Another English/Metric "Spacecraft" Problem 748
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."
Miscommunication (Score:5, Informative)
In September 1995, the design specifications for the size of the axle bearing for Space Mountain vehicles was changed from inches to the metric scale. Accordingly, the axle diameter was also changed, in this case from 44.14 mm to 45.00 mm. However, appropriate action to revise and maintain the design drawings was neglected. Consequently, two different drawings existed within our company after the changes were made and the old drawing showing the 44.14 mm diameter was used to order (in August 2002) the axles that were delivered in October 2002.
They actually changed the specs. The conversions were all done correctly but they failed to update everyone.
0.86mm? That's a HUGE difference! (Score:5, Informative)
Anything from rubbing away the lining of important wires or hoses, different stress locations resulting in tear apart pieces that shouldn't be tear apart can happen by being off by that much...
0.86mm might at well be 3 feet off. A part that comes out that far off is nothing but scrap material. (Well at least in our area of automotive work.)
Re:Who's at fault here, really? (Score:5, Informative)
Consequently, two different drawings existed within our company after the changes were made and the old drawing showing the 44.14 mm diameter was used to order (in August 2002) the axles that were delivered in October 2002.
English/Metric (Score:5, Informative)
Better ways to describe them would be "Imperial" (what we call them), "American" or "Archiac". I think it's about time the US caught up with the rest of the world and ditched these stupid and difficult-to-remember units once and for all.
Re:Imperial, not English... (Score:2, Informative)
To add confusion to the mix, "Imperial" to a Canadian is the same as "English" to an American - i.e. not the same as "Imperial" to an Englishman.
It had nothing to do with the conversion directly. (Score:5, Informative)
Google's Cache (Score:3, Informative)
The Japanese did the conversion. (Score:5, Informative)
http://www.laughingplace.com/News-ID108300.asp [laughingplace.com]
Great set of columns, by the way. I've always been a fan of how some of the disney technology was invented and implemented.
Re:Who's at fault here, really? (Score:3, Informative)
Re:Imperial, not English... (Score:4, Informative)
Maybe, just maybe, we can start using the metric system? Isn't 100 years enough time to transition?
Re:0.86mm? That's a HUGE difference! (Score:5, Informative)
Re:The source of the problem (Score:1, Informative)
Re:English units? (Score:4, Informative)
Only with respect to fluid units. And the base unit, the ounce, is the same. Measurements based on the pint are different: a US pint is 16oz an Imperial pint (the only legal Imperial measure left in the UK!!!!) is 20oz. A gallon is 8 pints, a cup is a half-pint, but a US gallon or cup is 4/5 of the British counterpart.
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). Then I found out that the US has been co-metric since Ben Franklin (http://www.nist.gov).
No system of measure is inherently better or worse than another. But, when everybody you trade with uses a different system, it might be time to reconsider (not that the UK should adopt the Euro....)
Re:The source of the problem (Score:2, Informative)
MANY persons, otherwise well-informed upon general topics, believe that railroads were constructed especially for locomotives, as the best-adapted road for the accom- modation of that peculiar machine and its train of cars. They never call to mind that a locomotive is a modern invention, and, for want of access to works such as we have referred to, they are not informed that a railroad is an ancient institution (if we may apply such a term to such a subject). They never have dreamed nor ever imagined that this peculiar kind of road was invented and in use several centuries ago, but, like the great auxiliary, the locomotive, was very defective and simple in its primitive state, and since that time, like the latter, has been subject to vast and continued improvements. Before, however, we enter upon the subject for which these pages were designedN" the history of the first locomotives in America"Nit will not, we trust, be deemed inappropriate here to devote a small space in our work in describing the peculiar kind of road upon which the locomotive travels, now known universally as the railroad; and to such information as we have gathered of its origin and early progress. Various devices have been employed, from the period when wheelcarriages were first used, for facilitating the movement over the ground in transportation. These devices, however, were mostly limited to the smoothing, leveling, and hardening the surface of the way. The early Egyptians, in transporting the immense stones they used in the erection of the vast pyramids from the quarries, learned the advantage of hard, smooth, and solid track-ways, and the remains of such, formed of large blocks of stone, are said to have been found on the line of the great road they constructed for this purpose. The ancient Romans made also some approach to the invention of railroads, in the celebrated Appian Way. This was constructed of blocks of stone fitted closely together, the surface presenting a smooth and hard track for the wheels. In modern times such tracks or roadways were constructed in several European citiesNLondon, Pisa, Milan, and many others. The first instance on record of rails being used on highways was as early as the year 1630, over two and a quarter centuries ago. They were invented by a person named Beaumont, and built and used for the transportation of coal from the mines near New castle, in England. Old Roger North alludes to railways as being in use in the neighborhood of the river Tyne in the year 1676, and he thus describes them: The rails of timber were placed end to end and exactly straight, and in two lines parallel to each other. On these bulky carts were made to run on four rollers fitting these rails, whereby the carriage was made so easy that one horse would draw four or five caldrons of coal at a load. We read of railways existing in Scotland in 1745, at the time of the Scotch rebellion. These railways were laid down between the Tranent coal-mines and the harbor of Cockenzie, in East Lothian. Improvements were made on these roads and continued until 1765, 2 when they began to assume the forms of our present roads, even to the use of flanges upon the wheels; but up to this period no iron surface was ever heard of The mode of constructing a railroad at that period was as follows: After the surface was brought to as perfect a level as possibleNor incline, as the case might be Nsquare blocks of wood, called sleepers, about six feet long, were laid two or three feet apart across the track; upon these two long strips of wood, six or seven inches wide mod about five inches deep, were fastened by pins to the sleepers, and parallel to each other, but about four feet apart. Upon this wooden rail was spiked a projecting round moulding of wood, and the wheels were hollowed out like a pulley to fit upon the round surface of the wooden molding upon the rails. The fir
Re:See!! (Score:2, Informative)
You don't ride horses, do you? (Score:3, Informative)
Re:English/Metric (Score:5, Informative)
The UK is effectively metric now, all schoolchildren are only taught metric units
Except by their parents, who will teach them the Imperial units anyway.
My experience is at odds with this assertion that all the youngsters talk metric. Although when at work, just about everything is metric (except if it's American :)), everyone I know (including those younger than me) measures their weight in stones and pounds, and their height in feet and inches. And, more importantly, their beer in pints!
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?
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!
P.S. Slashdot ate my ° markup, sorry!
Re:The source of the problem (Score:4, Informative)
Re:English/Metric (Score:2, Informative)
Stones are still used by the older generation, but no longer taught. Same with feet for height. (People are usually described in centimetres.) And a pint (of beer) is an entity unto itself, a piece of sacred anachronism.
Imperial is actually better. (Score:1, Informative)
Using imperial measurements, you can accurately cut a third of a yard, half a yard etc. And I don't mean none of this 33.333333 recurring crap either. You can cut a perfect third.
It's one reason why Imperial is still used on the building trade. Ten divides by 2 and 5, yet 12 divides by 2, 3, 4 and 6 without the need for additional measuring gear. Great if you're cutting planks or copper tube.
Sometimes, base 10 isn't the best solution.
Pre-emptive rant reply (Score:2, Informative)
Note that:
-Virtuall all US University engineering and science education is done using Metric units.
-The US Federal government is required to use the Metric system for doing business (Omnibus Trade and Competitiveness Act)
-The US FDA requires all consumer products be labeled in Metric units (actually dual labeling)
I guess some Euros wonder why the US doesn't pass laws saying like "You're not allowed to sell gas in gallons, you must sell it in Litres". Well, the US just doesn't work that way. If someone wants to sell gas in Litres, they are free to. Mostly, businesses choose not to.
Dare I say at the risk of downward moderation and flaming, that the US 'hands off' approach to business is working quite well in comparison to EU countries, where the recent recession hit much harder, largely blamed on overly beaurocractic governments that ensure companies are inflexible in changing economic times.
On the other end, starting this year, the EU will ban dual labeling. So, not only will Europe require US products to have metric labeling (the already do) they will not allow Imperial units to appear on the labels! That's just spiteful.
Re:Imperial, not English... (Score:2, Informative)
No. All trade in shops in England is now done in kg. Stones are hardly ever used.
And pints?
A pint is a measurement of beer. It is simply tradition, and isn't a hinderance to everyday economic transactions (well, drinking probably is). All other drinks are sold in litres (wine, juice, milk etc).
ANd miles, miles per hour?
Yeah, I don't quite get why we still do this. I guess from an engineering point of view you'd want m/sec, so converting from miles/hour or km/hour doesn't make much difference.
Re:Who's at fault here, really? (Score:2, Informative)
Re:English/Metric (Score:3, Informative)
In fact, the Kelvin scale is based on the Celcius scale. 0 degrees Celcius = freezing point of water, 100 degrees Celcius = boiling point of water. How hard is that?
The only reason why the Fahrenheit scale used a non-zero value for the freezing point of water was that people of the time didn't have a strong grasp of the concept of negative numbers. So, for simplicity's sake, the freezing point of water was set at 32 degrees.
The concept of negative numbers isn't too difficult for people to grasp now, so is there any reason to stick to such an antiquated temperature scale?
Metric (or SI) units better on so many levels, especially in science. For example, you can convert from one SI unit to another easily: eg, 1 Newtons = 1 kilogram metre per second squared.
Also, Imperial measurements aren't standard: some of them vary from country to country, which is equally ridiculous.
Your "kiloseconds" example is ridiculous, as the second is the SI unit for time. For simplicity and historical reasons we use hours and minutes (because those are easy to comprehend and interpret divisions of a day), but if you were going to perform a time-critical experiment or calculation then you would measure in just seconds. Of course, at the end of your calculation you might convert those seconds into days, hours, minutes and seconds so that your result can be more easily interpreted but you'd never do the mathematics in anything other than an SI-based unit.
Just because you were raised with Imperial measurements it doesn't negate the intrinsic "clunkiness" of them or the significant advantages SI units possess over them.
Re:Who's at fault here, really? (Score:5, Informative)
The .86 error was because someone decided that they wanted round numbers, so when they changed the spec, they decided to round up. Well, in the process they forgot to throw out the old documentation. So, they ordered the correctly sized part for the old spec and got it wrong.
Probably a good example for software engineering class. "See, changing the specification, once released, may result in bodily harm!"
Re:About the same time /. posters actually RTFA? (Score:2, Informative)
1 litre of water weighs 1kilogram and 1000 litres of water will occupy 1 cubic meter of space.
Metric system links the dimensions so very well. The above mention case is for water for other fluids it's simple too...just use the specific gravity number as a modification number. Makes thinking about physics a lot easier.
English units? (Score:3, Informative)
The right term is "U. S. Customary" (Score:5, Informative)
SI units are legal in the United States and have been for a very long time. The inch was set at precisely 25.4 mm _by definition_ in July 1959.
The additional units, such as inches, miles, quarts, pounds, etc. which I believe are all legally defined by reference to SI units, are officially and properly referred to as "U. S. Customary" units. They have, of course, a strong historical connection to English units.
Unofficially, "Metric" and "English" are the U. S. customary designations for "SI" and "U. S. Customary."
Re:About the same time /. posters actually RTFA? (Score:2, Informative)
For me, converting 38.1mm to kilometers is just a matter of adding 0's: 0.00000381km
Converting 1.5 inches to miles gives you the nice result:
1 inch = 1.57828283 x 10-05 mile
rouding results can become problematic, no ?
Re:About the same time /. posters actually RTFA? (Score:2, Informative)
Another issue that results in the english/metric unit problems is lack of intuition by engineers. Working with english units most of my life, until recently, I never had to design anything with metric units. Length and mass, I can deal with that. But when you throw stiffness, preasures, damping, etc., I can't look at the numbers and say "that seems right" or "that's physically not possible."
The US will have to make the leap eventually, but it will take a major change in political and economic environment to make that happen.
Re:The source of the problem (Score:3, Informative)
1. An imaginary great circle on the earth's surface passing through the North and South geographic poles. All points on the same meridian have the same longitude.
2. Either half of such a great circle from pole to pole.
So, the distance between the north pole and the Paris meridian == 0
Aren't these standards-based posts just wonderful for brining out the pedant in all of us?
Possibly you meant 'Parisian latitude'
hairsplitting (Score:1, Informative)
Thats not really true, because the dimension of water depends on the temperature.
1l water weighs 1kg if there are 4C
Ok, the difference is not big, but at disney it wasn't too:)
greets from Germany
Fahrenheit's reasons (Score:5, Informative)
Bzzzzt. Thanks for playing!
From boson.physics.sc.edu :
At the beginning of the eighteenth century, the Danish astronomer Ole Roemer (famous for making the first measurements that showed that the velocity of light is finite) devised a temperature scale of his own for use with the alcohol-in-glass thermometers that he constructed. His thermometers attracted the attention of Gabriel Fahrenheit (1686-1736), a manufacturer of meteorological instruments in the Netherlands. In 1708 Fahrenheit traveled to Copenhagen to meet Roemer and see his thermometers, which were based on two reference points. For one reference Roemer used a mixture of ice, water, and salt to reach the lowest temperatures then attainable in the laboratory, which he called zero. His other reference was the boiling point of water, which he arbitrarily designated as 60 degrees.
Fahrenheit returned home to make thermometers like Roemer's. In 1714 he overcame technical difficulties with alcohol thermometers by substituting mercury as the expanding liquid. The use of mercury extended the range of temperature measurements from well below Roemer's zero to well above the boiling point of water. Furthermore, mercury expanded and contracted more uniformly than the other liquids then in use. As a result, Fahrenheit could mark his mercury thermometers more accurately and with finer divisions.
By 1724 Fahrenheit had adopted a new scale, similar to Roemer's but with much finer divisions. For the zero point he chose the same reference as Roemer. However, since his thermometer was intended for meteorological observations, he wanted a second reference point that would be nearer the maximum observed temperature for weather. He chose the normal temperature of the human body as the upper reference point, which he called 96. Fahrenheit gave no reason for his choice of 96, but it may have been due to his desire for a finer scale and because 96 is evenly divisible by 2, 3, 4, 8, and 12.
Why didn't Fahrenheit choose the freezing point of water for his zero reference, as Newton had done before him and as Celsius did later on? Perhaps Fahrenheit was influenced by Roemer, or he may have wanted to avoid the inconvenience of repeatedly using negative temperatures during winter. Also, in the early 1700s it was widely believed that water did not always freeze at the same temperature. Soon, using his newly calibrated thermometers, Fahrenheit learned that water always froze at 32 on his scale. He immediately added this third reference point to his instruments.
Re:English/Metric (Score:2, Informative)
I used to work in railways. Railways are still measured in chains and quarter-miles (20 chains to the quarter mile).
Actually, a chain's really easy as any fule kno that it's the length of a cricket pitch from wicket to wicket
The railway example actually gives a pointer to why we retain certain units - it's at least in part about installed infrastructure. To re-do the railways in km rather than miles would require the replacement of tens of thousands of mileposts (one every 20 chains, roughly), re-marking of speed restrictions all over the place, probably reassessing safety calculations from scratch rather than just recalculating the final figures, since the safety rules are very strict like that.
To re-do the road speeds would be anightmare for the millions of cars with no km markings on the speedometer, and might well need either the re-designation of speed limits all over the place or re-grading the limits to much harder-to-remember figures like 48km/h in a current 30mph zone or 64km/h for a 40 zone.
The pint's just an emotive thing, I'm pretty certain of that.
Re:Who's at fault here, really? (Score:3, Informative)
Re:Imperial, not English... (Score:3, Informative)
Canada: the metric, imperial and american systems (Score:3, Informative)
and since the metric system is so great.. (Score:2, Informative)
Oh wait. That would be fucking retarded.
SI and CGS units (Score:1, Informative)
Not always. SI is the metre / kilogramme / second system. The centimetre / gramme / second system is also metric, but not SI.
airplanes too (Score:2, Informative)
The reason: The fuel was specified in kg, but was loaded in lbs. Needless to say, they plane only got 0.45 the distance it should have.
Re:The source of the problem (Score:3, Informative)
I pulled this from an article that I found via Google. From the same article:Also from the timeline:
No Longer "English" units. (Score:3, Informative)
I buy beer in pints but I know that 1 pint is approximately 568ml (except in the US where pints are only 0.8 "English" pints). There are probably other things that we still measure in the same way that pre-industrial Brits did, but I can't think of any. The only other situation where pre-metric units have any relevance is in speed limits. Many tourists think they are "quaint".
I expect I am older than many people here - I can remember Neil Armstron walking on the moon. My wight is 114kg and my height is 1.82m. I could not care less about what it is in units of measure that would have been familiar to Henry VIII.
The English, and the rest of Britain are managing to move much of their units into the 20th/21st century. It is curious to see the USA stuck in the 19th...
Re:The source of the problem (Score:2, Informative)
Re:English/Metric (Score:2, Informative)
The SI tempature unit is Kelvin not centigrade.