Another English/Metric "Spacecraft" Problem

SuperDry writes "There's been another spacecraft failure that's been attributed to an English/Metric units problem, this time at Tokyo Disneyland's Space Mountain. An axle broke on a "spacecraft" (a.k.a. roller coaster train) mid-ride, causing it to derail (nobody was hurt). The final investigation report has been released, and the root cause has been determined to be a part being the wrong size due to a conversion of the master plans in 1995 from English units to Metric units. In 2002, new axles were mistakenly ordered using the pre-1995 English specifications instead of the current Metric specifications. Apparently size does matter, even if it's only a 0.86mm difference."

English units?

[Anonymous Coward]

I don't know about you, but us English call the measurement system the Imperial system. Isn't the American version slightly different, in respect to fluid units, etc?

Imperial, not English...

[arafel]

Why do you call them 'English' units, when everyone else knows them as Imperial units? :-) We stopped using most of them some time ago.

Re:0.86mm? That's a HUGE difference!

[c_oflynn]

0.86mm might at well be 3 feet off.

Actually you'd be WAY better off it was 3 feet off. Even if it was say 10mm off, then the axle probably wouldn't fit or would be VERY noticably loose.

Instead you get the situation of something just fitting enough that it seems OK to the mechanic...

The US needs to catch up

[Listen Up]

The US needs to catch up to the rest of the world. The entire world uses Metric people. And it makes an infinite amount more sense to use Metric than the US system. If we don't, trade will continue to suffer as well as accidents such as this one.

Re:Who's at fault here, really?

[lone_marauder]

Hey, I like the metric system. I really do. But sticking to the english system has never caused an aircraft to run out of fuel at altitude, a roller coaster to break, or a spacecraft to crash. The zeal to enforce metric conversion, however, has caused all of those things.

About the same time /. posters actually RTFA?

[bluprint]

The problem had nothing to do with eglish->metric conversion.

Also, there is nothing inherently better about the metric system of measurement, vs. the english system of measurement vs. any other standardized system of measurment. If something is measured at 1.5 inches or 38.1 mm, it's the exact same length. The only advantage is commonality and not having to do conversions (which is an advantage, I admit). But there is no inherent advantage as to how well one system can perform over the other.

Re:The US needs to catch up

[mirio]

Hmm...the Space Mountain engineers were doing precisely that! They were converting Imperial to English units (i.e. playing catch-up).

Re:Who's at fault here, really?

[mgs1000]

But is 25.4mm/in precise enough for this kind of calculation? The failure was caused by a .86 mm error!

Re:Imperial, not English...

[ender81b]

Oh yeah? So stones is a metric measurement? And pints? ANd miles, miles per hour?

You guys are worse than americans! we consistently ignore the metric system but you guys just use parts of it.. kindof.. sometimes.

Imperial system indirectly responsible

[Anonymous Coward]

In this case, the Imperial system isn't directly to blame : the article states that it's a communication problem that provocated the troubles.
I applause the initiative taken by engineers in this case : they did switch the plan to the metric system, and that's a good move. I just wish the whole US country would do the same.

Unfortunately (this is where I start drifting toward offtopicism), frenchs are the initial designers of the metric system. I wonder if this refrains US to switch completely to it, and keep the imperial system.

Still, doing the switch would be the most reasonable thing to do (widely used in the rest of the world AND simpler to manipulate), and could perhaps even have some beneficial political repercussions at the international level (and you can't deny US badly need some these days).

Re:About the same time /. posters actually RTFA?

[radja]

then quickly tell me:

how many inches in a mile?

Not a metric/imperial drawing

[nuggz]

The problem has little/nothing to do with it being metric/imperial.

Someone ordered the wrong part. That's it.

This is why drawings should be controlled. Only current known valid drawings should be used for anything.

This problem is as basic as someone using patches for linux kernel 1.2.13 on a 2.6 series kernel

Re:About the same time /. posters actually RTFA?

[Anonymous Coward]

Yes, there is an inherent advantage. Consistency.
Compare:
1000 grams (g)= 1 kilogram (kg)
1000 kg = 1 tonne (t)
with
16 ounces (oz) = 1 pound (lb)
14 lb = 1 stone,12 stone = 1 hundredweight (cwt)
20 cwt = 1 ton (t)
(even the abbreviations are easier to remember!)

or compare
1000 mm = 1 m
1000 m = 1 km
with
12 in = 1 ft, 3 ft = 1 yd
1760 yd = 1 mile

Or think about areas. The common metric unit of area,1 hectare = 100m x 100m = 10,000m^2 and I know this without looking. The common Imperial unit, 1 acre = 43560 ft^2. No way could I have known that figure without looking it up.

Of course the very worst people of all are particle physicists, who measure everything in GeV regardless of dimension, and astrophysicists, who use parsecs, AUs, light-years, solar masses, solar luminosities, etc.

Re:If the U.S. hates the french so much

[Progman3K]

If the U.S. hates the french so much, they should dynamite the Statue of Liberty, because that was a gift from the french to the U.S.

It would serve the french and the americans right!

See how stupid all this french or american bashing is?

Grow up, people.

Re:Who's at fault here, really?

[Rhubarb Crumble]

Hey, I like the metric system. I really do. But sticking to the english system has never caused an aircraft to run out of fuel at altitude, a roller coaster to break, or a spacecraft to crash. The zeal to enforce metric conversion, however, has caused all of those things.

Hey, I like the imperial/english/mediaeval/whatever system. I really do. But sticking to the metric system has never caused an aircraft to run out of fuel at altitude, a roller coaster to break, or a spacecraft to crash. The zeal to make specifications understandable to people who think in terms of the size of kings' thumbs and the area of land that can be ploughed by an ox in a morning, however, has caused all of those things.

The simplest argument in favour of the metric system is that it's base-10... (or base-10^3 if you want to be picky...) Of course once all our civilisation is outsourced to India and China I guess we'd better get used to counting in 10^4 or 10^5... (wans and lakhs)

Re:English/Metric

[Kidbro]

I agree, C is better for science, but in the real world who cares where water boils or freezes.

When water freezes is extremely relevant in "the real world". Whether there will be rain/wet or snow/ice outside is extremely relevant - at least where I live.
Having 100 as the boiling point of water isn't quite as important, but still pretty sensible. Usually, one degree C is small enough to be sufficient in accuracy (I have really never seen anyone change the thermostat by half a degree, as you claim), and having two points on a scale that sort of relates to the same thing (water, in this case) is pretty intuitive...

But has the rest of the world really converted?

[glorf]

What about the OPEC nations who sell 42 gallon barrels of oil? Or how about Volvo, BMW, Honda, Toyota etc. whose automobiles measure performance in horsepower? And what about your furnaces that are probably rated in BTUs. And there are probably a bunch of other units I am forgetting. If you think your country has gone totally metric you are fooling yourself.

And then of course there is time. Is there a single country that has converted to metric time?

Re:The US needs to catch up

[Anonymous Coward]

I've got a bunch of eggs, and I want to sell them to people without calculators. If I group my eggs by the dozen, I can split a dozen it into two, three, four, or six equal pieces without having to sell any half-eggs.

Or why not just sell them one by one? Then you can sell 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or even 2647 eggs without selling any half eggs... And multiplying a price 6 is far easier than dividing it by 6...

Re:Pre-emptive rant reply

[mks113]

Um, I think you are being rather presumptive in your assertion that the US approach to business has been responsible for a "not as bad" recession.

Those of us to your north (or east, in my case) are somewhere between the european beurocracy and the american laissez-faire approach, but we haven't been hit with the recession in the same way. We do blame SARS and BSE with slowing the growth, but metric!?

And to state what a few dozen engineers have thought but not spelled out in the English vs. Imperial rants --- It isn't metric, it is SI.

Messes up my own projects too

[exp(pi*sqrt(163))]

I'm busy working on some robotics projects at home. So I go off to Ace hardware this weekend to get some measuring equipment as I need to do stuff acurately. Now I'm writing code that uses these real world measurements and most of the library calls for I/O of numbers (e.g. scanf, printf) support only the use of decimal to represent floating point numbers. So clearly it makes sense to use metric for measurements as I'm so lame I can't remember what a number like 3 7/32 looks like in decimal. Goddamnit! Do you think I could find any metric equipemnt anywhere in Ace? Maybe one steel ruler. And it was just a ruler. Stuff like levels, set squares and protractors all have rules on them marked in inches. It's pathetic. It's like waking up and suddenly finding myself in a medieval city measuring out my drinks in gills.

Re:English/Metric

[Unregistered]

Except Standard (English) units are more useful. They're divisible by more things. ex: a half foot is 6 inches a third of a foot is 4, a quarter is 3. In the real world metrics aren't really as pretty as people say. The only common conversion out there is volume to mass and for anything but water, metrics are no easier than Standard. And Celsius degrees are too damn big for lab use, imo. For some purposes Standard is better and for some purposes metric is. Its not tht hard to learn both.

Re:English units?

[Carnivore]

No system of measure is inherently better or worse than another.

I disagree. You can truthfully say that no system is any more accurate than another, but since people have to work with the system and convert from unit to unit, some systems are inherently better.

Let's take an expmple from last night's Mythbusters episode:
The rowing 8 that Stanford used for the demonstration has a mass of ~ 1000 kg when loaded with crew. If you were to design one, what volume water would you have to displace to float the boat?
Since water is ~ 1 kg/l, we have 1000l, which is the same as 1 m^3.

The process is much more complicated in the imperial system.
We have ~2200 lbs.Water weighs ~8 lbs/gal, so that's 265 gallons of water. According to units, that's 35.42 cubic feet, which is, of course, pretty much the same as 1 cubic meter.

The difference here is that it took me 5 minutes and 2 different programs (calculator and units) to do it in the imperial system.

Besides this rather geeky calculation, people who use and defend the use of the imperial system don't know how to use it! I was talking to someone about DSL, and I said something like, "even if you're 15000 feet from the CO, and you're much farther, performance would suck." and she had no idea how far that is in miles (it's a little less than 3, for our metrified friends).

Re:English/Metric

[Ianoo]

Yeah, and why do you think the only surviving commonly used base in the world (outside of computing) is 10? Because we have 10 fingers. So effectively (ten fingers) -> (ten numerical digits) -> (base 10 number system), so the reason metric is based on 10 is still because we have 10 fingers.

The only really important historical exceptions I can think of are the Romans who used base-5 (but the way they wrote numbers was so horrendous that it didn't survive) and the Babylonians, who used base-60 (because their mathematicians were all pretty smart!).

Blah blah US economy blah blah

[Imperator]

Don't give me that crap about how much better the US economy performs than the EU. The median standard of living in the EU is higher than in the US. The US economy is great at producing wealth at the top, but conservative Americans have an aversion to using the economy to solve social problems ("communism! class war!"). I think this is a major reason why Europeans view the US as "backwards". Yes, both the US and the EU have economies that have solved the problems of food, shelter, and medicine. But the US has not seen to distributing those solutions to the people.

Many Americans have an ingrained sense that the only job of the economy is to grow. Things like social nets and environmental protections interfere with the ability of the (total) economy to grow at the fastest rate possible, so they must be inherently bad. This is the unifying economic philosophy of the conservative Republicans: government itself is inherently bad precisely because it siphons money (taxes) away from investment and consumption. If you believe in Reaganomics ("a rising tide lifts all boats") this makes some sense. But in the real world, it leads to a morally bankrupt society obsessed with money.

</rant>

So in conclusion, there are 36 inches in a yard.

Moan, moan moan... The metric is alive in the US.

[Hackie_Chan]

Around Universities in the US every roadsign in kilometers. My father works for a vitamin company in the US, and he use the metric system anyway. Big deal if it's not official in the country, if enough many people start to use it, it's going to catch on -- just like the word THRU.

Re:Imperial measurements rock...

[slim]

Seriously. Metric is base 10, Imperial units are base 12.

Some of them are, some of them are not.
1 pound = 16 oz
1 stone = 14 pounds
1 foot = 12 inches
1 yard = 3 feet
1 US pint = 16 US fl oz
1 UK pint = 20 UK fl oz
1 Gallon = 1 pint

You're deluded if you think this mess has any value beyond familiarity (and, being unfamiliar with it, I had to look up all those conversions with Google Calculator...)

Maybe you'd like to go back to Imperial coinage too? 12 pennies to the shilling, 20 shillings to the pound, two shillings to the florin, 2 shillings and sixpence to the half crown...

Re:English units?

[sketerpot]

Hear hear. I find Imperial units extremely painful to do conversions with, so I propose that we go to the much easier Metric system [metric4us.com]! It's all for the better! You can do conversions in your head! Complicated conversions! We will CRUSH OUR ENEMIES WITH THE METRIC SYSTEM!

Besides this rather geeky calculation, people who use and defend the use of the imperial system don't know how to use it! I was talking to someone about DSL, and I said something like, "even if you're 15000 feet from the CO, and you're much farther, performance would suck." and she had no idea how far that is in miles (it's a little less than 3, for our metrified friends).

That's exactly what I'm talking about. I live in the US, and I couldn't for the life of me do that conversion without the aid of a reference and a calculator. With metric, it would be so easy that I could just say it in meters or kilometers without missing a beat.

Base 12. Right.

[Rupert]

A hogshead, as mentioned elsewhere in this thread, is 54 gallons (3 kilderkins). Unless you're measuring wine, in which case it's 63 gallons (you get an extra firkin).

A yard is 3 feet. A rod is 5.5 yards. A chain is 4 rods. A furlong is 10 chains. A mile is 8 furlongs. A league is three miles. A cable is damn nearly metric, at 10,000 links, or a bit more than 12 miles.

A pound is 16 ounces. A stone is 14 pounds. A hundredweight is 8 stone. A ton is 20 hundredweight. I would break the ounce down into drachms and grains, if I could remember them, but I'm pretty sure no factors of twelve are involved.

Have You SEEN The Size Of A Millimeter?

[cmholm]

If you'll take a look at a metric ruler you're sure to have close at hand, you'll see that 1mm (or 8/10 mm) is more than adequate for a good air gap. Trains, planes, automobiles, and virtually all other machinery uses MUCH closer tolerences than that, life-supporting or not.

A 1mm gap/variance leaves bearings, seals, valves, and gears unusable in most situations.

Re:margin of error?

[spike hay]

I am still continually amazed that the English System is still used at all. I can somewhat understand NASA needing to use some english measures for old lathes and such. But for our entire country to still use the english system for all applications is ridiculous.

I was getting a haircut the other day. I didn't want a whole inch off. So I asked for a centimeter taken off. The stylist had to ask me how long a centimeter was.

Bad rap for English units

[frink_exp]

Why do English units get such a bad rap? 1 pound mass (lbm) weighs 1 pound force (lbf) on Earth - simple. 1 kg weighs 9.81 Newtons on Earth. Why do people think 9.81 more simple than 1?

This really isn't the problem. The problem with the English system is derived units. For example, energy:

metric: 1 J = 1 N*m

English: 1 Btu = 778.169325 ft*lbf

If English units defined derived units in terms of its basic units, I'd find both systems equally appealing.