Combining a Radius 21 with an Optimus spirit burner kit

Discussion in 'Stove Forum' started by Trusty McTrad, Jun 20, 2021.

  1. Trusty McTrad

    Trusty McTrad Norway Subscriber

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    I always thought that the Trangia 25 and 27 kits were an excellent design; how the wind screen keeps the heat enclosed inside and how the heat moves up along the wall of the pot before escaping the wind screen at the top. However, since a porpane. It is truly storm-proof, and I like how the base and the wind screen, the two pots and the lid-slash-pan, all packs away tucked inside each other into one small-ish package.

    That said, in winter and sub-zero conditions you have to be very patient with your boiling of water or cooking in general, and you have to carry a lot of denatured alcohol. Which is why a lot of people substitute the spirit burner for a propane burner with an external gas canister.

    So I thought; why not combine the power (and the sub-zero performance) of a traditional kerosene stove, and combine it with the efficiency and packable design of a Trangia kit? I am probably not the first to do this, but I wanted to share my experience nonetheless, and if you have any experiences with this kind of setup, please share.

    I got hold of an Optimus style kit (similar to the Trangia 27, but somewhat cone-shaped), and leaving the base and the spirit burner itself aside, I drilled three holes in the wind screen, so that it would fit the pot stands on a 1 pint stove. The result is a kit that is entirely wind-proof, not just in terms of the burner, but interms of the efficiency of the stove and the heat lost to the wind and the surrounding air.

    I went for a hike this morning, and decided to test my new combo.

    Here is the kit packed up:

    IMG_6680.jpeg

    The Optimus kit is housed inside another aluminium pot, which allows me to carry a non-stick pan with a folding handle as well as an insulating "cosy" which allos you to put a pot of hot food onto the snow without loosing heat. The top lid is the lid/pan of the Optimus kit inside. Out of the green canvas bag comes my 1930s Radius 21F:

    IMG_6681.jpeg

    Then, the alcohol kit is placed on top of the Radius, tightly held in place by the pot stand legs of the kero stove.

    The top rim is the pan/lid, the second from the top is the pot now sitting inside (cooking noodle soop, ramen-style), and the bottom rim is the top edge of the wind screen. You can see below how the flames from the Radius enters the wind screen exactly where the flames leaves the flame ring (which seems to have been poorly adjusted, probably from moving the Radius wind screen after lighting the stove). Note: A silent burner would not be preferred for this type of use, while a roarer allows you to dial the heat up and down by sound and experience, as the flames are hidden from view.):

    IMG_6683.jpeg

    I did not time the boil, but my impression was that it was very fast.

    Another bonus is that when using a frying pan on top of this setup, the pan (unlike the pots) would sit on top of the wind screen, probably 10cm above the burner head, but since you get the same benefits of the wind screen that is actually a plus, as the heat spreads out warming the entire base of the frying pan evenly, without the blow torch effect that you get in the middle of thin aluminium pans.

    And since the alcohol kit does not take up any more space than any other set of pans, I reckon this is something I will use more.

    All the best,
    T
     
  2. Mr.stove

    Mr.stove Subscriber

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    Very nice.
     
  3. Dean

    Dean United Kingdom Subscriber

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    Have you read the thread
    ?
    Slightly more enclosed, for possibly somewhat more extreme cooking.
     
  4. ROBBO55

    ROBBO55 Subscriber

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    Interesting, and certainly worth investigating further. :-k :thumbup:
     
  5. Trusty McTrad

    Trusty McTrad Norway Subscriber

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    @Dean - Thank you, I had not read that thread. A great post by @Spiritburner and some very interesting reading at that!

    I agree that the Everest rig by Westcliff Engineering is definitely
    ..but I find the lack of space to operate the release valve and filler cap to be a problem with the design. Surely, raising the lower part of the casing/enclosure one inch would not compromise the efficiency of the rig?

    My test in the pictures above was done in about 18 C and no wind, but one observation was that the heat transfer from the burner head was massively increased by the presence of the enclosed space receiving the burner head flames. After cooking the soup, the tank of the Radius was hotter than usual, and the stove seemed to be self-pressurising after the initial five or six pump strokes. I certainly would not have wanted even more heat transfer that day, and was not missing the enclosure of the riser tube and burner head. I originally thought about using the base/lower windscreen of the Optimus kit for this, but decided to skip that in order to make use of the normal pot stand legs rather than make new shorter ones for the lower enclosure.

    That said, in -25 and gale force winds you would definitely want that extra efficiency and the absence of convective heat loss, and an outer wind screen leaching well below the burner head could be warranted.

    Having seen the original Westcliff Engineering design, I will definitely have a go at making a fully enclosed version, for sub-zero temperatures and/or strong winds. (I sometimes go skiing on the Hardangervidda plateau, were winter conditions are arctic in every sense. This winter we had both -35 and hurricane force (70mph) winds, but even in more pleasant winter conditions it is always rather cold and windy to some degree, so creating a completely storm-proof rig that would allow me to start cooking or melting snow while pitching the tent, would definitely be worth the effort.)

    I will keep you posted and share some pictures once I have made my own mini-version of the Everest rig.

    Best regards
    T
     
  6. Trusty McTrad

    Trusty McTrad Norway Subscriber

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    So, dear friends, I have made a kit that should be able to perform better than most in arctic conditions. Inspired by the Everest rig by Westcliff Engineering mentioned above, I took my storm-proof Radius 21 kit a step further, both in terms of winter performance and in terms of pack size.

    I wanted the kit to have the following properties, limits to modifications and improvements to the Wesstcliff design:

    1. An all-in-one package, i.e. unlike my kit featured in the pictures above, the Radius stove fitted innside the kit for transport.
    2. A fully enclosed cooking operation with mimimum heat loss to the environment.
    3. The ability to fill the pot with snow well beyond its capacity for water, as you need 3-5 litres of snow to produce 1 liter of water.
    4. No screws that would be a pain to handle with bare hands or with small tools in severe cold, or any other small parts that could easily get lost in the field (i.e. sticking with as much kero stove simplicity as possible).
    5. Easy access to the release valve and filler cap, i.e. more gap between tank and base of wind screen.
    6. Finally, if possible; The spirit burner kit should still be perfectly usable in its original form and with the original spirit burner, i.e. no modifications rendering the kit useless as a normal alcohol stove.

    As much as my contraption is purely utilitarian, and not a work of art like some impressive examples of copper and brass constructions I have seen from the likes of @HONDA , I do believe I have managed to achieve all of the above.

    First, I made some short legs from stainless steel wire, slightly bent at the end to fit securely in the sleeves on the Radius tank, and attached them to the lower part of the wind screen (the alcohol stove "base"). The legs are secured to the base and folds away for transport, as well as for when I might be carrying the spirit burner inside it:

    IMG_6709.JPEG

    Then, I made cuts in the base to fit on top of the Radius and accommodate the filler cap and the pump:

    IMG_6707.JPEG

    The frying pan can be used as a lid as always, or as a base or "snow shoe" for the stove on fluffy snow:

    IMG_6710.JPEG

    The base fits to the stove with the legs having been cut to achieve the correct distance between the base of the pots and the burner head:

    IMG_6711.JPEG

    The upper part of the wind screen then goes on top as normal. Note how the burner head is completely protected from the wind, and I suspect that the original wind screen for the burner head may be redundant in actual use of this kit:

    IMG_6713.JPEG
    IMG_6712.JPEG

    The pot then goes into the upper part of the wind screen, as normal:

    IMG_6714.JPEG

    Rather than using the frying pan as a lid, I added a handle to the base of the smaller pot, so that 2x the amount of snow may be loaded into the heated space for melting and producing water en-route;

    IMG_6715.JPEG

    The handle is in steel wire for heat tolerance and has oblong shaped hinges so that it folds flat and secured for later, when you want to use the lid as a second pot for cooking, and the handle would be facing the burner head.

    The whole rig is 32cm /12.5 inches tall, and because of the fact that the pot is sitting exactly where any pot would sit on the Radius in normal operation, but since everything is balancing on circular edges, perfectly centered and prevented from any sideways sliding; it is marginally more stable than a normal setup:

    IMG_6716.JPEG

    All the parts and tools (burner head, flame ring, wind screen, pricker needle, meths bottle, lighter/matches, and a small leather strap to aid the tightening of caps for transport) fits inside the kit:

    IMG_6706.JPEG

    IMG_6704.JPEG

    I also made a piece of styrofoam with some felt stickers to keep the folded stove legs from damaging the lid/frying pan when packing everything up tight and firm:

    IMG_6705.JPEG

    Finally, my new winter kit packs up into a nice little bundle, with the Radius 21F and all the parts inside:

    IMG_6703.JPEG

    Your comments, as always, are most welcome!

    All the best,
    T
     
  7. Spiritburner

    Spiritburner Admin SotM Winner Subscriber

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    Certainly more compact than the Westcliff outfit. :thumbup: Nice one!
     
  8. dogface

    dogface United States Subscriber

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    Trusty McTrad,

    Your idea is inspirational, having given me ideas for my own version, tailored to my climate and utilizing an Optimus 00 with a Czech mess kit. I have a lot of those mess kits and search for ways to use them.

    Good job, keep it up.
     
  9. Trusty McTrad

    Trusty McTrad Norway Subscriber

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    Thank you, gentlemen!

    I will add som photos to the action shots forum once I have had an opportunity to use it in the field.

    All the best,
    T
     
  10. BigScott

    BigScott Subscriber

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    Looking at the way you have 'balanced' the unit on the upturned frying pan I thought ' why not fold the legs under with the frying pan the right way up. I feel, from the photos, that this might be more stable and even lend itself to a hanging system
     
  11. Trusty McTrad

    Trusty McTrad Norway Subscriber

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    Thanks, @BigScott , I had the same inclination and actually did that first, but the legs damaged the surface of the pan on the cooking side. But for the same reason, they bite into the aluminium quite well, so the pictured configuration is actually rather stable. Third, on the snow the upside down pan will probably be a more stable and fixed base than the right way round, or what?
     
  12. afoton

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    My experience is that Radius 21 stays very sturdy right into the snow. Unlike Optimus 111 that will melt down into the snow.