The other day when I wrote about how Cooking Odors can Blow Your Cover When Bugging In I mentioned the Dakota Fire Hole. This a method currently taught by the US Marines for making tactical fires because they have a low light signature, reduced smoke, and are easier to ignite under strong wind conditions.
The Dakota Fire Hole is a bit harder to make than a traditional fire, but the extra effort is offset by its efficient consumption of fuel. The amount of fuel you need to cook food, treat water or keep warm is greatly reduced.
The Dakota Fire Hole is just what it says it is a fire in a hole, with a second vent hole to feed the fire oxygen.
When you are ready to dig your Dakota Fire Hole take a little time and find a good location. Avoid areas that are rocky or have many tree roots that require cutting. Areas that are extremely wet or sandy do not work well.
Once you find an ideal area, remove a plug of soil and plant roots about 10 or 12 inches in diameter. Dig straight down to a depth of about 12 inches. This will be the main chamber of the Dakota fire hole.
Dig a 4 to 6-inch diameter tunnel starting about one foot away from the edge of the fire hole to allow for airflow. This tunnel should intersects with the base of the fire chamber as shown in the attached diagram.
When the fire is burning, because hot air rises it will create a vacuum and draw air in through the vent tunnel. If you place the vent tunnel on the side of the prevailing wind, this will increase your airflow to the fire and it will burn hotter. Smoke is unburned products of combustion so the hotter the fire the less smoke.
The fire in a Dakota Fire Hole is below the surface of the ground and therefore less visible. If you save the dirt and the plugs, you removed from the holes you can cover up the evidence of a fire having been there.