Door on half pyramid tent – on the grain vs on the bias

[Jerry Adams]

I’ve been fooling around with this for years.  I have a better solution.

Rather than a rectangular pyramid tent, I have a half pyramid with a triangular vestibule door.

I used to lay out the door with the ridge on the grain.  Cut out of the roll of fabric like:

The side panel I sewed the ridge to was along the grain, so I made the door panel also along the grain to match.  Also, it just barely fit onto my 58 inch wide fabric.

When I set up the tent, it looked like:

That red line is the dotted “line along grain” in the schematic above.  The zipper is the front right ridge – goes all the way from the ground to the peak.

Fabric stretches a lot less along the grain, so it pulled the side the side panel down about 3 inches.  So it’s in my face when I’m sleeping.

I slept many nights just fine, but it bugged me.

So I cut another panel out differently:

The door panel no longer fit onto my 58 inch wide fabric, so I had to patch on an extra piece.  No big deal.

Note the two dotted lines “lines along grain”.

When I set up the tent, it no longer pulled the side panel into my face, mission accomplished:

Those two red lines correspond to the dotted “lines along grain” in the schematic.  That is a little funky, because rather than taut panels, you get some wrinkles in weird areas.  Not to worry.

I did a 1.5 inch deflection catenary curve (using Roger’s spreadsheet) along the ridge on the door panel.  There was no catenary curve on the side panel.  I just sewed on the door panel starting at the peak.  As I got down to the ground, the door panel was stretched a little relative to the side panel.  No big deal, I had anticipated this.  I just left the door panel unfinished along the ground.  After I sewed the door panel to the side panel, I just marked a straight line on the door panel to match the bottom of the side panel, and hemmed it, so it was then even.

I didn’t do any catenary curve on the other two edges of the door panel – zipper edge or ground edge.

If you do a rectangular pyramid tent, you don’t have to worry about any of this.  The half pyramid design weighs a little less and uses a little less ground area – a little easier site placement.

Maybe this would be applicable for a vestibule door on other tent designs.

[Monte Masterson]

I tried doing a true half-pyramid like you describe, but it was a failure.  I saw that in order to have it 3.5′ to 4′ wide, the peak height would need to be at least 56″ or more, or else it wouldn’t pitch correctly. For example, the Duplex XL is 7.5′ wide and is 59″ high. So what you’re proposing, if I understand you correctly, is basically a half Duplex XL with a door. My cat cuts probably weren’t spot on. but the main mistake I made was calculating for a 50″ peak height and it just wasn’t near high enough. Maybe you can get the concept to work with the shorter height though.

There’s a reason why the hexagonal shape of the Lunar Solo and Hexamid came to be so popular. But I know what you mean about wanting a smaller footprint. The Lunar Solo for example takes up a lot of real estate. That’s why I sold mine.

On a thread drift here, but speaking of SMD, I now even see their products are on a Slovakian website. Ron is definitely international. I’ll argue that the Lunar Solo and Skyscape are the best tents in the world for the money. I noticed Borah Gear tarps and the Gossamer Gear Two on the European site too.

[Jerry Adams]

Mine is 61″.  I like a little extra headroom.  Plus, I have one guyline that pulls the side out a bit.  I’m 6’2″ and my torso is a bit longer than average – I like extra height.  And I live in the rainy corner of the country.

A rectangular pyramid is straightforward.  Only a little more footprint and weight.

Making it a half pyramid causes a number of problems, including this door issue which I’m fairly happy with now.

You could make a half hexagon, that would add insignificant footprint and weight.

Yeah, a lunar solo is almost the same and looks like it would work good.

One question I have, is if you leave the door open, and rain drops vertically, or gets blown slightly towards you, will it get on the sleeping bag? I like to have an overhanging roof.

And is the pole set at an angle?  It loses strength if it’s not vertical.  I use a 0.44″ aluminum pole to save weight.

Of course the biggest problem with the lunar solo, is Ron gets all the entertainment of figuring it out : )

[Sam Farrington]

Jerry,
I was schooled by looking at tents on display, and later by Roger, to think that the edge of a fabric panel that runs along the ground should also have the warp or weft running along the ground.

Your approach seems to challenge this, but your photo shows the improvement. More food for thought.

[Jerry Adams]

If the grain was along the ground, then there’d be a line along the grain, perpindicular, from the middle of the edge along the ground, up to the peak.  That line wouldn’t stretch as much.  So that point on the middle of the edge would be raised above the ground a few inches.

That wouldn’t be too bad.  Air would get through.  If it was really windy dirt and sand could blow in.  But, I could just put gear there that didn’t mater so much.  That’s a spot where it wouldn’t be as bad as the other edges of the tent.

I wonder if the middle of the edge really would be raised above the ground a few inches like I claim : )

[R]

I think you’ll be ok.

The ground edge on your door is the same length as the end of a Duo Mid.  Take a close look at the apex photo and you can see the ripstop grid is horizontal, so the ground edge is on the grain.

Pitches straight across the bottom: https://backpackinglight.com/forums/topic/fs-2017-silnylon-duomid/#post-3533412

[Jerry Adams]

That’s different.  The duomid is rectangular (that is the footprint on the ground is rectangular) (that is, each panel is a right triangle).  That avoids the problem.  You make the two “right” sides along the grain, the diagonal side on the bias.

It looks like the door on the Gossamer Gear The One is not a right triangle so would have this problem, I wonder where the grain goes on it.  I can’t tell from the pictures.  It’s up in the air, that is the side is off the ground, so that makes it easier.  I want all sides to be touching the ground because I’ve spent too many nights when stuff has blown under and I get sand and stuff all over inside.  Of course, if the tent had a floor this wouldn’t be a problem.

 

[R]

The head/foot panels on the Duo don’t have a seam up the middle.

Your door panel is fairly symmetric, and only ~9″ shorter than the Duo’s, so would likely perform similarly.

 

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