trajectory making a good estimate for required delta V is difficult. Therefore, to validate the designed launch vehicles, an orbital trajectory simulation code is developed based on MATLAB. Using this simulator, the designed launch vehicles are trajectory simulated and if successful they are validated or if they are unsuccessful the design parameters are updated accordingly in launch vehicle design code and the process is repeated to find good performing launch vehicles. Designing a launch vehicle is a complex multi-disciplinary and multi objective problem. To rapidly design the launch vehicle the most important parameters are selected as payload capacity, vehicle delta V capacity and T/W ratio at liftoff. The payload capacity and delta V capacity mostly influence the mass of the launch vehicle. Whereas the T/W ratio at liftoff determines the engine thrust and orbital launch performance of the launch vehicle. The optimization algorithm is developed such that it searches for the launch vehicle with minimum liftoff mass while ensuring the design input parameters are met with minimal error.
  • Öge
    Development/ testing of software for a cubesat for high resolution earth observation in a low earth orbit
    (Graduate School, 2024-06-24) Azam, Mehreen ; Aslan, Ali Rüstem ; 511221120 ; Aeronautical and Astronautical Engineering
    CubeSats, ranging from 1U to 27U, are small satellites many nations pursue for academic and commercial purposes. The success of their missions depends greatly on the design of their software architecture. Beyond merely achieving functionality and optimal performance, the software must also be resilient to faults and shielded from the effects of radiation, potential failures, and errors. As CubeSats accommodates more advanced subsystems, developers worldwide are exploring agile development methods. Consequently, software development must prioritize three essential factors: Modularization, refactoring, and generalization. This study aims to describe the design, implementation, and testing of software modules of a 16U CubeSat, focusing on its onboard computer (OBC) software. A comprehensive software platform has been developed featuring a flexible architecture capable of supporting a multispectral payload and other subsystems. Multiple studies were done to familiarize the current work with experience from past projects, coding standards, and rules. Three fundamental requirements were derived to ensure software development quality: Concurrent documentation, version control for efficient tracking, and Debug tools support. The mission software has been developed using the Free RTOS Real-Time Operating System for real-time scheduling functionality, inter-task communication, timing, and synchronization. SEU/SEL management is considered for relevant subsystems. The development environment of choice was the Eclipse IDE, with code crafted in the C language. The code architecture is structured around creating libraries for individual subsystems, which serve as building blocks for developing higher-level applications specific to each subsystem. Followed by creating subsystem managers and various operating modes (Initialization, idle, Payload operation mode, etc.) ensuring reliable operation. Finally, a mode manager is implemented which acts like a state machine handling decision-making and switching between operating modes. Additional peripherals like packet routing, housekeeping, timekeeping, data logging, and even power management have been designed to match the mission profile in these modes. Following code development, the subsequent phase involves testing the code on actual hardware. The chosen OBC hardware has 03 interfaces; I2C for housekeeping/telemetry, JTAG for programming and debugging, and UART for development and testing. Testing of the developed code is in process for various subsystems. As future work, implementation of developmental changes is an ongoing process to ensure robustness and reliability.