Lightest USB wood stove

This article describes a 125g lightest USB wood stove that can burn damp wood sticks and simultaneously cook in two pots

Background

For years I was searching for the lightest wood stove for alpine walking and skiing backpacking where abundant heat was always welcome when the action was over. Unfortunately, only wet cold and sometimes frozen fuel sticks were usually encountered and they were difficult to burn in natural draft stoves twig stove article. I also wished to eliminate the tedium of preparation of little fuel sticks to keep the stove burning.

The inspiration

I was at the same time encouraged by the intense controlled heat that could be produced by a hand full of bush sticks in my ultralight tent stoves. These stoves have a tall flue pipe that produces a strong draft that causes strong incoming airflow that creates an intense, controlled and clean burn. This means that even damp fuel sticks will burn well, as they are dried by the heat from the glowing coals, before they are used for combustion Ultralight alpine tent stove.

The above combustion is a complex sequence and I have described the process in combustion of wood and charcoal. I applied these combustion principles to stick stoves for outdoor cooking with wet alpine sticks. I also developed them so that I could use the abundant clean heat to cook two pots at the same time for thirsty/hungry outdoor adventurers.

‘Dragon-fire’ breakthrough

A tiny fan from a discarded laptop enabled me to establish a tongue of ‘dragon fire’ in a small bundle of damp bush sticks that would otherwise support only a stodgy, smokey small fire with little useful heat. I subsequently turned assorted tin cans and kitchenware into backpacking blower stoves. My challenge was to control the burn of my new ‘fire breathing dragon’ and harness the heat for a fast boiling pot and at the same provide gentle heat for a dinner simmering pot. I also wanted a backpacking stove that would be; light, compact, durable and pack friendly. Ideally, I required it to be able to burn long damp fuel sticks with minimal preparation, such as ‘breaking the sticks over my knee or under my boots’.

The potential power of a blower stove unleashed and then tamed

The following photos reveal the potential power of some of my experimental backpacking blower stoves. Such flames can be maintained for 2-3 hours with a single 18650 lithium-ion battery ~45g) in a USB power pack. They also tell of the progression toward control and utilization of the ‘dragon fire’ that I unleashed. I have included them to assure you that I did not instantly dream up my ideal design. It was a journey of fun, failures and above all else lessons. I hope from the photos you can appreciate the improvement that the blower can make to an otherwise stodgy smouldering bundle of damp sticks.

A view looking down on a boiling pot on a powerful ring backpacking blower stove. Much heat is wasted as flames escaping between the three pot stand legs. For years this effective but inefficient type of backpacking stove was my favourite. “It would burn any wood that could fit in the tiny burn chamber”. The cook also had to frequently dodge the flames while removing the pot to add little broken up fuel sticks to the small burn chamber. Stirring the pot in situ was just not possible. Nevertheless, this little stove produced a lot of free boiling water for many happy campers and volunteers would happily keep up the supply of suitable little broken up fuel sticks, bark, root, nuts and charcoal in exchange for unlimited boiling water.

An example of a ring backpacking stove that results in the flame pattern shown above. The 30g (1oz) stove burn chamber has a fine ‘tongue and groove’ joint in the wall that allows it to be rolled up for backpacking inside a mug.

A C-ring backpacking stove easily boiling a pot of water. It has a slot in the side of the burner ring that at least lets a single flame be directed away from the cook, but its potential to heat a second pot is wasted.

An example of a backpacking stove that provides mastery of combustion with long damp fuel sticks and can provide rapid boiling in one pot while simmering another pot is shown in the photos below and is described in Blower Stoves.

A large roll-up titanium two pot backpacking blower stove including a wing wall support for a second pot. It all rolls up to fit inside two nesting large (~1L) pots and only weighs about 600g including the two pots. This stove is provided with a little LED cooking light. There is ample heat for simultaneous rapid boiling of water for hot drinks, soups etc while simmering dinner. It also dries the incoming fuel sticks in preparation for their easy combustion and provides heat to keep the cook warm. It is suitable for 2-4 people or more if cooking communal meals.

Blower Stove Minimization- to make the lightest USB wood stove

The above backpacking stoves are made of fine stainless steel and titanium and they became more and more sophisticated to improve their functionality and packability. Consequently, I considered it was time to take the combustion principles discovered with these stoves and apply them to primitive stoves (lowest weight and cost) that required no formal stove body other than rocks collected from a campsite. If rocks are unavailable or they are the ones that explode when heated, the burn chamber and pot support can just be a hole in the ground. This was the genesis of the Rock-N-Hole backpacking blower stove or the lightest USB wood stove that can cook two pots. It is for those who want convenient cooking without needing to carry the stove or fuel.

Rock-N-Hole stove- the lightest USB wood stove that can cook in two pots

All my backpacking stoves use the same blower unit with various ~5V dc power supplies. My favourite Lithium-ion 18650 battery of about 45g housed in a USB charge management tube (blue colour in the photos). It can provide cooking for 2-3 h or much longer if it has an on/off switch to conveniently regulate the combustion rate pulsing switch.

Simmering on hot coals without a fan-forced air supply is also possible. The lightest wood stove requires an air tube extension to protect the fan from radiant heat from the burner. In another configuration, a tiny air elbow attachment is required to bend the air flow downwards into a hole in the ground air extension tube and a dragon head.

My lightest USB wood stove is formed by earth or rocks that act as a good heat insulator so there is more heat for cooking. If the burn cavity is long it can support multiple pots. This is convenient as the stove naturally has a fast boiling position closest to the blower outlet and a simmering position beyond. Another delight of the rock stove is the residual heat stored in the rock can make a nice ‘sleeping bag warmer’ when wrapped in a suitable cloth.

Fire starting with USB fire blower

Lightest USB wood stove. A three rock blower stove rapidly boiling a pot of water.

Discussion

I can hear some people saying; “Why not just use a fire for cooking?” Well, my lightest USB wood stove has the following advantages:

• It can be much smaller than a campfire, particularly when fuel is wet.
• Uses much less wood where wood is scarce.
• The fuel sticks can be quite thick and fed in as long sticks.
• Very quick to start and reach cooking temperatures.
• Fast recovery of cooking power after an idle period.
• Heating is concentrated on the bottom of pots and not on their walls.
• Easily burns damp and wet wood.
• Pots are less likely to spill.
• The cooks’ hands are free of flames and radiant heat and in situ stirring is easy.
• The long fuel sticks can be simply be pushed in without interrupting cooking.
• A blower stove can be used for convenient cooking in conjunction with a campfire for warmth.
• Lastly, the blower unit is just great for starting campfires under difficult conditions.

See the video of starting of a campfire with a USB fire blower.

“I remember my friend Jack saw the stove for the first time one evening. The next morning was cold and damp. Before I was out of my sleeping bag he had my blower in his hand and was rapidly ‘breathing fire’ into a bed of remnant charcoal from the previous evening’s campfire to encourage us all to get up and going.”

For the whole blower stove story please see  Full Article.

Tim

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