OT: US Army and metric system

[Yaab]

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

https://www.amazon.com/AEF-Way-War-Amer ... ywords=Aef

and do saw no mention of the metric system adoption.

Any feedback from the US bros on this issue most welcome.

[Uncivil Engineer]

ORIGINAL: Yaab

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

https://www.amazon.com/AEF-Way-War-Amer ... ywords=Aef

and do saw no mention of the metric system adoption.

Any feedback from the US bros on this issue most welcome.

Depends. My Dad was a gunner on a 105 mm Howitzer in WWII. Metric. But, the artillery also has an 8 inch gun.

Smaller stuff is 7.62 mm (I guess they still use that?), and 5.56 mm, but also 20 mm and 40 mm. I think the .45 caliber pistol has been replaced with a 9 mm. So, it's a mixed bag, but mostly metric.

[Bullwinkle58]

ORIGINAL: Uncivil Engineer

ORIGINAL: Yaab

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

https://www.amazon.com/AEF-Way-War-Amer ... ywords=Aef

and do saw no mention of the metric system adoption.

Any feedback from the US bros on this issue most welcome.

Depends. My Dad was a gunner on a 105 mm Howitzer in WWII. Metric. But, the artillery also has an 8 inch gun.

Smaller stuff is 7.62 mm (I guess they still use that?), and 5.56 mm, but also 20 mm and 40 mm. I think the .45 caliber pistol has been replaced with a 9 mm. So, it's a mixed bag, but mostly metric.

I took him to mean distance and maps. From movies I think the US land military has used metric at least since Vietnam.

The US Navy, and I believe all NATO navies, uses miles and yards. Fits into chart work easier, as well as several rules of thumb (the Three-Minute Rule, etc.)

I believe aviation and ATC worldwide also still uses knots for speed and miles for distance (horizontal) and feet for altitude. And English for radio comms.

[Denniss]

7.62mm is .3 inch.
Since WWI the US Army used several french-based artillery guns. They may have based new developments on these guns or at least on their projectiles to avoid an all-new gun and ammunition.

[Reg]

ORIGINAL: Yaab

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

By coincidence I ran across this YouTube video the other day - The American Kilogram

Apparently the US signed the metre convention* and bases all customary units (feet, pounds, etc) on SI standards.
ie An American foot is defined as so many millimeters in length.

* (also known as the Treaty of the Metre, is an international treaty that was signed in Paris on 20 May 1875).

P.S. The UK signed it too....

Who would have known.

[pnzrgnral]

Short answer: yes. I'm not old enough to have served in either World War, and just missed being old enough for Vietnam, but I served in the US Army 1979-1999 and 2002-2003. In the infantry, and later as staff ops. All of our maps are metric and based on a grid reference system, whereas USN & USAF use lat-long, and as Bullwinkle said, English measurements for mapping. The compasses used by our mortarmen measured in mils, which is metric. All of our small arms calibers are metric, the exception being the M2 heavy machine gun: .50 cal, and the .45 cal M1911A1 pistol but that hasn't been in service for quite awhile. I never used GPS much but it (the hand-held version in the 80's)could be read out in grid or lat-long. I'm quite positive mapping in Vietnam was metric. All of my foreign deployments used metric, grid-based maps, regardless of location.

[geofflambert]

AA was all metric in WWII except the DP guns. Tank guns were metric, 75mm and 90mm mostly. The Navy still used knots and nautical miles and still do and are unlikely to change anytime soon, I think. Artillery frequently was expressed in mm but conformed to the inch system in large part, 75mm = 3", 105mm = 4", 120 or 125mm = 5 inch, 150 or 155mm = 6 inch and on up. Naval calibers were generally in inches except for Ack Ack. Map reading was surely a hodge podge affair since good maps were often not available and you used whatever you could lay your hands on, especially in the Pacific. Range to target always, always in yards.

[palioboy2]

ORIGINAL: Bullwinkle58

ORIGINAL: Uncivil Engineer

ORIGINAL: Yaab

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

https://www.amazon.com/AEF-Way-War-Amer ... ywords=Aef

and do saw no mention of the metric system adoption.

Any feedback from the US bros on this issue most welcome.

Depends. My Dad was a gunner on a 105 mm Howitzer in WWII. Metric. But, the artillery also has an 8 inch gun.

Smaller stuff is 7.62 mm (I guess they still use that?), and 5.56 mm, but also 20 mm and 40 mm. I think the .45 caliber pistol has been replaced with a 9 mm. So, it's a mixed bag, but mostly metric.

I took him to mean distance and maps. From movies I think the US land military has used metric at least since Vietnam.

The US Navy, and I believe all NATO navies, uses miles and yards. Fits into chart work easier, as well as several rules of thumb (the Three-Minute Rule, etc.)

I believe aviation and ATC worldwide also still uses knots for speed and miles for distance (horizontal) and feet for altitude. And English for radio comms.

We use nautical miles for distance... unless you are getting the visibility in a weather report and then it is statue miles because why not. We use feet for altitude and English is the official ICAO language of aviation... unless you are in Quebec, and then you and the controller are allowed to speak french even though half the people on the frequency don't have a clue of what you are talking about.

[JeffroK]

ORIGINAL: geofflambert

AA was all metric in WWII except the DP guns. Tank guns were metric, 75mm and 90mm mostly. The Navy still used knots and nautical miles and still do and are unlikely to change anytime soon, I think. Artillery frequently was expressed in mm but conformed to the inch system in large part, 75mm = 3", 105mm = 4", 120 or 125mm = 5 inch, 150 or 155mm = 6 inch and on up. Naval calibers were generally in inches except for Ack Ack. Map reading was surely a hodge podge affair since good maps were often not available and you used whatever you could lay your hands on, especially in the Pacific. Range to target always, always in yards.

It would be fun seeing a tank gunner trying to fit a 3 inch shell into his 75mm gun, 3" = 76.2mm!
Arty was 99% metric, yes a few odd 8inch guns but also 203mm Howitzers (This could be deliberate to avoid getting the wrong ammo)

The Navy is different, their main guns were in inches, AAA was based on place of origin, 50cal, 1.1inch, 3 & 5inch based on US designs. Metric was used for European based 20mm Oerliken/Hispano and 40mm Bofors.

Same for the Air Force who used 30 & 50cal MG or 20/37mm cannon.

Map reading is easy, the scale is the scale. As the major conflicts fought by the USA were in countries using the metric system, its not surprising that most maps used were also in the metric system.

[Yaab]

ORIGINAL: Bullwinkle58

ORIGINAL: Uncivil Engineer

ORIGINAL: Yaab

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

https://www.amazon.com/AEF-Way-War-Amer ... ywords=Aef

and do saw no mention of the metric system adoption.

Any feedback from the US bros on this issue most welcome.

Depends. My Dad was a gunner on a 105 mm Howitzer in WWII. Metric. But, the artillery also has an 8 inch gun.

Smaller stuff is 7.62 mm (I guess they still use that?), and 5.56 mm, but also 20 mm and 40 mm. I think the .45 caliber pistol has been replaced with a 9 mm. So, it's a mixed bag, but mostly metric.

I took him to mean distance and maps. From movies I think the US land military has used metric at least since Vietnam.

The US Navy, and I believe all NATO navies, uses miles and yards. Fits into chart work easier, as well as several rules of thumb (the Three-Minute Rule, etc.)

I believe aviation and ATC worldwide also still uses knots for speed and miles for distance (horizontal) and feet for altitude. And English for radio comms.

Sorry, should have been more specific. I meant maps, distances, plotting artillery fire etc. Also weapon calibers, theough I reckon some legacy weapons use imperial system i.e 0.5 inch MGs.

[wdolson]

ORIGINAL: JeffK

ORIGINAL: geofflambert

AA was all metric in WWII except the DP guns. Tank guns were metric, 75mm and 90mm mostly. The Navy still used knots and nautical miles and still do and are unlikely to change anytime soon, I think. Artillery frequently was expressed in mm but conformed to the inch system in large part, 75mm = 3", 105mm = 4", 120 or 125mm = 5 inch, 150 or 155mm = 6 inch and on up. Naval calibers were generally in inches except for Ack Ack. Map reading was surely a hodge podge affair since good maps were often not available and you used whatever you could lay your hands on, especially in the Pacific. Range to target always, always in yards.

It would be fun seeing a tank gunner trying to fit a 3 inch shell into his 75mm gun, 3" = 76.2mm!
Arty was 99% metric, yes a few odd 8inch guns but also 203mm Howitzers (This could be deliberate to avoid getting the wrong ammo)

The Navy is different, their main guns were in inches, AAA was based on place of origin, 50cal, 1.1inch, 3 & 5inch based on US designs. Metric was used for European based 20mm Oerliken/Hispano and 40mm Bofors.

Same for the Air Force who used 30 & 50cal MG or 20/37mm cannon.

Map reading is easy, the scale is the scale. As the major conflicts fought by the USA were in countries using the metric system, its not surprising that most maps used were also in the metric system.

8 inches = 203.2mm, it's probably the same size. 7.62mm = .30 caliber

[Major Shane]

ORIGINAL: Yaab

Do US Army use the metric systm? The Web says they adopted it during WWI in Europe but I have read this book

https://www.amazon.com/AEF-Way-War-Amer ... ywords=Aef

and do saw no mention of the metric system adoption.

Any feedback from the US bros on this issue most welcome.

The U.S. Army, and the other services, switched to metric once we joined NATO. During WW II we didn't use metrics as a primary system. However some items such as some cannons and howitzers did use metrics. Examples such as the 75mm on the M4 Sherman tank or the 155mm "Long Tom" howitzer.

I hope this helps.

[MakeeLearn]

A mixture of both. The M30 106.7 mm (4.2 inch.) Units call themselves "Four-deuce"

[Yaab]

ORIGINAL: pnzrgnral

Short answer: yes. I'm not old enough to have served in either World War, and just missed being old enough for Vietnam, but I served in the US Army 1979-1999 and 2002-2003. In the infantry, and later as staff ops. All of our maps are metric and based on a grid reference system, whereas USN & USAF use lat-long, and as Bullwinkle said, English measurements for mapping. The compasses used by our mortarmen measured in mils, which is metric. All of our small arms calibers are metric, the exception being the M2 heavy machine gun: .50 cal, and the .45 cal M1911A1 pistol but that hasn't been in service for quite awhile. I never used GPS much but it (the hand-held version in the 80's)could be read out in grid or lat-long. I'm quite positive mapping in Vietnam was metric. All of my foreign deployments used metric, grid-based maps, regardless of location.

Thanks! Did you have any problems switching from imperial to metric system when enternig the military? A faintest thought of imperial system gives me a mild headache.

[Lokasenna]

ORIGINAL: Yaab

ORIGINAL: pnzrgnral

Short answer: yes. I'm not old enough to have served in either World War, and just missed being old enough for Vietnam, but I served in the US Army 1979-1999 and 2002-2003. In the infantry, and later as staff ops. All of our maps are metric and based on a grid reference system, whereas USN & USAF use lat-long, and as Bullwinkle said, English measurements for mapping. The compasses used by our mortarmen measured in mils, which is metric. All of our small arms calibers are metric, the exception being the M2 heavy machine gun: .50 cal, and the .45 cal M1911A1 pistol but that hasn't been in service for quite awhile. I never used GPS much but it (the hand-held version in the 80's)could be read out in grid or lat-long. I'm quite positive mapping in Vietnam was metric. All of my foreign deployments used metric, grid-based maps, regardless of location.

Thanks! Did you have any problems switching from imperial to metric system when enternig the military? A faintest thought of imperial system gives me a mild headache.

Can't speak to your actual question, but in general I actually find imperial to be more useful for day-to-day things like sizes because it is less granular than metric. Metric is more precise, but it's also a headache for things like measuring household projects.

For example, 5-foot lengths are easy. It's 5 feet. However, in metric, that's something like 150cm or 1.5m. It really is an issue of granularity there - for quick measurements, less granular is best as there are fewer "ticks"/hash marks on whatever you're measuring with for your eyes to keep track of and scan. Maybe I'd sing a different tune if I grew up with metric, but I think chances are that I'd have the some complaint while using it anyway because that's what everything around me was measured in.

Not sure how that translates into military usefulness, but I'm sure there's something. I'd rather talk about .50 caliber bullets than 12.5mm, for example. Smaller and fewer numbers are better for faster references. Whole numbers are better and the meter is just too large sometimes.

There's also the already-mentioned velocity/time/distance relationship. In some common military applications, this apparently is easier to reference in imperial than in metric (like that 3 minute rule Moose mentioned).

[jamesjohns]

Yes, metric is what the Army has used for decades and still uses.

I had no problems with it but I was a science major in college and science is all metric

[pnzrgnral]

Yaab, I didn't have much of a problem using metric or Imperial systems. Since all of our geographical stuff was metric, it was just the ONE standard, little need for any conversion. However, I can say that all of our vehicles use MPH instead of KPH, so converting speed to map distance can be somewhat problematic especially with vehicular convoys or the like, especially over long distances. Weapons calibers, as I stated earlier, are 99% metric, and there's no need to convert since there's only the military supply chain. Now, if you owned, say, an AR-15 chambered in .223, it'd be useful to know that it's the civilian equivalent of 5.56mm when shopping for ammo at a sporting goods store.

[Rafid]

ORIGINAL: Lokasenna

For example, 5-foot lengths are easy. It's 5 feet. However, in metric, that's something like 150cm or 1.5m. It really is an issue of granularity there - for quick measurements, less granular is best as there are fewer "ticks"/hash marks on whatever you're measuring with for your eyes to keep track of and scan. Maybe I'd sing a different tune if I grew up with metric, but I think chances are that I'd have the some complaint while using it anyway because that's what everything around me was measured in.

I think you would. People get used to what they use and see around them in their childhoods, without there being much of an advantage either way.

For once you could use 15 decimetres instead. I know it is a unit less commonly used in talking, but it does exist and is used by some trades that need that specific granularity. In this and the other example (0.5 caliber) you also simply started with measurements that are round in imperial and then complained about them beeing frickly in metric. What if we start with 16 decimetres instead of 15, that is 5 feet 3 inches. Doesn't sound as nice anymore. Also 40mm Bofor sounds a lot better than “one and nine sixteenth of an inch Bofor” (4cm Bofor might sound even simpler, though also a bit odd to me). If you start with round values in one system you end up with difficult values in the other, doesn't prove anything.

For me where the metric system really shines is conversion of length to volume to weight. I put a tank in front of students which is about 4x3x2 feet (note that I start in imperial, it won’t matter) and ask: How much water does fit in it how much does it weight?

Metric: That’s about 12 x 9 x 6 ~ 650 cubic decimetres = 650 litres of water = 650 kg

Imperial: 4 x 3 x 2 = 24 cubic feet. Unfortunately most people don't know that a cubic foot is around 7.5 gallons, at best they know 1 gallon is 231 cubic inches: 24 cubic feet = 24 * 1728 cubic inches = 41472 cubic inches ~ 180 gallons. For the weight, some lucky might know that the density of water is 62 lb / cubic foot, so: 24 * 62 ~ 1500 lbs.

The metric problem could be solved by six graders with nothing, but a sheet of paper (really smart kids could get a decent answer in their head). The imperial problem is best reserved for undergraduate engineers with calculators and some might still need to look up conversion values.

ORIGINAL: Lokasenna
There's also the already-mentioned velocity/time/distance relationship. In some common military applications, this apparently is easier to reference in imperial than in metric (like that 3 minute rule Moose mentioned).

Part of the problem here is, that the clock is not truly metric (60s = 1 minute, 60min = 1h). But the 6 minute rule can easily be translated to metric (since 6 minutes is 1/10 of an hour): speed (km/h) x 100 = distance travelled in 6 minutes in meters. Basically the same formula as the 3 minute rule for imperial. But I can see that a knot is a much better unit on a sea chart.

[Bullwinkle58]

ORIGINAL: Rafid

I think you would. People get used to what they use and see around them in their childhoods, without there being much of an advantage either way.

For me where the metric system really shines is conversion of length to volume to weight. I put a tank in front of students which is about 4x3x2 feet (note that I start in imperial, it won’t matter) and ask: How much water does fit in it how much does it weight?

Metric: That’s about 12 x 9 x 6 ~ 650 cubic decimetres = 650 litres of water = 650 kg

Imperial: 4 x 3 x 2 = 24 cubic feet. Unfortunately most people don't know that a cubic foot is around 7.5 gallons, at best they know 1 gallon is 231 cubic inches: 24 cubic feet = 24 * 1728 cubic inches = 41472 cubic inches ~ 180 gallons. For the weight, some lucky might know that the density of water is 62 lb / cubic foot, so: 24 * 62 ~ 1500 lbs.

The metric problem could be solved by six graders with nothing, but a sheet of paper (really smart kids could get a decent answer in their head). The imperial problem is best reserved for undergraduate engineers with calculators and some might still need to look up conversion values.

Yeah, but how often do you do that calculation if you don't build swimming pools for a living? I'm with Lokasenna. A foot is useful in construction, and it's part of your body if you forget. An inch is closer to useful than a centimeter, which is too small. When I'm cooking I can make a cup with my hand. A teaspoon with a bent hand.

To me the most useful measurement is temperature. F. is more granular than C. in the comfort range for humans, without decimals.

One area I wish the US would get with the world on is slash-dates. 3/10/17 here is March 10th. My ESL students constantly miss appointments because they mentally do the world standard.


Part of the problem here is, that the clock is not truly metric (60s = 1 minute, 60min = 1h). But the 6 minute rule can easily be translated to metric (since 6 minutes is 1/10 of an hour): speed (km/h) x 100 = distance travelled in 6 minutes in meters. Basically the same formula as the 3 minute rule for imperial. But I can see that a knot is a much better unit on a sea chart.

Six minutes is a lifetime when you're piloting around other vessels or rocks, as well in a fire control situation. Three minutes is too.

[Lokasenna]

The universality of metric is nice on paper. For science and research, it's great. No need to convert anything.

But in the real world, using the best unit for the job is what should be done. So long as you don't need to convert units within the same workflow or task, there's no problem because by definition that task is compartmentalized from any others that would be in different units. And for most folks, the best unit for the job is the one with the fewest possible digits and fewest possible delimiters (decimals/commas). In lots of real-world applications, this is imperial rather than metric.

I can't stand when my "FIL" requests unit dimensions from me in metric (mm too, no cm allowed) rather than inches. Every single damn tool I'm using is in inches because that's the standard. But he's an "on-paper engineer" first and a real-world builder second. I also think he just likes being difficult/perfect about how much more precise metric is.