After a couple years of solid rocket tests utilizing Potassium Nitrate/ Sucrose propellant held within a single-use PVC chamber and ground-up oil dry clay, I set out to find a way to make a reusable, steel chamber and nozzle. Without the use of a lathe. After around four months of development, the Drebin Mk. I solid rocket engine was successfully static fired. At the time of static fire the design was in the middle of major changes, prompting a new name.
The Spencer Mk. I Nozzle was created using a a 3/8 inch steel plug, found at Home Depot. A drill press was used, incrementally changing bit sizes to roughly match the desired nozzle contours. A conical sanding Dremel bit was then used to smooth out the steps, forming our nozzle.
For the chamber a 19 mm O.D. steel conduit is used. One of the major safety factors is the seam weld, keeping the majority of the chamber from fragmenting in the event the chamber wall ruptures. A roughly 140mm length of tubing is cut and the interior of each end threaded.
A similar method to the nozzle is used for the cap housing the powder ejection charge. A small hole is drilled through the entirety of the plug, this smaller hole resting against the delay charge. On the other side a larger hole is drilled, housing the ejection charge. A small paper towel/toilet paper sheet is used to plug the powder. A 3D printed, single-use ejection cap was considered, but heat and reusability eliminated it.