The "Magic" of the Caldera Cone

Posted by: Hikin_Jim

The "Magic" of the Caldera Cone - 12/27/11 08:55 PM

OK, so the Caldera Cone is an efficient alcohol stove system. But why is the Caldera Cone so efficient?



In today's blog post, I take a quick look at The "Magic" of the Caldera Cone

HJ

P.S. This is the last installment in my series on the Caldera Cone. I promise that I will move on to other topics although I may review some other Trail Designs equipment at some future point.

In case you missed any of the series:
Posted by: bacpacjac

Re: The "Magic" of the Caldera Cone - 12/28/11 02:21 AM

Thanks Jim. I'm definitely going to check them out!
Posted by: Hikin_Jim

Re: The "Magic" of the Caldera Cone - 12/28/11 04:37 AM

They're a pretty sweet little stove system.

HJ
Posted by: EMPnotImplyNuclear

Re: The "Magic" of the Caldera Cone - 12/28/11 07:06 PM

In your blog you say
Quote:
Quote:

I was wondering about the Caldera 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?

If, as in the above question, you have a cylinder within a cylinder, there won't be any space for air to flow up the sides of the pot. Yes, the conical nature of the Caldera Cone does provide for stability, but that's not the main reason for the cone shape. The conical shape creates separation between the walls of the pot and the walls of the cone so that heated air can be directed up the sides of the pot, transferring heat to the pot as it goes.


smile Well, a straight-wall will most definitely work , given adequate gap (10mm, or 8mm-12mm) I refer you to Pot Skirt Investigation, ETHOS 2010

I believe what the cone shape does better than a straight wall is promote swirling (venturi effect) at lower temperatures. This might mean slightly cleaner combustion; this might mean longer use-life for the cone; though I believe the difference at this scale is insignificant

I agree with your analysis of the purposes the cone serves
1. Entraps heat near the pot.
- yup, the air entering from the bottom robs heat from the cone (prevents cone melting), ie, the cone preheats primary combustion air (aluminum is reflective)

2. Protects against wind.
- yup, it protects the flame from blowing out
- the holes control the maximum amount of air available for combustion, and thus, maximum firepower

3. Controls internal air flow to maximize heat transfer.
- yup, it forces the hot gasses to scrape against sides of pot to maximize heat transfer (its a hot skirt)


You should definitely check out ( via translate.google.com ) All-round all-weather stove "The most comprehensive all-weather stove"
I really like the cardboard and aluminum foil prison smile its insulative and reflective

No screws or epoxy!! Pop-Up Fosterís Pot and Fin Shells , its a great folding/flanged/aluminum potskirt/windscreen, with 12.5 grams of alcohol ( 1 tablespoon ) it cooks 200 grams of rice in 400 grams of water ( 400 ml ) in a 750ml pot, using LannyPlans Builds an Alcohol Beverage-Can Stove


And this TLUD The Pop-Up Two Buck Stove , esentially the beefier version of the Pop-Up Foster's Pot
Posted by: Outdoor_Quest

Re: The "Magic" of the Caldera Cone - 12/28/11 08:08 PM

Great work Jim. Much appreciated.

Blake

www.outdoorquest.blogspot.com
Posted by: Hikin_Jim

Re: The "Magic" of the Caldera Cone - 12/29/11 10:05 AM

Originally Posted By: EMPnotImplyNuclear
In your blog you say
smile Well, a straight-wall will most definitely work , given adequate gap (10mm, or 8mm-12mm) I refer you to Pot Skirt Investigation, ETHOS 2010

I believe what the cone shape does better than a straight wall is promote swirling (venturi effect) at lower temperatures. This might mean slightly cleaner combustion; this might mean longer use-life for the cone; though I believe the difference at this scale is insignificant

I agree with your analysis of the purposes the cone serves
1. Entraps heat near the pot.
- yup, the air entering from the bottom robs heat from the cone (prevents cone melting), ie, the cone preheats primary combustion air (aluminum is reflective)

2. Protects against wind.
- yup, it protects the flame from blowing out
- the holes control the maximum amount of air available for combustion, and thus, maximum firepower

3. Controls internal air flow to maximize heat transfer.
- yup, it forces the hot gasses to scrape against sides of pot to maximize heat transfer (its a hot skirt)


You should definitely check out ( via translate.google.com ) All-round all-weather stove "The most comprehensive all-weather stove"
I really like the cardboard and aluminum foil prison smile its insulative and reflective

No screws or epoxy!! Pop-Up Fosterís Pot and Fin Shells , its a great folding/flanged/aluminum potskirt/windscreen, with 12.5 grams of alcohol ( 1 tablespoon ) it cooks 200 grams of rice in 400 grams of water ( 400 ml ) in a 750ml pot, using LannyPlans Builds an Alcohol Beverage-Can Stove


And this TLUD The Pop-Up Two Buck Stove , esentially the beefier version of the Pop-Up Foster's Pot
Cool stuff! Looks like I've got some reading to do.

HJ
Posted by: Hikin_Jim

Re: The "Magic" of the Caldera Cone - 12/29/11 10:06 AM

Originally Posted By: Outdoor_Quest
Great work Jim. Much appreciated.

Blake
Thank you, Blake. Hope it's useful stuff.

HJ
Posted by: Chisel

Re: The "Magic" of the Caldera Cone - 12/30/11 12:07 PM

EMP mentioned "promote swrling" and that popped a question in my mind : the Swiss volcano stove has a ribbed wall ( otherwise straight up, not conical) so what is the purpose of those ribs in the wall ?? Strength of the wall ?? Swiriling ??

Also, have you compared the caldera conical design with the volcano straight up design ??

mmmm ... I think there are many variables to compare , like the ribbed /vs/ straight walls, the diameter of the pot ..etc. In the volcano stove , the cooking pot has a larger ratio of surface area to volume, but in the caldera, you have a larger area at the bottom of the pot, where most of the heat is.

Posted by: Hikin_Jim

Re: The "Magic" of the Caldera Cone - 12/31/11 06:20 AM

Originally Posted By: Chisel
EMP mentioned "promote swrling" and that popped a question in my mind : the Swiss volcano stove has a ribbed wall ( otherwise straight up, not conical) so what is the purpose of those ribs in the wall ?? Strength of the wall ?? Swiriling ??

Also, have you compared the caldera conical design with the volcano straight up design ??

mmmm ... I think there are many variables to compare , like the ribbed /vs/ straight walls, the diameter of the pot ..etc. In the volcano stove , the cooking pot has a larger ratio of surface area to volume, but in the caldera, you have a larger area at the bottom of the pot, where most of the heat is.

I haven't compared the Swiss Ranger Volcano set up with the Caldera Cone.

You can't fit an alcohol stove in it easily, and, frankly, it just looks kludgey. I know there are those who like it, but I've never been that attracted to the Swiss Ranger set up.

HJ
Posted by: Richlacal

Re: The "Magic" of the Caldera Cone - 12/31/11 07:24 AM

I have had & use the swiss volcano stove for quite a few yrs,I have not seen any swirling effect via the ribbed design.I believe the ribs are there for ridgidity purposes alone,afterall they are military stoves built for the military rigors of abuse.If they were straight walled w/o the ribs,they would be creased/folded in short order upon the 1st bivouac!They are as Jim describes & bulky!I load mine up with tinder& wood & pack it into a gas mask pouch,usually slung over/around my main pack.I've observed hikers using them with alcohol burners,though I'm not an alky or gasser myself,I prefer a wood fire,I have gasser's & an Alky they don't get used much!