High Power Sugar Rocket Motor

This project gives you a behind-the-scenes look at how I design, build, and test my sugar-based rocket motors, from defining performance goals and simulating in OpenMotor to designing parts in CAD, getting them machined by JLCCNC, casting the propellant, and finally assembling and static testing the motor. I use tools like custom jigs, load cells, and pressure transducers to ensure everything runs smoothly and safely while collecting valuable performance data. This isn’t a full tutorial, just an overview of how I do things, so make sure to do your own research and stay safe if you're getting into rocketry yourself. You can see more of this process in action on my YouTube channel, click the link below!

YouTube channel: https://www.youtube.com/@AeroPropulsions?sub_confirmation=1

JLCCNC: https://jlccnc.com/

Many of the components for these rocket motors need to be custom-made to match your specific design and performance goals. This includes parts like the nozzle, bulkhead, and casting jigs. I design these in CAD based on my OpenMotor simulations and get them professionally machined by JLCCNC to ensure precision and durability. Off-the-shelf parts rarely meet the demands of high-powered motors, so customization is essential for both safety and performance.

The first step in designing a rocket motor is to define your performance goals, target thrust, chamber pressure, and specific impulse. I use OpenMotor to simulate how the motor will behave under those conditions. It helps me optimize the nozzle geometry, grain configuration, and overall design before building anything physical. Simulation is key to understanding how the motor will perform, and how to avoid catastrophic failure.

Once I’ve sized the motor and dialed in the performance in OpenMotor, I move to CAD design. I create detailed models of the nozzle and bulkhead, factoring in critical features like O-ring grooves to ensure a proper gas seal. Material selection is just as important:

1. I use stainless steel for the nozzle because my sugar-based propellant (rocket candy) doesn’t burn hot enough to erode it.
2. The bulkhead is made from aluminum, since it sees less heat and allows for lighter weight without compromising strength.

Reference video: https://www.youtube.com/watch?v=uOOzzTUp6B0

With the designs finalized, I send the files to JLCCNC, my go-to for custom CNC machining. They’ve been excellent at turning around quotes quickly and delivering high-quality, tight-tolerance parts in just a week or two. Their parts have never let me down, which is crucial when you're dealing with hundreds of PSI.

Once the hardware arrives, I move on to casting the propellant. For these motors, I use rocket candy, a sugar-based propellant that’s relatively safe when handled properly. I use custom 3D-printed jigs, also made by JLCCNC, to ensure the propellant grains are formed consistently and accurately. Safety is critical here, if you’re new to this, get trained or consult someone experienced before handling or mixing any propellant.

Reference video: https://www.youtube.com/watch?v=tWuXqjuadro&t=4s

With the grains cast and cured, I begin assembling the motor. The nozzle and bulkhead are secured using radial bolts, which handle the internal pressure and keep everything in place during firing. After that, I insert the igniter into the grain core and prep for testing.

Finally, it’s time to fire the motor. I bring it to a remote, controlled test site where safety is top priority. The motor is mounted in my custom-built static test stand, equipped with a load cell to measure thrust and a pressure transducer to capture internal pressure. The data recorded here is essential for calculating total impulse, burn rate, and refining future designs.

Reference video: https://www.youtube.com/watch?v=kS9Sj2VthyY&t=269s