This was an interesting challenge!  Blacksmith friend, who was involved in medieval reenactments, asked for bellows for his field forge.  So, something portable between fixed forge bellows usually around 6 feet long and my fireside bellows at 2 feet long.  Not simply a scaled-up version of my fireside bellows either as these required two chambers, or lungs, to ensure a continual blow of air to keep the forge heat really high.

Specifications or ratios of intake valves and nozzle diameter to bellows size not to be found anywhere!  The build would also be completed, with the single piece of leather completely tacked onto the three panels, before knowing if anything actually worked…

After quite some time for this build (and much head-scratching!), the bellows were mounted on a frame built by the blacksmith. A lovely, steady flow of air was just perfect – much jubilation, mixed with huge relief!

Reenactments have discontinued, so the bellows are looking for a home in a forge or on a battlefield…