I am not going to discuss the theory and applicability of a backpackable wood stove here. For that, go elsewhere. If you are interested in the lightest and most compact such stove currently available, read on.
The Big Sibling is the lightest wood stove on the market because it dispenses with a lot of what makes a stove a stove, namely a floor and cooking surface. Instead, it’s a titanium cone capped by a damper, fed via a door (also made of thin ti sheet), and anchored to the ground by three ti tent stakes. The cone is 12.5 inches tall at the base of the damper, and has a 10 inch diameter at ground level. The body and door weigh 3.5 ounces, the damper 1.5, and the three stakes a further ounce, bringing the total to an even 6 before adding an appropriate length pipe.
The whole arrangement, including a 5 foot pipe, rolls into a cylinder 3 inches wide and 15 inches long.
The cone fits together via folds in the metal on each side, and a wire attached to the door laces through five holes to hold the whole thing together. A wire loop on the bottom of the door allows it to be raised for feeding.
Putting the stove together is not complex, but is precise and a bit finicky at first. As befits an extremely light piece of gear (by which I mostly mean one abstracted beyond that which is conventional, to its essentials), there is a something of a learning curve before you come to the point of optimal efficiency.
The damper has a wire mesh screen in the bottom, to act as a spark arrestor. The damper flap is welded on to a ti stake. Getting the flap assembly into the body of the damper requires a bit of trickery; thread the curved end of the stake through the hole on the side, slide all the way to the flap, then squeeze the damper body to flex it enough and allow the far end of the stake to get through. Easy and obvious once you’ve done it once.
Drafting is allowed because the door is a bit shorter than the body of the stove, leaving a ~1cm gap. As can be seen and heard in the video below, this arrangement is extremely effective. Once a modest bed of coals has been built up, the Big Sibling will burn fast and very hot with the damper wide open. Damper control is very effective, and burn rate can be controlled widely and fast.
The most acute limit of the Big Sibling is the size of wood it can be fed. 2 inch by 6-7 inch pieces are ideal, and to facilitate this a small saw or hatchet is almost mandatory for good performance. Even stuffed full of big, dense pieces of fuel of damped low, the Big Sibling will burn through its cargo fairly quickly. It is not a stove for heating your shelter all night while you sleep, it is a stove for cranking heat to drive off the cold and dry gear while you eat dinner, hang out, and get ready for bed. It can drastically warm a pyramid shelter, but will not allow for a lighter sleeping bag than you would otherwise take.
The floorless nature of the stove naturally makes use on snow problematic. No doubt a metal foil floor atop green sticks could be arranged, something I’ve yet to experiment with.
The only other limitation might be the relative fragility of the titanium stove body. The metal is thin and prone to bending if not handled prudently. I’ve no concerns about longevity, but it should still be handled with care.
Overall, I could not be more pleased with this stove. The weight and space penalty are perfectly acceptable for all but the most light and fast trips, and after a modest bit of learning the functionality is impressive. Outside summer, and the most weight-sensitive trips, it should get a lot of use.