Wood fired downdraft kiln was only a quick experiment I did to see what temperature can be achieved. I did not fire any objects inside the kiln, because I did not have enough wood to keep the temperature at the maximum for at least a couple of hours.
Downdraft concept for the kiln is simple but effective. As the illustrations explain, the fire box is located at the bottom of the front, whilst the kiln space is above the fire box. The heat rises and travels down into the chimney providing a consistent heat inside the kiln.
The concept appeared to work great creating an extremely high draft on a calm sunny day and achieving up to 900C inside the kiln space.