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Imperial versus metric


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2 minutes ago, Deddly said:

For example, even in Europe, we use inches to describe the size of wheels on our cars, even if every other component is measured in metric.

Yes, and as we can see, the Soviet howitzer uses inches. 6 exactly.

But why the Americans didn't?

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13 minutes ago, kerbiloid said:

Yes, and as we can see, the Soviet howitzer uses inches. 6 exactly.

But why the Americans didn't?

Quote

It depends on which country the weapons were adopted from. Guns produced to US specifications would use inches from the large 14″ guns used by the USN Battleships to the caliber of small arms. Before WWI the US would adopt arms from the UK or other European Arms manufacturers. (Krag-Joergensen rifles from Norway) But when WWI started, the US lacked modern arms other than rifles and hand guns. The UK and French had placed orders for artillery in the US and so many were adopted by the US for the War. The US Expeditionary Army also had to use arms supplied by the Allies in France.

Generally if not US in origin, if a weapon is measured in inches, it is an adoption of a British weapon. Examples are the 8″ howitzer, and in WWII the 4.5″ gun. If it is measured in millimeters, it usually means that it was adopted from a French weapon. Examples are the 155mm gun and howitzer, the 75mm gun, 60mm and 81mm mortars. For the first two, after the War, the US developed their own versions of the gun and howitzer but kept the 155mm designation. The 105mm howitzer came from an examination of the German WWI weapon and they decided that that caliber would be used for the new light howitzer. The 37mm anti-tank gun also was adapted from a German weapon. From the mid 1950s most weapons would be measured in millimeters but some habits die hard, such as the 50 cal heavy machine gun and the 4.2 inch/107mm mortar.

Source.

The bigger question is why the Soviets used inches? 

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9 minutes ago, Deddly said:

The bigger question is why the Soviets used inches? 

Exactly this is absolutely natural.
The backward compatibility with stored shells and with equipment for their mass production which was in use much longer than in US.
As in pre-Soviet times the industry was historically not developed, the Western standards were prevailing in ammo, pipes, etc. So, in inches.
Some later cannons are metric: 73, 100, 125, 130. 

Edited by kerbiloid
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Gotta wonder if the Russians will switch to metric artillery calibers eventually too. Due to the ongoing hullaballoo, Ukraine is running out of 152 mm shells, and the neighbouring ex-Soviet countries are emptying their stores to support Ukraine. But now everyone is running out of those, and NATO is re-supplying with 155 mm artillery ammo (and by necessity, guns) instead. Effectively, 152 mm ammo is phased out all over Europe, which means Russia is left having to maintain a supply chain for 152 mm ammo only for their own use, or make the switch themselves as well. There are a few other countries that still use 152 mm artillery, but those are being phased out all over the place too. 155 mm is emerging as the global standard, and recent events only serve to accelerate it.

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On 4/25/2022 at 1:36 AM, kerbiloid said:

Soviet howitzer: 152.4 mm = 60 lines = 6 inch. Round inches, not round mm.
American howitzer: 155 mm = 61 line = 6.1 inch. Round mm, not round inches.

Where is logic?

Why make 6.1 when others make 6.0?

Or why round millimeters being fond of inches?

I'm not sure if this is exactly the same issue, I would have to do more research (and, contrary to popular belief, I do have a day job) but it may be that they have the exact same diameter but just measure different dimensions. For example, in small arms, the 5.56mm NATO cartridge is dimensionally identical to the .223 Remington in the United States. Even though 5.56 millimeters directly converts to (roughly) 0.219 inches, not 0.223 inches. (Or .224 inches, which is the actual diameter of the bullet. Are you thoroughly confused yet?) The difference is that in the United States the round is named via the dimension of the bore as measured by the diameter of the grooves in the rifling. In Europe the round is named by the bore diameter as measured by the diameter of the lands in the rifling, which have an ever so slightly narrower diameter.

boredia.jpg&f=1&nofb=1

So my guess would be that the two howitzers have the same issue. They are dimensionally identical, at least as far as their bore diameters. But the difference in nomenclature is based on land diameter vs. groove diameter. Because us Yanks just have to be different.

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On 4/25/2022 at 11:04 AM, Codraroll said:

155 mm is emerging as the global standard, and recent events only serve to accelerate it.

PLA like this*

https://en.wikipedia.org/wiki/PLZ-05

https://en.wikipedia.org/wiki/PCL-181

But actually, for the PLA, the replacement of the army with new equipment is in a sense similar to poverty alleviation work: there are some units got very brand new weapons and at the same time a considerable number of troops still using the equipment from the 1980s and 1990s. So sometime you can see both 152mm howitzers and 155mm howitzers in same video about the PLA's exercises.

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On 4/9/2022 at 11:55 PM, benzman said:

I have often thought that the British national sport is dreaming up freakishly weird standards of measurement! Brilliant graphic.  I could stare at it for hours, and it all makes sense. Well, kind of.

Well they came up the Guinea https://en.wikipedia.org/wiki/Guinea_(coin) to top up an over complex system https://en.wikipedia.org/wiki/Coins_of_the_pound_sterling
Why? to confuse people or to mask prices like games tend to do with their micro transactions? 

 

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4 hours ago, TheSaint said:

I'm not sure if this is exactly the same issue, I would have to do more research (and, contrary to popular belief, I do have a day job) but it may be that they have the exact same diameter but just measure different dimensions. For example, in small arms, the 5.56mm NATO cartridge is dimensionally identical to the .223 Remington in the United States. Even though 5.56 millimeters directly converts to (roughly) 0.219 inches, not 0.223 inches. (Or .224 inches, which is the actual diameter of the bullet. Are you thoroughly confused yet?) The difference is that in the United States the round is named via the dimension of the bore as measured by the diameter of the grooves in the rifling. In Europe the round is named by the bore diameter as measured by the diameter of the lands in the rifling, which have an ever so slightly narrower diameter.

boredia.jpg&f=1&nofb=1

So my guess would be that the two howitzers have the same issue. They are dimensionally identical, at least as far as their bore diameters. But the difference in nomenclature is based on land diameter vs. groove diameter. Because us Yanks just have to be different.

Note that cartridges name is not defined by the bore but also the size and shape of the breach, so its more like an standard. 
Same is true for artillery, 155 mm artillery tend to use powder charges and you can use fewer a closer range, but modern naval guns and tanks tend to use an single cartridges
The ww 2 manually loaded 5" guns had an projectile and a charge as two units. Battleship guns had multiple charge packages like modern 155. 
As I understand the 152 shell is longer than 155 so heavier. 

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25 minutes ago, magnemoe said:

Note that cartridges name is not defined by the bore but also the size and shape of the breach, so its more like an standard. 
Same is true for artillery, 155 mm artillery tend to use powder charges and you can use fewer a closer range, but modern naval guns and tanks tend to use an single cartridges
The ww 2 manually loaded 5" guns had an projectile and a charge as two units. Battleship guns had multiple charge packages like modern 155. 
As I understand the 152 shell is longer than 155 so heavier. 

Yes, the cartridge is always defined by the entire package: bore diameter, bullet weight, case dimensions, propellant charge, etc. (Trust me, I reload. I could write you pages on the subject.) But in this specific instance he was asking about why one was named 152.4mm and the other was named 155mm, when ostensibly they're both 6" tubes. In this case it's about the nomenclature rather than the actual standards.

Edited by TheSaint
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today i had to drill some holes in an old gpu heat sink so i could mount it to a pcb that needed cooling. while i have metric drills and taps, i ended up spacing the holes out in freedom units. the reason for that was that the square i have has a ruler with inches on one side and mm on the other. it just so happened that when i went to score a line on the pcb to setup my hole pattern, that side was inches. i couldn't maneuver the square the other way around and get a good line. so i spaced my holes in inches. i suspect at some point in the future, when someone recovers the bits from the junk heap, they are going to scratch their head and wonder why the hell i was mixing units. 

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I did a calligraphy birthday card for my father yesterday, and I laid out the margins in inches, but ruled the guidelines in metric. *shrugs*

I do know a place where feet will never go out of use. It's pipe organs. Ranks of pipes have their pitches measured in feet. I can't imagine a 2.4384 m Gedackt, but I use an 8' Gedackt all the time.

Edited by SOXBLOX
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3 hours ago, SOXBLOX said:

I do know a place where feet will never go out of use. It's pipe organs. Ranks of pipes have their pitches measured in feet. I can't imagine a 2.4384 m Gedackt, but I use an 8' Gedackt all the time.

The piano and guitar makers should think about it.

Why use all that solfeggio voodoo instead of just write the notes in length units.
Especially since the string lines actually make the music noise sound by the string free length.

(A problem could be with drums, as they mostly depend on the hit force.

But this also can be easily solved.
For drums they can use the jump height amplitude (in Metric or in British) of a standard tennis ball, if hit it with standard ping-pong racket with same force as you hit the drum).

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  • 2 months later...
11 hours ago, StrandedonEarth said:

3Mg83h7.jpeg

I'm surprised that wrench doesn't have a Cummins part number on it. Mixing units happens all the time with them. Recently I had to run a volume and pressure control solenoid test on a Cummins 5.0L that requires replacing a fuel rail banjo bolt with one that has an AN fitting on it. the banjo section was 14mm but the AN was 9/16 (which is just enough larger than 14mm and too small for 15mm). I haven't use a 9/16 wrench in probably more that 10 years.

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The main reason why to use SI units in formula calculations is this:

https://en.wikipedia.org/wiki/Coherence_(units_of_measurement)

I can clearly say from experience that is is very hard to transform formulas to non-SI-unit systems without making mistakes (by far the hardest I meet until now: Fahrenheit ...   olala... very dangerous, don't try to land probes on Mars with it ;-) )

For presentation of results you can switch back to your favorite units (I suggest, e.g. using "bar" (the pressure unit) instead of pa (Pascal) often makes sense, or you like "inch" instead of "mm" and the person (not me) you are talking with has ever seen an "inch" and has a feeling what this could be ;-) ). The dimensions of output then should be hand-able (clearly not the case if you say "rail pressure is 100000000 pa" instead of "1000 bar" ...  "is o.k." also works ).

Very funny for me (please forgive me) is the plural usage of units I often see (like "meters", "kilograms" etc.) instead of m, kg or Meter and Kilogramm. Or "Watts" instead  of W (in memory of James Watt  ... or Joan Watson perhaps... ;-) ). Very funny. What's up hehe :-)  Is it 1 watt then ? And what to do with 1.2 W ? Plural ?  1.2 watts ? And 0.9 W (less than one) ?

"kg" is furthermore interesting since there is a double meaning of letter "k" in it: The unit is "kg", it has been defined as the basic mass unit of the metric system but it is also 1000 g (1000 Gramm).

What I very often observe is people having problems with electrical units (like charge quantity, energy, power, voltage etc.). and wild mixing these up.  So I nearly never see the unit C (Coulomb, or Ampere Second, As) which is the standard unit for electric charge. Even in KSP, which is the most physically based "game" (it's much more than a game) I ever met, I didn't find it yet, but no problem, just something I discovered.

So enough nonsense for today I wish you all a happy Kerbal time !

Tom

 

 

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5 hours ago, TomKerbal said:

Very funny for me (please forgive me) is the plural usage of units I often see (like "meters", "kilograms" etc.) instead of m, kg or Meter and Kilogramm. Or "Watts" instead  of W (in memory of James Watt  ... or Joan Watson perhaps... ;-) ). Very funny. What's up hehe :-)  Is it 1 watt then ? And what to do with 1.2 W ? Plural ?  1.2 watts ? And 0.9 W (less than one) ?

How many Newtons was weighting Newton?

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I use nearly entirely metric in non-school calculations, with one minor change, I scrapped newton and replaced it with kilogram force. It’s soooo much better!

Need to lift 1 ton at two g?:

1x2 = 2ton x1000 = 2000kg

Displacing 100 cubic meters of air, weigh one kg?:

100x1.4 = 140-1 = buoyancy of 139kg.

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43 minutes ago, kerbiloid said:

Imperial or metric?

I'd lean towards imperial. A banana is subdivided in a dozen slices, 7 bananas make up a "bunch" and there's probably 9¾ bunches in a bushel. When scaling units gets you arbitrary numbers, preferably primes or fractions instead of factors of ten you're definitely in Imperial territory.

(*dons flame-resistant suit*)

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On 7/31/2022 at 6:17 PM, TomKerbal said:

For presentation of results you can switch back to your favorite units (I suggest, e.g. using "bar" (the pressure unit) instead of pa (Pascal) often makes sense, or you like "inch" instead of "mm" and the person (not me) you are talking with has ever seen an "inch" and has a feeling what this could be ;-) ). The dimensions of output then should be hand-able (clearly not the case if you say "rail pressure is 100000000 pa" instead of "1000 bar" ...  "is o.k." also works ).

My experience is that European (ok, Dutch speaking...) weather forecasters will use the unit "hecto pascal" which is equal to the ("obsolete") often used milli bar. They're talking in the same quantities but the units are now named correctly.

Also, at least in the Netherlands, the terms "pound" and "ounce" are still used, but meaning "500g" and "100g" Those are not legally valid terms but everyone knows what they mean.

On 7/31/2022 at 6:17 PM, TomKerbal said:

What I very often observe is people having problems with electrical units (like charge quantity, energy, power, voltage etc.). and wild mixing these up.  So I nearly never see the unit C (Coulomb, or Ampere Second, As) which is the standard unit for electric charge. Even in KSP, which is the most physically based "game" (it's much more than a game) I ever met, I didn't find it yet, but no problem, just something I discovered.

Not to mention expressing measures as units, referring to  current as "amperage" and power as "wattage". No one will refer to voltage as "potential" so I'll forgive that, but we have solid names for the rest. The worst is that it spills over in other fields, distance in American Football is referred to as "yardage" and in other fields I see "acreage" for area. Again I'll forgive "mileage" as it's a shorthand for the rather cumbersome "miles per gallon," I don't want to be an unreasonable purist.

Finally. sideways related to the well made points you made, I see a lot of my imperial friends being completely stuck in thinking that size references can't change. "How impractical it is to call a 2×4 a 5.08x10.16" well yes, and even if those beams were actually 2"×4" (I'm not a carpenter but I know that's not the actual size), you'd still call them "5×10" in metric. The same when you see translations in books or subtitles. "It's about ten miles (16.52km) away." Aside from widely accepted rules on using precision when applying factors, no one would ever give an estimate like that and while numerically incorrect, the word about suggests that a metric speaker would refer to it as "fifteen km."

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Imperial evolved over time as a system that could maintain a reasonable level of accuracy with little or nothing in the way of tools.

You have a gallon and you need a quart?  Divide it in half twice.  Need a pint, divide that in half.

Units are centered around day-to-day needs, and conversions generally involve halves and thirds, which can be estimated by eye with a reasonable level of accuracy.

 

Metric was engineered from the out-set to be useful for engineering and scientific purposes, simplifying the usage of both scales and conversions that a pre-industrial farmer would never need or use.

 

If you want something that is easy to use in your day to day life where you can eye-ball the difference and make conversions without any tools, Imperial works best.

If you want precision engineering, or you want to do complex calculations, or you want to use macro/micro scales, then metric is better fit for purpose.

 

In our highly mechanized world, Metric tends to make more sense, but that will not stop curmudgeon like myself from holding tight to our yard-sticks, gallons of milk, and wanting a pleasant day to be around 70 degrees.

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There were a lot of Imperial-like systems before the Metric, and every of them was claiming it as a very handy.

So, we have several tens definitions of "pound".

***

What looks weird is that some unit names begin from capital letter, while others are lower case. "kg" vs "W"

Also, who was Gram?

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