Why the x-dome and arc dome inner tent geometry?

[Albin Zuccato]

I am looking at the designs of the x-dome and arc dome and do not understand the why so I wanted to ask here?

What I see is a dome which is not used to its potential. Why not extending the floor-sheet to cover this and get more floor space? (The weight argument does not make sense as a smaller dome could solve that if less floorspace is wanted for even less weight.?!  – This as the proportions of dome material to floor material is improved when aligning to full usage  – not to mention the triangle shaped corners which are hard to use anyhow. (arguably mathematically a full circle shaped floor would have the best ratio.).)

Secondly, without having tested it but extrapolating from tarptents I use, the “free floating” inner tent indicates complexity in setup for me. Always harder to gauge for me where it is landing compared to the visible outer tent and more work to align and stiffen. Or is there any advantage here?

Furthermore , my final uncertainty is the loss of stability this must imply. Knowing from my Hilleberg, and seeing in the Slingfin design (which even has extra cordage for tensioning from the inside) the inner tent can stabilize the poles and stiffen the tent. Why give that away?

What am I missing?

PS: My intention is not to trash or criticize but to understand the rational behind tent design to become a better tent user (and butyer).

[Henry Shires / Tarptent]

A quick summary is that the ArcDome design offers a rectangular, two-pole, free-standing design which includes gear storage space between the interior and fly edge.  Other comparable rectangular footprint dome-style designs do not and gear storage space has to be under extended vestibule(s) which makes the actual footprint pentagonal or hexagonal.  With regards to stability, ALL tents blow away in wind unless held to ground but the strength of the ArcDome is the non-stretch UltraTNT fabric which completely locks the structure from compressing downward under snow load.  Nylon and polyester fabrics are unable to do that and hence have to relay on internal and external tension lines to resist compressive forces.

[Brad W]

Layman’s quick observation. You need vestibule space for gear-hence the inner shape. 2) It’s a 4th season tent designed for snow-where the inner ends up is less important than when pitching on dirt/rocks.

[Dan @ Durston Gear]

The nice thing with the X-Mid floorplan (a parallelogram floor inside of a rectangular fly) that is being used our upcoming X-Dome freestanding tent (and being adopted by competitors), is that it provides all the normal amenities of a tent inside of a simpler fly shape. You’ve got the floor of course, but also side entry doors and conveniently sized vestibules that can put the main area out of the way of the door (not blocking it). Other hexagonal tents have a variety of disadvantages in terms of complexity, while other rectangular tents typically have downsides like end entry doorsways and inefficiently shaped vestibules.

So the X-Mid floorplan is both convenient and also allows for a simpler fly shape, which leads to a wide range of other potential benefits in terms of the structure, ease of pitching and other things. Right now it would be pre-mature for me to fully explain these advantages since we have competitors closely following our ideas, but as the inventor of this floorplan and as the ones who have been studying this geometry for much longer than anyone else, you can be confident that our version will be extremely well thought through with a long list of interesting benefits. I am looking toward to unveiling it soon, but in the mean time I can tell you that it is lighter, stronger, simpler and more spacious than even an excellent tent like the SlingFin Portal.

[Jerry Adams]

With the xmid design, there’s more headroom

With a regular mid, with one pole, the pole has to be longer because the space narrows as you get towards the top

[Dan @ Durston Gear]

With regard to the loss in stability and some other issues, there is some merit to what you say. This is something I discovered in early prototypes. I mentioned how the X-Mid floorplan could be combined with traditional tent poles in my 2018 patent and started working on it about 2020. My early prototypes in 2021 had stability issues for sure, but the design has evolved dramatically since then. The reason why it took so long as that there are important things to solve. When our X-Dome launches in a few months it’ll have 4 seasons of field testing on it and over 10 generations of prototypes, so there are a variety of issues with the basic design but also some really nice solutions.

[Albin Zuccato]

Thanks for taking the time to explain!

I look forward to the solutions when they are revealed.

[Joey G]

Dan, will the X-Dome have an inner that is separated from the fly or integrated to the fly?

[Dan @ Durston Gear]

We’re saving most of the info for the launch, but the first version is a woven fabric, doublewall. So yes it would have a separate inner and fly.

[Kevin M]

Both Henry and Dan, as the respective designers, have replied with some really good info, but to expand on that both of the designs you mention really follow on from Dan’s X-Mid tents.

While there have been somewhat similar offset tents before (including TarpTent’s own StratoSpire, which while not using the parallelogram shape, does have similar offset poles), Dan has really taken this design idea and made it more popular than ever (I love mine).

The diagonal, “parallelogram within a rectangle” design of the inner along with the offset poles really makes the most of the headroom inside, and it makes a big difference to the vestibules. Normally with tent vestibules the largest part of the space is right in front of the door to the inner tent. the X-Mid design concentrates this space off to one side, much more usable to put your pack and equipment in while making it much easier to get in and out of the inner tent.

However while this tent is great, all trekking pole tents have their limits, and people have been anxious to see what a freestanding or semi-freestanding version of this would look like, trying to take some of the advantages of the offset sleeping area and combining it with the extra strength and other advantages of a more traditional free standing pole structure. This is what these new tents address.

Plus as both Dan and Henry say, with the actual outer dome shape being a simple rectangle this way (while still providing good vestibules) rather than the hexagon shape that normal dome tents use to create the vestibules, so perhaps a little easier to fit into some tighter camping areas.

I am looking toward to unveiling it soon, but in the mean time I can tell you that it is lighter, stronger, simpler and more spacious than even an excellent tent like the SlingFin Portal.

Will be interested to follow this, while I can see it being lighter no problem, the combination of internal and external guylines, the extremely high quality silnylon etc make the Portal incredibly strong for it’s weight (I have a portal 2 as well as my x-mid 1). If the x-dome can match or exceed that I’ll be very interested.

[Dan @ Durston Gear]

Thanks Kevin. As you mention, these tents do follow from the X-Mid. Other previous tents had innovative aspects to their geometry such as offset poles, which is great, but offset poles aren’t relevant to a freestanding tent. What these new freestanding tents are is a combination of a traditional freestanding pole set (e.g. dual arches) with the unique X-Mid floorplan, so the unique part is the floorplan, which is 100% an X-Mid invention.

Six years ago the X-Mid invented the idea of using a non-rectangular parallelogram floor inside of a rectangular fly to provide normal tent features like thoughtfully shaped vestibules inside of a simpler rectangular fly shape. Previously rectangular shaped tents had less desirable floorplans (e.g. lacking vestibules, or end entry). Other tents like the Strat and Swiftline were great tents and innovative in other ways, but did not show any elements of this floorplan (e.g. the Strat floorplan is still a hexagonal fly with a traditional rectangular floor so it has no commonality to the X-Mid floorplan).

I think it’s unfortunate to see other companies trying to take credit for the X-Mid floorplan, but what should matter to customers is not debating who invented what, but how good the tent is. For this, I am confident the X-Dome will be the strongest in this category because (1) as the inventor of this geometry I think I understand it best, and (2) I have been refining this tent through numerous generations over 4 seasons of field testing which is a much more robust development period. That tent is done now and well into production. I’m looking forward showing the many ways we have taken this geometry to the next level.

[Max O]

Sounds to me like they have a patent issue running, very unfortunate even though competition might have its benefits as well…😕

I pefer free standing tents myself an look forward to both designs.

[Jerry Adams]

“The diagonal, “parallelogram within a rectangle” design of the inner along with the offset poles really makes the most of the headroom inside”

That, to me, is the biggest advantage to x mid.  Just based on reading, I don’t have personal experience.  But I do have experience in a single pole mid when it’s raining and I want to sit up and do something

[Author]

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