An Accidental Discovery

[matt walker]

Well, I've been alluding to it for a while now, and now that I've had a bit of time to test burn a prototype I think it's an idea worth sharing. We've been talking about cook top height rockets, and I think I've got a good solution for building these using fairly standard known proportions, with a slight twist.

First, a little back story on how I discovered this. In the weeks running up to the Decathlon in DC last month, I was burning my Walker Stove daily. Sometimes inside, sometimes outside, to test various chimneys and the like. In the course of doing that, I was moving it around a bunch. Well, one night, after burning it outdoors that day, I moved it back indoors and lit it up to warm up the house. It was running just perfectly, and I went about my business. I came back into the room after a couple loads and as was my usual habit I pointed the IR gun at the surrounding combustibles to make sure I wasn't getting anything too hot, since I just kinda rigged up a place to burn the thing so I could test it. To my surprise, the ceiling, which usually was my foremost area of concern, was not hot at all. Weirder still, as I got near the stove, it was throwing a TON of heat off the front, which usually was the coolest part of the radiator. I pointed my IR gun at the top of the stove, and it was less than half of what I should have seen there. Pointed it at the front, and it was 900°f+! I pretty quickly figured out what happened, but what was surprising was that the stove was running so well.

The riser had fallen over inside the radiator! And it still worked! I was excited, and I told Manny about it when I was there on the way to DC, but it's taken me this long to get back into the swing of building test stoves and such and verify that this works. Well, it does, for sure. What this does is offer a whole slew of new options for shape/size/configuration of these stoves. By not having to set the first radiator on top of the core, you can save a bunch of height. In that way, it's a great solution for cook top height stoves. So far I've tested what I call the "broken riser," which replicates what happened inside my stove. I still make the core with the initial 12" high riser stub, then form an angled flange on top of that to mate the riser to. I tested one with about a 20° angle, and I've tested one that is almost horizontal. Both worked great, a little harder to start than normal, but once going they draw wonderfully.

I haven't built the "angled riser" version, but I suspect it's even better. I'll try that next. Here's a couple quick drawings of the concept. In both cases I drew it as a double barrel bell system, but I think they would work with a variety of configurations. It doesn't seem to act any different than a regular J with a vertical riser.

Broken Riser



Angled Riser

[DevilsBrew]

Would the gases wear down the riser pipe on the left side? I'm thinking it is going to run up the left side of the pipe. The same goes for the broken riser. The heat would be concentrated at the bend. I would think so any ways. There is a lot of heat coming out of the tunnel. It will want to head straight up.

[DevilsBrew]

Why don't you guys just make an addition on to the main barrel of a standard rocket stove? Cut a second barrel to the height you want and in a 3/4 or half moon shape. Cut a hole in the original barrel. Weld the two together so you have a main barrel with a cooking shelf/ledge barrel attached. It would be so much easier.

[pa_friendly_guy]

I think that you are correct Devil that the heat would run to the top of the pipe and heat it up much more than the bottom of the riser. Because of the materials used in its casting I do not think that will have much effect in the durability of the riser or effect how long it will last. The idea of adding a half moon shaped bell to the main barrel and using that as your cooking surface may have a lot of potential. I really liked that idea. Having the exhaust much lower than that 1/2 moon should guarantee that it has substantial heat for cooking. You would have to worry about the welds around the 1/2 moon to make sure they were air tight and did not leak exhaust. You would also have to contend with a lot of heat radiating from the main barrel into your face. But I think the idea has merit. For many years men cut down tree with cross cut saws, so when the stream engine came around they simply powered a cross cut saw that went up and down to saw the tree into boards. It was a woman that thought out side the Box and came up with the idea of a round buzz saw blade to improve the speed and efficiency of cutting boards from logs. Your idea may prove with experimentation and some trial and error to be that kind of break through.

[DevilsBrew]

Thanks, Guy. I was even thinking that you could have two levels of hot plates. The uppers (on the higher barrel) could be used for tea pots and such and the lowers for cast iron pans. You could make your breakfast all in one shot.

Maybe it would work, maybe not. But I haven't seen anyone combine two barrels by welding them together. I'm wondering if that would work for a wall of heat by adding masonry.

Sorry for the drift, Matt.

[matt walker]

[pa_friendly_guy]

I take it that you think the idea will work Matt. I think it might work as well if you have a good welder on your team. Even if you use your idea of slanting the riser to lower the cook top, adding the 2nd 1/2 moon barrel to the 1st would give you so much more cooking surface. And because it is part of the main barrel it should be hot enough for cooking. Your diagram showing a 2nd barrel could also give you more cooking space, but I am guessing at a much lower temperature than the main barrel would produce. Maybe a warming plate, or a place to put things to simmer for the day. Any way, do you have the welding skills to try the idea?

[matt walker]

You're a peach, Guy.

I'm going to get to work on my heater, you kids have fun. Can't wait to see the system you've designed for me when I return.

[pa_friendly_guy]

Oh, I see, The Double Face Palm was for, Oh my God what were they thinking, How could they be so Stupid, and not for, Oh my God, why didn't I think of that, its so simple.


PS. I still think the idea has potential. You can cut the sections out of the barrel and let the metal attached to the barrel. Than bend it around so the barrels fit together, weld from the inside and then finish with a single bead of weld around the out side. It might just work.

[DevilsBrew]

Ouch