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Cuben Tent Question?
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Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
It works on 12/20/2009 08:10:01 MST Print View

Hey Al, Let me rephrase my statement, It seems to work with a hoop design, limited testing and a heavy nylon/mylar sail laminate! I dreamed about a cuben version last night and think it needs to be done.

But what design? Hoop, Dome, Tarp tent, A Frame, Mid? Do you include a floor?

I personally think it makes the most sense to build a Cuben shelter with a floorless trekking pole design.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Either/Or on 12/20/2009 14:15:32 MST Print View

Don't read too much into my previous statement. A simple tent built a bit like a tarp would probably work OK, as long as you didn't want it to withstand extremes of weather. Lots of possibilities there, and we would welcome photos.

> couldn't the less stretchable (diagonally to the warp and weave) fabrics be used
> in tunnel tents if a catenary-like seam is added at just the right point on the canopy?
Well ... yes, I guess so, up to a point. But if you have a real wobble in a catenary seam it will still show up when the tent is pitched. But would it matter? Dunno. Good question. It's never the foreseen which catches you.

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. Could one use bungee cord instead? Maybe, but considerable tension might be needed in the bungee cord, and this might place too much loading on the tent stakes or the eyelets. They could pull out - of the ground or from the fabric.

As I see it, the really big problem is the cost of the Cuben fabric for the experiments!

Cheers

Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Re: Re: cuben tent on 12/20/2009 14:23:12 MST Print View

"As I see it, the really big problem is the cost of the Cuben fabric for the experiments!"

Touche. But I do think there is some merit in judicial placement of bungys. This was IMHO one of the strong points in the design of earlier MacPac tents (dunno if they still use them). Bungy cords on the tent peg and guyline loops meant you could set the tent up when it was warm, and as the tent cooled it would maintain it's pitch. Could work with cuben as long as the attachment points were very well reinforced.

Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
cuben tent on 12/20/2009 15:37:19 MST Print View

I will buy some Cuben if I can get some feedback on what kind of design folks would like to see. In my opinion an A frame would probably be the cheapest and easiest to build.

Lets say something that looks like this and uses two trekking poles up front on the exterior of the tent and one small carbon fiber pole in the rear center outside the tent and under the ventilation vestibule Cuben A-Frame Tent

Edited by Mountainfitter on 12/20/2009 15:39:48 MST.

Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Re: cuben tent on 12/20/2009 16:48:52 MST Print View

What weight of cuben do you plan o using?

Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
Cuben Weight on 12/20/2009 18:29:24 MST Print View

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

1 or 2 person?

Edited by Mountainfitter on 12/20/2009 18:30:01 MST.

George Geist
(geist) - M

Locale: Smoky Mountains
Re: cuben tent on 12/20/2009 20:53:44 MST Print View

> 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.

Dan Durston
(dandydan) - M

Locale: Cascadia
Re: cuben tent on 12/20/2009 20:59:16 MST Print View

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.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: cuben tent on 12/21/2009 00:04:10 MST Print View

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

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
cuben tents on 12/21/2009 00:04:31 MST Print View

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

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: cuben tent on 12/21/2009 00:05:17 MST Print View

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

Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Re: cuben tents on 12/21/2009 01:19:34 MST Print View

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?

George Geist
(geist) - M

Locale: Smoky Mountains
Re: cuben tents on 12/21/2009 08:05:34 MST Print View

> 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.

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Re: cuben tent on 12/21/2009 11:05:53 MST Print View

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.

Ross Bleakney
(rossbleakney) - MLife

Locale: Cascades
Re: cuben tent on 12/21/2009 12:29:17 MST Print View

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

Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
Cuben Tent on 12/21/2009 13:40:01 MST Print View

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

Edited by Mountainfitter on 12/21/2009 13:44:05 MST.

Lynn Tramper
(retropump) - F

Locale: The Antipodes of La Coruna
Re: Cuben Tent on 12/21/2009 13:44:28 MST Print View

"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.

Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
Cuben Tent on 12/21/2009 13:55:13 MST Print View

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.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: cuben tents on 12/21/2009 13:56:09 MST Print View

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

Edited by rcaffin on 12/21/2009 14:02:49 MST.

Lawson Kline
(Mountainfitter) - M

Locale: LawsonEquipment.com
cuben tent on 12/21/2009 14:08:04 MST Print View

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