Model rocket motors are expensive, so a friend and I decided to make our own fuel from potassium nitrate and sucrose (KNSU). We followed the method used by James Yawn, which gave us a start on both safety and procedures.

The initial fuel attempts were a bit rough. We used store-bought stump remover of questionable quality as an oxidizer.

No, its not supposed to look like that

Our cooking method was also far from optimal:

Yikes

We weren’t harmed, possibly because of the lack of oxidizer strength. We bought some higher quality potassium nitrate on Amazon (I’m still surprised that I could buy it so easily). We also used an old camping pot to cook the propellant. These upgrades made the propellant much more exciting:

Improved propellant

Even at atmospheric pressure, this propellant was far more powerful. To get KNSU to burn hotter and faster (better for rockets), we needed to increase the pressure.

After a few failed attempts, we discovered that 3D-printed ABS is not a good nozzle material.

Rocket with no nozzle

Failure mode: melting. The nozzle flew out of the rocket, bounced off the fence, and landed behind the rocket. Good thing we were wearing safety glasses.

Nozzle flew far

Clearly, we need a better nozzle. I am working on getting the lathe at school up and running so that we can cut one out of a stronger and more heat resistant material.