Canister Topped Stove Performance in the Wind
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I just compiled a bunch of photos and videos of various canister topped stoves operating in my wind tunnel. The visuals provide a bit of insight with respect to fuel efficiencies and sensitivities to the wind.
Photo Overview
Bill,
The Snow peak LiteMax / Kovea SupsLite stove is not known for being robust in the wind. The pot support arms divide the burner head up into 3 sections. If you look at teh furtherest jet to the right, you can see that it is not lit. You can’t see it but 1/3 of the jets that are facing teh wind are also not lit. This shot is when the wind is blowing at 8-mph.
GearSkeptic just released this video about canister topped stoves and windscreen performance in the wind. Long but valuable. My 2 cents.
Thanks, Jon. Just for grins, this is where I am now. I’m prototyping with flashing stock from Home Depot, but the final will be 0.1 or 0.05mm titanium from Ali Express. I plan to hold the shield shut with hammer-in snaps, where you see the office clip.
The diameter of the main shield is set to fit snugly around my smaller pot that does a 300 ml boil for dinner and breakfast oatmeal. Over a trip, most of my fuel goes to the 740ml boils for tea in in the narrower, taller kettle. The curly thing is a heat exchanger that wraps around the kettle, filling the gap between the kettle and the shield. Maybe it traps some heat, but anyway it makes the shield more stable.
The reflector, made from a foil pie dish, fits nicely in the slots in the Hornet II pot arms.
So far, blue flames. Haven’t tested it with a fan yet.
Hey Jon. This is the beta titanium version of my tall windshield. It’s made from 0.05mm foil that’s plenty stiff enough with a 10mm fold along the edges. So a 150mm piece, available from AliExpress, gives me a 130mm tall windshield. Currently, it’s held closed with a paperclip, but I plan to try making a toggle from 1mmx8mm magnets. Weight is 13g.
The windshield doesn’t get at all hot, at least with a medium or low flame. For my tests, I’m fueling with cheap butane, which gives much less vigorous flame than isobutane-propane mix. The temperature of the lower end of the shield never got above about 120°F. The canister chills to 50–60°F under all conditions. No danger of overheating.
The effect of wind on an unshielded Hornet II is dramatic. With a 4mph breeze, it took 28g of fuel to do my standard boil. A windshield cuts fuel use significantly. Full details are in the graph.
I used the same delta-T (45–200°F) as the Gear Skeptic. But I did a larger 750ml “boil” to reduce the effect of timing and measurement errors. Also, that’s what I use for my tea boils on the trail which is where most of the fuel goes. Breakfast oatmeal and freeze-dried dinners are only 150–300 ml boils.
I used cheap spray-can butane, but I think the results are valid for isobutane-propane mix. The calorific value and latent heat of n-butane is about the same as for isobutane. The only difference is the lower vapor pressure. This limits the fuel rate at wide valve openings, so at 60°F I couldn’t do a full-power fast boil. But that would probably be past the point where efficiency is dropping due to flame spillage.
So the takeaways are …
In perfectly still air, the windshield only saves a gram or so per boil. At 2mph—slight air movement, not even a breeze—the windshield saves 3g per boil. At 4mph, a light breeze on the Beaufort scale, the windshield saves 15 or more grams per boil.
In most cases, a 13g windshield will pay for itself in fuel weight savings. The only exception might be a 2–3 day trip, cooking in shelters or places where still air is guaranteed.
Low fuel rates make for more efficient use of fuel, particularly when the air is calm and the pot is well shielded.
For comparing stoves under real-world outdoor conditions, a realistic baseline seems to be 2mph wind with a windshield. Under these conditions, the Hornet II did slightly better than a Pocket Rocket 2. Other testers have reported the Hornet II to be less efficient than the PR2, likely because the flame and heat blow away in the 28mm gap between the burner and the pot bottom. But the windshield traps this heat. Maybe there’s more secondary combustion of CO under the pot. So a windshield and an enclosed flame area are the keys to efficiency.
It might turn out that there’s not much difference between any stoves if the flame area is enclosed. Anyway, the Hornet II looks good. Cheaper and 24g lighter than the PR2.
Windshields rule!
Of course, I love looking a data, great charts. Keep up the great work!
The Fire Maple Hornet II and the BRS 3000t suffer from the same sensitivity to the wind: too large of a burner to pot distance.
Agreed, at 4 mph and above tends to really separate stove performance. Maybe Ryan could include it in his Stovebench test. It would be nice to see the addition of the PRD at 4 mph.
There are some oddities like “why are some of the slopes positive? Negative slopes make sense to me”. I wonder if a third data point would help (to the right maybe?)
What are the advantages of plotting the X-Axis as g/min rather than minutes? Curious.
BTW, below are the results of running the BRS 3000t at varies speeds in calm conditions (minutes for me not g/min). It shows the nonlinearity of stove outputs in order to optimize fuel efficiency.
For grins, I replotted the datat using your format g/min. One of the differences is that I go to much higher burn rates (g/min).
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