The name "rocket stove" refers to a stove where combustion takes place in a fairly short vertical section of pipe. While they are commonly used to make indoor cob benches, smaller portable versions make excellent camp stoves.
They have the advantage of totally free fuel (twigs collected from nearby) and are brilliant for large scale outdoor cooking. Personally I've built 3 of these stoves, and bought two others commercial ones and love them. You cook over them like a powerful gas burner - great for boiling water, cooking stews or frying a hearty breakfast.
Here is a simple stove you can knock together in about an hour and for less than $30. You will need:
You are aiming for an L shaped section of pipe, supported within the can by the perlite. At the top, the pipe should sit around 1cm below the top of the can. On the side, the pipe should extend a few cm out of the side of the can, and leave a gap of approximately 10cm between the bottom rim of the can and the bottom of the pipe.
Measurements don't need to be precise so you can eyeball the stove pipe along side your can and mark any cuts etc... measurements will vary depending on your can anyway.
Before you start cooking your bacon and eggs, you need to collect some fuel. You need a good bundle of twigs, around finger thickness, the length of your forearm and dry.
Even in bad conditions you can find dry twigs if you know where to look. Try to find twigs that have died naturally, blown out of the tree but got caught up some how off the ground. Alternatively, you can look for "dead, dry and standing" - branches on a tree that have died but not dropped yet.
For convenience I tend to use paraffin fire-lighters to get my stoves going (when you are cooking breakfast for 40 hungry school kids you need to be able to get it going FAST). Just light and drop it down the chimney. Feed a decent bundle of sticks in from the side, starting with your thinnest and driest. Once these catch you'll soon have a roaring rocket going, shooting flames up to the top.
StoveTec have been making and selling high quality rocket stoves for the past few years. Their mission is to replace as many polluting and dangerous unimproved stoves in the third world as possible. Cooking fires are the cause of many health problems in countries which rely on wood for fuel - they rarely have chimneys, and often smoke collects indoors where women, young children and the elderly are exposed to it. Over long periods of time this smoke damages eyes and lungs and can even lead to blindness.
By selling their stoves to you and I, they get to fund their projects overseas.
I've bought two of these, when I decided to upgrade my homemade models to something a little sturdier, and have been delighted by them. The construction quality is everything promised on the website and they burn really well. They are a little heavier than one filled with perlite, but only marginally so, and if you are travelling by vehicle and setting up base camp then this isn't a problem. Prices come it at about $100, but you also get to support a good cause while buying a fantastic product.
Stovetec also make much larger models, for permanent installations - these have been installed in schools, orphanages and refugee camps around the world.
These stoves burn woody material down fast, with hot flames, but leave a layer of unburned char behind. If you buy one of the more expensive stovetec models with two doors you can burn this away as well. Alternatively you add it to your soils as biochar.
Biochar can help improve soil fertility by raising soil carbon content and reducing nutrient loss due to leaching. It is particularly effective in sandy poor soils and tropical areas with high rainfall. Using a stove routinely and collecting the biochar can build up sizeable quantities over time.