there's a fucking equation.. somewhere, that follows *something* like this:
VxCxO=C
Volume X Combustibles x Oxygen = Heat (calories)
this may be entirely *WRONG*, ok (please refine as required) but the main thing is the common sense understanding of how to build a fire within a cylindrical structure..
for V/H (the *constant* ratio of volume to height) a cylinder is (arguably) the most efficient..
aluminum is better if calculated in a mass/volume/caloric output for an ideal updraft cylinder, but *only* if you wish to build an ideal chimney based upon mass & specific heat before phase transition..
ie, aluminum melts at a higher temperature than steel, so per gram of aluminum encompassing am equal volume, yes, the same mass of steel melts fat sooner.. by fucking far..
the problem is getting equivalently thick aluminum, because when you get down to it?
the difference between building a stove out of 4" diam, 6" high steel stove that distributes the heat through the mass of the chimney is a ratio of 2.7 (aluminum) to 7.85 (steel).
the thing is how much heat cal be applied (m/c) before the chimney fails..
this is actually very complex, but what it says is that a steel can of twice the mass of an aluminum can, can take about 50% more heat before failing of an aluminum can *of the same mass*..
THEREFORE, if you want the most efficient (mass to volume), low cost, cylindrical hobo aluminum stove, DO NOT USE AN ALUMINUM CAN, unless you are willing to build an ancillary chimney.. (stone, clay, bury in dirt, whatever)..
get a THICK WALLED ALUMINUM DRINK CAN OF THE WIDEST DIAMETER YOU ARE ABLE TO FIND from at thrift store, flea market, whatever.
NOT a steel drinker..
although steel drinkers are thicker than steel cans, generally..
THEN build yer stove & burn grass, gasoline infused grass, scrap wood, scrap wood & paraffin (crayons) whatever.. follow the standard airflow / chamber geometry commonly posted..
personally?
steel is great, specifically because it is *denser*..
a steel wall deforms *less* than an aluminum wall of the same mass, because the force of deformation is distributed over a smaller *area*.. this is only true, however, when the wall thickness is the same *mass* per area as steel..
the mass/density ratio is about 3 :1 (steel :alum)
the specific heat of steel is 0.45 kj/Kg & alum is 0.91 Kj/Kg..
the mass to specific heat ratio, then, is about 1:2..
this is critical when you start applying forces to heated/radiating elements..
ultimately i *think* this means that you get about a 1.5 :1 pre-failure performance ratio of alum vs. steel for a *single load bearing event* near the specific heat (ie melting point) threshold
aluminum cans are milled *way* thinner than steel.. about 1/3 for usage at ambient temperatures..
if you want to make a *stove*, though, that functions as a single unit & is reusable, use a steel can..
better yet, use a broken ceramic cup with no bottom, or a piece of clay pipe..
the main constrain is chimney temp prior to failure, & silica beats the fuck out of iron & alum..
the other thing is bellows..
you want HOT, asap??
get a nice steel, aluminum or copper pipe, about 1/2" in diam, 2' long & use that fucker to light up yer stove..
i *GUARANTEE* you, that if you oxygenate a fire in a steel or aluminum chimney, steadily, for 5 minutes, with steady breath, using just fucking scrap wood or dense dry plants, the fuckers will start to melt, physical; constants be damned.,.
a non-porous ceramic chimney will be fucking rocking, however..
anyways.. a can is nice, but if yer going to *cook*, instead of just heat, use the can/s as chimneys & combustion chambers, with widening diffusers, rather than as the place you rest your pan to cook.
the efficiency of *any* straight cylinder stove can be improved, just by adding aspiration (a blow-tube or bellows. or breathing) & a flared outlet to distribute the caloric energy..