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Another English/Metric "Spacecraft" Problem 748

Posted by Hemos
from the oh-the-joys-of-system-management dept.
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."
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Another English/Metric "Spacecraft" Problem

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  • by agentZ (210674) on Monday January 26, 2004 @11:25AM (#8087905)
    So in other words it wasn't a metric/inches conversion problem, but rather just using the old blueprints instead of the current one?
  • by GileadGreene (539584) on Monday January 26, 2004 @11:28AM (#8087938) Homepage
    Sigh. When is America going to ditch its archaic measurement system and use the same standard as everyone else? I work in the space industry, and I see this idiocy going on all the time: half the team works in metric, the other half in english. Most of the time everyone manages to keep it straight. But every now and then, a mistake happens. Scientists all use metric. Most engineers are trained in metric. Let's just switch to metric for everything and be done with it.

    A side note: in New Zealand (and possibly other Commonwealth countries - I haven't checked) they don't even refer to "English units". Their term is "Imperial units". Which tells you how long it's been since they made the switch...

  • by swoebser (148435) on Monday January 26, 2004 @11:38AM (#8088032)
    What do you think would be the biggest hurdle in the US conversion to the metric system? I, at first, thought it would be automobile manufacturing/repair, but all auto shops already have to deal with foreign cars already with metric parts. My vote now would have to be for gas pumps and speed limits. I think it would take people a long time to adjust to liters and kilometers per hour.
  • Re:Gotta ask... (Score:2, Interesting)

    by mrdogi (82975) <mrdogi@sbcglobBOYSENal.net minus berry> on Monday January 26, 2004 @11:42AM (#8088075) Homepage
    Just in case anybody's curious, Using 16.5 feet = 5 rods and 63 gallons = 1 hog's head, I come up with 4032 gallons per mile for Grandpa Simpson's car.
  • by Anonymous Coward on Monday January 26, 2004 @11:42AM (#8088078)
    Seriously. Metric is base 10, Imperial units are base 12.

    Now, the cool thing about this is that 12 can be divided by 2, 3, 4, 6 - giving you the ability to easily measure a third for instance. It's why it's still used in the building trade. Metric only lets you divide by 2 and 5 - and is not as flexible.

    Anyhows, totally off topic, but kinda interesting, and one reason why Imperial mesurements aren't going to disappear any time soon (no jokes about TIE fighter blueprint errors please).
  • Re:English units? (Score:3, Interesting)

    by Oddly_Drac (625066) on Monday January 26, 2004 @11:43AM (#8088090)
    "I thought the Brits moved glacially since the UK has been metric since 1971... officially (except for beers. I don't know how long road measure will remain Imperial)."

    Until they pry miles and pints from our cold, dead hands.

    Seriously, I was never taught any imperial measures, and had to work out a lot of conversions myself, particularly as we have a hybrid system in place that mixes different units according to application. I'm long since out of the school system, but I was born in 1972.

    The odd thing is that America still refers to them as 'English' units despite us not really using them.

    Milk has moved over to metric without much fuss, but I think there was a bit of hoohar regarding licensing regulations in moving to the litre/demi-litre for beer measurement. So we haven't, although all glasses currently display the measuring line...glasses without a measuring line are sorta illegal if I can remember back to my barwork days.

  • by Anonymous Coward on Monday January 26, 2004 @11:45AM (#8088111)
    Some things that would be nice to standardize (but will probably not happen in my lifetime)

    - imperial - metric
    - Letter paper - A4
    - Fahrenheit - Celcius
    - AM/PM - 24 hr notation
    - month/day/year - day/month/year

    Anything I left out?
  • by aduthie (530266) <andrew&duthiemm,com> on Monday January 26, 2004 @11:49AM (#8088144) Homepage
    I worked in automotive engine factories in Detroit for two years. We had a problem with a cylinder head casting from a South American supplier once that was a direct result of them not updating their tool drawing when they fixed the problem the first time. Since the print was never updated, when they built a new tool to cast the heads, they left in a certain ejector pin. Once again, the pin wore out, sand built up around the pin, and we ended up with a little hole in the cylinder head after we machined it.

    We caught the hole on the assembly line via the standard air pressure testing, but the mistake ended up costing the supplier an entire warehouse full of scrap parts that they had shipped (by ship) to the U.S.

    Moral of the story: Update the damn prints, people!
  • When will this stop? (Score:4, Interesting)

    by photonic (584757) on Monday January 26, 2004 @11:53AM (#8088175)
    First of all i want to applaud the Japanese culture. The press report seems to originate from the company that made the error: A public statement about the how and why of the error, with apologies and even in english. I wish more companies were like that.

    This incident (although caused by a transition TO the metric system) leads us to the question how many more years until we finally get rid of the imperial system. The US standard bureau has a page [nist.gov] that describes their effort in the conversion. They quote the metric conversion act of 1975, but i don't know how much has happened since then. How many years do I have to buy US stuff here in Europe that is half metric and half imperial? For god sake, even the UK has switched! Does anybody know a real time-table for the transition??

    Obligatory Pulp Fiction quote:


    Vincent:
    And you know what they call a Quarter Pounder with Cheese in Paris?
    Jules:
    They don't call it a Quarter Pounder with Cheese?
    Vincent:
    No, they got the metric system there, they wouldn't know what the fuck a Quarter Pounder is.
    Jules:
    And what'd they call it?
    Vincent:
    They call it Royale with Cheese.

    If you ever run into a imperial system freak ask him to calculate how many square inch there are in a square mile ... without blinking.
  • by jorlando (145683) on Monday January 26, 2004 @12:04PM (#8088286)
    That made sense when people didn't had calculators. It was easier to use a base 12 system. The other problem is the change of units. 12 inches perform a foot. So John is 5foot6", or 5.5 foot, or 66"... another inheritance of time when calculators weren't available. You can say that John is 1.6764m tall, or 167.64cm or 1676.4mm, the measurements are more consistent.

    the metric system isn't advantageous in itself by being base 10. The advantage comes from the fact that the unit is constant all the time. You don't change names or add new units in the measurement, nor use fractions.

    It's hard to cope with different units in the same measurement. The imperial system was good once... it had it's time, time to move on.
  • by Metryq (716104) on Monday January 26, 2004 @12:13PM (#8088376)
    Meanwhile PLENTY of errors have been made by people (admittedly with weak math skills) incorrectly adding fractions. I've seen decimal inch rulers; why couldn't that be the norm? But no, wacky fractions like 7/54 are so much more fun. In an effort to avoid metric I'm surprised no one has suggested binary rulers. Water freezes at 32F and boils at 212F -- who came up with that?

    I'll take metric, thanks.
  • by hoofie (201045) <.graeme. .at. .graemeandkim.com.> on Monday January 26, 2004 @12:20PM (#8088460)
    Actually you are wrong !!!

    In 1983 an Air Canada flight ran out of fuel [mines.edu] mid-flight. Disaster was averted due to a long-enough disused runway being available.

    Its now know as the "Gimli Glider" named after the abandoned air-force base where it landed. It was luck that one of the pilots was a glider pilot. Apart from the complete-cock up, it showed some fantastic flying and emergency management.
  • by Alan Partridge (516639) on Monday January 26, 2004 @12:34PM (#8088612) Journal
    Stones are used in the same way shoe and dress sizes are used, they have no relation to anything other than people's body size.

    As for retaining miles, ALL the road markings are in miles and MPH, it would cost a FORTUNE to replace them - though I rather think new speed limit signs should be bi-measure. In fact, a conversion from imperial to metric for the roads would give a great opportunity for a new speed limit system with higher highs and lower lows.
  • Re:English/Metric (Score:2, Interesting)

    by Mikkeles (698461) on Monday January 26, 2004 @12:52PM (#8088834)
    "... at least we have the Centigrade scale. I'm all for keeping the old-fashioned units alive, but really! Who thought water freezing at 32 and boiling at 212 was a sensible scale?

    I know the significance of 0F as being the lowest acheivable temperature where salted water remains liquid, but can anyone explain the rest? It still completely baffles me!"

    Fahrenheit originally picked the normally coldest and hottest temperatures that were likely to be encountered in his area of Europe. It was later, so as to use convenient reference points, that he pegged the 32 and 212 degree points; those being slight adjustments to his original scale.

    Also interesting is that Celsius' original scale was inverted (to what we now have): 0C = boiling point of water and 100C = freezing point of water! It was Linnaeus (of binomial classification in biological taxonomy fame) who suggested that Celsius' original scale be reversed.

  • by Aidtopia (667351) on Monday January 26, 2004 @01:03PM (#8089012) Homepage Journal

    A friend of mine in college in the late 80's did an internship with Disney Imagineering. At the time, they were redrawing plans for several attractions that were to be copied almost exactly from California and Florida version for use in Euro Disney. There was great concern that the Imperial to metric round-off would be a problem. The contractor's union in France mandated that they only use metric units in the blueprints, which is reasonable. But if you're trying to duplicate a ride that was originally designed in Imperial units, you need to keep in mind quite a few significant digits when you're measuring. For example, a section of track in a given ride might be 10 feet in the US. In metric that's 3.048 m. Would the French contractors really measure to that precision? Or would they round off to 3.05 or event 3.0? They were concerned that roundoff might be systematic causing the errors to accumulate in one direction. This was a big concern, and there were debates over whether some rides needed to be redesigned in metric from the start and possibly give up economies of standardized parts.

    That this happened in Space Mountain is also interesting, because Space Mountain was the first rollercoaster to have ATIS (automated track inspection system). Since it was a tightly wound coaster in a confined space it was difficult to do visual inspections. ATIS uses two techniques to detect problems with the track. The rails are actually tubes and they're pressurized in sections. When small cracks start to develop, the pressure drop is detected. Sensors also time cars through different sections of the track. If there is a trend of cars slowing through a section over time, it indicates that the ties between the rails are starting to give. ATIS is so much better than visual inspections at detecting problems early that it's used on most modern roller coasters.

  • Mixing paradigms (Score:4, Interesting)

    by slim (1652) <{john} {at} {hartnup.net}> on Monday January 26, 2004 @01:48PM (#8089695) Homepage
    I can live with people insisting on using Imperial measures.

    What bugs me is when they then only halfway use the Imperial paradigm.

    Case in point: when the iPod Mini was announced, I went to the web page [apple.com] to check out the specs. 2" x 3.6". Not having any intuitive feel for what that might mean, I wandered around the office trying to borrow a ruler, and once I'd found one, started to draw an iPod-sized square on a piece of scrap paper.

    A 2" line across the bottom was easy. Then I set about drawing the vertical. 3", then another 6 gradations... oh, wait a minute, each inch is subdivided into 16ths. Tricky. Grab calculator.

    So please, either use mm, or go the whole hog and state 3 inches and (10/16)".
  • Re:English/Metric (Score:3, Interesting)

    by dublin (31215) on Monday January 26, 2004 @04:26PM (#8091958) Homepage
    I much prefer units I can relate to, personally. If the metric system has given us nothing else (which it hasn't), at least we have the Centigrade scale. I'm all for keeping the old-fashioned units alive, but really! Who thought water freezing at 32 and boiling at 212 was a sensible scale?

    This is one place where English units *definetely* make much more sense than Metric/SI units, *especially* for everyday use:

    Tha problem is that a cEntigrade/Celsius degree is just too damn big to really be useful, especially for temperatures that really matter to *people*.

    For instance: I used to own an Alfa Romeo 164S that, like many "metric" cars, had a climate control system that "thought" in Celsius degrees. The problem is, they're just too big to allow fine enough control for comfort: setting an AC system at 72 degrees and letting it try to stay within a degree of that works fine with Fahrenheit degrees, but doing the same thing, with a one-degree tolerance in Celsius degrees results in a temperature swing that is almost *twice* (9/5, actually) as large, so the system cannot really keep things comfortable.

    Any sort of reasonable thermostat in Celsius has to resort to using half-degrees.

    Who the heck cares where water boils? Especially since pretty much everyone (even metric bigots) knows that it boils at 212 degrees F.

    Fahrenheit degrees are just more useful in the real world. (And they also make having to deal with negative degrees fairly rare, unless you live someplace unsuited for human habitation anyway...)
  • Re:margin of error? (Score:2, Interesting)

    by Golias (176380) on Monday January 26, 2004 @05:51PM (#8092952)
    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.

    So? Being somebody with a better education than a hair stylist, you could have politely told her that you wanted a little less than half an inch taken off, and moved on with life.

    The amazing thing is not that the English System has lasted so long in the US, but that Napoleon's system was adopted so quickly in Europe. The reason is simple: until the early 20th Century, most of Europe was ruled by dictators and monarchs, who could tell you to use their chosen measuring system and like it. In the US, the system which would get used is the one which the most people were using, and nobody really had enough power to change it.

    The English still use pints to measure beer for much the same reason... there's only so much that even people under a monarchy will put up with. Drop inches in favor of cm if you must, but don't you dare mess with the beer. :)

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