Elfie this is a great idea! Let's play with some calculations: Conclusions at the top for convenience:
1. The 1.2 x 2.4 meter panels don't appear to work for the Octayurt as they are too short to span the distance from the wall to the center. 2. Longer panels do work but may not be available in Australia. If you construct your own structural panels this won't be an issue. 3. Octayurt encloses 53% more space than Hexayurt while using 33% more materials. 4. IMPORTANT: MY CALCULATIONS COULD BE WRONG, SO DOUBLE-CHECK THEM! Showing my work: Using the The Regular Polygons Calculator that you used at http://www.cleavebooks.co.uk/scol/calpolyg.htm and assuming an 8-foot wall length we see that the hexayurt has a floor area of 166 square feet and the octayurt has a floor area of 309 sf. That's a gain of 143 sf for the addition of 2 wall panels and 2 roof panels. Adding 33% more wall panel increases the floor area by 53% (166/309=.53). Using the The Right-angled Triangles Calculator on the same website http://www.cleavebooks.co.uk/scol/calrtri.htm and The Regular Polygons Calculator at http://www.cleavebooks.co.uk/scol/calpolyg.htm we can see what the roof angle will be: Regular Polygons Calculator: Hexayurt in-radius 6.93 and Octayurt in-radius 9.66 Right-angled Triangles Calculator: Given edge b as 6.93 feet and edge c as 8 feet it shows edge a as 4 feet, and the standard hexayurt roof height is 4 feet, as shown here: https://secure.wikimedia.org/wikipedia/en/wiki/File:All_hexayurts_web_dimensions.png so that calculator works for determining roof height for a hexayurt. I'm going to guess that it will also give a correct number for the roof height of the octayurt: Given edge c as 8 feet again (same roof triangle as the hexayurt) and the octayurt in-radius of 9.66 feet, it gives a roof height of .... oh! that's not going to work, is it? The radius is larger than the length of the roof panel. So now let's see what 10-foot and 12-foot panels do? Also, I see on http://www.gunnersens.com.au/products/building-products/plywood/exterior-plywood.html that you can get 3050 x 1220 mm panels in Australia, so I will run those numbers too. Using 4x10 foot sheets: Panel length (edge c) 10 feet, in-radius (edge b) 9.66 feet = roof height 2.59 feet (edge a) Ratio of radius to roof height: 9.66/2.59 = 3.7 (a measure of outward force on the roof-wall edge, this is also the Tangent function of a triangle) Using 4x12 foot sheets: Panel length (edge c) 12 feet, in-radius (edge b) 9.66 feet = roof height 7.12 feet (edge a) Ratio of radius to roof height: 9.66/7.12 = 1.4 Standard Hexayurt using 4x8 sheets: Panel length (edge c) 8 feet, in-radius (edge b) 6.93 feet = roof height 4 feet (edge a) Ratio of radius to roof height: 6.93/4 = 1.7 We know how the Standard Hexayurt holds up, so a 1.7 ratio works well enough. So the 4x12 sheets (probably) work even better at a 1.4 ratio (less force on the roof-wall edge), and the 4x10 sheets at a 3.7 ratio might be putting too much force on the roof-wall edge. Australian plywood dimensions (I'm guessing that the insulating panels come in this size too?): 3050 x 1220 mm panels Regular Polygons Calculator: Length of edge = 2440mm > in-radius = 2950mm Panel length (edge c) 3050 mm, in-radius (edge b) 2950 mm = roof height 775 mm (edge a) Ratio of radius to roof height: 2950/775 = 3.8 3.8 might be putting too much force on the roof-wall edge, just as the 4x10 foot sheets do, but as you said, you have no snow or storm issues, so maybe this will work? My non-engineering guesstimate is that if 3.8/1.7 = 2.2 then maybe that's also about 2 times the force on the roof-wall edge comparing the standard hexayurt and the octayurt with 10-foot or 3050mm panels. Also, searching for Australian plywood dimensions I am not finding anything larger than this 3050mm panel so your quest for a longer panel, if you want one, may be lengthy (no pun intended :) My conclusions, also posted at the top so you don't have to read to the bottom to see that: 1. Since the in-radius of the Octayurt is 2950 mm and the panel you want to use is 2400 mm long, it's not going to work at all because the roof triangle is not long enough to span the distance from the roof-wall edge to the center. 2. In English measurement the 12-foot panels will probably work very well for the roof panels, and the 10-foot panels will work but they might put too much force on the roof-wall edge. The Metric equivalent of the 10-foot panel is the 3050 mm panel and that will have the same force issues as the 10-foot panel. 3. I'm not finding anything longer than 3050 mm sold in Australia. Maybe if you make your own structural panels with plywood and foam core you can get the shape exactly as you want it. 4. IMPORTANT: MY CALCULATIONS COULD BE WRONG, SO DOUBLE-CHECK THEM! The roof panels of the standard hexayurt are 8 feet long from tip to base, being made from 8 ft panels cut diagonally. On Mon, Jul 11, 2011 at 9:57 PM, Elfie Sullivan <[email protected]>wrote: > ** ** > > ** ** > > I am thinking if 15 sheets of 2.4meter x 1.2meter sheets to make a > 1.80meter high hexayurt gives me about 15 square meter area.**** > > Is it possible to make an octagon Yurt using 20 sheets of 2.4meter x 1.2 > meter to make a 1.80meter high octayurt that gives me a much bigger area > around 27 Square meter. I would really like some feedback if it would work, > be strong enough and has anybody done one. I am aware the roof would be at a > different angle but think it is Ok as I have the 1.80 meter high wall. I > used the polygon calculator here > http://www.cleavebooks.co.uk/scol/calpolyg.htm**** > > And just put 8 for number of sides to get my calculations.**** > > ** ** > > P.S I live in ****Australia**** so I don’t have to worry about Snow, > hurricanes or sand storms. I would like to make it a permanent structure > with adding a skylight/ clear umbrella at the tip of the roof. **** > > My email is [email protected] any advice is appreciated. **** > > Cheers > Elfie > > www.reikitoyou.com.au**** > > Share <http://www.facebook.com/sharer.php?u=www.reikitoyou.com.au&src=sp> with > your Facebook friends. > **** > > ** ** > > -- > You received this message because you are subscribed to the Google Groups > "hexayurt" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/hexayurt?hl=en. > -- You received this message because you are subscribed to the Google Groups "hexayurt" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/hexayurt?hl=en.
