A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Ah, give someone a calculator.......
From: Gary LaPook
Date: 2010 Aug 17, 03:57 +0200
From: Gary LaPook
Date: 2010 Aug 17, 03:57 +0200
Marcel, don't get me wrong I love the metric system and I use it all the time when it is convenient and useful to do so. However, in aviation, English units have proven to be useful and convenient to use so there is no pressure to change to metric units which offer no advantages. In addition there is a large infrastructure based on these units that would have to replaced at great cost and for no advantage. This is true in many things in our world, we have systems that reflect decisions made by prior generations that are locked in stone and are not going to be changed. An obvious example is the gauge of railroad tracks. The standard gauge used in the U.S., most of Europe and a large part of the rest of the world is four feet, eight and a half inches and resulted from that choice being made in 1826 in England by a railroad developer and was then written into English law in 1845. This spacing was chosen giving regard to the sizes of existing wagons which ultimately had had their widths determined by the width of a team of horses. Once such arbitrary choices are made and then implemented it becomes very expensive to change due to the great investment costs involved. About 720,000 km of track world wide is of this gauge. Russia made a different arbitrary choice and standardized on a different gauge and their cars cannot run on their neighbor's European or Chinese standard gauge track and vice versa. There are about 220,000 km of the Russian gauge track and they are not going to incur the great expense of replacing all of their rolling stock and the cost to move all of their rails to a different spacing just to have interoperability with their neighbors (even though this would be advantageous) as their present system serves them well since most of there shipping is internal. There are many other examples of our world being tied to ancient arbitrary choices. I have attached a photo showing a European electrical plug and a three way socket along side an American equivalent. The European connectors are much bulkier and the American system is more compact, which is an advantage. But the Europeans are stuck with the choice of electrical connector size because of of the extensive investment in the electrical grid and of all the electrical equipment that must plug into that grid. Same thing in navigation where we continue to use nautical miles and degrees and minutes for measurement and for defining locations on earth. One could switch to the UTM grid which has coordinates in meters but then all the navigational charts would have to be redone and celestial computations would be more complicated. The location of the Blue Mosque is 41� 00.321' north, 28� 58.613' east. The latitude tells us how far it is north of the equator as measured in angular units. The UTM coordinates for the Blue Mosque are 35T 66245 4541233. The third group gives the location in meters north of the equator, 4,541,233 almost half way to the north pole. The meter is a "natural" unit, originally defined as one ten-millionth of the distance from the equator to the north pole. But then too the nautical mile is just as much a "natural" unit being defined as equal to one 5,400th the distance from the equator to the north pole so there is no reason to switch to the metric system if you just want "natural" units. If you drive a French car you will see that the tachometer is marked in revolutions per minute (r.p.m.) and the speedometer is marked in kilometers per hour. However, neither of these are metric units. The metric unit for rotation is radians per second and the metric unit for speed is meters per second. But neither of these SI units are very useful to normal human beings doing everyday things so even the inventors of the metric system realize that there are occasions where you should forgo using metric units when other units serve better. For instance, if you are driving to grandmother's house and she lives 544 kilometers away and your car is traveling at 25 meters per second will you need to stop for lunch and will you get to her house before dark? Not a very convenient unit for everyday things this the metric unit for speed. So there are lots of compromises made in this world and there is no reason to switch from something that is working well just for the sake of going metric. BTW, we were in Istanbul in April 2009 and we were really impressed. gl Marcel Tschudin wrote: > Yes, I'm more familiar with metric units but I'm aware that for > certain applications, like aviation, the English units are kept being > used. I don't know why in aviation they can't use 300m instead of > 100ft. May be one fears that a change to metric would create a too > high risk. > > So, if English units are the "decent" ones for you, why then you don't > click on the link "Page Preferences" at the top of wunderground's page > and adjust the units to be shown to those? Since the METAR are in > English units you would see the original data without conversion. > > BTW, regarding English units: I noticed recently that the department > stores here in Istanbul indicate the power of air conditioners in BTU. > I guess that only a very, very small part of the population in this > country knows what this stands for. > > Marcel > > > > >