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Old February 4th 07, 05:31 AM posted to alt.binaries.pictures.aviation
Henry_H@Q_cyber.org[_1_]
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Default Need help with a rocket motor ID

On Sun, 4 Feb 2007 12:28:20 +1030, "Dave Kearton"
wrote:

wrote in message
.. .
On Sat, 03 Feb 2007 02:47:10 GMT, "William R Thompson"
wrote:

I could go on, but I won't. I am the only person in the world
completly happy with both systems, and who thinks they are both
equally screwed up.

Henry H.




We all understand the difficulty of migrating from one system to another.


So, don't migrate, use what suits, which is what people do, anyway.

At least in the U. S. and to my observation, a lot in Europe, too.

I use to be involved with some standards activity. (in ordinary
language, you could have said I was a mermber of a ISO working group).
Some one once told me that the nice thing about standards was that
there were so many everyone could have one of their own. After a
while, I concluded that the result of having more standards ws that
there were more choices, because the old ones don't go away.

So, I went away.


Australia's change to metrics started on the 14th Feb '66 with the change to
decimal currency - dollars and cents. All Aussies over 45 can still
remember the TV jingle. A currency based on multiples of 10 makes more
sense than one based on 12s (unless your family tree doesn't branch)


The US has had decimal currancy for a while.

Once that was achieved, switching to Celsius from Farneheit in the mid '70s
wasn't such of a chore.


The question of temperature scales (very near and dear to me, a
mechanical engineer who is suppose to know about thermodynamics) is
really quite seperate from the "Metric" issue. The original Metric
system didn't even include temperatrue, as the concept was not really
established at that time.

In promoting the Centegrade scale, the proponents tried to paint
Farneheit as being stupid. Who would make a scale that went from 32 to
212 for Gods sake.

Well, he didn't. He had variations as the progresed in his work, but
basiclly he intended to go from zero to 96 degrees. The zero he had a
bit of trouble standardizing, but he intended it to be the coldest
temperature that would be expernced. The 96 was suppose t be avrage
human body temperature. (Why 96? A bit of numerology, apprently, but
it was at least three times a power of two. A power of two is very
handy when you are laying out scales. 100 has no advantage.)

The fact that water freezes at about zero is handy, maybe. But you
have to use negative numbers for ordinary temperatures. Not good in
Farneheit's day.

Water boiling is not really very relevant.

Neither the freezing point or the boiling point have actually be the
definitions of the scale for almost almost as long as the scale has
existed.

The actual definitions now are that there is only one refernce point
and that is zero, absolute. The "Celsius" scale is defined in terms of
the "Kelvin" or "degree" to ordinary people. The only difference in
that and Farneheit now is that a Farneheit degree is 1/1.8 times the
size of a Kelvin. Big deal.

What is the boiling point of LOX? Who cares what the scale is?


At one point, for a couple of years in the early '80s, as I recall, it was
illegal to posess for sale rulers with imperial units on them. It was
a ridiculous and draconian measure - but effective in getting some of the
older farts to consider using metric units.



Ridiculous and draconian measure, I say. The law is a fool, I say.




Road signs and speeds followed next, closely followed by weights and
measures in general. All up, the conversion for the general public
was completed by the mid '80s, I'd imagine it was completed a lot faster in
specialist industries.


Specialist industries in the US converted any time they wanted to, and
many, like the drug industry, have been metric forever.


The US had a fit of metrication fever about the same time. It got as
for as putting up a few speed limit signs. And "kilometer" posts.


When people saw those, the said what the F*** is this, and when they
figureed out how much money this was going to cost, most states said
"Forget it."

That was one of those "unfunded mandates" (that is not the right term,
maybe). The Federal government mandated it, but the states were going
to have to pay for it.

I live near the state of Deleware. They not only have mile posts on
their turnpike, they have kilo posts, too. In fact, they have HALF
kilo posts! Deleware is so small you can almost see all of them at
once. There are about 20 or 30 of them.

(I am not really sure about the mile posts. They may have the speed
limit signs in mph and kph also. They can if they want to.)


One thing that I find quirky with the US metric experience is your parochial
spelling of metric units. Whereas the rest of the world has adopted
the original spelling of Litre, Metre etc, why does the US prefer to use
the 'er spelling ?



I don't really remember. That has been going on for at least 150
years.

I think it has something to do with the idea that we speak, more or
less, English here. And we couldn't pronounce "metre."

I think that the US was the first country other than France to adopt
the meter/metre. A long time before the British. We just didn't make
it mandantory.

A few years ago, the inch was redefined so that it is now 2.54 cm,
EXACTLY. You just don't have to say it in cm. When that happened, the
US shrank by 20 feet. No big deal except to those with beach property.

In the metrication exercise, there was one part of it that did "catch
on." That was that the BATF (Bureau of Alcohol, tobacco and Firearms)
did mandate compulsory metric bottle sizes for all Alcoholic
beverages.

Of course, they completly screwed it up. Actually, they jsut made
brand new metric sizes for the old bottle sizes. So they are metric,
but wierd metric.

The main size is 750 ml, which is very close to the old 4/5 US quart
size (746 ml, IIRC). Not worth the effort. "Twice" that is not 1.5 l.,
as you might suppose, but accordign to the BATF is 1.75 l. Beats me.
Just makes it hard to compare prices.

The people who squeeled the loudest? The French wine industry, who not
only had to change bottle sizes, they had to have STANDARD sizes. 200
years and there was not a standard size for wine bottles!

The French said that was because the wine bottle was a standard in its
self, the perfect size for two people to consume at a meal! Known to
them, even if not to you.

There are several "funny" thing about the liter/litre. It has driven
the SI guys, who have a lot of time on thier hands, in to various fits
of stupid.

It is not as simple as I once thought, but the liter got "double
defined" like a lot of other stuff in the orginal metric system.

The kilometer was the orignal "base" unit, and was 1/40000 the Earths
circumference, (Paris meridian, of course. )

Before they even got the survey done, the scratched lines on a bar for
a "practical standard". Of course, those don't agree, and on, and on.

The kilogram was based on the weight (or mass, take your pick) of
1/1000 of a cubic meter.

The liter was either 1/1000 o f a cubic meter or the volume of one
kilogram of water, it fluctuated. And, those were not the same, of
course.

Just a few years ago, the SI banned the liter entirely. No matter how
you spelled I think maybe it was out for 6 years.

Then they let it back in, with the cobic meter definition.

The other oddity of the liter/liter is that the SI says you cannot
abreviate it except as "l.". Even though that is very confusing to
read often. "L." is not allowed because capitals are resereved for
units that are named for people.

Some genius tried to fix that by submitting a bio of Andre Litre, the
great physicist who was a the son of a wine merchant. The Si woudn't
by it. No sense of humor.

After haveing been following measurement issues for about 100 years, I
got a big surprise lately when I discovred the explanation for the
size of the US gallon. I always thought it was just dumb. 231 cubic
inches. I had read somewere that the people responsible for the
British standars at one time just happened to have a nice cup that
size.

Not so. In Queen Anne's day, there were several gallons, various
sizes, used for various things in various parts of Britian. So , Queen
Anne, or her agents, decided to have a new standard, so that there
would be one more gallon, "Queen Anne's Wine Gallon."

In order to demonstrate their scientific talents they defined that as
exactly the volume of a cylinder seven inches in diameter and six
inches hight. They picked those numbers because using them, you get an
exact whole number for the volume. 231 cubic inches! They also defined
the gallon as just that, 231 cubic inches.

Problem was, those are only the same on days when pi is equal to 22/7.
Most days, pi is closer to 355/113/

That is a differnence of 0.1 cubic incehs, or something. OH, well.

Later, after we ran them off, the British tried to catch up with the
French by defining yet another gallon, This one equal in volume to 10
pounds of water, at some conditions.

Well, happy metrication, and have a good 1/365.24 of a mean solar
year.

Henry H.