Aug 6, 2009 at 12:32 pm #1238377
I'm working on a 'mid design right now, playing with ideas on peak height, and thought I'd try to eliminate some of the fussing by getting your input.
This'll be a shocker to hear, I know, but I'm trying to use as little material and to keep it as low as possible while keeping decent usable internal space. 48 inches at peak is what I have in mind… but the DuoMid is 54 inches for the outer, and my SL3 is about 62.
According to some calcs I roughed out, the difference between 48 and 54 inches would be about 1.5 inches of additional clearance one foot away from the outer edge. Not sure that's a big deal.
Another part of the reason for the height is to accommodate my poles… 49 inches, or to easily use them with a short extension for an inverted "V."
Thoughts? What's the shortest you think I could get away with?Aug 6, 2009 at 5:18 pm #1519239
Walter CarringtonBPL Member
There is not a large amount of difference in weight as the height changes. I made up a spreadsheet to calculate this.
Assumptions: This is the weight of only the fabric.
For example, using silnylon at 1.35 oz/sq yard
base area 8'x8'
Height= 7' weight=19.35 oz.
Height=6' weight=17.31 oz.
base area 7'x7'
h=7' weight=16.44 oz
I'll be eventually making a Royce tent (modified half pyramid) ala Horace Kephart.
I like having it high enough that I can stand up (I'm 5'8", so 6' or so is good).
An alternative might be an arrangement with a foot or so of vertical on the bottom of the slant; this would work better with a sewn in floor. I.e., the walls go down on a slant till they are a foot from the bottom and then drop down vertically. A long time ago I made a double wall Royce tent like this.
Post or PM if you want the calcs done on another size.Aug 6, 2009 at 9:13 pm #1519269
Jan RezacBPL Member
@zkoumalLocale: Prague, CZ
With the edge of a mid staked to the ground, the usable floor area will decrease sharply when you made the mid too low, making it heavier for the same usable area than higher one.
To keep the design and pitching simple, consider higher center. It should be possible to optimize the wall slope to get best area/weight ratio after you define the min. height of the useble space. I guess it'll be close to the standard design.
Other possibility would be to add a vertical wall around the perimeter that would made the whole footprint usable, but such a tent would be more difficult to pitch.Aug 7, 2009 at 7:49 am #1519335
Walter, thanks- Since there's only about an ounce of difference between the two lowest heights, and I'll be using material about half that weight (or so goes the plan), the weight is insignificant. At this point I'm more interested in being able to use my trekking poles without extensions and in reducing my profile to the wind. Most likely not a big difference in the narrow cone at top if raised 6 inches, but it would net a broader base, too… Looks like I might need to sell my unused poles and get the long versions. Drat!Aug 7, 2009 at 7:52 am #1519336
Jan, thanks for your thoughts. The calculations I did showing only a 1.5 inch difference in height clearance 12 inches in from the outer edge inside were based on pitching the outer shell all the way to the ground. Even changing the height by a full foot only changes the outer edge clearance by a couple inches or so… the question is whether that'll be a noticeable couple inches. The slope of the wall will take form based on overall finished floor dimensions and, of course, the height. I'm looking at a finished inside of ~5×8 feet. Outer will be slightly larger.
EDIT: I've been looking at stats for comparison… The Shangri-La 2 has about a 4' peak height with 4.75' floor width. Not a mid, but the Seedhouse SL2 makes do with a 3'2" peak and avg. 4' width, while the Seed. 3 has a <4' peak and 4.5' floor width. Yes, I know those both use some pole structure, but they are still markedly A-frame. I think I'll be able to pull off my 5' x 8' with a 4' peak… any doubters?Aug 7, 2009 at 2:24 pm #1519419
@owareLocale: Steptoe Butte
The steeper pitch the less snow load and condensation drip
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