The Nightstar Zoo

Nightstar IRC Network - irc.nightstar.net
It is currently Tue Aug 21, 2018 3:16 am

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 7 posts ] 
Author Message
PostPosted: Mon Feb 09, 2004 3:57 pm 
does anyone know how to calculate the amount of material I'd need to build a Geo-disic dome of a given size?


Top
  
 
 Post subject:
PostPosted: Mon Feb 09, 2004 4:10 pm 
Offline
Knight of Daisies, Tulip Slayer
User avatar

Joined: Sat May 11, 2002 3:03 am
Posts: 1621
Location: Sector ZZ9 Plural Z Alpha
Here ya go. http://www.desertdomes.com/domecalc.html

This site will give you strut lengths for a 1V thru 6V dome if you plug in the desired radius of your dome.

Surface area, that I'm not so sure about. Although you could always count the number of triangles in your desired dome (hint: A regular dome, 1V thru 6V, *ALWAYS* has the same number of triangles, no matter its radius) and figure an area of each, and add 'em together.


I believe geodesic domes are about the perfect structure. They're self-supporting, they have no interior walls so arranging the space is incredibly flexible, they can stand just fine with only 50% of their sidewall, allowing you to join other domes to a dome to create a complex, they use significantly less materials, they are about 45% more heat efficient than a square home, and they can withstand much higher winds and snow loads than a square home.

Oh, and did I mention, a 50' diameter dome (which has about 1,900 square feet at floor level, and an extra 1,000 square feet if you build a second floor into it) can be assembled by two or three people in an afternoon. Well, the struts and the exterior sheathing, at least.


I'm gonna build me a dome home one day...


Anyway, Travellar, what are your plans with this dome?

_________________
Fandemonium 2010 -- No Boundaries.
http://www.fandemonium.org
Friday - Sunday, August 6th - 8th, 2010
Nampa Civic Center - Nampa, Idaho (Only 20 minutes from the airport!)
(Idaho: It ain't just potatoes anymore.)


Top
 Profile  
 
 Post subject:
PostPosted: Mon Feb 09, 2004 4:27 pm 
LOL!!!!!

Thanks for the link. I'm actually trying to figure out whether something I heard a long time ago is true. I heard a theory once that if you built a dome one mile in diameter, and lowered the air pressure inside by 1 PSI, you could float a city inside it. so far the numbers look promising, as I figured the bouyancy at about 117 thousand metric tons. (I mis-calculated the internal volume at first) So if the structure, main flooring or deck, and anything you'd care to put inside all weigh less than a combined total of 117K Metric tons, it could in fact, be made to hover like a blimp.

fortunately, the surface area is easily enough approximated, just calculate as a sphere. but the struts that support so much of this structure are another matter... oh well, this link puts me dangerously close to being able to calculate what this monstrosity would weigh. thanks.

**edit** dang, now I gotta find something to take this out to about 20V, (though I don't quite understand that either) 1 181 Meter segment just might not get the job done as efficiently as I'd like... :(


Top
  
 
 Post subject:
PostPosted: Mon Feb 09, 2004 5:13 pm 
What media are you planning on floating your 'city' on? Air? Water? Something exotic?


Top
  
 
 Post subject:
PostPosted: Mon Feb 09, 2004 5:30 pm 
Offline
Knight of Daisies, Tulip Slayer
User avatar

Joined: Sat May 11, 2002 3:03 am
Posts: 1621
Location: Sector ZZ9 Plural Z Alpha
Hmm, I started on a post about how I didn't understand how a vacuum vessel could be lighter than air, but then I realised, it's just like floating on water... All you need is for your vessel to do is displace MORE air than it weighs.

Displacement is the key.

So, considering a geodesic dome is effectively a half-sphere, then what's the weight of a half sphere 1 mile in diameter of air at normal pressure?

If you can make a half sphere 1 mile in diameter that weighs LESS than this, then it *should* float. But I can't imagine being able to stuff a city in there and not have to drop the air pressure to an unlivable level.

_________________
Fandemonium 2010 -- No Boundaries.
http://www.fandemonium.org
Friday - Sunday, August 6th - 8th, 2010
Nampa Civic Center - Nampa, Idaho (Only 20 minutes from the airport!)
(Idaho: It ain't just potatoes anymore.)


Top
 Profile  
 
 Post subject:
PostPosted: Mon Feb 09, 2004 5:40 pm 
If you want, I can post all the math that went into it, but I'll sum it up here in a nutshell.

I converted that mile diameter into Kilometers, then figured out how many Liters that was. (metric is good for that)

21.5 Liters of Gas at STP= 1 Mole, which is just enough atoms or molocules to give you the atomic weight in grams. 1 Mole of Nitrogen weighs 28 Grams. Sea level air pressure is about 14 PSI, so I'm actually just reducing the internal air weight by 2 grams per Mole. (1/14th) Then some really big multiplication problems, and appropriate decimal point movement. Voila, hundreds of thousands of metric tons. less whatever construction weighs.

I still haven't figured out why anyone would want to do this, but it does appear it could be done.


Top
  
 
 Post subject:
PostPosted: Mon Feb 09, 2004 5:46 pm 
Ya have to remember, Fuller was all for minimizing things, making them out of the least amount of stuff he could get away with and still function. He was pretty much a genius at this, as all the various websites out there seem to agree.

Unfortunately, this minimum-material life can be... rather different from what you or I are used to. For instance:

"The four, stamped sheet metal or molded plastic sections are each light enough to be carried by two workers. They'll fit up tight staircases and through narrow doors, allowing retrofitting in existing structures. All the appliances, pipes, and wires are built-in, limiting on-site construction to mere hook-up.

With the sections bolted together, the interior has no germ-harboring nooks, crannies, grout cracks or anything that can rot. Large-radius corners make germicidal swabbing easy and complete. Downdraft ventilation draws fumes and steam to the undersink vent. Both sink and (deep) bath-shower are arranged to ease the care of children and seniors. The mirror doesn't steam up, the sink doesn't splatter, and the toilet paper stays dry."

Doesn't sound bad, does it?

Then you get to look into the details....

"Dymaxion Bathrooms are to be equipped with "Fog Gun" hot water vapor showers that use only a cup of water to clean hygienically without soap. Remarking that "Nature had designed humans to separate urine and excrement. Both are valuable chemistry, and should be collected for further use," Bucky specified a waterless "Packaging Toilet" that deftly shrink-wrapped the stuff for pickup for later composting. (Ordinary toilets use approximately 2000 gallons of pure drinking water per year to flush - and waste - one human's "exhaust" that, if dried out, would scarcely fill two 5-gallon pails.) "

Site: http://www.thirteen.org/bucky/bathroom.html

Interesting stuff, nonetheless.

-John


Top
  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 7 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group