Such a fire is also called the Dakota hearth in honor of the American Indians of the Dakota tribe, who, apparently, invented it, not knowing the laws of aerodynamics, but simply relying on practical experience.
The Dakota hearth has many advantages:
- the flame is more intense due to good traction;
- less fuel is used;
- such a fire will burn well even in strong winds and give uniform heating, since the flame will not be carried away;
- an underground fire will not give out your location with its light, and there is less smoke from it;
- it is less fire hazardous, it is easier to extinguish it;
- when the fire burns out and the flame is extinguished, in a well-heated place you can quite comfortably settle down for the night.
As you can see, there are enough advantages, although you will have to work a little. So your actions:
1) Dig a hole in the ground with a depth and diameter of 30 cm.
2) Having departed from its upper edge about 10 cm, expand the hole at the bottom so that it turns out to be 50-60 cm in diameter.
3) Having retreated from the main hole about 30 cm, dig a second hole with a diameter of 15 cm so that it runs obliquely, diagonally to the first, and as a result, it is connected to it by a kind of tunnel.
4) Lay firewood at the bottom of the main pit and light a fire. Due to the fact that we have got a kind of wind tunnel, albeit curved, from the main hole, the flame and smoke will go vertically upward, and the additional hole will create a suction moment that will draw air to the wood through the tunnel. To further increase traction, it is best to dig an additional hole upwind.
5) And then you have several options:
- if the boiler or other cooking container is larger than the main pit, you can simply put it on top of it;
- you can put on top of an iron grate and put containers on it with a smaller diameter than the hole in the pit (for example, a kettle);
- you can put an iron sheet and thereby build a hob;
- if you don't have any of this, you can simply take a strong stick, rest it with one end against the ground, substitute a forked twig under it so that it reliably holds the stick at the angle you need, and hang a kettle or kettle on the end of the stick so that its bottom was just above the opening of the hearth.