I purchased two more 5 gallon aluminum tanks from KMW Performance and proof tested them to 400 psi (27.6 bar). I’m presently looking for somebody to clean one for LOX service; the local welding supply stores could not recommend a vendor for cleaning parts for LOX service. These tanks are going on a test stand, but I plan to use the same ones on my vehicle.
I also started machining the 100 lbf heatsink engine. I decided drilling the chamber and converging portion of the nozzle would be easier than working it with a boring bar, though the surface finish on the chamber ID is a little rough. I bought a 2 1/8” drill bit from eBay, a local machine shop sharpened it for $35, and the sharpened bit made quick work of drilling the chamber. Huzel/Huang say the convergent half angle ranges from 20 degrees to 45 degrees – my drill bit gave me a 60 degree half angle. The next step is to step drill a conical diverging section (15 degree half angle) and clean up the profile with a boring bar. Richard Nakka’s website has a handy calculator for forming nozzles.
Drilling the chamber and converging section. Stock is 4″ OD 1018 carbon steel.
Looking into the chamber and through the throat.
I bought this tiny trailer from Harbor Freight and I’m going to turn it into a portable test stand. Every Harbor Freight purchase is hit or miss: the 3/16″ steel plate I bought for the top cost more than the trailer kit and the wheel bearings get disconcertingly hot after short trips.