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Are the Americans going to adopt the metric system anytime soon. Just asking cause I thought it would be a safer world if everyone talked the same numbers. Some blunders have happends... most notably the crash of a satellite because of miscommunication between imperial and metric engineers.
Any chance the whole world will change to the imperial system? Thank you.
Any chance the whole world will change to the imperial system?
Considering the speed with which some countries out-manoeuvred the rest of the world, thru ICAO, to bring us the dreaded metric measurement system, I don't think I'd bet on any wholesale move back to imperial measurements. And, at this stage, I suspect THAT sort of change would be more likely to create greater confusion than the way the system is right now.
At least the imperial unit of the nautical mile has a natural relationship to the way we measure distances and positions on the globe (1 minute of angle in latitude is equal to 1 nautical mile, 60 nautical miles equals 1 degree of latitude etc.)
I understand the metric system is based on a (now known to be incorrect) measurement of the distance from Paris to the North Pole. With remarkable hubris, the French (and some collaborateurs) decided this would be the system of measurement for the whole world.
As far as I am concerned, the only decent thing about the metric system is it is all base ten so you don't have to take your shoes and socks off when counting! It's convenient but it has no natural relationship to the geometry of the earth. The continental system of dividing a circle into four right-angles each containing 100 "grads" is just about extinct...or should be
I am perfectly comfortable with either system. For cutting a piece of wood to length I'll use metric. For navigation (and aviation) I'll use the old system. If it comes to that, I'll even trust a sextant and compass in preference to a GPS receiver. The US DoD doesn't own the stars or the sun and has no control over the earth's magnetic field or magnetic variation.
The definition of the metre was selected as 1/10 000 000 of the distance between the north pole and the equator.
One of the scientists appointed to survey the distance did fudge his figures, but only in such a way that the overall accuracy was maintained. This was caught and the other surveyor, in secrecy, reviewed and corrected the data and found the final data to be correct.
When they did the survey, the Earth was known to be an oblate spheroid, but the ellipticity was not known with certainty. A meridian distance for an ellipticity of 1/334 was selected. Satellite measures now put the ellipticity at 1/298·4, which means that the length of the metre is within 0·2 millimetres of the intended length. Not bad for the time.
Radians work well in calculus and formulas since no conversion factors are required.
(This reply is from someone who was raised in the Metric system)
One problem I had with the "uneven" system, as I called it some time ago, was to recall e.g. how many feet were in a mile. Then there were to kinds of miles: the nautical mile and the statue mile. So 5280 ft and 6080 respectively. This never made sense to me. I'd rather prefer 1km equals 1000 meters. 1 meter = 100 cm etc. To make things worse I discover the yard, and then the gallon which also exists in two different versions. So for a metric guy, this can be quite a mental challange at the beginning.
...but thanks to the CAA I was given numerous conversion challanges
Speaking of the statue mile... I heard that this mile was "invented" or "requested" by Queen Victoria. Any truth in it?
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DMP, I forgot to mention that some parts of Arizona, USA use the metric system. Drive on a road through the desert and between cacti you suddenly see signs like "Nogales 76km". The speed limits are still in miles though ...
The statute mile predates Queen Victoria by several centuries. It derives from the Roman milia which is actually 'metric', being 1000 steps (passi). Bluddy big steps though at 5.28ft each, although the accepted value of a passus is 4.85ft. Don't know where the discrepancy comes from.
Victoria probably decreed that since the Empire encompassed most of the 'known world' the British mile should be the universal value. Why they are called Imperial Measures I imagine.
The nautical mile we use is an arbitrary value too, being only accurate along the equator, viz. "the length of an arc of meridian that subtends an angle of one minute at the centre of curvature of the place". In other words one minute of latitude, measured at your latitude on the Earth's surface, equals one Nautical mile and will be less than 6080ft except at 0deg long.
And we won't mention the German mile which equalled 4 equatorial nm.
ive no problem with either metric or imperial in fact i prefer imperial, the problem in aviation is that we use both systems! we give height and altitude in feet distances in nautical miles except for the old berlin control zone which had a radius of 20 statute miles. the reason for the berlin zones difference was due to field marshal montgomery. but to continue we give the met vis in metres and kilometres wind speed in degrees and knots and the temperaure in degrees celsius. aand the army use mils to direct their artillery, no wonder people get confused!
Where and what's the UK gallon (=4.54609 litres for the ones who care) used for? As far as I remember the petrol stations in the UK use litres. I guess this is done to make the fuel look cheap ... :o
I tend to use a mixture of both systems depending on what I'm measuring.
Though what confuses me is the different types of nautical miles. Theres a UK Nm, International Nm and a NATO Nm.
I UK Nm = 1.00064 International Nm = 1.01333 NATO Nm
This caused a fair bit of confusion when checking over a colleagues calcs that converted from ft/sec to knots as there three different types of Knots to go with the nautical miles.
I spent all day reviewing a very large spreadheet only to discover it was the wrong bleeding conversion factor.
The nautical mile is a minute of arc along a meridian (i.e. a minute of latitude). If the earth were a perfect sphere, all would be well, but unfortunately it's not, so the length of a minute of arc depends on where you measure it.
At about 45 deg N, a minute of arc is almost exactly 6080 ft, so that was the Admiralty (UK) definition. The ICAO definition actually uses a whole number of metres (1852) instead as a definition, which comes out about 4 ft shorter.
I've never come across a NATO nm. Do you have any further info or references on the definition?
The US DoD .......has no control over the earth's magnetic field or magnetic variation.
I guess you haven't heard about the top secret work being done by the US DoD Earth Sciences Division in Massachusetts. They have been working on a device.....
Hang on, someone's at the door, I'll be right ba............................
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Any organization that mixes its systems like that ought to be drowned slowly in its own excrement. That's right in there with the EPA with the grams per mile emission requirements.
The United States passed a metric conversion act sometime around 1900 but it didn't get off the ground.
The nice thing about the SI subset of the metric system is that most constants drop out except for the horribly inconvenient electrical and magnetic characteristics of free space.
Canberra
Yeahbut...
The mil is a natural unit of measurement (milliradian) and is real handy for directing gunfire as for small angles the angle is equal to its own sine if radian measure is used. Thus at a range of 1000 whatevers, traversing the gun 10 mils moves the point of impact 10 whatevers. The radian and its subdivisions, being dimensionless, leap back and forth among systems of measurement gleafully removing the dreaded 2*pi from many equations involving rotation.
Personal preferences are one thing (I have great difficulty thinking of my petrol consumption in the car in anything but miles per gallon).
In aviation, I can see excellent reasons for using knots and nautical miles. I see little reason why we should not convert to altitude in metres and windspeed in metres/sec.
I dislike fuel gauges in lbs. You tend to run into problems with ordering fuel in pounds, getting it on the bowser driver's sheet in litres, accounting for it on the trim sheet in kilos, and then being back in pounds for consumption purposes. Remind me - where IS Gimli?
Kilos (or tonnes) and litres for fuel makes total sense. Weight (kgs) = Volume (litres) x S.G.
Why pray tell Flash is there a problem multiplying any convenient force unit by any convenient distance units.
It happens that, for small aircraft with a datum somewhere around the middle, if you use kgf", you never need more than 4 digits and can ignore anything past the decimal point - it happens to work rather well. Confuses a few people I'll grant, but technically perfectly sound.
Personally I save my own ire for people who fly aircraft in mph, or the Swedes where they have combined military:civil airports, but civil traffic work in feet, and military in metres. Now that is seriously confusing.
No-one has mentioned how different ATC's worldwide use either feet or metres for vertical separation, and I think we all know how much danger can ensue from this confusion with conversion.
Yeah, I used to do energy calculations in stone-barlycorns just to wind the physics professor up. However I stop at using kgf, let alone mixing systems. There's a perfectly servicable unit called the newton. If you only ever do one sort of calculation I s'pose you can use any units you want that are dimensionally correct. If you do a lot of calculation, best to stay within 1 system. I don't much care which one, I am equally uncomfortable with SI, BES and the various colours and flavours of imperial. Little problems with measurement systems can cause incorrect separation between spacecraft and planets, aircraft and Winnipeg etc.
Anyone who has been involved with science or technology for more than 30 years may have noticed that so called metric units change with monotonous and confusing regularity.
At least so called imperial units remained more or less fixed, except for the errors the Americans introduced into the system that is.
Decimalisation of imperial units within the system worked fine, thous of an inch for precision, or tenths if really precise, or decimals of a foot for road buildingetc etc.
Ever heard the confusion with metric users when confronted with dc/cl/ml etc etc, and aren't millibars now some derevision of hectopascals, or are they the same thing?
With another half dozen or so nations being introduced into the EC, I expect each will require a unit to be named after their favourite scientist. Stand by for yet more post rationalisation additions to our unit vocabulary.
Just because Napoleon was a lousy mathematician, we have a metre which is not a metre.
the British mile should be the universal value. Why they are called Imperial Measures I imagine. 
