Can you use a Bear Can as windscreen for a stove?

[Jon Fong / Flat Cat Gear]

Results from placing the Bear Can sideways

BRS 3000t / 500ml / 68F water / Garcia Bear can Sideways / 1: away / 8-mph wind

@ 1″ test stopped after 15 minutes.  Fuel consumption 20.5 g, water temperature 102 F

Clearly, the worst configuration for trying to block the wind.   My 2 cents.

[Terran Terran]

The other sideways. Flat side to the wind.

[Dan]

The other sideways. Flat side to the wind.

Yes, my idea is to use the canister in a blunt configuration, not a streamlined configuration. I don’t know if it will help, but it might. TBH, I’ve never even seen a bear canister that I can recall, so I’m not sure what they are like, but I assume they are cylindrical. I’ve seen bears in my backyard a few times, but only once while backpacking, and he stayed far away.

Drag coefficients could be a starting point to identify and classify shapes and configurations, but really you  are dealing with the wake region, which is a bit complicated.

[Jon Fong / Flat Cat Gear]

I can measure it when I am back home. Cd gives you information on drag forces but only implies what the wake or vortex looks like.  The ideal tool would be to add a smoke generator to visualize the vortex.  Turning the can on the side will produce the smallest cross section and therefore the shedded vortex will be closer to the burner head.  The Garcia can has very rounded edges from an aerodynamic standpoint.  A Bearikade would probably offer better wind protection due to its sharp edges.

keep in mind that this test is using the BRS 3000, probably the most sensitive stove in the wind.  So far, the data indicates that even with objects in close proximity to the stove (1”), the vortexes will significantly impact fuel efficiency to a level that is probably much higher than people would had guessed.  My 2 cents.

[Dan]

So far, the data indicates that even with objects in close proximity to the stove (1”), the vortexes will significantly impact fuel efficiency to a level that is probably much higher than people would had guessed.

That’s interesting for sure.

[Alan W]

Turbulent mixing is scale dependent. It’s not just the shape; it’s also the size. Behind a big enough cylindrical or spherical rock, the stove will be just fine. Of course, we want to carry small light stuff, but keep scale in mind when assimilating and internalizing.

[Jon Fong / Flat Cat Gear]

For clarity, this is a photograph of a Garcia Bear Can (cylinder). The red line defines the central axis of the can. All tests were performed using a Snow Peak Trek 700 and a BRS 3000t stove. The test was conducted in a wind tunnel at 8-mph. All tests were conducted with the cylinder 1” away from the fuel canister. Results:

Cylinder vertical – I stopped the test after 15 minutes as the water only reached 187 F. The stove consumed 21.4 g of fuel and the linear projection was it would require about 26 g to reach a full boil.

Cylinder perpendicular to the wind – stopped after 15 minutes. Fuel consumption 20.5 g, water temperature 102 F

Cylinder parallel to the wind and in line with the burner –  32.2 g of fuel use, reached a boil in 18:44

The best bear can configuration to block the wind if vertical and 1” away from the gas canister. That being said, fuel consumption on the BRS 3000t was still almost 4X that of calm conditions.

[Bill Budney]

It appears that you have definitively proven that a bear canister is not a good windscreen.

Cool.

[jscott]

I remember reading about a scientist who operated on cats to remove the muscle inhibition that works during sleep. And so when the cats dreamed they would act as if awake. He did this to several hundreds of cats. Result? Cats dream about chasing birds and mice.

kinda a long way around to prove what we already know.

[Jon Fong / Flat Cat Gear]

Keep in mind these key points:

The original experimental design was to look at stove performance at 1”, 6” and 12” away from a Bear Can. The fact that the stove was disrupted and consumed a lot of fuel at a 1” clearance really caught me by surprise.

The wind tunnel creates a steady airflow and in the real world, the wind fluctuates and is rarely steady. I use the 8-mph level as a reference to sort out the differences between stoves. Many people have stated that they have completed the PCT, AT and CDT using a BRS 3000t with no problems. That being said, no one really tracks their fuel consumption so real-world data is unknown. Nominal fuel consumption for a 2-cup boil is around 7 grams so a 4 oz canister should be able to achieve 14 burns or so. If your stove was affected by the wind for only 2 of those days, you probably wouldn’t notice.

The BRS 3000t is probably the most sensitive stove to the wind (The Fire Maple Hornet II may be worse). While the brunt of the wind was blocked, the trailing vortexes significantly impacted the stove performance. Other stoves should fare a lot better.

The point of this experiment was that a number of people claim that a rock, tree or a small piece of foil will resolve the issues with wind. Since there was no quantitative data out there, I decided to produce some. You can achieve a boil however; it can consume 3X-4X the amount of fuel compared to calm conditions.

[Bill Budney]

A windscreen is really a separate topic from the stove. If you are trying to prove that a BRS-3000t is somehow inefficient, then good luck with that. I’m not sure it is possible because I’m not sure it is true. All of these stoves are pretty simple, and a regulator shouldn’t matter much to efficiency. Burner design could make a small difference, but probably not much.

Rocks, trees, and foil all are possible solutions for some conditions. Shrug… it’s not highly useful information for the general case.

Using any stove without a windscreen is pointless in much wind; you have demonstrated that.

A large piece of foil, several layers thick, in a loose cylinder, is effective, light, and easy to make; it is a proven design. You may need rocks or stakes to keep it in place. It’s flimsy and not very cool, though.

Most of us really want an ultralight, compact, windscreen that we can carry with us. You, Jan Rezic, Dan, and Trail Designs are the leaders at that kind of thing.

(If you were to put the bear can OVER the stove, propped up on rocks to allow air for the stove, then you might get it to work better. If you can do it without melting your expensive bear canister, then you would have a winning solution.)

EDIT: As a bonus, the bear-can-over-the-stove-and-pot would act as a heat shield that eliminates the need for an HX pot to achieve peak efficiency.

[Jerry Adams]

the point of using BRS3000 is that is most sensitive to wind

if a windscreen or bear can will work with BRS3000, it should work with any other stove

[Jon Fong / Flat Cat Gear]

Bill,

I will have to respectfully disagree with you with respect to difference in stove design.  In this thread, I show a graphically representation of the differences with respect to wind speed.

In addition, the Soto WindMaster will boil water in and 8-mph wind with no windscreen.  It used about 18 g of fuel, but it was still better than the BRS 3000t while using a Garcia Bear Can in any configuration position 1” away from the fuel canister.  That is a striking difference and solely due to stove design.
These differences have been qualitatively reported all over but no one has actually tried to measure it before.  My 2 cents.

[Piney]

Jon, I would be very interested to see a test of a BRS with your Ocelot screen(s) vs. a Windmaster or Pocket Rocket Deluxe with no additional windscreen. In the 8-12mph range.

[Bill Budney]

Jon, that’s not a disagreement, that’s a topic change. :)  One that I already agreed to: You clearly demonstrated a difference in wind resistance at low wind speeds; a difference that becomes meaningless above 8mph.

I’m not criticizing you. I did tease a bit about your trying to use a wing for a windscreen, but ALL of your measurements help increase the knowledge pool. I would never have expected a cylinder to work in the way you used it, but others might, so now we all know for certain.

(So… does anyone know the melting point of bear canisters? )

I like Piney’s idea. I expect THAT is the test we all want to see.

[Jon Fong / Flat Cat Gear]

I will have to update that particular test.  The Ocelot for the BRS was developed over 2 years ago and my early wind tunnel was only good to 3 mph.  I’ll be back home early next week.  Jon

[dirtbag]

Whatever ya’ll do, please DO NOT use my Ursak!!

On our trip “Edge of Comfort ” my buddies tried to us my Ursak. Gust of wind came from different direction and blew it over onto the stove and pot. Spilled hot coffee all over and all over the Ursak,  then the flame torched a nice half dolla size hole thru the Ursak!  Umm.. user error there!! Seriously guys?  The only good news I got from that was, the sack was EMPTY! Luckily it was our last day there and morning of our short hike out, and I had planned my food 100% accurately! For once!!

John interesting testing for this. I would find a spot and use my bear can and something else to aid it.

[Terran Terran]

I appreciate the inclusion.
The 1 caveat I see in real world use is that I’d be sitting facing the stove with my back to the wind and hopefully in a somewhat protected area.

The wind block would be interrupting the turbulence .
Looking at flame direction in your pictures, if they’re not just happistance to the snapshot, I’d perhaps put the bear can on the opposite side of where I was sitting. Even with a windscreen, turbulence will have a cooling effect.
What is the best way to break the turbulence?

[Jon Fong / Flat Cat Gear]

There answer is……

Using the BRS 3000t along with an Ocelot Windscreen, we boiled 500 ml of 68 F water in an 8-mph wind.  It took 7:55 and consumed 16.3 grams of fuel.  Far better fuel efficiency than using a Garcia Bear Can (in any orientation) as a wind block even 1″ away from the fuel canister.  Note that the performance is only slightly better than the Soto WindMaster with no windscreen.  It all starts with the stove design.

[David Gardner]

I gave one of Jon’s Ocelots to the lady attending GGG 2023 (name withheld to protect the innocent), and she was blown away with the improvement in performance. I think she had a Pocket Rocket or PR Deluxe. And if I recall correctly it all fit neatly in her pot with one 110 g canister.

[Piney]

Thanks for the test Jon! I’m curious if that was a low, medium, or high flame level on the BRS that achieved the 16.3 grams, and if it was able to reach a boil at lower settings.

What was the fuel consumption of the Windmaster at 8mph? Gear Skeptic has the Windmaster using roughly 15 grams at 5mph, so achieving anything close to that at 8mph would be impressive. You have the Pocket Rocket Deluxe failing to achieve a boil at 8mph, what is the failure point for the Windmaster?

[Jon Fong / Flat Cat Gear]

In the wind, I have found that higher burn rates are required to achieve a boil. The higher rates increase the pressure a bit and keep the flame in contact with the mug/pot. You can determine this by looking at the time to boil and weight. In the last example: 16.3 grams in 7:55.

The Soto WindMaster fuel consumption @ 8-mph was just over 18 grams. I order to test to failure; I would have to re-build my wind tunnel with a much larger fan. Since the only canister topped stove to pass at 8-mph was the WindMaster, I decided against the upgrade.

I recently did a test using a Freeze Dried pouch 1“ away from the canister. I was able to boil 500 ml using 18.3 g of fuel in 8:46: not bad. The wind was high enough that I had to use C-clamps to hold the pouch still, but it worked. Now, when the pouch was moved to 6” away, the temperature rise stalled at 185 F at 23 minutes and consumed 42 grams of fuel. Whatever is used as a wind block, it has to be extremely close to the stove.

Note: comparison of this data to GearSkeptic’s may not be valid. I use a wind tunnel to create the airflow (pulling air in) while he uses a fan (pushing air out). There are differences between the two methods.

[Piney]

This is good info Jon, thank you!

[Jon Fong / Flat Cat Gear]

Updated Video

 

[Author]

Posts