Rocketry, the culinary version

I was having a chat the other day with some online friends about cooking in any medium-term grid-down emergency, and it was a little sobering. I have a one-ring camping stove for short term, with several gaz canisters – but if I had no power for longer than a week, I’d end up having problems. It’s amazing how we as humans can just ignore the blindingly obvious.

I scouted about on Amazon, and found quite a few possibles, at varying prices, and in themselves they’re great, I love the look of some of them, and I’ve included my single burner gaz stove for reference.

I was just about to buy one when I remembered the rocket stove I’d three-quarters made a couple of years ago. I’d got stuck making the top – all the online instructions I’d found tended to gloss over that bit, they seemed to focus on applying the principles of the rocket stove (which are quite something to get your head around, of course) rather than the finicky bits of finishing off the whole thing.

So, I’d got a big tin, I found one of tinned veg going cheap in Poundland (a size ten tin, in US terms), and I got a second from my local chippie, on standby, in case I made a mess of things, or another local family member wants it. I wanted it insulated, to help with the secondary ignition of the wood gases and help it burn hotter, so I needed insulation: I chose vermiculite, from an ordinary B&Q. The inner surface was provided by a supermarket tin of tinned potatoes – they’re about 1lb in gross weight. The funnel for feeding the fuel in, I used an ordinary size baked bean tin (I have a lot of those!). The leftover vermiculite can be used later in gardening projects, or a second rocket stove.

Fitting all the tins together was much more difficult for me than all the youtube videos imply. I love these sorts of projects, faffing about with little stuff, but I don’t have a long history with them, so trial and error is tough. I worked on the three tins (minus the insulation) for quite a while, with my dad’s old electric drill, until they fitted together as well as I could manage.

That wasn’t very well at all, quite honestly, there were gaps here there and everywhere. So I went to Wickes, which has almost as many branches as B&Q, and bought some fire cement – I reasoned that if it can be used on fires, then it can be used on rocket stoves. I used that to seal the joints between the cans, and after letting it dry for a few days, I gradually filled up the insulating wall with the vermiculite.

That’s where what instructions I could find stopped making sense. I knew I needed exits for the air and flames that were immediately underneath whatever pan I chose to heat up. But I didn’t know how to make those vents through the thickness of the whole wall. I tried fixing on another can to the funnel, with more fire cement, then making a sort of fan on which the pan would sit, but I could tell it wouldn’t last long, and anyway there was nothing to stop the vermiculite flying away every time I turned the stove upside down to get rid of whatever ashes had accumulated. I was stuck.

And thats how it stayed for a few years, to be honest. I moved on to other things, including research, and getting my garden straighter, and then I came across this video.  Eureka!

It showed me how to use the top that had been cut off my biggest tin to create a cover for the insulation, cutting a sort of chimney in it. I made a pretty bad job of placing the hole correctly – I knew the chimney on my rocket stove was wonky, and it all just fitted together badly, there’s no two ways of saying that. To make up for it, I made an insert from the thick aluminium of a disposable barbecue tray, much heavier than a roll of aluminium foil – light enough to be cut by scissors, but still fairly heavy duty. And then I lashed everything down tight with layers of fire cement. I skimmed over the inside of the biggest tin with the cement too, because it was lined with plastic, and I didn’t want to see that catching fire.

I tried to copy the sort of crenellations at the top of the stove, that would support the pan and provide air spaces, but I didn’t have the right tools for the job, and by then I just wanted it finished, quite frankly. So I decided to compromise: I’d bought an old cast iron barbecue way back, but I’d found out its lining (which was leaking from the underside) was made of asbestos, so it was useless to me. But the grid was still good to be used, so I’ve put that on top of the stove. I’ve used the lid from a big tin of potatoes as the insert that guides the twigs into the fire and still leaves a big space underneath to create a draft, and it’s good to go!

It’s not smooth, it’s not pretty, but it is securely functional. And all it cost me was a tenth of a bag of vermiculite, plus a little tub of fire cement. In using them, I gained a ton of skills and experience. I think it’s a win-win, and I’ve become quite proud of it.

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