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Cuben Tent Question?


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  • #1555733
    Lawson Kline
    BPL Member

    @mountainfitter

    CT2K.08 (.75oz sq yard) for the walls and silnylon or spinn for the floor.

    1 or 2 person?

    #1555767
    George Geist
    BPL Member

    @geist

    Locale: Smoky Mountains

    > Could one design storm tents to use non-stretch fabrics?
    > An interesting question. My worry is whether they would
    > start to flap or flutter in high winds. A stretch fabric
    > can be tensioned fairly easily to not flutter, but this
    > might be hard to do with a non-stretch fabric.

    Hi Roger,

    What makes a stretch fabric work in this case is that when you pull on the fabric from a tie out the stretch of the fabric causes the tension to spread over a wide area of the fabric. With just a few well placed tie outs you can get tension spread throughout silnylon.

    What happens in non-stretch fabric is that the tension does not spread out. It runs in a fairly narrow strips between where you are pulling and the nearest fixed points on the tent body. The work around to flutter then is to place tie outs to create crisscrossing lines of tension in the tent body.

    I agree that Cuben is (too) expensive to experiment with,
    but to get the geometry and tension right all it takes is a non-stretch fabric. Mylar is non-stretch and a very inexpensive option to experiment with different tent designs. You can tape panels together and you can even sew Mylar if you stick a strip of Scotch transparent duct tape on the seam line first. Once a good design is found for a storm tent, the Mylar can be replaced with Cuben, which is nothing more than reinforced Mylar.

    #1555770
    Dan @ Durston Gear
    BPL Member

    @dandydan

    Locale: Canadian Rockies

    An two trekking pole A frame would be okay but it would be nice to see the tops of the trekking poles spaced apart to dramatically increase the head area. So instead of having the poles like this: / you could have them like this: /

    It could still taper to an A frame at the back so you'd just use the single pole back there. So the birds eye view would be that it has a triangle shaped roof, if that makes sense. The vestibule in your drawing looks nicely sized.

    I would prefer to see a 2 person version roughly 50" wide at the front door tapering to about 45" wide at the feet with a total interior length around 90".

    This is a different route, but I actually think that the old SMD Refuge-X was nearly the perfect design for a trekking pole shelter. Starting with something similar to that and then making improvements would be not a bad way to go. The improvements I would suggest are a bathtub floor, larger vestibules, additional reinforcements where needed and an improved method of tensioning the top of the tent as suggested in the BPL review. Using colored cuben would be a plus too.

    #1555792
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Al

    I agree with your analysis. I just wonder what else there is which we haven't yet thought of!

    Space blankets for prototyping? Sounds a neat idea.

    Cheers

    #1555793
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    Lawson,
    Probably the Hilleberg Suolo best matches my list; but did not mention light weight on the list. Also think that Roger's tents are both comfortable and superior in extreme conditions as shown in his "When Things Go Wrong" article on this site, albeit not free-standing. But it's about the weight, which may be one of the reasons for this discussion about Cuben. Cuben would be good, for example, for large door covers that use a lot of yardage, hence weight (I like big doors), but that are covered by an awning or vestibule and are not a structural part of the canopy, and are rolled up except in downpours, so for all those reasons are less likely to 'crinkle' too loudly in the wind. Also, using cuben only selectively will save a lot of money, and if the door shape is already established by the zippered netting, there should be no need to do much experimenting in fashioning the cover to be unrolled and zipped over the netting in wind driven rain or snow.

    Al,
    Thank you for the insights about designing with no-stretch fabric. Much food for thought.

    Roger,
    Not persuaded that a no-stretch tunnel or dome could not be designed taut. But I do agree that even if taut, cuben and spinaker (moreso) have a potential to make a racket that some, including myself, cannot abide. Not from Missouri, but would like to see a quiet no-stretch tunnel or dome tent before spending considerable time (and money) trying to make one, even though cuben could mean saving around a quarter pound over silnylon on a 5 square yard canopy. And even though I realize that many are very satisfied with their GG Ones.

    Sam Farrington, Chocorua NH

    #1555794
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Lawson

    A typical design, but taking it literally as shown, you are going to have a lot of condensation. You need to get smart with some ventilation.

    Cheers

    #1555805
    Miguel Arboleda
    BPL Member

    @butuki

    Locale: Kanto Plain, Japan

    Mountain Hardwear makes high altitude, expedition tents that use mainly stretching fabric, but that are reinforced by non-stretching panels where the walls clip to the poles (the evolution tension arch). I was wondering if the opposite could be done with a cuben tent, wherein the main panels are non-stretch, but the critical areas where tension would create the problems Roger pointed out use stretch fabric instead. Wouldn't that relieve the stress of high winds?

    #1555826
    George Geist
    BPL Member

    @geist

    Locale: Smoky Mountains

    > I agree with your analysis. I just wonder what else there is which we haven't yet thought of!

    Hi Roger,
    What else?
    Well here is something useful to consider in the design and it helps explain why Lawson's tunnel prototype worked.
    I've done some more analysis. If the tunnel sleeve is silnylon (i.e. stretchable), analysis shows that tension spreads across this fabric and all along the edge of non-stretch Cuben fabric sewn to this strip of silnylon. Instead of a narrow line of tension flowing through the Cuben, there is a broad triangle of tension from the edge to the nearest fixed point. Taking the analysis one step further… replace the "nearest fixed point" with the next pole sleeve in the tunnel tent and the analysis has the silnylon sleeves spreading the tension load across the two opposing edges of the non-stretch Cuben. There is then tension flowing through the entire area of Cuben.
    (It is not uniform tension, but there isn't uniform tension through a tent canopy of silnylon either)

    Using silnylon to spread the load to a broad edge of the Cuben could be key to designing a practical storm tent using Cuben. But I still suggest to prototype first with Mylar.

    #1555880
    Ross Bleakney
    BPL Member

    @rossbleakney

    Locale: Cascades

    Lawson: Your sketch is exactly what I would like to see. I bought (and still own) the Refuge X. It is a good tent, but I don't like the fact that there isn't much room above your head when you lie down. There is even less now, because I use a NeoAir (instead of a closed cell pad). The design you suggest would make the highest point right above the head. I think this is an ideal setup. Also, if this is a two person tent, it would be nice if you could use a trekking pole to support the rear of the tent. Perhaps this could be accomplished by simply attaching the rear pole via a tab that contains a hole (as opposed to sticking the pole into the edge of the fabric). This is a minor improvement, though, as those little poles weigh very little.

    #1555911
    Ross Bleakney
    BPL Member

    @rossbleakney

    Locale: Cascades

    I might also add that I would recommend the use of Nanoseeum netting, as opposed to standard Noseeum netting.

    #1555931
    Lawson Kline
    BPL Member

    @mountainfitter

    Hey Roger,

    In regards to the A frame tent. I think a good way to alleviate some of the condensation I planned to build more of a beak then a vestibule in the rear with the foot wall constructed of no-sea-um mesh. I plan to use a bathtub floor so the mesh didn't go all the way down to the ground. In the front of the tent I planned to build a high vent in the vestibule and since it has a partition door (no-sea-um mesh) you could always leave the vestibule door open to air out the space. Please remember the drawing was quick (1-2 mins) and leaves out alot of details.

    Three pole hoop:

    I just spent a few more minutes and designed a 3 hoop tunnel that I think you might approve of. If I used nylon for the pole sleeves and shock cord for the stake out points the tent might just be dynamic enough to be a 4 season cuben fiber tent. To keep the pole weight inline with the material you would have to use Carbon Fiber. The tent would cost you an arm and a leg. It might be cheaper to build a mountain side cabin hahaha.
    Cuben 3 Pole Hoop

    #1555935
    Lynn Tramper
    Member

    @retropump

    Locale: The Antipodes of La Coruna

    "the tent might just be dynamic enough to be a 4 season cuben fiber tent"

    Depends on the weight of the cuben, and whether you can tape the seams or merely stitch them. Taping is the way to go for cuben seam strength. That, and some really beefy sail cloth patches (glued, not stitched) to reinforce stress points.

    #1555940
    Lawson Kline
    BPL Member

    @mountainfitter

    You would have to use at least the .75oz and as you said tape the seams and sew with a long stitch so you don't loose peal strength.

    #1555941
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Miguel

    Thanks for the URL to the Mountain Hardwear site.
    I studied the diagram there for some time, and I remain 99% UNconvinced that their little strips of VX02 fabric would add anything to the stability at all. (I have a range of those fabrics on the shelf here.)

    The tent shown has the poles barely attached to the fabric – I don't like that method myself and far prefer sleeves to hooks. The distribution of load is far better with sleeves and you don't need their fancy VX02 reinforcing. And pitching that design in a gale is going to be really tricky: real risk of damage to the tent and/or pole clips half way through.

    On the other hand, they also refer to 'the practice of internally guying the tent', and that IS something I have used with great success. Not often seen, but great for wind.

    > the critical areas where tension would create the problems Roger pointed
    > out use stretch fabric instead. Wouldn't that relieve the stress of high winds?
    Yes indeed, it would, but that still wouldn't solve the problems of wobbling stitch lines. On the other hand, if the pole arch seams were rendered slightly elastic that way, maybe a slight catenary cut on the ridge line would be adequate. Possible. Interesting thought.

    Cheers

    #1555942
    Lawson Kline
    BPL Member

    @mountainfitter

    I agree with Roger. The VX02 might help with seam tear strength but at the end of the day pole clips are junk and will always be a weak link. In my opinion there are only two ways to attach a tent to a tent pole.

    1. Pole Sleeves
    2. Internal Poles

    #1555944
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Lawson

    With ventilation at each end, yep. A bit like this in fact:

    ColDePalet4119
    Col de Palet in France.

    > The tent would cost you an arm and a leg.
    Yeah, about $1,000. At $3/hr for the labour.

    But as I said just above, with a judicious blend of fabrics it just might be possible. Hum …..

    Cheers

    #1555972
    Miguel Arboleda
    BPL Member

    @butuki

    Locale: Kanto Plain, Japan

    Rpger, thanks for the information about how tent sleeves and such work. As someone who has made his own tents and tarps it is very educational. SO much to learn!

    How about these two ideas from two tent designers here in Japan:

    Arai Tents. Take a look at the way the tension is spread out in the sleeve.

    Nippin Messner Tents. These tents use a continuous cord to attach to points on the seams. Probably has the same problems as clips though.

    #1556010
    Roger Caffin
    BPL Member

    @rcaffin

    Locale: Wollemi & Kosciusko NPs, Europe

    Hi Miguel

    At the top of the Arai page there are two diagrams of poles in sleeves. One has the sleeve very wide at the base – I don't see that idea being of much use – in fact I strongly dislike it (pending a better explanation of what it means!). The diagram on the right shows the sleeve coming together where it joins the tent. That is the method I use. I make the sleeve about 20 – 25 mm high (seam to pole centre). The sleeve securely locates the pole wrt the tent, and distributes the tension uniformly. Definitely snow tents, not for rainy weather.

    The Nippin Messner design – it's a cheap consumer pop-up. The cord system … kinda cute, but heavier than a sleeve. I wouldn't want to be trying to get it erected safely in a storm though. Strong risk of ripping out some of the point attachments. Too much stress concentration. But it probably wasn't made for that anyhow.

    Pity I can't read Japanese … :-)

    Cheers and thanks

    #1556020
    George Geist
    BPL Member

    @geist

    Locale: Smoky Mountains

    > the tent might just be dynamic enough to be a 4 season cuben fiber tent
    > …would have to use at least the .75oz and as you said tape the seams

    I curious to learn from folks who have Cuben shelters where have you seen the Cuben fail because that helps determine what (weight/type) of Cuben it takes to stand up in a storm tent. All I've heard about are tears around the tie-out points. That could be remedied by learning how to better reinforce this type of material rather than simply using heavier material in the bulk. On the other hand if folks have experience with the really light Cuben failing out in the middle, then that is a good reason to use the heavier versions in the bulk.

    I've also heard about folks being able to tear the edge of the lightest Cuben, but can you tear a finished edge? Because that is what is going to be on the tent.

    #1556036
    Lawson Kline
    BPL Member

    @mountainfitter

    Hey Al,

    The CT1K.08 17.4GM2(.50oz)Cuben has similar break strength(68 lbs/in) to most silnylon at (70 lbs/in).

    I talked to the folks at Cuben Tech the other day and they said they have never done any tear testing but they feel it would be similar to silnylon which ranges from 8-16 lbs/in depending on the type of nylon (nylon 6 or nylon 6,6) and coating method along with weight.

    I think it would make more sense to use the CT2K.08 25.4 GM2(.75oz) Cuben since it's similar in cost but it's load @ 1% strain is 50% more (24 lbs/in vs.35 lbs/in)and it's break strength is 55% more at 105 lbs/in.

    But then again as you said, if you properly seam the material and add extra support at critical area's why not use the lighter material especially if it's on par with silnylon. If the shelter took 6-8 yards of cuben you would save roughly 3-4 onces by going with the lighter stuff.

    #1556038
    Lawson Kline
    BPL Member

    @mountainfitter

    Ross,

    Sorry I didn't address your comment earlier. Good idea on the 2 person design using both parties trekking poles. If you go alone you can bring poles for the rear.

    I was thinking of going with a front width around 54" and a back width around 40" and a front height of 42" and a back height around 30". What do you think?

    #1556089
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    1. There was a tunnel tent, maybe a Kelty, that used a triangular panel on the roof, with a corner top dead center on one of the hoops, and the base of the triangle centered on the top of the other hoop. The apparent purpose was to max the tautness and catenary cut with the fabrics used. But it might be a thought with cuben, which could also serve as a translucent skylight. But you would want the straight grain edge of the nylon attached to the cuben, so that the fabrics wouldn't have different coefficients of expansion where joined, which would create all kinds of problems. So it would have to be at or close to a right triangle, with the right angle at the TDC vertice. (Note: Nylon fabric only stretches very much on the bias (diagonally to the weave. There was some discussion of this in the current BPL article about the Montbell spiral wrap bag.)
    Also seem to recall a 3 or 4 pole hoop tent by Early Winters that used seams parallel to and between the hoops to obtain a taut catenary pitch. They had one made of Goretex laminate, which did not stretch much due to its thicker lamination, and maybe that's why they had to add the seams between the hoops.

    2. I don't think crossed hiking poles really create enough space to replace a hoop at the high point of the tent. Maybe at the lower end, or maybe using just one pole to support an awning that could also be rolled up for high winds.

    3. Agree that sleeves and internal poles are stronger than clips, all other things being equal. Sleeves do contribute significant weight, however. The trick is to figure a way to get the internal poles installed and stablized without having to crawl into at least part of the tent.

    4. Looking at the above tents and designs, am tempted to put on a flack vest and sunglasses, visit Warmlite in Gilford NH, and ask them if they could make a their 3 hoop model 3 mostly out of cuben supplied by the customer. If I survived to tell the story, the response would be interesting.

    Thank you for the Japanese links. Especially liked the video of the wedge being pitched in real time.
    Sam Farrington, Chocourua NH

    #1556091
    Miguel Arboleda
    BPL Member

    @butuki

    Locale: Kanto Plain, Japan

    The Nippin Messner design – it's a cheap consumer pop-up

    Hmm… well… those are top-of-the-line mountaineering tents designed in collaboration with Messner himself (hence the name, though that doesn't necessarily mean the tents are good!). The tents come in at around $600~ $700 and are not meant for the average consumer's use. I've never used one myself, but a mate of mine hikes in one all the time and they are his favorite mountaineering tents.

    I've been pondering the issue of clips versus sleeves and wonder why clips are considered inferior? We use tremendous force on guylines, much greater than on roof panel sleeves, which normally pull at only one point, and yet also require the load to be as spread out as much as possible. Why should clips be any different that way?

    My Soulo uses both sleeves and clips and the clips are mighty strong. The tent (not mine) has proved itself in extremely harsh environments. Don't clips also relieve some of the stress by not acting as wind-catches?

    Edit: I meant to write, "A mate of mine hikes with one all the time… be kind of interesting watching someone hike in a tent!

    #1556100
    Sam Farrington
    BPL Member

    @scfhome

    Locale: Chocorua NH, USA

    Miguel,
    The answer I've most heard and makes most sense to me is that pole sleeves distribute stress more evenly and over a broader area. This was what Moss tent maintained, for example. Suppose only scientific tests could tell us whether well reinforced clips can do as well.
    But the sleeves must be sewn well into the lap or flat fell seam, and because they will get constantly poked with pole tips during threading, must be a stronger (read heavier) material. You can note this on a TarpTent Scarp or Moment. And that may add as much weight as clips with reinforcements. That is why I'm trying to figure a way to get internal poles easily installed and stabilized. And as you point out, they don't create little snow fences (or rain collectors) either.
    Sam Farrington, Chocorua NH

    #1556114
    Derek Goffin
    Member

    @derekoak

    Locale: North of England

    I have enough of the .75 breen cuben to make my tent design. I intend to make a cuben mid for 2 with a single trekking pole. That is all we carry. It is set up with string on my lawn at the moment, covered in snow. It is a bit like an SMD lunar solo but wider, (space for 2 behind the angled pole), with a relatively pulled out entrance vestibule to give more entrance room. It is basically an asymmetric 4 sided pyramid so the flattest triangular roof panels of the lunar solo are replaced by higher sloping ridges/edges that end in small triangular openable walls at foot and head. It is likely that the ends of the sloping ridges will be supported by 5mm CF tubes about 60 cm long a bit like our Terra Nova Laser. To get more width of head room each side of the pole I plan on guying out both central edges.(To look at the lunar solo one would be just above the entrance door one a bit lower on the back edge)It is likely to be worth pushing both guy out points apart internally with an horizontal CF rod between the guying points. This rod will be at about 37- 39" high. There should then be 6 perimeter guy points at the corners,4 long guys pulling out the 4 edges at the ends of the described CF poles and maybe 4 mid panel elasticated pull outs.
    I bought some aqua seal and Steve Evans has sent me some hysol 09fl. You cannot buy it in Britain. I plan the perimeter tie outs to be dyneema cord loops with the core ends unbraided and fanned out into glue and another say 4" semicircle of cuben sandwiched over and pressed until set. No sewing if the hysol works well. The other tie outs do not pull wholly in the plane of the cuben so will be more tricky.

    If this works as a non midge proof tarp tent. I would probably make an inner of: silnylon floor, lighter cuben and large panels of midge net, for use in the winter and the midgy times.

    I think the design covers most of Samuel's feature list except perhaps: too many pegs and non free standing and a maybe a bit of contortion to get in. Another unmentioned feature, the slope of all faces of this mid is about 45 degree so condensation in the inside of the tarp should nearly all run down rather than drip off. With low through, and high ventilation condensation should be minimized anyway

    I have taken on board the suggestion of trying this with space blanket first. So next step get more space blankets.
    I struggle with photos and graphics except on paper so the best I can suggest to visualize is look at the lunar solo and imagine the differences. If anyone can see where I am going wrong it would save me from the expensive mistake when I commit to the cuben.

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