Spin Stabilization
The image above shows our results (numerical model) in comparison to Open Rocket's simulation, and the image below is a more detailed view of how our mathematical model works. The slight variation could be due to motor and rocket variation in our speed model. Our accelerators saturated at takeoff and couldn't be used to determine velocity so we needed to rely on the model.
Our capstone project had an ever changing end goal as the rocket we were supposed to design fins for was constantly changing along with any stabilization forms - our canted fins were potentially not going to make it to the rocket. The uncertainty prevented us from perfectly creating a model for the project karman rocket we were tasked for but allowed us to create a tool that could be used by the future project karman team at Northeastern (A subdivision of NUAerospace). We wanted the tool to help determine the fin cant requirment for the rocket in order to achieve the desired spin rate.
My role in the project was generally the math, and flex player role. I initially did a lot of the ANSYS simulation but ended up taking over the majority of the hand calculations and algorithm determination. I was also sure to be available to help any of my other group-mates with issues that arose, especially around electronics. Most of my time was spent creating MATLAB code for the spin algorithm that took in the rocket flight data and output spin rate, as well as analyzing our actual flight data and comparing it to our model and ensuring that the model matched our results. We initially found our data was off in the expected timescale, however we were able to determine that this was due to an incorrect recording frequency and our lack of recording timestamps. After testing our recording frequency and adjusting for this factor we were able to obtain results much better than the currently available programs.
The two images below show our model, which basically treated the fins as flat plates and integrated the force caused by the air at each of the fin slices. The force was a function of air velocity as well as rotation rate, and we needed to determine the rotation rate at each time-step by utilizing the rocket's roll moment of inertia. All images are directly from our final presentation. Copies of the presentation and the final report are available upon request.
Our capstone project had an ever changing end goal as the rocket we were supposed to design fins for was constantly changing along with any stabilization forms - our canted fins were potentially not going to make it to the rocket. The uncertainty prevented us from perfectly creating a model for the project karman rocket we were tasked for but allowed us to create a tool that could be used by the future project karman team at Northeastern (A subdivision of NUAerospace). We wanted the tool to help determine the fin cant requirment for the rocket in order to achieve the desired spin rate.
My role in the project was generally the math, and flex player role. I initially did a lot of the ANSYS simulation but ended up taking over the majority of the hand calculations and algorithm determination. I was also sure to be available to help any of my other group-mates with issues that arose, especially around electronics. Most of my time was spent creating MATLAB code for the spin algorithm that took in the rocket flight data and output spin rate, as well as analyzing our actual flight data and comparing it to our model and ensuring that the model matched our results. We initially found our data was off in the expected timescale, however we were able to determine that this was due to an incorrect recording frequency and our lack of recording timestamps. After testing our recording frequency and adjusting for this factor we were able to obtain results much better than the currently available programs.
The two images below show our model, which basically treated the fins as flat plates and integrated the force caused by the air at each of the fin slices. The force was a function of air velocity as well as rotation rate, and we needed to determine the rotation rate at each time-step by utilizing the rocket's roll moment of inertia. All images are directly from our final presentation. Copies of the presentation and the final report are available upon request.
Objectives:
- Create a tool that allowed for dynamic rotation calculations of model rockets based on fin cant angle
- Attempt to model the flow over the rocket in ANSYS Fluent CFD - Ran into issues with meshing and student licence limits
- Obtain avionics hardware and build a system for mounting within a rocket
- Launch test rockets to test our algorithm
- Analyze data and adjust the algorithm
- Present the findings and MATLAB code model
- Very accurate estimation of rocket spin rate - much more accurate than that of current open source simulation software
- Winning "Largest Impact" for our capstone section -- for the impact potential in the model rocket community, not for a crashed test rocket.