I made a small rocket stove from 2" box section steel in an 'L' shape with a separator in the horizontal section to separate air flow and fuel feed. It worked well enough to boil water - eventually - but required almost constant attention (blowing air through a tube) and the flame burned only orange. I then built another one, this time with an insulated double wall chimney and this was more or less impossible to keep alight even when encouraged with blowing air and adding white spirit. Perhaps this was because of the reduced fire chamber size resulting from the insulation layer. I am unable to find a video or any evidence of this type of stove working effectively. Has anyone actually seen a small rocket stove work effectively or should I conclude that they are useless?