Canister Topped Stove Performance in the Wind

[Jon Fong / Flat Cat Gear]

Counterintuitively, at high wind with no screen, the small diameter bowl is more fuel efficient: https://youtu.be/6r-2hZ8UCeA?t=1378

you have to take high fuel usage/no windscreen with a grain of salt (or more).  The variability or errors associated can only be reduced by replicate runs in the neighborhood of 4-8 replicates.  The big take away is efficiency in high winds with no windscreen is bad: mug or pot.  My 2 cents.

[Bill in Roswell]

Whether Jon or Gear Skeptic, seems to me just 2-3 mph wind current can make a noticable difference in fuel used.

[Adrian Griffin]

This thread got me thinking about stove design. Comparing the PR2 and the Hornet II ….

The PR2 has better fit and finish that the Hornet II.

The PR2 has design features that add weight. The valve block is bigger than needed. The double pivot on the arms and the side lugs on the mixing riser add weight compared to the simpler Hornet II.

The Hornet II arm assembly is brilliant. Light, easy to deploy, and stable when deployed. The slots make it easy to add a windshield.

On the Hornet II, the burner is too far from the pot base. I wonder why they did it this way. If the pivot points and the pot arm heels were reconfigured slightly, the arms could swing out a little further, making them a few mm lower and increasing the support radius. Also the upper (light gray) riser tube could be a few mm longer.

Perhaps FireMaple’s engineers found they needed space between the burner plate and the pot bottom to get adequate air entrainment and secondary combustion of CO. Alas, this clobbers efficiency in the slightest breeze.

[Roger Caffin]

Perhaps FireMaple’s engineers found they needed space between the burner plate and the pot bottom to get adequate air entrainment and secondary combustion of CO. Alas, this clobbers efficiency in the slightest breeze.
For me, I always use a windshield with my stove, so sensitivity to wind does not matter (to me). But anything which avoids CO production when I am cooking inside my tent in a howling snow storm is a Good Thing (TM).

As my windscreen with hold-down stakes weighs less than 10g, its weight does not worry me, and I will be saving more than that weight in fuel over a few days.

Cheers

[Adrian Griffin]

Roger, remind me of the thread that has your windshield. Ten grams, you have my attention.  BTW, any thoughts on NOx formation if the isobutane-air mixture is too lean. It’s endothermic, so it would rob the pot of heat.

[Roger Caffin]

Hi Adrian

thread that has your windshield
Ah, that could be difficult, as I don’t think that windshield has appeared on BPL.
YET!
(No promises, but play around with 20 micron Ti foil . . . Yes, it is strong enough.)

NOx formation: unlikely to happen as I believe it needs temps over 2,000 C. A stove flame gets at best to maybe 1,300 C, but often a bit less than that.
We dodge that bullet!

Cheers

[Adrian Griffin]

Yikes, Roger—20µm titanium! I thought I was close to the edge with my 50µm. But it was stiff enough with a 10mm foldback along the edges. Next time, I’d do a 6mm foldback.

Please post pictures when you’re further along with the project. Info on sources would be useful. Rolls wider than 100mm are hard to find, even on Ali. I like a tall windshield to cover the flame area and most of the pot, so I need 150mm or wider.

[Roger Caffin]

Aghh. My error.
That should read 4 micron hard Ti foil, not 20 micron. Note that it is a HARD temper. Treat gently. 80 mm high. I wrap it around my round water bottle inside a very light stuff sack.

Do not buy the 99.9% pure stuff (Gr 2). That is SOFT (for a certain meaning of the word). You need grade 5 or 6Al4V alloy at least. It has been available on ebay at times, certainly. 100 micron stuff is routinely available – which does not really help – sorry.

Yes, I hope to publish.

A thought: that 10 mm foldback you mention may actually be a bad idea. Not sure. I can’t help thinking the different radii as a result of the foldback could lead to problematic stress at the edges. I have seen problems with Al foil. Not sure, needs testing.

Cheers

[Roger Caffin]

You can get 10 micron Ti foil on AliExpress. Not sure about the alloy.

Cheers

[Roger Caffin]

Double aaarrgghh! Total stuff-up by me. I apologise.
The Ti foil I am using is 0.04 mm or 40 microns, absolutely NOT 4 microns. What was I thinking???

There is plenty of Ti foil 0.1mm or 100 microns on ebay, but thinner than that is hard to come by – today.

Cheers

[Eric Blumensaadt]

On The Other Hand… Using the Fire Maple BLADE 2 remote canister stove with a standard size MSR aluminum windscreen may be very close to the weight of an average canister top stove with big windscreens and of course have much better stability.

The BLADE 2 has a vaporizing fuel loop by the burner, necessary for inverted canisters in cold weather.

jus’ sayin’

 

[Lennox N]

On the Soto Windmaster stove, have you tested, or noticed, any difference between using the supplied 4 arm pot support vs. the lighter optional 3 arm support?

[Jon Fong / Flat Cat Gear]

I myself have not looked to see if there was a difference between the two different support arms.

[Bill Budney]

any difference between using the supplied 4 arm pot support vs. the lighter optional 3 arm support?

I don’t have one, but three points are “statically determinate” while four are not. That’s why a tripod can be stable on uneven ground, while a four legged table can wobble.
It makes sense that most stoves use a three arm pot stand. I cannot guess why the Windmaster comes with four. It is nice that you can buy the three arm stand, but why isn’t it the default?

[Bill Budney]

*determinant

[Eric Blumensaadt]

David,

I STILL think that all things being equal in terms of pot material and wall thickness, pots that are wider than tall are more efficient as MOST OTHER TESTS have proven this.

[Roger Caffin]

pots that are wider than tall are more efficient
+1

[David D]

Eric, I think you meant “I STILL believe that all things being equal…”  Alleluia!

[Adrian Griffin]

Here’s the final beta of the windshield I’m using on my Hornet II. It’ll also work on any 3-arm stove. Diameter and handle cutout is sized for an Evernew ECA 532 500ml pot and Evernew Mug pot 900 ECA267R aka ECA539. Pics of earlier betas are with my early-March posts.

Material is 0.05mm TA1 foil. Closure is two pairs of 1x8mm dia magnets. Works well, but next time, I’d try 1x5mm magnets. There’s a 10mm foldback along the edges to provide rigidity. Next time, I’d try 6mm. Some crinkling along the inside. Time will tell if this is a point of weakness.

No danger of the tall shield getting too hot—the temperature never gets above 130°F.

The shield is attached to the pot arms with hooks made from 1.2mm stainless steel wire.

Weights are shield—14.5g, hooks 1.5g.

I use it with a pie-plate aluminum reflector (2.4g), a curly heat exchanger made from 0.25mm flashing stock (2.5g), and a cozy lid (2.7g) made from reflective bubble-wrap insulation. I haven’t tested the effect of these three items on fuel use, though.

[Jon Fong / Flat Cat Gear]

Looks good.  How are you measuring the windscreen temperature?  Looking forward to seeing your efficiency results.  Some magnets can lose flux when exposed to high temperatures (Neodymium for one) .  All good stuff here.

[Adrian Griffin]

Jon—I measured the temperature with a cheap NJTY T600A infrared thermometer from Temu. I left the emissivity setting at its default value of 0.95. I’m not planning to do any more efficiency tests. The windshield is the same as the one I used for the March 10 tests, exept it closes with magnets instead of a paperclip. I think the fuel savings from the reflector, curly, and cozy will be small, but I’ll take them all the same.

Time will tell whether I get past the Curie point of 300–400°C for the magnets, but in the interests of efficiency, I’ll keep the flame low.

[Author]

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