What we have so far is a functional but relatively untested ultralight winter stove. To be sure, we tested the burner chamber and splash plate well in Part 2, but those were simple tests with a narrow focus. Part 3 covered a lot of design, development and some field testing of a prototype. It did not cover very much routine testing of production models, however. You need a whole lot of testing to get a satisfactory and reliable stove in the field (a lot more testing than most software ever gets too).
So in this Part 4, we will cover a whole lot of lab and field testing, and some of the gremlins found along the way. There were a few heart-stopping moments when Murphy announced a continuing presence, but fortunately, Murphy was kind.
Needle Valve
I gave basic details about the needle valve in Part 3. The long shaft of the valve and the matched bore in the stove body form a very effective heat exchanger, such that you do not need a "preheat" tube over the top of the stove. If anything, I had to take a fair bit of care to minimise the way the stove body heated up. I mentioned some of this in Part 2.
But there were more issues. Given that the bore is 13/64 in. (5.1 mm), and that we want a thin film of fuel running down the inside, a long needle of about 3/16 in. (4.8 mm) diameter seemed suitable. That gives a .006 in. (0.15 mm) clearance all around in the ideal case, which is reasonably "thin film." All that is fine, but there were problems when the stove was running on a gas feed, one of which was that the power was very limited. I didn't mind the power being a little limited with a gas feed. This model is meant to be a liquid fuel stove after all, but the limitation seemed a bit too severe. However, the needle valve and the jet were clean.
Read on for the full story!
Article Outline
- Introduction
- Needle Valve
- Overheating - again
- Filters
- Stove Stability
- The Finished Stove
- Assessment
- Availability
# of Photos: 14; Word Count: 4300