Thrust-Vectoring Solid Rocket Motors

Rather than pursue an internship or job the summer after my first year of university (mainly because I was late to the application period), I chose to fill my break instead with a collection of independently-led technical projects, this being one of them. In collaboration with a friend, we spent weeks of near-daily work sessions to build a reusable solid rocket motor and data acquisition structures the complete ground up. The ultimate goal is a working vectoring mechanism using jet vanes within the nozzle to redirect exhaust. This process included designing and manufacturing the motors and 4-axis force-reading test stand, cooking up grains and igniters, and writing data analysis code using some interesting math

Overview of Contents

Project Overview and Goals
Timeline
Sourcing Parts
Rocket Motor Design
Thrust Stand Design
Rocket Motor Manufacturing
Test Stand Manufacturing
Hotfire Procedures and Safety
Vectoring Mechanism Design
Data analysis and controls

Project Overview and Goals

The ultimate goal of this project was to develop a solid rocket motor with a thrust vectoring mechanism capable of guiding/stabilizing a theoretical rocket with the implication that infrastructure to complete and test the motor (the test stand and code) would be made as well.

The project was chosen and pursued with a few restraints in mind:

Must be achievable in 1-3 months
Cost is a limiting factor
Work must be able to be done safely and with available tools (ie. be done at my house or the local high school machine shop, motor must be able to be tested locally)
Must involve a variety of skills, in this case mechanical, material and structural engineering, thermo & fluid dynamics, 3D printing, CNC machining, manual metal machining, chemistry, electrical design, programming, data analysis, and higher level & applied math.
Must have a significant "cool factor"

Having chosen this project, a few, more technical, goals were also set for the project:

Use a high impulse and long-burning (ish) rocket: >500 N-s total impulse, >2 sec burn time
Produce and record thrust axially (regular thrust), laterally (both "x" and "y"), and torsionally (twist around the central axis)
Use a cheap but workable fuel
Account for mass loss in data collected from vertical thrust (a known issue from previous attempts. Can significantly affect data but is difficult to account for)

With these goals in mind, the project can be considered as three different "components" that all work together, but will be mostly discussed independently:

The rocket motor itself, which focuses on optimizing the design for the fuel and intended impulse/burn time, as well as accounting for forces and material failure, thermal interactions, and simulation (FEA, CFD, etc.)
The test stand, which focuses on force isolation and structures, design for manufacturing and assembly (DFMA), electronic design, modularity, a bit of flexure design, and C++ and Python programming.
The vectoring mechanism, which focuses on fluid/aerodynamics, material properties, mechanical design, and control algorithms.

Timeline

Below this is the resultant timeline that we operated through when working on this project. After our first hotfire, my friend left for a month-long international trip and as a consequence, progress slowed. The engine was fired a second time after the test stand was fully wired and programmed shortly before the school year began

Sourcing Parts

Part of the challenge of this product was to make a fairly large scale test setup with minimal cost.