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SavageLlama
08-06-2004, 10:07
Good read.


Not even the Kitchen Sink

By Paul Sharke
Mechanical Engineering-CIME (http://javascript<b></b>:NewWindow(%20'FIISrcDetails','?from=article&ids=meng');void(0);)
August 1, 2004

Go fast and light, say today's hikers. Outdoor gear designers trammel lots of ground getting them there.

On January 1, 2001, a 39-year old systems engineer began -walking north from Springer Mountain in Georgia, the southern terminus of the Appalachian Trail. Early into his journey, Brian Robinson picked up the moniker "Flyin' Brian." Like most other through-hikers who finish the trail in four to six months, Robinson reached the forest pathway's northern end in Maine before the calendar turned. Along the way, however, his path diverged from that of his fellow hikers by many million steps.

More than midway between Georgia and Maine, Robinson turned left, heading west by bus to walk the two other great north-south routes that gild the western ranges. In addition to hiking through 14 eastern states, Robinson, by the time he finished this first-ever calendar-year Triple Crown, had followed the Continental Divide Trail across the highlands of New Mexico, Colorado, Wyoming, and Montana. And he walked the Pacific Crest Trail over the mountains of California, Oregon, and Washington. Setting a blistering pace, he trod 7,371 miles in ten months, walking nearly the equivalent of 300 marathons in as many days. he slashed his winter pack weight of 19 lbs. to an ephemeral 10 lbs. for the summer, not including water or food. A new stove will introduce capillary force vaporizing as a way of atomizing fuel, stepping away from cartridge and metal-tank stoves that dominate the market.

A member of hiking's rarefied but growing long-distance community, Robinson carried a minimum of commercially manufactured gear. For this group, a 3 oz. propane stove is too heavy. Many members favor lithe running shoes to bulky boots. The fringe element cuts its own alcohol stoves from empty cat-food cans and parses every pack item for its multi-task functionality.

This rivulet of fast-and-light hiking has joined backpackings mainstream who would prefer to skip, rather than trudge, its way across hill and vale. Mainstream members insist on camping comfortably, though, and even luxuriously. Equipment manufacturers happily oblige them.

For example, Mountain Safety Research of Seattle will introduce a new stove this month that could threaten traditional travel cook sets with its efficiency and simplicity. According to MSR's vice (president, Jeff Bowman, the stove will vaporize white gas fuel with a single device that combines capillary action and phase transition. For hikers, that means the traditional stout metal fuel tank disappears. The stove, which requires no tank pressure to feed its burner, instead uses a light plastic tank in its place, Bowman said.

Dubbed a capillary-force vaporizer by developer Vapore Inc. of Richmond, Calif., the tablet-size device at the stove's heart merges a high-porosity ceramic element with a heat-conducting orifice disc and an insulating capillary wick. According to Vapore s CEO, Robert Lerner, micrometer-scale holes make up 80 percent of the high-porosity element, or vaporizer. These pores carry the fuel to the underside of the orifice disc where heat-conducting posts expand the liquid through an array of fins and channels. These, in turn, direct the pressurized gas toward a central orifice where it escapes as a vaporized jet. By the time they reach Washington's North Cascades, Pacific Crest Trail through-hikers are racing to finish before the first flakes of winter fly.

Fuel for the vaporizer comes up from the tank through a series of larger capillaries running through the insulator. A glaze binds together the entire ceramic stack, Lerner said. Light and cheap: Homemade alcohol stoves can boil a cup or two of water, about all some hikers require.

Vapore uses a microfoam process to manufacture the high-porosity vaporizer. It produces the fins and channels covering the bottom of the orifice disc with a process it. calls micro-detail gel casting.

According to MSR's senior design engineer, Redwood Stephens, the stove makes an ideal commercial introduction of the new technology. Many hikers, climbers, and paddlers relish innovative designs that can enhance their adventures. Because it will pair canister-stove simplicity-no pumping or maintenance-with the refillable convenience of a white gas or liquid stove, the new design carries MSRs hopes of diverting stove sales away from both of these established categories. The stove will start without pumping or priming.

An important aspect of the new stove is the interface between the burner and the pot, Stephens said. It extracts much more heat from the burner than is possible with an open jet. A heat exchanger focuses heat on the pot bottom that would otherwise escape up the sides. The entire creation pays close attention to industrial design, Stephens added.

Forest Test Bed

Engineering of the pot/stove interface was a key element of another high-efficiency design introduced this past January. Jetboil Inc. of Guild, N.H., integrated a pot, burner, heat exchanger, canister, and insulator into a single unit to promote efficient fuel use, said chief technology officer, Perry Dowst. As a result, the stove uses less fuel in the field, about half that of a conventional pot-and-stove setup that lacks an engineered interface.

Early in the development process, Dowst and the company's co-founder, Dwight Aspinwall, realized that many travel stoves-and kitchen stoves as well-lose a great deal of thermal efficiency during the heat transfer from burner to the cooking vessel. They also realized that the most popular form factor in the outdoor industry-the thin, tall Nalgene bottle-was the shape most pack pockets were sewn to accommodate. The heat transfer characteristics of a tall, slender cooking pot were lousy, at best.

Dowst, whose background includes heat exchanger design and combustion research and development, said he and Aspinwall decided an integrated system would be the best way to increase efficiency while staying within the unusual confines of the popular form factor.

Although they relied on some theory, the stove builders took a mostly empirical approach to developing a heat exchanger for the cooking vessel-a cup, really. In about a year's time, the pair had developed a system that almost doubled the heat-exchanger efficiency of most commercial backpacking stoves. The heat transfer efEciency of a typical stove under laboratory conditions fell between 35 and 45 percent, Dowst said. Jetboil brought that efficiency up to between 70 and 85 percent.

The heat exchanger reduced the temperature of the exhaust gas to about 250°F; Dowst said. That opened a design possibility that would be immediately evident to users. The benefit of reducing fuel use by half, though big, was "sort of invisible," he explained.

But the reduction in exhaust gas temperature opened the possibility of a high aspect ratio pot that could be held by the user. Wrapping a Neoprene jacket around the cooking vessel furthered its ability to hold heat and be held at the same time. That eliminated the need for pot grippers and handles. The pot secures to the stove during cooking to prevent spills. A Jetboil system brings high efficiency outdoors. Inset shows its built-in heat exchanger.

Though Dowst and Aspinwall both are fervent mountaineers who know their market, the duo relied on usability tests at several key junctures in refining the prototype. Setting up a trailside table in New Hampshire's White Mountains, they asked the first hiker coming by to test the stove. he said, "I come up here to get away from guys like you." But the surveys proved invaluable; after three such sessions the design direction had changed dramatically, Dowst said.

They also engaged instructors in the Peterborough, N.H.-based Eastern Mountain Sports mountaineering school to carry the stove prototypes aloft. The testers brought comments and critiques back from the hills that helped refine the design.

Manufacturability played an important role from the beginning, and brought about major design diversions from the initial prototypes, Dowst said. Jetboil worked with local suppliers, many of whom responded quickly to pleas for help during last-minute changes to the design. That kind of support would have been difficult to come by if the company's suppliers had been located many time zones away, Dowst said.

Out of Cat Food Again?

Variants abound on the Web, but the basic homemade stove jams together the bottom ends of two aluminum beer cans, stuffing between them a wad of building insulation or similar wicking agent. A series of holes, produced using a fine drill bit or needle and pliers, rims the top of the inner can, which is slotted along its side to provide interference for the assembly. Half-filled with denatured alcohol, then lit, the stove fires full blast until it burns through its fuel.

The primitive stove dovetails appealingly with the minimalist approach many long-distance hikers adopt for their meals: Boil water. Add rice, pasta, or another quick-cooking staple. Do not simmer. Do not sauté. Top with tuna or canned chicken.

Unlike fuel canisters or white gas, alcohol stove fuel is readily available at many stores in trailside towns, so hikers don't have to stock up on the stuff. It travels readily in lightweight, cheap plastic bottles, too.

Once a trip extends beyond a certain duration, the advantage of the homebuilt's near weightlessness bogs down in alcohol's low heat content, compared to white gas or isopropane (11,500 vs. 20,000 Btu/lb.). Hikers relying on alcohol end up paying a fuel-weight penalty if they can't resupply every four to five days.

Low tech as they are, homemade stoves sum up for many outdoor enthusiasts the very reasons they head into the back country. Simpler living. More views. Less news.

Many hikers are closet gear heads, however. They spend hours evaluating the latest equipment designed to bring them lighter and faster into the wilderness, and then safely home. Manufacturers are always trying to give them less with hopes that they can do more.

A hiker travels relatively unburdened along an exposed ridge on the Long Trail.

Debugging 101

When the folks at Mountain Safety Research offered to lend Mechanical Engineering a Miox water purifier, "sure" was the only appropriate response. Hikers accept almost any handout. The purifier rode along on a brief visit to Vermont's Long Trail.

The slender micro plant, about the size of a C-cell flashlight, produces a mixed-oxidant cocktail with salt, water, and electricity. After pouring the cocktail into a measured volume of water, a thirsty traveler need only wait 30 minutes to kill bacteria and viruses, according to MSR's senior design engineer, Paul Smith. Bigger bugs such as Cryptospor/d/um, with their rugged, encapsulating sheaths, take longer to die-about four hours. They are easily filtered, however, and live mainly in still water.

Iodine and other chemical treatments have been around for years. They impart a taste to water that most hikers mask with drink mix. That means lugging along empty powdered calories.

Filters, too, are a popular way to sanitize water. Unlike in-line filters at home, though, most trail models require a user to force the water through by hand pumping. Try pumping a couple of gallons of river water through a filter to keep a group of canoeists hydrated, Smith suggested. You'll quickly discover if s hard work, he said.

Out on the trail, Jeff, a novice hiker, thirsted for a quenching mountain stream taken without the hose-play of filters or chemistry. His partner had spent a college summer years back traipsing a length of the Appalachian Trail. he drank his water straight up the whole way, even during the hot southern summer. No consequence had come of it.

This time, these guys were high up in northern Vermont, in late spring. The rain had just stopped. What the heck. Out came the cups.

After that first dip, doing the right thing felt about as pointless as trying to recover a good reputation. So, they dipped from there on out. A day later, when the veteran's knee said, "You're finished," Jeff ambled solo on up the trail for a few more days, unprotected by the purifier. Neither party has reported any ill effects-yet.

The lightweight purifier in the pack never made its presence felt. Had the water quality been even slightly questionable, there would have been no reason not to commission the treatment plant right then and there.

Copyright American Society of Mechanical Engineers Aug 2004 | By Paul Sharke, Associate Editor

Fiddleback
08-06-2004, 11:03
For more on ultra light, see the Travel Channel show, "Travel Gear", tomorrow (Saturday) afternoon. It will feature Ryan Jordan of BackpackingLight.com .

In the meantime, I'm going to go Google that new stove from MSR...

FB

weary
08-06-2004, 11:52
Reading between the lines of hype and sloppy transitions, it sound to me like a high tech version of the ancient and reliable Svea.

Weary

Grimace
08-06-2004, 12:18
http://www.bizjournals.com/eastbay/stories/2004/06/07/story4.html

pretty cool stuff.

SGT Rock
08-06-2004, 12:48
Actually it is some pretty cool technology. I did some research on it and tried to get in on the Army test for the MSR stove. Basically it is a ceramic piece that extends to the bottom of the fuel container. Through capilary action it "pumps" fuel in the correct amount to the top of the ceramic "wick". You just put some fuel in the container and light the top of the ceramic, the fire will stay fed until the fuel runs out or you snuff it. The Army has been researching this type of stove to replace the old ways of heating food by using diesel fuel from any military vehicle and a canteen cup. The original stoves with windscreens were about an ounce or two, but with any military oriented equipment, it had to be overbuilt. The last word I read on this was something like 3 to 5 ounces.

I think the MSR camping version they are working on will run off white gas and weigh about 3 ounces. Given the BTUs in gas, you could probably make a very fuel efficient, lightweight stove. It would most likely look like a canister stove with a sealed fuel container and no pump unit. The burner and pot stand would sit directly over the fuel container so it siphons the fuel up to the burner. A windscreen might work, but with the more volitile gasoline, the construction would have to be planned out to prevent explosions. I imagine that once this is out and some lightweight oriented gear companies mess with it, alcohol stoves may become a novel idea of the past. Just imagine all the simplicity and light weigh attributes of a soda can stove combined with the BTUs of gasoline.

SGT Rock
08-06-2004, 12:54
Here is a peek: http://www.natick.army.mil/soldier/media/fact/food/miwh.htm

sgtjinx
08-06-2004, 13:46
Top

The stove sounds neat. But it takes out all the fun of the good old heat tab. No more gassing oneself in buildings. The good old day's sure are gone!:-?

Streamweaver
08-06-2004, 15:13
I saw a picture/article once of a mountain climber who lost his fuel bottle/pump so he took a soda bottle put fuel in it duct taped a hose (I think from his hydration bladder)from the bottle to his stove and just applied pressure with his foot on the bottle to keep the stove pressurized .Was pretty slick but Id be a bit nervous doing that kinda jerry rigging!!! Streamweaver

Fiddleback
08-06-2004, 18:16
Thanks guys for all the info (especially Sgt Rock's Army info). This system is just too cool! (I think...I hope) Now if only MSR can keep the price down...


FB

SGT Rock
08-06-2004, 18:28
Here is also something to think about - this technology will still work for DIY stoves. :D

According to what I have read, you will not need to have a airtight fuel container to make this work, and the company that makes the ceramics even offers them for different applications so you can get them from the company directly. You COULD get a ceramic Vaporization thinggy and make a fuel cup yourself from aluminum cans, and a stand from hardware cloth or something. I would imagine that the trick would be getting the right flow rate chip from the company. Once these stoves come out and the tinkering stove guys figure out the right flow rate, places like www.thru-hiker.com and maybe even www.hikinghq.net could carry the part and put up instructions so we could all be doing KISS DIY fuel stoves. You might even be able to retrofit some stoves like the Brasslite stoves by simply putting one of these chips on the top of a Turbo F stove right in the exsisting burner hole like a fuel cap after filling the chamber.