Michael, I have not tried to control the air in the outer sleeve. I really can't see how heating the air in the outer chamber is going to help combustion. The fire inside the inner container is blazing hot and doing quite well on it's own. It's burning hot as all get out. When the flames and gases reach the upper rim of the single can stove they mix just fine with air and combust like right now. My single wall stoves burn hot and heat 2 cups in 8 min or less. (Globe Stove, Veggie Strainer Stove, Martha Stixx stove, Hobo Elite stove and my Modified Zip single wall stove)
The modified Zip with one wall removed proved to be more efficient than the double wall.
Michael, remove the outer wall from your stove and do some test burns next week when you can make some time for some fun stove work.
I don't think the double wall is worth a hill of beans.
Nobody that pays the extreme price for a BB is going to admit there are any cons about the stove. Let's be realistic, a small veggie can stove can do just as well as a BB. The ones that have purchased the BB will do nothing but say good things about it because they paid the price, don't want to be known as a sucker. They got Stainless Steel for their money, just like the ones that buy Titanium goodies. Just some quality metal, that's all.
Nobody is going to prove to me that air traveling 4 inches up the outer wall is going to have an effect on the ignition of gasses coming out of the inner can. It's hype to sell a stove. My modified Zip stove tests proved to me that the double wall is insignificant in the performance of the stove.
High Performance car engines introduce cold air for better performance. Think on that for a while. It's not apples and apples, but something to think about.
Nobody questions my findings, why? Where are all the big guys that develope these third world country stoves? Why are they not sucessful in their sales to those under developed countries?