Boeing and metrcication question

And why do we see air pressure in BAR instead of Pascals?

Remember the Gimli Glider

It's the same as some countries using 50 cycle ac power when

Gerry :-)} London, Canada

They didn't jump. They were pushed off that cliff by a sick practical joke from the French. No one realized it was a joke because, quite frankly, they aren't that funny. It has snowballed to the point it is out of control.

Pressure is a full bladder, a diuretic, and no bathroom available.

A 'Newton' is a fruit filled cookie.

Yawn. Like none of England's corporations EVER received ANY government money.

Newton a vague name ?

A Pascal describes a programming language.

Parsec is a what ?

Newton-meter now that is fun.

Martin

Mart> Ted Frater wrote:

Sekunde: "sek." or "s"

Nick

Many Americans are quite happy with metric units. Unfortunately, they are subject to mandatory constraints. In a free market, many more products in the supermarket would be labeled just in liters and grams. Manufacturers such as Proctor and Gamble have said that they would use metric-only labels if it were not for Federal laws such as the FPLA making it illegal. Such laws are called 'Technical Barriers to Trade' because it makes it difficult for products to cross international boundaries even if customers want to buy them.

In US aviation, the FAA controls the pace of metrication by its rules. The mandated unit was Fahrenheit up until 1996, then it changed to Celsius.

Not if they wanted to sell them.

I'm sure that most people here realize why the US never adopted the metric system for everything. Until the last couple of decades, and even now, in fact, the US market is so self-contained compared to other developed countries that the pressures European countries felt to adopt a uniform system (the UK agreed kicking and screaming, and they still kick a little -- witness the pint/pub fiasco that was decided by the EU last week) never existed here.

Without market and political pressures, and with the supposed "advantages" of the metric system applying mostly to specialized areas, consumers and much of manufacturing just did the most economic thing, which was to stand pat. As the Europeans, Australians, etc. here likely know by now, the US is fully metricized in those fields in which it provides an economic or other substantial advantage. Once you move beyond the fields in which most use of physical units is confined to linear dimensions or volumes, metrics dominate in the US.

I was once a big advocate for metrics but decades of questioning its advantages in the marketplace has led me to realize we're doing the thing that provides the best economic result. The cost of converting would be far greater, I believe, than the slight friction it adds to trade. If that changes, we'll finish converting to metrics, but not until it pays to do so.

-- Ed Huntress

I mean coherent according to physical theory, rather than to sense experience. It's based on theories of fundamental physics rather than the kinds of things we see and feel when we do most of our measuring in life.

And yes, if you're involved particularly in design work involving more than diminsional measurement and you're doing calculations, it's a neat system -- particularly if you have enough knowledge of physics to be comfortable with the derived and multi-dimensional units. For the rest of the world, the advantages, if any, are slim or nonexistent.

Most people don't do the math. If they do, in the US or anywhere else, they're probably using metric units and possibly SI units.

Don't forget to double-check your decimal places. If people would stop using that damned centimeter they'd have far fewer errors of that type. d8-)

Arghh! I thought you were arguing for accuracy. Ten N does not equal a kg of force. 9.80665 N equals a kg of force (by gravity, at the earth's surface at the equator, anyway, which sure beats the hell out of the accuracy you get when you "multiply the kg by 10"). It's one of those nice, neat, whole-number relationships in the metric system, so useful when rocket designers are calculating thrust-to-mass ratio.

What famous proof? And what "result"? Most current "Imperial" measurements are defined in terms of metric units.

Tell me, does the average consumer who weighs his kilogram of potatoes keep in mind that he's actually measuring force, and that he's not actually getting a kilogram of potatoes unless he's using a beam- or pan-balance? Do they not use springs in the scales at grocery stores in Europe? Even if he knows Newtons, is he fully aware of the difference between mass and force? I bet no.

If Joe Bar is calculating the Euler's buckling resistance of columns, he is not part of this discussion.

It can, if you're being fussy. But the errors are nothing like the ones you get when you say to multiply the number of kilograms by 10 to get Newtons.

Nick, I wish I could summarize my points on this sufficiently to clear up all of the arguments. It may surprise you to know that a big bottle of Coke in the US is a 2-liter or 3-liter bottle. It is not a 2-quart bottle. Furthermore, the engine in a Ford or Chevy is not identified on the trunk as a 183 cubic inch engine; it's a 3-liter engine. Despite this we don't encounter enough problems involving, say, the speed of light and the mass of a banana to have much trouble with the dual system.

And so on. The US is not hidebound to the Imperial system. We just use it as a matter of economic good sense. Given the economic filtering process that free-market economics puts us through, you can be sure we'd be 100% metric if it truly was an advantage. We're much better at that than any country in Europe has been, although you do seem to be coming around to a fuller appreciation of the useful power of markets.

And the people doing complex calculations with force, acceleration, and so on are using metrics with few exceptions. As for the SI, it's a mixed bag, in the US as well as in the rest of the world. There are a lot of holdouts for CGS (usually expressed as "cgs," but who's editing...) everywhere in the world.

-- Ed Huntress

.Thank you!

Those who pursue the metricattion road are mostly political and not creators of things who must economize at every step of the way. A quater twenty tap/die/drill/screw is a penny. A six MM with all the off-size drills and taps make it cost a dollar. That's the bottom line.

I couldn't even buy that crap here without hunting around. That's why I don't buy products with imperial screws.

What is a MegaMega?

A 5mm drill (for M6) costs 35 cents.

Now what's your point?

Nick

It will happen, given time. Why? Because US manufacturers also buy and sell from other countries. When Imperial components cost more than metric ones because of lower production volumes and additional inventory costs, then the American manufacturers will be at a competitive disadvantage. When a customer has to buy non-standard tools to fit US fasteners, it becomes an item in the purchasing decision. So eventually, Metric production will creep across the US. As it does, sticking with imperial measure will become less and less attractive. Add to this, undergraduates being taught science in metric measure will take that with them and will see Imperial measure as clumsy. And so it goes.

It's already happening isn't it? The auto industry is IIRC using more metric components even on US vehicles. Of course The foreign branches of the US auto manufacturers have been making pretty well entirely metric vehicles for a couple of decades now.

I have no axe to grind one way or the other. In the workshop at home. I'll stick with Imperial measure except when I'm working to metric dimensions. At work we use Metric measure for everything except for where we are working to Imperial dimensions (a 2 1/4" BSW Turbine half-joint bolt is unlikely to fit a

regards Mark Rand RTFM

Mark, when I was in high school, in the early- and mid-60s, they told us that the US would be 100% metric within ten years. Then we heard it again in the '70s, after Caterpillar converted. Then the US car makers started their tortuous, two-step conversion, and we heard it again.

It hasn't happened, obviously. Now, that being said, a lot of US manufacturers make their products in metric dimensions and with metric fasteners, and they have for 30 years. There is very little serious machinery in production today that can't switch from inch to metric with the push of a button.

Those factors have been in play for more than 40 years, and none of it has happened.

I was a science student in the '60s and early '70s, and we were 100% metric then. Which US is it you're talking about, anyway? d8-)

You're roughly 30 years late with that one.

I think it's more like most of a century.

And beer in your pubs.

-- Ed Huntress

A good example of why working in the same units that the rest of the world uses will reduce problems :-).

To be fair, in the mid 70's a Viscount turbo-prop did a dead stick landing in a farmer's field a couple of miles short of Exeter airport in the UK, IIRC The Spanish airport had delivered 600lbs less fuel than the paperwork said. In that case, it was probably simple incompetence.

Mark Rand RTFM

Did you bother to read the quoted post that I was responding to before you snipped it? Doesn't seem like it.

regards Mark Rand RTFM

I would have no problem with quaffing my draught ale by the half litre, provided that it was a good real ale and had been carefully cellared at 55 deg F. It would, of course, be illegal for the pub to sell it in that volume, that law has been in place since 1699. I might complain of short measure if the publican gave me a 16oz pint though :-)

Mark Rand RTFM