The ‘skin’ of a tipi is very nearly a semicircle. If it is a ‘normal’ 60 degree (cone) tipi, then (apart from a slight overlap for keeping out drafts), that’s exactly what it is. A semicircle with radius ‘R’ (eg 10’ – the width of the widest roll of Tyvek) will make a tipi which is approximately 10’ wide at the base. (C = 2xPixR – divided by 2 for a semicircle; D= C/Pi, so C = 2x3x10 = 60/2=30/3=10 – taking Pi as approx ‘3’). So, any width of fabric will make a tipi which has a diameter the same as its width.
You will need a piece that is twice as long as its width to make your tipi. If you cut out a little more of a circle than a semicircle, you will get a tipi which has a less acute angle than 60 degrees (say 45 degrees) and which is correspondingly wider (and shorter). (You would need to stick this piece on with Tyvek tape). You can work out how wide by dividing the piece’s circumferential length by 3. This is close enough.
A 10’ wide tipi is quite a handy size, (will obviously sleep at least four people) but is hard to erect unless you tie the ‘skin’ to the pole first (otherwise you can’t reach). If you are using only one pole you will need someone to hold the pole whilst you peg the sides down. That’s why folk normally used 3 or more poles (usually six) tied together at the top where you attached the skin’. You can even pitch it with no poles by throwing a rope over a branch.
You can cut the circular edge into eg six equal straight lines (a hexagon) if you like, and it will still pitch flush to the ground, and give better angles to the wind. Of course this works even better if you catenary cut them: http://www.theultralighthiker.com/catenary-curves/
You can make such a tipi out of a readily available blue poly tarp for less than $20 if you want (I have). If you are going to have a fire in your tipi, you must beware of carbon monoxide. You need airflow in at the bottom and out at the top. Any open fire is almost impossibly smoky. The Plains Indians must have been plagued by lung ailments. A chimney is a great idea, failing that some sort of chimnea arrangement. Titanium Goat (http://www.titaniumgoat.com/cstove.html) has lightweight (titanium) stoves and chimneys for just this purpose. The chimney will probably not be hot enough to melt the Tyvek at the top, but if you are worried you can wrap that section of pipe with some fibreglass cloth or etc.
As you will see at his website, he also makes really lovely tipi tents out of silnylon (pictured). This is something like what your Tyvek tipi will look like, (sans the cost!) Such an arrangement would suit car, motorcycle or horse based camping better than backpacking, but maybe you and your friends are quite strong!
I have now actually made one out of a single piece of Tyvek – how easy is that? Seamless Tyvek Tipi
http://www.theultralighthiker.com/does-spot-like-to-hunt-deer/
http://www.theultralighthiker.com/tyvek-solo-fire-shelter/
http://www.theultralighthiker.com/tyvek-tent-designs/
http://www.theultralighthiker.com/tyvek-twin-fire-shelter/
http://www.theultralighthiker.com/one-pole-tyvek-tipi/
http://www.theultralighthiker.com/tyvek-bivi/
http://www.theultralighthiker.com/new-tyvek-forestertent-design/
http://www.theultralighthiker.com/tyvek-jack-russell-rain-coat-13-grams/
http://www.theultralighthiker.com/catenary-curves/
http://www.theultralighthiker.com/ultralight-chairgrounsheet/
Hi i love your articles, you are full of such great ideas and really impress and inspire me with your ability to create what you need, rather than just rushing out to buy the latest over priced gear.
I recently got my hands on some tyvek and would love some pointers on design, although I have my own ideas. But more importantly if you have any recommendations and sources on tie outs tapping methods bits and pieces etc.
Im currently just planning on using a waterproof cloth backed gorilla branded tape for joins and also using it to form the tie outs.
Keep ip the great work
Thank you so much Scott – good luck with your projects. I use Tyvek Brand tape. I bought mine from Alpacka rafts but I’m sure it’s available elsewhere too. It works splendidly. I haven’t tried any other types. Let me know how they work. Mostly I sew the tie outs to the Tyvek. I usually start with tarp clips to see how the position will work. I’m afraid I have no idea where my design ideas come from. Yesterday, going around the lambs in the rain I was thinking about how useful a hands free umbrella would be! I know it can take a long while (even after several prototypes for a very obvious solution to ‘pop’ in to my head. I have just had some other ideas about my ‘Deer Hunter’s tent’ for example. If you make something interesting (or etc) please let me know. I can post your project for others to enjoy! Cheers, Steve.