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Tetrahedron vs Pyramid tents for MYOG
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Alan Bradley
(ahbradley)
Tetrahedron vs Pyramid tents for MYOG on 07/27/2011 06:35:32 MDT Print View

I wondered why there are several pyramid tarp/tents but no tetrahedron style tarp/tents (one less side, so perhaps lighter/less sewing).

The pole could be biased to the narrow end (ie made from unequal triangles).

http://www.learner.org/interactives/geometry/print_tetrahedron.html

jerry adams
(retiredjerry) - MLife

Locale: Oregon and Washington
Re: Tetrahedron vs Pyramid tents for MYOG on 07/27/2011 08:24:41 MDT Print View

You need maybe a 3 x 7 feet area for a person to sleep on

If you have a rectangular base tent you can more easily allocate 3 x 7 foot areas for people

But, I suppose you could have two people with their feet at one triangle point

I wonder if it would be lighter? Probably a little.

When you set up a pyramid, you have to eyeball that the base is square, or two of the ridges will be slack, with tetrahedron you wouldn't have that problem. Also, if the four corners of the pyramid aren't all on the same plane, then the tent doesn't set up right, with a tetrahedron you wouldn't have that problem - sort of like a three legged stool doesn't rock.

Kevin Beeden
(captain_paranoia) - F

Locale: UK
re: Tetrahedron vs Pyramid tents for MYOG on 07/27/2011 12:10:00 MDT Print View

A three-sided structure provides a poorer use of material for available volume than one with four sides.

I once considered the optimal shape for sidewall weight vs grate area for a wood burner (i.e. 3 sides, four sides, 5 sides...). It turns out that it's a circular grate/sidewall plan (i.e. an infinite number of 'sides')...

Tohru Ohnuki
(erdferkel) - F

Locale: S. California
Re: re: Tetrahedron vs Pyramid tents for MYOG on 07/27/2011 13:36:04 MDT Print View

"A three-sided structure provides a poorer use of material for available volume than one with four sides.

I once considered the optimal shape for sidewall weight vs grate area for a wood burner (i.e. 3 sides, four sides, 5 sides...). It turns out that it's a circular grate/sidewall plan (i.e. an infinite number of 'sides')..."

So a yurt is best... Hmm, how to make a UL yurt...

David Olsen
(oware)

Locale: Steptoe Butte
three sided mid on 07/27/2011 13:36:47 MDT Print View

bigwallshelterstuffsack

Made this one for Dean Potter. single point suspension, toss your climbing gear in the
corners to guy it out. Very quick to set up. To be used on a ledge.

Also there is volume and their is usable volume. If sleeping people were yurt shaped, (no offense to those who might be) then a yurt shape would make sense. When you increase
the number of sides you also make a correct set up more difficult if it is a floorless
shelter. Things go all pear shaped.

Edited by oware on 07/27/2011 13:41:16 MDT.

David Olsen
(oware)

Locale: Steptoe Butte
3 sided oops on 07/27/2011 13:48:20 MDT Print View

I also once had a 3 sided mid made by mistake. Someone out there bought and then resold it on bpl and posted pictures. It was olive colored. Maybe they might comment on how it has worked for them.

Edited by oware on 07/27/2011 13:49:04 MDT.

Drop Bear
(DropBear) - F
Re: three sided mid on 07/28/2011 04:08:44 MDT Print View

Montbell does a 3 sided poncho/midMontbell poncho mid

Kevin Beeden
(captain_paranoia) - F

Locale: UK
re: pear-shaped yurts... on 07/28/2011 06:15:21 MDT Print View

> So a yurt is best... Hmm, how to make a UL yurt...

> Things go all pear shaped.

There is, of course, a big difference between the requirements for a wood stove grate and for a shelter...

On the other hand, if you look at a pear shape, it's actually quite a good representation of the optimal shape for a human shelter. Provided your upper body is at the fat end. The thin part of the pear accommodates the legs, and the fatter part allows room to move the arms about, and generally do stuff...

;-)