This article discusses research we are doing with university students to look at existing standards of design, manufacturing, and materials of ultralight shelters and relate these standards to observed performance in response to adverse environmental conditions.
Shelters of interest to the ultralight backpacking community may be characterized by one or more of the following attributes:
- The use of lightweight fabrics to save weight;
- The use of construction techniques that are less reinforced to save weight;
- The use of construction techniques that are less sophisticated due to the lack of availability of commercial equipment, the desire to minimize labor costs, or design and/or manufacturing inexperience.
- The use of minimal structure (e.g., pole supports) to save weight and increase simplicity.
The combination of these factors results in a product market that is challenging to analyze, because of the wide variability in materials, style, design, and manufacturing quality. In addition, because most of these products are sold direct via the websites of cottage manufacturers, the consumer doesn't have the ability to carefully inspect the products prior to purchase.
Finally, as the trend towards ultralight backpacking continues to expand, users are either trying to extend their ultralight shelters into "shoulder seasons" and even winter, or they desire to add another ultralight shelter to their inventory to handle stormy conditions that may challenge a shelter's design. The two primary storm conditions we are interested in include snow loading and wind resistance.
Thus, we embark on a new journey to investigate the storm resistance of ultralight shelters.
ARTICLE OUTLINE
- Introduction
- Modes of Failure
- Design Considerations
- Snow Loading
- Wind Loading
- Failure Limitation Hypothesis: It's All About the Fabric
- Inadequate Staking
- Pole Breakage
- Seam Failure
- Fabric Panel Failure
- Designing for Fabric Panel Tension
- Testing Methodology
- Summary
# WORDS: 4290
# PHOTOS: 7
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Discussion
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"The average nylon fly’s useful life at sea level, during full sun days, is 21."
That's good news for those of us who make tents, right?
However most backpackers don't leave tents up during the day. I get reorders for shelters
after 7 to 10 years when the organization is using them daily during the summer months.
That ends up being 600 to 1200 days before the fabric deteriorates. (Most common fabric used in these shelters is 70d PU coated). I also had a scrap piece of 200d PU covering
my woodpile for 3 full years at 6000 ft elevation that was still waterproof and held
together. It was dark green.
21 days- well then, glad that's settled.
Huzefa, It should help dramatically.
David,
The following is a nylon fly useable-life deterioration graph for two flies. The first one appears to be close to what you tested; 70d PU coated Olive Drab (OD) nylon; this is the standard for small tents deployed by the US armed services. The second is a 30 denier yellow fly of the type that would be commonly used by an UL backpacker. It was a 1.1-oz (37g m2) nylon rip-stop fabric dyed with a shade (3) of yellow.
Do we know how cuben fares with UV? Assuming the common 0.74oz variety.
Hi Richard
That is consistent with my experience. Yellow nylon went like paper afetr a couple of years of heavy use, while the (same fabric) blue was unaffected. I think it has to do with the dye used.
cheers
Ready for part 2
Same here
There is a big difference in uv exposure vs colors from the testing I have done
Kevin,
+1
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=58954&skip_to_post=512288#512288
I have a TT Moment "tunnel/cone" tent. It's design makes it VERY wind-worthy and it can handle a snow load better than most solo tents.
Although its perimeter floor and inner door venting nets make it totally unsuitable for winter (or dust storms. it still is an inherently strong and stable design. And with its optional light ripstop liner it can handle high condensation situations very well. I'm even considering extending the lining to cover the net inner door with a sanp-on panel.
I just wish this great design came in Cuben fabric. but then it would be a bit noisy in the wind, and very 'spensive.
As for "wet sag" of its silnylon I've painted the top 1/2 of the canopy with a 5:1 ratio of odorless mineral spirits to GE silicon caulk. Seems to keep it taughter when wet than before I did the coating. For sure some hard rains I've endured in the Moment resulted in no "mist-thru" so I think the light canopy coating did its job very well.
To further reduce sag I've found some light elasticized cord (about 3/16 " diameter) and made loops at each end tie-out. These cords are new so I only know it keeps the tent fairly taught all night in non-rainy conditions.
Ready for part 2 too
It's been nine months. When should we expect to see part two?
Been so long that even Roger's tents will be available.
Almost a year out, at this point I think we should be asking will there be a Part 2?
I'm still waiting for the updates to the HMG pack and MLD Trailstar, both of which were published before this article.
Hmmm… I wonder if this constitutes a trend?
Ryan, will there be a part 2 or not? And if so, when?
… Is not here. Just trying to get Ryan's attention to ask whether this is still planned or still born.
Bumping once again in the faint hopes of an update. I'm particularly interested in the amount of force exerted on tieouts, which of course depends on shelter shape, # of tieouts, etc.
I love this article, has the inline force transducer setup been described in details somewhere?
I just bought an Ultamid 4 and are making plan to storm proof it for the winter. What do you guys think of the idea of using these Micro carabiners to attach the guylines on the upper part of the shelter?
<span style=”display: inline !important; float: none; background-color: #ffffff; color: #000000; font-family: ‘Helvetica Neue’,Helvetica,Arial,sans-serif; font-size: 15px; font-style: normal; font-variant: normal; font-weight: 400; letter-spacing: normal; line-height: 1.74em; orphans: 2; text-align: left; text-decoration: none; text-indent: 0px; text-transform: none; -webkit-text-stroke-width: 0px; white-space: normal; word-spacing: 0px;”><span>https://www.extremtextil.de/en/micro-0-carabiner-40mm.html</span></span>
Also, should I trust the Linelocks with 2,8mm HMG cord along the bottom to hold or should i tie in fixed loops there?
Would there be any benefit in adding some kind of shock absorbers to limit dynamic forces to the 7 high tieouts of the Ultamid 4?
/Jens
Jens in my experience thos carabiners will not take any force
I bent 2 on my Duplex doors
Thanks Mark, specifically where did they bend, they also have these with 1g more aluminium, could be that much stronger…
https://www.extremtextil.de/en/mini-carabiner-with-wiregate-and-eyelet-35mm-no-print.html
“I just bought an Ultamid 4 and are making plan to storm proof it for the winter.”
What would you actually need to do in order to “storm proof” it?
It’s already pretty “storm proof” the way it is.
Although I’ve had one for several years, I’ve never used it in more that 50mph winds (and no snow on that particular trip). I’m sure there’s a bunch of folks out there that have pushed it much further. The only thing I might consider is to double up the upper guy lines, but not add a carabiner. Not sure what that would do since the weak link is probably the tie out itself. And if that were to tear out… well you probably shouldn’t have parked it there in the first place..:
The entire C section bends and doesn’t bend back, so the gate becomes useless
It’s more reliable and a lot lighter to tier a loop knot then thread through the line, works great
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