Decided to try an air throttle on the Pocket Stove. Achieved a 33 minute burn.

The air throttle is crude consisting of two tin cans. One is approx. 3 inches in diameter and the other six. A vegetable can and a coffee can. Notches are cut in the vegetable can to allow air in and it's trimmed down to about three inches in height. No notches are cut in the coffee can. The pan I'm using covers the inside can completely so that the main air flow is through the notches. The uneven fit, however, at the top allows more air in. The larger outer can is only there for stability, but may cause some restriction in air flow.

It's hard to see the flame. The evidence is when it slips out through the cracks in the uneven fit between the pan and the tin can base. Also for the first half of the burn the alcohol seemed to boil over in blotches and spill onto the surface below further exposing the blue flame.

Boiling is an indication of flame underneath the pan. However the boiling was sporadic. A couple of times I lifted the lid off the pan to check the boil and the movement of the pan allowed more air in and the boil increased. Also lifting the pan off the base allowed more air in and the increased flame increased boiling.

Surprisingly a full boil lasted as long as the flame. This is due in part to the container which has a tight lid.

There doesn't appear to be much purpose in extending burn time much longer except for warming or snow melt applications. The BTUs released are pretty much the same if the full burns full or partial throttle. However I will try to construct a more efficient throttle and do some more tests.