Here is the chart made from the resulting figures. You can see the line at 11 min. when the stove is ready to have the pot placed on it.
The globe Stove and the Vegetable Strainer stove and the Martha Stuart flour sifter stove had 2 cups boiled in less than 10 min. There are other single walled stoves that will do the same.
In the article the author states that the air for combustion comes from the bottom of the stove and rises upward. When you read the article it clearly states that the stove was named downdraft because the pile of wood burned from the top downward. Hard to do if air flow is not precise coming through the bottom and rising upward.
What you see in the above photos are stoves made of a thick walled "riser" sleeves. They are used in the Foundry industry to line the sprue hole when pouring molten cast iron and other metals. They are single walled stoves.