Author Topic: No excuse  (Read 13702 times)

Offline NickG

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Re: No excuse
« Reply #30 on: August 05, 2013, 09:10:56 AM »
In ballistics and gunnery we use mils
Which is almost a milli radian but not quite - 6400 in a full circle!

In excel use degtorad( or radtodeg( to covert.

Offline Admiral_dk

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Re: No excuse
« Reply #31 on: August 05, 2013, 11:35:09 AM »
Quote
In ballistics and gunnery we use mils
Which is almost a milli radian but not quite - 6400 in a full circle!

Uh - Oh .... not good for me .... I've been doing PCB (Printed Circuit Board) layout for most of my life - though not for a living the last many years - and there a mill or mills plural are 1"/1000 = 0.001". This all started with the first IC's having 1"/10 = .1" = 2.54mm. as the between pin centre or the drill distance. So when I started doing PCB layouts professionally some 15 years later, all data was in mills, pin diameter, trace with etc.

I can't remember the correct Danish term for what NickG calls mils, but when explaining such a compass to non users, we call them Military Degrees.

Offline NickG

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Re: No excuse
« Reply #32 on: August 05, 2013, 01:02:13 PM »
I've only heard them called 'gunner mils' but sure there's probably a more correct term!

Offline tangler

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Re: No excuse
« Reply #33 on: August 05, 2013, 01:20:35 PM »
I noticed a disturbing trend amongst my younger scientific colleagues to refer to millimetres as mils, thus providing scope for even more confusion with our transatlantic friends who refer to thous as mils :facepalm: - not that the youngsters have any idea what a thou is.  It all makes life interesting :-\

Rod

Offline Mosey

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Re: No excuse
« Reply #34 on: August 05, 2013, 01:51:48 PM »
or read an analog clock. :headscratch: :old:
Mosey

Offline mklotz

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Re: No excuse
« Reply #35 on: August 05, 2013, 05:05:43 PM »
Quote
1 knot = 1 nautical mile

Want to try that one again, Bob?  A knot is one nautical mile per hour, a unit of speed, not distance.  With a naval background, I know you know that but let's not confuse the landlubbers.

All these relations between angle and distance are based on the assumption that the earth is a perfect sphere.  [The real figure of the earth is an oblate spheroid.]  The circumference at the equator is 24900 miles.  The polar circumference is 24860 miles.

There are 360 * 60 = 21600 arc minutes in a circle.  If we assume that one arc minute subtends a distance of one nautical mile (6076.12 ft) the calculated circumference becomes:

21600 * 6076.12 / 5280 = 24857 miles

which is close enough to the measured circumferences to make the approximation useful.

Bob has pointed out the annoying fact that the length of a minute of longitude decreases as one approaches the poles.  However, the 1 arcmin = 1 nautical mile approximation remains valid on any great circle route (a circle whose plane passes through the center of the earth).  Since great circles are the shortest distance between two points on earth they're frequently the path sailed by ships.  As such the approximation is very useful.
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Offline steamer

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Re: No excuse
« Reply #36 on: August 05, 2013, 05:12:20 PM »
I noticed a disturbing trend amongst my younger scientific colleagues to refer to millimetres as mils, thus providing scope for even more confusion with our transatlantic friends who refer to thous as mils :facepalm: - not that the youngsters have any idea what a thou is.  It all makes life interesting :-\

Rod

To say nothing of "tenths"...( 1 "tenth" = 1/10000")  which is bantered around all the time....on this side of the pond...amoungst Engineers and Machinists....it's a lock.....beyond that,    over here anyway......glazed looks only...

Dave
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Offline mklotz

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Re: No excuse
« Reply #37 on: August 05, 2013, 05:29:45 PM »
What about the numerous folks on this and other fora who refer to 0.001" as "thousands" rather than thousandths?  [Which they then measure with their "guages".]
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Online sco

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Re: No excuse
« Reply #38 on: August 05, 2013, 05:40:25 PM »
A possible 'excuse' might be that in order for them to be that cheap they must pay their workers very poorly  :ThumbsDown:
Ars longa, vita brevis.

Offline Admiral_dk

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Re: No excuse
« Reply #39 on: August 05, 2013, 08:48:22 PM »
I forgot to mention that Mills in the electronic world originates in Silicon Valley California - so it isn't an European confusion added to the mix.
Most if not all new electronic components, connectors etc. are in millimeters in the datasheets, with the weird consequence of the EU influence being that all new mechanical componets like connectors + discrete componets are in easy millimeter fractions and the IC's are in easy fractions of Mills (.001") - still influenced from Silicon Valley.

Googling "compass 6400" gave as first hit : http://www.compassdude.com/compass-units.shtml

And it's even worse than I thought - Mils are 6000, 6283 and 6400 to a circle, depending on witch military we're talking about  :???:

+ I totally forgot what my father learned me as a kid, but the unit 6400 to a circle on a compass are called Mils here in Scandinavia too  :facepalm:

Quote
To say nothing of "tenths"...( 1 "tenth" = 1/10000")  which is bantered around all the time....on this side of the pond...amongst Engineers and Machinists....it's a lock.....beyond that,    over here anyway......glazed looks only...

I wondered about that one on these pages too  :???:  but has accepted the text members has provided.

Offline Maryak

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Re: No excuse
« Reply #40 on: August 06, 2013, 01:12:51 AM »

Want to try that one again, Bob?  A knot is one nautical mile per hour, a unit of speed, not distance.  With a naval background, I know you know that but let's not confuse the landlubbers.

Bob has pointed out the annoying fact that the length of a minute of longitude decreases as one approaches the poles.  However, the 1 arcmin = 1 nautical mile approximation remains valid on any great circle route (a circle whose plane passes through the center of the earth).  Since great circles are the shortest distance between two points on earth they're frequently the path sailed by ships.  As such the approximation is very useful.

Thanks for the correction Marv.

Great Circle routes are only contemplated when the distance to be traveled >1500NM and there is nothing in the way such as reefs, islands and the like. I would think they are ideal for long distance air travel.

Best Regards
Bob
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Offline Tin Falcon

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Re: No excuse
« Reply #41 on: August 06, 2013, 02:36:42 AM »
You are a bad influence Marv . I just went to the dollar tree and spent five whole dollars of my hard earned  tool fund for a hand full of these calculators.

And if we travel 201.16800 meters at a rate of 0.514444444 m / s. how long does it take ?   knot furlong !!

Tin

Offline Alan Haisley

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Re: No excuse
« Reply #42 on: August 06, 2013, 04:45:11 PM »
What about the numerous folks on this and other fora who refer to 0.001" as "thousands" rather than thousandths?  [Which they then measure with their "guages".]
Marv, they are afraid people will think they lisp.
Alan

Offline Alan Haisley

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Re: No excuse
« Reply #43 on: August 06, 2013, 04:52:46 PM »

Want to try that one again, Bob?  A knot is one nautical mile per hour, a unit of speed, not distance.  With a naval background, I know you know that but let's not confuse the landlubbers.

Bob has pointed out the annoying fact that the length of a minute of longitude decreases as one approaches the poles.  However, the 1 arcmin = 1 nautical mile approximation remains valid on any great circle route (a circle whose plane passes through the center of the earth).  Since great circles are the shortest distance between two points on earth they're frequently the path sailed by ships.  As such the approximation is very useful.
Don´t knots predate clocks? Something about trailing a knotted line with a piece of wood (a log?) and counting knots while the sand runs out.
Alan

Thanks for the correction Marv.

Great Circle routes are only contemplated when the distance to be traveled >1500NM and there is nothing in the way such as reefs, islands and the like. I would think they are ideal for long distance air travel.

Best Regards
Bob

Offline mklotz

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Re: No excuse
« Reply #44 on: August 06, 2013, 04:56:15 PM »
What about the numerous folks on this and other fora who refer to 0.001" as "thousands" rather than thousandths?  [Which they then measure with their "guages".]
Marv, they are afraid people will think they lisp.

What are they afraid of when they use expressions like:

It runs real good.
Where it's at.
Regards, Marv
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