The Caldera Cone is a proven and effective ultralight alcohol stove system -- but there are a lot of options.

Today, I thought I'd take a look at a couple of different versions of the Caldera Cone system.


If you're interested in alcohol stoves, perhaps this brief look can help you decide What Color is your Caldera? (with apologies to What Color is Your Parachute?)

HJ

Thanks alot Jim

I was wondering about the Calkdera being a cone shape.
Is it for stability or other purpose ?

If I take a can ( say a #10 can ) make holes up and down, and buy a pot that just fits in, will that be almost as effective as the cone ? Or is there something else I am missing ?

Heat source within the #10 can , can either be some sort of home-made alcohol stove or esbit.

My question is related to car camping , not backpacking.


Thanks

I've never seen this before. What a great idea! Le Chisel, I'm wondering about making one out of a #10 can. Does the cone shape concentrate the heat more? I'm assuming that a can with tightfitting cup would work but if it's too snug it could be difficult to get the cup in and out without spilling.

If you have a cylinder within a cylinder, there won't be enough space for airflow up the sides of the pot. Yes, the conical nature of the Caldera Cone does provide some stability, but that's not the major issue. The conical shape create separation between the walls of the pot and the walls of the cone so that heated air can flow up the sides of the pot. The conical shape in and of itself affects the air flow in such a way as to cause more efficient heat transfer. Most stove set ups just heat the bottom of the pot via the flame. The Caldera Cone makes use not only of the flame but also the heated air. This is why the Caldera Cone set up is more efficient than other stove set ups.

Take a look at this photo.


Notice the vents at the top of each cone. Air is heated by the burner within, flows in a controlled fashion up the sides of the pot, transferring heat as it goes.

This is really a brilliant design. The cone serves (at least) four purposes:
1. Entraps heat near the pot.
2. Protects against wind.
3. Controls air flow to maximize heat transfer.
4. Supports the pot.

Most stove set ups, if they have a good wind screen configuration, do only one and two. The "magic" of the Caldera Cone is that you get all four in one neat, practical package. The conical shape and the placement of the air vents is not random nor is it optional if you want the kind of efficiency that you can get with a Caldera Cone.

Now, if you're car camping, you could just "throw fuel at it." In other words, since you don't care that much about weight, you could go with a really inefficient design and just burn lots of fuel. Personally, I like efficiency, but that's just my particular idiosyncratic persona.

Yes, you could do a DIY alcohol burner. The 12-10 burner is really well tuned though. In my experiments with DIY burners, I haven't been able to get as good of results as with the supplied burner. My DIY stoves produce a fair amount of soot in a Caldera Cone which is a low oxygen environment. The 12-10 burner burns cleanly.

The real issue though is not the burner but rather the cone. Speaking for myself, I'd prefer a good cone with a DIY burner over a good burner with a coffee-can-with-cutouts type "cone".

HJ

Ho over to Jim Wood's Base Camp and you will see a pretty decent set up - his "Fire Bucket" windscreen and pot holder is a cheap, decent windscreen that is quite effective, although as HJ says, not as efficient as the Caldera Cone. Cost is easily under five bucks.

I'm sold! Thanks Jim!

I understand what you are saying HJ, and I would love the stability of the cone since I am near-paranoid when it comes to safety around fire and other hazards... However, there are ready-made cans ( like new paint cans at Home Depot ) that have a half-inch space between the wall and top opening where the lid fits.



When you drill holes near the top , the space between can wall and the inserted pot will be equal or even greater than is there in the cone.

Re: some stoves being highly tuned comapred to home-made ones, well, we can always steal ideas from your great blog and end up with great stoves. :-)

Thanks HJ.

You got a point there.
What if the pot gets stuck in the can !!!!

I can find a pot with a rim that sits ON the can.

Ah, a paint can.

Now, that might work. And it doesn't have to be as efficient as a Caldera Cone to still be a good stove.

Definitely an important thing to find a pot with a rim. The pot rim needs to mesh with the rim on the paint can to support the pot at the correct height. Either that or you'll need to rig something up inside the paint can.

I've found that a pot height of about 2 to 3 cm above the burner seems to be about right.

The other trick is to get the ventilation right. Too many openings, and your system doesn't work well in wind. My experience is that wind resistance is still important even when car camping. Too few openings, and your stove will be starved for oxygen, and you'll get a lot of sooting. You also need the placement to be correct so that you create the kind of controlled air flow that will optimize your heat transfer. Generally, you want more holes at the top than at the bottom.

I guess better soot than a stove that gets blown out in wind (in other words better to have slightly too few than too many holes), but better still would be a system that really works well.

HJ

A lot of my homemade stoves are what I would call open jet type stoves. These are the classic "Pepsi Can" style of stove. They're light, they're easy to make, they're easy to use, and if you use the basic design principles I've laid out in my blog, you can make a pretty decent stove if you're using a normal type windscreen set up.

I've tested my DIY stoves in the Caldera Cone, and they all produce a lot of soot. They're all starved for oxygen inside the low-oxygen environment of the cone. They work, but I'd hardly call them optimal.

The style of stove that comes with the Caldera Cone is called a "chimney stove". My testing indicates that this style is a better style for use with a restricted airflow type system. You can buy the burner alone for $15.00 or you can make your own. The link to buy one is Trail Designs 12-10 alcohol burner. No affiliation on my part although I have "talked" with the proprietor, Rand Lindsly, via forums like this, the comments feature on my blog, etc. I certainly have no financial interest in the product; I just find that the product works well for the intended purpose.

Of course, now, if your name were Hikin' Jim, you might be this very moment experimenting with your own model of a chimney stove, but I digress...

HJ