Planer tent walls

Divide your fly up into triangles… as you said, triangles always define a plane.

Have the ratios the same

For example have the foot end height be 44 * 52 / 60 = 38 1/8

When you actually lay it out have a catenary curve along the ridge

Yeah that's kind of what I was thinking. I was kind of hoping that someone would have some superior knowledge of materials science and engineering who could either verify that having non-planar walls was a problem or dismiss my fears.

Cantenary curves are awesome for creating tension in the fly.
I was thinking I would use cantenary curves on all the seams, maybe a 1" deflection for every 36" of seam. So like 3" for the ridge line.

Anthony

I've done non planar walls before and the panels weren't tight, bad idea

Only need catenary curve for ridgeline

3" for ridgeline good if it's silnylon

Planar on non-planar is not necessarily bad but it will be trickier to get the tension right. Think of it this way – if you have a quadrilateral panel with all four points coplanar, and you move one corner up out of the plane, you are in essence creating two triangular panels (which are in themselves automatically planar) – there just isn't a seam defining the panels. So it's quite possible to tension that panel properly, but once it is connected to the other panels in your design you may have a harder time getting it all taut. My experience is that with any tent it can be hard to get it all taut the first time you sew that design. A tarp is easier; you can essentially reshape it as you pitch it. So I would suggest that you sew up your fly first, set it up, get it nice and taut, and then measure from that to derive the final configuration and size of your inner tent.

good idea

you have to accomodate the stretchiness of the material

I don't know if sketchup could model that

OK, after reading subsequent posts, it seems that "planar" or "planer" is intended to mean flat.

With that in mind, please note that tent walls are never flat, even with sail cloth, cuben, or other non-elastic materials. I understand there are CAD programs that will calculate the dimensions of every catenary seam on a structure; but I haven't seen any on this site, and they would probably be way over my head anyway.

That is why I tailor all the seams on MYOG tents. And to get them taut, few if any of the seams have turned out to be straight lines. The process used on Roger Caffin's FAQ pages on Bushwalking.org, often posted about here, is to build a totally rigid frame and tailor the tent over it. In doing so, the catenary curves on the seams become apparent. Sometimes less expensive sailcloth is used to determine the dimensions for cuben fabric panels. But cuben has a bunch of other seam issues as well, all discussed at length here.

I've tried to find ways to avoid the extra work of building a rigid frame, and have posted about them, and hope to post more in the future with the next tent project.
Using straight line seams may be possible with silnylon on tunnel tents, especially if several hoops are used and the panels do not have longer ridge lines. So the use of more hoops not only makes the tent stronger; but also easier to construct. Roger might be able to comment on that. I've been trying other techniques that I'll post about if and when successful.

Using the computer drawing programs is helpful in a number of ways, but won't give you dimensions of slightly curved edges on the fabric panels on a taut tent unless you are a real wiz with the advanced CAD programs. In the long run, I think the tailoring has saved a lot of time.