The Indians knew what they were doing without a bunch of MIT graduates to give them directions which is something that may be surprising to a lot of people that are firmly entrenched in the idea that only scientists know how to make things work.
The process of having an open fire in a tipi is fairly simple. It is all about draft.
Most people do not realize that there are two layers to a tipi. There is an outer shell that everyone sees.
On the inside there is a liner that goes up about four feet.
The inside liner is firmly held against the ground and the outer liner is a few inches above the ground allowing air to enter and be driven upwards to the smoke hole at the top.
The smoke hole is actually kind of a slot that has a flap on either side and the smoke flaps are manuvered ont position by poles to utilize the outside wind to add to the draw effect that is created by both the rising heat of the fire and the air entering the base of the tipi and going up the liner.
It's a pretty slick system and it works well. The flaps are long enough so they can actually loosely wrap around the smoke hole in case there is a wind coming in directly from the east, which is the direction the door of a tipi traditionally faces.
The harder the wind blows the more draw is created and the more efficient the system is.
Of course, if it is dead calm the system still works like a charm as the heat rising from the fire creates its own draw anyway.
It is a pretty foolproof system.
The other thing about a tipi is that it is conical and as a result has no flat sides and when the winds pick up they simply swirl around the tipi. It is a pretty foolproof wind cheating design tha enables it to stay up during pretty fierce winds.
While it looks pretty simple the entire set-up is pretty ingenious when you look at if from a scientific point of view.
All in all it isn't a bad design from a people that never set foot in a classroom.
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