[TML] Environmental domes

[shadow at shadowgard.com]

On 4 Sep 2007 at 10:23, Joseph Paul wrote:

> Design this in concentric rings so that you have walls also and then you
> have compartmentalization. You don't lose every one to a puncture.

Have to be one *hell* of a puncture to be much of a problem.

Since most designs *won't* be pressure supported, the flow rate 
depends solely on the pressure differential and the size of the hole. 

For hole size, it's area that matters. But as the dome gets bigger 
the amount of air inside goes up as the cube of the size. 

So even for a hole that is bigger, a bigger dome will have longer to 
fix it. 

Say the hole is the same proportional size. Make the dome twice as 
big and while the area of the hole goes up by a factor of 4, the 
volume of air goes up by a factor of *8*. So it'll take twice as long 
to be a serious loss.

Since the holes are apt to be *smaller* (as fraction of the dome 
size) as the size goes up, then you've got even longer to fix things. 

A hole a foot across into vacuum is a catastrophe for a a 100 ton 
ship. In a dome a hundred meters across, it's bad news. In one 10 km 
across, it's a major nuisance. In one 100 km across it's a serious 
maintenance item.

> How big is a shire? Counties here (Indiana) seem to be about 400 square
> miles or 20 miles on a side.


On the other hand, Harney county here in Oregon is roughly 80 x 120, 
or close to 10,000 square miles. 

Ah. A bit from wikipedia:

At the 2000 U.S. Census, the median land area of the 3,077 U.S. 
counties was 1,611 km² (622 sq. miles), which is only two-thirds of 
the median land area of a ceremonial county of England, and only a 
little more than a quarter of the median land area of a French 
département. However, this figure hides large differences between the 
eastern and western United States. The land area of counties in the 
western United States is much larger than the land area of counties 
in the eastern United States. For example, the median land area of 
counties in Georgia it is 888 km² (343 sq. miles), whereas in Utah it 
is 6,286 km² (2,427 sq. miles)

The largest county equivalent by (total) area is Yukon-Koyukuk Census 
Area, Alaska at 147,843 square miles (382,912 km²), while the largest 
county is North Slope Borough, Alaska at 94,763 mi² (245,435 km²). 
The smallest county-equivlant is the independent city of Falls 
Church, Virginia at 2.0 square miles (5 km²), while smallest county 
is Kalawao County, Hawaii at 13 mi² (34 km²). The smallest self-
governing County is Arlington, Virginia at 26 mi² (72 km²).

At the 2000 U.S. Census, only 16.7% of U.S. counties had more than 
100,000 inhabitants. This reflects the essentially rural nature of 
U.S. counties, whose grid was designed in the 19th century, in a 
country still largely rural and only marginally affected by 
urbanization. Today, the vast majority of people in the United States 
are concentrated in a relatively small number of counties The most 
populous county equivalent is Los Angeles County, California with 
10,226,506 inhabitants as of 2005, and the least populous county is 
Loving County, Texas with 60 inhabitants as of 2005.

The most densely populated county (or county equivalent) is New York 
County, New York (coextensive with the Borough of Manhattan, and 
consisting primarily of Manhattan island) with 66,940 people per 
square mile (ppsm) as of 2000, and the least densely populated county 
is Lake and Peninsula Borough, Alaska with 0.0767 ppsm as of 2000. 
The least densely populated county equivalent is Yukon-Koyukuk Census 
Area, Alaska with 0.0449 ppsm as of 2000.
--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com