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The Evolution of a Winter Stove - Part 3
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Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Roger stove ? on 07/26/2013 21:16:51 MDT Print View

> the boiling point is 32 F or whatever. If you put it in your pocket you can warm it
> up and use below 32 F. With your stove you don't get evaporative cooling so you
> should be able to use it as long as contents are above 32 F.
True, and if it's a Ronson lighter with iso-butane you could be on a good thing.

You can use n-butane (which boils at 0 C) at sub-freezing temperatures IF you use all the tricks, but it's going to be more tricky. It's not something I would recommend to a novice, but an experienced winter walker could do it OK.

Cheers

Robert H
(roberth)
Re: Pot support on 07/27/2013 05:07:02 MDT Print View

Hey Roger,

With the new design tripod design is the plywood board and micro-stakes (what are these and where do I get them by the way?) still needed?

Cheers.

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Re: Re: Roger stove ? on 07/27/2013 08:09:34 MDT Print View

Jerry, if it is not at or above the boiling point, then little pressure is generated in the canister.

I hadn't really thought about evaporative cooling, but you are right. Very little.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Re: Re: Re: Roger stove ? on 07/27/2013 08:26:21 MDT Print View

"I hadn't really thought about evaporative cooling, but you are right."

You obviously haven't used upright canister in cold weather : ) It always gets covered with frost. I bet it gets 10 degree F colder than ambient or even more.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Pot support on 07/27/2013 16:14:35 MDT Print View

Hi Robert

> With the new design tripod design is the plywood board and micro-stakes still needed?
The plywood base is nice to have when camping on soil or rock. It is essential when camping on snow.
The micro-stakes are useful, but not essential.

> (what are these and where do I get them by the way?)
Plywood base - that's an MYOG thing. Artistic licence allowed. I recommend ply rather than any sort of craftwood: the latter goes soggy rather quickly. Metal is a bit slippery.

Micro-stakes - hum, yes. I use Ti welding wire. Maybe you can find a welder who can give you one, or maybe you could use some stainless steel MIG wire. Or you could use high tensile bicycle spokes from a bike shop - you can even get Ti ones. The stakes don't have to be very long - under 10 cm.

I am sure creative minds will come up with all sorts of variants in time. Please let us know about them!

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Re: Re: Roger stove ? on 07/27/2013 16:15:41 MDT Print View

> I bet it gets 10 degree F colder than ambient or even more.
10 C or more.

Cheers

James Marco
(jamesdmarco) - MLife

Locale: Finger Lakes
Re: Re: Re: Re: Re: Roger stove ? on 07/27/2013 18:11:51 MDT Print View

You obviously haven't used upright canister in cold weather : ) It always gets covered with frost. I bet it gets 10 degree F colder than ambient or even more.

For an upright I can see that. I thought the discussion was for Roger's stove.

No, I havent used a canister much below 40F, if that. I usually use WG on longer trips or alcohol for short ones.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: Roger stove ? on 07/28/2013 00:50:47 MDT Print View

> With your stove you don't get evaporative cooling so you should be able to use it as
> long as contents are above 32 F.
Entirely correct.
But young novices do some strange things...

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Update on Legs, part 2 on 07/31/2013 04:41:12 MDT Print View

Update 1

I was sitting there in the evening playing with a stove on my workbench, thinking vaguely about the leg stability problem, when I actually SAW what I was looking at. That is, I actually looked closely at what the legs were really doing - and it was not at all what I had been assuming. I went to bed thinking about what I had seen, and in the morning I shot out to the workshop to make some replacement parts.

To cut a long story very short, the replacement parts made the standard tripod legs much stronger and more stable. The whole idea of a centre support is fine, but if the tripod is stable enough it is not needed for a little stove like this.

A longer story is that I had been slowly upgrading the legs from a quite different titanium version which combined the tripod with the pot supports. There are some photos of these in Part 2. But I had not gone the whole distance.

5396 Winter Stoves with updated legs

The new legs look like this. Well, OK, you may not even see any difference at first, except that the outer end of each leg now has a stylish tilt to it. The critical difference is at the pivot, where the rather small 14 mm shim washers which I had been using have all been replaced with much larger 22 mm Ti washers and brass shim washers. This has made a huge difference. (Anyone want a large supply of brass shim washers 14 mm diameter?)

There is one other small change in the leg profile: the small tab at the outer corner. This merits an explanation too. I machine each set of three legs together. That's a bit slow, but it makes for a much nicer set when they are folded together. The trouble was when the legs were all folded together they were packed really close together, and it was hard to separate them out. You could be sitting there at -20 C trying to set the stove up with gloves on and be cursing me for making the legs so hard to open. Not good enough.

The tabs on the two outside legs in the set are given a slight bend outwards, while the middle leg has a straight tab. Now it is easy to separate the legs. I should have forseen this as well, but I didn't.

The older tripod legs have been withdrawn and scrapped. The centre-support legs have also been withdrawn, although if anyone really wants them I can supply them from the existing stock. All stoves have been upgraded to the new improved legs.

Cheers

Franco Darioli
(Franco) - M

Locale: Melbourne
The Evolution of a Winter Stove - Part 3 on 08/01/2013 15:54:31 MDT Print View

The 116T RC has just arrived at my place.
Unfortunately I am almost packed up (moving house) so no tests for about 1 week.
As first impression feels incredibly light (90g on my =/-5g scale) for what it is.
My other two stoves of this type are almost twice and over twice that weight..
It holds a heavy pot with 2 liters of water and that is more than I need.
There is a bit of flex when you put that weight on but still sits nicely as you see in the photo.
Must remember (same as with my Kovea) to check that the arms are correctly open.
RC 116T 1
RC 116T 2

Edited by Franco on 09/30/2013 19:46:38 MDT.

Paul McLaughlin
(paul) - MLife
A little test if you get the chance on 08/04/2013 15:15:20 MDT Print View

Roger - testing published here on BPL in the past showed remote canister stoves having lower fuel efficiency on average than top mounts. Now that you have a remote with the identical burner head as a top mount, I'd love to see whether there is a difference in fuel efficiency between the two configurations when the burner head is identical. If you have the time.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: A little test if you get the chance on 08/04/2013 16:19:15 MDT Print View

Hi Paul

> testing published here on BPL in the past showed remote canister stoves having lower
> fuel efficiency on average than top mounts.
Um - got a URL for that? I don't remember publishing that sort of data myself. Could be failing memory of course.

On the other hand, people using a remote are often starting with colder water, and may run the stove a bit higher in power because of the cold. Both of those will certainly affect the fuel used.

I'm prepared to stick my neck out and say that there should be no difference in fuel efficiency provided that all other factors are equal. After all, how far away the canister is should not really affect the result - should it?

Cheers

Paul McLaughlin
(paul) - MLife
Re: Re: A little test if you get the chance on 08/04/2013 18:19:26 MDT Print View

http://www.backpackinglight.com/cgi-bin/backpackinglight/canister_stove_efficiency_p2.html

Scroll down to "Analysis" and "Uprights vs. Remotes"

So here's our chance to see if it's all about burner size/design or if there is something more mysterious going on. And for even more fun, you could run the remote version in canister inverted and canister upright modes and see if that makes a difference.

M B
(livingontheroad) - M
remote on 08/04/2013 22:00:43 MDT Print View

technically, the liquid feed could be sucking heat from the burner zone to vaporize the liquid, where a normal cannister feed can be using more ambient air heat. Or maybe not.

but the heat of vaporization has to come from somewhere, all depends on how heat is retained by the windscreen.

When somewhere around 1/2 of the heat of combustion is lost to atm anyway instead of going into the water, its easy to either creaste false small differences in efficiencies, or hide them.

Edited by livingontheroad on 08/04/2013 22:01:49 MDT.

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: remote on 08/04/2013 22:11:15 MDT Print View

Butane - heat of evaporation 320 kJ/kg, heat of combustion 45,000 kJ/kg

takes less than 1% of combustion heat to evaporate

shouldn't be significant

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: Re: A little test if you get the chance on 08/05/2013 04:17:34 MDT Print View

Hi Paul

Um and Oh. My own series of articles. Oh Dear. :-)

OK, part of the problem there was that we were comparing apples, oranges and the odd bunch of grapes. Some of the remotes had rather large burners which were less efficient for a given pot diameter than the smaller uprights. Some of the remote burners were just a bit strange too. I am going to blame most of the variation between the two classes on flame or burner diameter, as I noted in that article:

What is surprising is that the Remotes are generally less efficient (blue diamonds) than the Uprights. We believe that part of the reason for this is that the average flame diameter for the Remotes is larger than for the Uprights, and the flames are therefore closer to the edge of the pot. When the flames curl up around the edge of the pot, you know the efficiency is going to fall, as heat is being wasted.

However, with a remote canister stove based on the FMS116T or FMS-300T (ie mine), we could expect that the performance would be the same since the burner is the same. Perhaps one day, when I have built all these stoves for beta testing, I will get the time to run this experiment and report on it.

Cheers

M B
(livingontheroad) - M
significant on 08/05/2013 08:40:01 MDT Print View

totally agree it shouldnt be significant.

But as I said, when you are losing half your heat to the environment anyway, detecting small efficiency changes only works if you can keep other losses constant.

Or better, completely optimized for each individual stove. Without this, any data has a chance of being invalid.

Michael Driscoll
(Hillhikerz) - F

Locale: Monterey Bay
The Evolution of a Winter Stove - sound on 08/28/2013 15:50:08 MDT Print View

remote canister stove based on the FMS116T or FMS-300T of the 2 models you are selling which would be the quieter running stove... could not remember if it was mentioned in the series or not...

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: The Evolution of a Winter Stove - sound on 09/13/2013 17:35:03 MDT Print View

> FMS116T or FMS-300T of the 2 models you are selling which would be the quieter
Oh, very definitely, the FMS-116T version.
I have one or two of those left still.

Cheers

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Update on beta-test stoves - why the delay on 09/13/2013 17:36:38 MDT Print View

Hi all

I have to apologise for a bit of a delay in getting the beta-test stoves
built and shipped. Such delays are why I did not want to accept any money
earlier: they happen.

First, the X axis on my CNC machine started to jam. I knew what was
causing this: dust from machining Corain plastic had got past the brush
seal into the oil in the ball-nut. This turned the oil into very thick
grease and the little balls were jamming in their grooves. never again
will I machine any Corian plastic! Fixing this meant stripping the X axis
drive system down, cleaning the double ball-nut out, and rebuilding it.
That includes actually disassembling the double ball-nut itself, cleaning
it, and then putting all the balls back in without losing any. This was
not easy - the machine weighs 240kg (530 pounds) and had to be jacked up
for access underneath, but it was done. I lost a good part of a week here.

Then we had problems with the greywater disposal system we use on the
farm. (No sewer connection on farms.) The washing machine stopped working
properly. You don't argue when this sort of thing happens! Fixing this
took a good part of a week too. Lots of spade work. All OK now.

Then, just as I was getting back to the workshop, I went down with this
year's flu. It was a good dose (if 'good' is the right word): I was out
for about 3 weeks and am only just now starting to get back into action.
Imagine: a tiny 0.01 micron virus able to flatten an adult human being.

Anyhow, I will be back in the workshop pretty soon, working on the final
parts needed to be able to start shipping the FMS-300T version of the
stove. It will take a couple of weeks to have some ready. Then I will
contact all of you who have expressed an interest (by direct email).

Cheers