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Yellow Jacket Space Program: Rocket Launch Lug Design for Vespula Rocket
Project Objective
The project aimed to design the launch lugs to ensure secure attachment and precise guidance of the rocket Vespula during launch. The primary goal was to create components that meet stringent mechanical requirements, including high stress and shear tolerance, while ensuring proper interface compatibility with other systems like the stringer and clamshell.
GoldiLOX Static Fire
Impact of Work
YJSP Subscale Rocket Launch
The design of the launch lugs plays a crucial role in the overall performance and safety of the rocket during launch. By developing precise CAD models, performing stress and material analysis, and generating detailed engineering drawings, the work ensured that the launch lugs will meet required performance standards. This contributes to the overall success of the Yellow Jacket Space Program’s mission and furthering Georgia Tech's involvement in space technology.
Structures Team
My Role
As a member of the Structures team, I focus on the CAD modeling, mechanical design, and manufacturing of critical components for the rocket. My responsibilities include designing and refining the launch lugs, ensuring precise geometric interfaces and load-bearing capacities. I also contributed to the fabrication process, utilizing tools like CNC machines and lathes to manufacture parts with tight tolerances, ensuring the rocket's structural integrity and performance during launch.
My Contribution
Design Process
I was responsible for the entire design process of the launch lugs, starting with creating the CAD models and progressing through detailed calculations, material selection, and engineering drawings. This process was critical in ensuring that all components would meet the necessary mechanical and safety requirements for the rocket's structural integrity.
Critical Design Review (CDR)
For the Critical Design Review (CDR), I finalized the CAD models for the launch lugs, ensuring they included a 9.5" curved diameter to interface properly with the stringer and clamshell. This step was key in aligning the design with the rocket's overall structure and performance goals.
Section View
Assembly View
Fasteners & Material Selection
I designed the fasteners for the launch lugs, including bolts, latches, and load pins. I selected 6061 aluminum for the launch lugs due to its high strength-to-weight ratio and 60 stainless steel for the pins, ensuring durability and resistance to corrosion in the harsh environment of spaceflight.
Stress Analysis
To ensure the launch lugs would withstand the mechanical stresses during launch, I conducted hand calculations for bending, shear, and bearing stresses. These calculations resulted in a factor of safety (FOS) of 28.2 for the basic stress, far exceeding the required minimum standards, ensuring a robust and reliable design.
Pyrotechnic Ejection Calculations
I also calculated the amount of black powder required to trigger the pyrotechnic ejection of the launch lugs. These calculations resulted in an acceleration of 19,270 ft/s² at a 45-degree angle, ensuring the lugs would be ejected efficiently once the rocket cleared the TSI-200 rail.
Engineering Drawings & Manufacturing Steps
The final deliverables included detailed engineering drawings for each part of the launch lug assembly, along with specific manufacturing steps for components such as the latch and load pins. These drawings and instructions provided a clear roadmap for the fabrication process, ensuring that the components would be manufactured to precise specifications.
Image Carousel: Central Launch Lugs, Right Side Lug, Load Pin, and Latch Pin
Challenges & Solutions
Design in CAD
Challenge: One major challenge was achieving the precise geometric interfaces between the launch lugs, stringer, and clamshell. The tight tolerances required for the fasteners and pins meant that every part had to be designed with precision to ensure proper fit.
Solution: To address this, I conducted multiple iterations of the CAD model, adjusting dimensions to refine the interfaces between parts. I ensured proper clearance for fasteners and pins by performing thorough checks and simulations, verifying the fit before finalizing the designs.
Problem: Screws Interfering with Lugs
Solution: Added Holes with Clearance
Manufacturing the Components
Challenge: Manufacturing the components, especially the latch pin and load pin, posed significant challenges due to the tight tolerances required for their interfaces. Achieving these precise fits, particularly with the press-fit load pin and CNC-machined latch pin, required careful planning.
Solution: For the latch pin, I implemented a CNC machining process to ensure the required precision, while for the load pin, I accounted for the press-fit into the lug and selected appropriate tolerances. The complexity of machining aluminum and stainless steel was addressed by using precise tools like CNC machines and lathes, while also considering the potential need for lubricants to ease the pin insertion process.
Latch Pin in Lathe
Close-up of Latch Pin
Results
The CAD models for the launch lugs and related components have been completed, and stress analysis confirmed the parts would meet the necessary safety margins. Engineering drawings for the launch lugs, latch pins, load pins, and side lugs have been finalized, including material specifications and detailed manufacturing instructions. I have already begun the manufacturing process for the latch and load pins, with the central and side lugs yet to be fabricated. Testing for pneumatic ejection and pyrotechnic ignition remains to be conducted to validate the components' performance in real-world conditions.
Shaping Future Experience
This project has provided hands-on experience in designing and manufacturing critical aerospace components, enhancing my skills in CAD modeling, stress analysis, and manufacturing techniques. The challenges faced in ensuring tight tolerances and accurate interfaces will contribute to my understanding of precision engineering in future projects. The project also strengthened my problem-solving abilities in dealing with both design and practical manufacturing constraints, which will be invaluable in my future career in engineering, particularly in the aerospace and space exploration sectors.
CDR Launch Lugs Presentation
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