Very good comments.
And made me think of Wendelbo’s early experiences. After our initial
email excnanges (in great detail), I met him twice. Once at an
Aprovecho Stove Camp and once at the PCIA Forum in Lima, Peru (2011).
1. His discription of what he observed (and possibly also did himself)
in the 1940s in Norway included what Neil mentions about placing small
amounts of dry fuel onto small fires (and avoiding smoke).
2. But he never mentioned that there was an initial tall-ish pile of
fuel, sufficiently tall to say “light the top, not the bottom.” Instead,
a small amount of fuel is likely to be rather flat and only maybe 10 cm
(4 inches) in diameter, and maybe only 2 to 5 cm (1 to 2 inches) thick,
which is not packed tightly and could be only 2 o3 “fuel pieces” in
thickness. Such a “pile” hardly has a top versus a bottom. Bring in
the match under the upper-most twigs or leaves and ignite this small
amount of fuel. That can be translated a being “top lit.” But the
important thing is to have some tiny fire that can be nursed with the
addition of small amounts of fuel, which are being places on top. This
3. Alternatively, imagine a tiny teepee of 4 or 5 twigs, with some dry
leaves or paper purched at the top. THAT could be intentionally top
lit. But the careful nursing of the tiny fire would be at the tip of
the teepee. In stealth fires, there is no intention (that I know of)
to be interested that the fire moves downward into a larger amount of
fuel. Stealth fires are tended at the top, adding new fuel at the top,
and not depending on fuel that is below. In the stealth fires of the
1940s and of the 2010s, there is not any recognized nor intended
downward-moving migratory pyrolytic front (MPF), which is the most
fundamental characteristic of true TLUD stoves. So Wendelbo did not
see this gasification of fuel down below the upper fire..
4. Therefore, this actually INCREASES the accomplishments of Paal
Wendelbo in the 1980-90s. In his countless experiments, somehow he not
only “containerized” the fire, but he came to the action of creating a
vertically tall column of fuel (which is not the case of the stealth
fires) and intentionally ignited it at the top. That alone is an
accomplishment, but it does not ensure success of a TLUD fire.
5. In addition, he would have observed in the (now called TLUD) process
that if the cylinder is of moderate size (such as 15 cm (6 inch)
diameter), the flaming of the gases tends to drift unevenly across the
top of the cylinder. So he eventually (this was in the years of work
that he told me about) he created the “concentrator disk” (or
concentrator hole in a disk) to bring together the created gases and
stabilize the flame. He did this sometime in the early to mid 1990,
creating the Peko Pe stove, with a claim of 5000 units made in northern
Uganda before he became ill (severe malaria) in 1999. Not one of
those early stoves is known to exist, even in terrible condition. The
modern Peko Pe stoves are quite similar to the initial ones, but now
there are adjustments for industrial production that differs from
6. Personal note: I can relate to Paal’s experiences and what must
have been his excitement to have the Peko Pe stove function well because
independently in 2005 I devised the “concentrator disk” in the Champion
Stove. Only in 2007 when Wendelbo entered contact with the Stoves
Listserv did we learn that he beat me to it by about 12 years. (Also,
Paal Wendelbo started from a youthful memory, but I did not start from
scratch. Tom Reed mentored me since April 2001, but Reed never derived
the concentrator disk concept for natural draft micro-gasifiers.)
Note: Any reader who desires more history of TLUD stoves should read
“Origins and History……” at www.drtlud.com .
On 5/27/2017 4:40 AM, firstname.lastname@example.org wrote:
> On 26 May 2017 at 9:23, Paul Anderson wrote:
>>>> PSA: Everything Paal Wendelbo told me about the origins in Norway I
>> have already written. He did not elaborate more to me. He did not use
>> the term “stealth fire”.
> No, but clearly that is what he described, and Baden Powell did use the
> term, but offers no evidence his was a TL fire. When I looked the term
> up on youtube, I variously found fires lit in ventilated pits to hide the
> light from the fire at night presumably, but also very small thin dry
> twigs in a small stack that flared quickly making minimal smoke, and
> additional small fuel added at a rate that could be sustained without
> creating significant smoke, so that is also other peoples answer to
> Crispin’s Q as to how I suppose it is done, that does not utilise top
> lighting. It quite surprised me to find unawareness of top lighting in
> specific instructibles for stealth fires.
>> But I really like that term. Note that it
>> distinguishes a top lit fire that is in the open from a top lit fire that
>> is in a container, which has become a gasifier device. A gasifier means
>> that the creation of the combustible gases occurs in a different place
>> (different level) than does the burning of those gases.
>> This distinction between a “stealth fire” (in the open) and a
>> TLUD_GASIFIER _(in a container) is fundamental!!!!
> Yes, I appreciate that, having tried both. We do ‘stealth car camping’,
> by which I mean mostly not using camp sites, and either sleeping in the
> reclining seats of a hire car when abroad, or in our car, home converted
> temporarily into a basic camper when closer to home, but wherever we
> aren’t obviously going to be in anyones way and doing no harm, usually
> moving on early after a nights sleep. All land is ‘owned’ by
> someone/some entity. The TLUDs and even the kelly kettle, well fired,
> constitute good stealth equipment though. We’ve never been challenged or
> encountered unfriendliness. Both fit into cabin luggage only, with no
> problem carrying fuel or finding it at the other end.
>> Neil wrote:
>> We have heard the Norwegian resistance stealth fires
>> story, which I found interesting in relation to Baden Powell who
>> describes bunking off into the woods while at boarding school and
>> lighting “stealth fires” and trapping and cooking rabbits, but then the
>> top lit idea is entirely missing from ‘Scouting for Boys’, and its hard
>> to imagine he would have known the technique but not shared it.
>> About C: TLUD gasifiers as camping stoves.
>> Perhaps someone will do more study of “stealth fire”. But please do
>> NOT start calling TLUDs to be “stealth” devices.
> Well clearly they can be if you want to use them that way, and the
> Chinese stoves don’t even call themselves TLUDs or instruct in any way
> their use, but they have that basic architecture and work well as TLUD.
> Not exclusively stealth devices obviously, and an unlikely use for the
> larger stoves.
>> Note: it is already known that when campgounds and parks prohibit “open
>> fires” (therefore NO stealth fires are allowed, not even if in a
>> “campfire ring”), the TLUD stoves are “contained fires” and can probably
>> be allowed (check with your local authorities) , along with propane/LPG
>> stoves and charcoal burners and alcohol stoves.
> If there is ambiguity, better perhaps to ask for forgiveness than
> permission, provided as you say you operate them safely.
>> But for the visual benefits of seeing flames and having light from a
>> fire at a camping event, a TLUD can far exceed the fire-light from LPG,
>> alcohols and charcoal that show essentially no flames for
>> ambience.!!!!! And if the TLUD is operated “rich” (much gases because
>> of primary air with relatively deficient secondary air), the visible
>> flame grows taller (seeking oxygen in the ambient air), and gives more
>> campfire-style light. This is another topic for backpackers and
>> campers to experience and to tell us about. ***** But always be careful
>> with fire!!! We want TLUDs to be welcome and acceptable at
>> Further note: TLUDs as camping stoves do not send up sparks. TLUDs burn
>> gases. The “sparky” particles of traditional wood-burning are absent.
>> This is extremely important for the prevention of forest fires/
>> grass-fires that are a danger from open campfires.
> In Scotland where free wild camping is a protected right in law I saw a
> poster encouraging responsible fire making, illustrating one of Tom’s XL
> Best wishes, Neil Taylor
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