Metric or Imperial

[Spam3d 54]

17 hours ago, Garys said:

Nah, Boeing is 100% Imperial. All measurements are in inches from the datum, all fasteners are SAE and all torques are in inch pounds. The metric equivalents come in 2nd.

GE is also the same, Interestingly you'll note that they state you can convert Imperial into Metric, but never the other way around as it creates a round up

Edited September 25, 2020 by Spam3d

[Ray Proudfoot 8,931]

How do metric people say "give him an inch and he'll take a mile"? 😁

[Howellerman 104]

Having owned and worked on multiple Japanese motorcycles the metric systems comes easily to hand. My most recent bike, a Triumph Bonneville, is also metric. However, having owned and worked on many 1960's Fords, imperial units come equally to hand. Let's just say I am cross-confused.

That being said, there is certain "romance" to imperial units. "Doing the ton", as in 100mph. Fathoms of depth, 20,000 leagues under the sea, etc. 

My personal metric favorite is that 1 calorie of energy will heat 1 gram (or cubic centimetre) of water 1 degree Celsius. 

[HighBypass 2,339]

47 minutes ago, Ray Proudfoot said:

How do metric people say "give him an inch and he'll take a mile"? 😁

Easy... "give him 25.4 mil and he'll take 1609.344 metres.. " ..OK back to imperial for the saying.. 

[G550flyer 1,011]

   This comes up a lot and you never really think of it until you come across a situation that forces you to go one way or the other. Some will debate that one is better than the other, but it all comes down one thing. That is, what ever you grew up with. Grow up with one measure and the other will always seem foreign to you. Currently I am a international type and will find myself all over the world just as I did during my USAF time. You can imagine my very first international flight dealing with conversions. For example, I need about 120,000 pounds of fuel. When I would make the request, sometimes they would ask, how many liters? Of course, I know that a gallon of fuel on average is about 6.7 pounds. But now, I have to do conversions to ensure I tell them the correct amount needed. Luckily for me, after flying heavies, the FMC in the Gulfstream has a conversion page. I can type in the amount I need and it will give me the number in every format. Plus, I don't need as much fuel as I did flying heavies. I can also preset the fueling system to shut off at a desired amount of fuel. I still use the "trust but verify" theory and will figure out how many liters that would be on the conversions page. Though the fuel will automatically stop, I can look at the liters on the truck while during the walk around in case I need to run over and stop the on load. Sometimes the co-pilot(PNF) is heads down and isn't paying attention. In all, you just have to watch your conversions depending on where you are.

   Now, I have dealt with hpa and it's as easy as a button push, but transition altitudes and levels are the tricky ones. These change and can be lower than the 18,000 standard that I'm used to. I have seen it as low as 4000ft. The most interesting ones are meters and QFE. I have been flying in some airspace where I've been switched back and forth between Russian and American controllers. I had to have the book in my lap and converted between meters and feet. Much more fun when every other controller is giving you meters on descent through approach. Again, after getting to Gulfstreams, the conversion page has it for you though the book had all the altitudes in feet with meters beside it. I did have a controller clear me down to meters that were below the MSA in feet. I contacted him and told him I didn't want to go below certain meters. He was probably checking to see if we were paying attention lol. QFE on the other hand gets really interesting. For departure in the Gulfstream, I have to first set the altimeters to QNH. I then perf the box and hard select my takeoff speeds. I then spin the altimeters down to QFE/zero. The FMC uses outside temperature, current location and Captains BARO settings to calculate V Speeds using weight. This is why we have to set QNH and then hard select the numbers to keep them from changing. If not, as I spin down the BARO, the V speeds would start changing. Other than that, it's normal as normal can get. I heard that QFE would go away, but it's been a while since i've flown in that type of airspace.

   Again, it all depends on what you are used to or grew up with. A lot of American aircraft manufactures will use a combination of measurements. For example, reported temperatures are always in Celsius. If you are looking at air conditioning settings or temperatures such as heat exchangers, duct temps or cooling turbine discharge, it's in Fahrenheit. If you are looking at oil temps, fuel temps or exhaust gas temps, it's in Celsius.                

[dave2013 1,123]

Like some have already said, it really depends on what discipline or field the measurement is used in.  We use both systems in the U.S., and children are taught both systems in school. 

The scientific community uses metric measurements.  For example, at a place where I worked for a long time we measured wind speed in meters/second, but when the guys working out on the instruments asked me what the wind speed was I told them in miles/hour.  The military largely uses the metric system, e.g. kilometers, also called "clicks", but they use imperial units as well, like gallons.

In everyday communication most Americans speak in terms of inches, feet, miles, ounces, quarts, gallons, pounds, fahrenheit, etc.  I believe that the UK is somewhat similar in that respect, but they use the metric system for more things than we do. 

Dave

[JRMurray 214]

Some further comments ...

Canada starting going metric in the 1970s, I think, when I was heading into my teenage years. The conversion to metric was graduated: if I recall correctly, we started the change with temperature, and then distance (such as inches to centimetres and miles to kilometres), and then mass.

It's interesting to note that for the most part, I'd say that Canadians are very well accustomed to temperature in terms of Celsius and distance in terms of kilometres. However, when it comes to people's weight and height, I think that in speech, a lot of people express weight in pounds and not in kilograms and height in terms of feet and inches and not centimetres. For me, if someone describes a male as being 5 feet 11 inches and 200 pounds, I can easily visualize the person. 1.8 metres and 90.7 kg ... not so much.

Also interesting to note is that I'd say that many Canadians are more comfortable using Fahrenheit for cooking and ounces and pounds for food--even though metric and Imperial are listed side-by-side in signs, and ovens with digital readouts can be set for either metric or Imperial. Anyway, I can visualize a 12 ounce steak pretty easily. A 340 g steak ... again, not so much.

[G550flyer 1,011]

44 minutes ago, JRMurray said:

Anyway, I can visualize a 12 ounce steak pretty easily. A 340 g steak ... again, not so much

Exactly, I can easily visualize that my 590,000 pound aircraft means a long takeoff roll and high V speeds while 267,619 kilograms sounds more like an operating empty weight to me. 

[The Flight Level 2,112]

Use both equally well as I was just a young lad when Canada made the switch to phase in metric over a few years! My kids are always amazed how accurately I estimate dimensions and distances in imperial units!

[regis9 4,004]

I really use both.  Metric for most things, but I couldn't tell you my height and weight in cm/kg.  

[C2615 319]

10 hours ago, Ray Proudfoot said:

How do metric people say "give him an inch and he'll take a mile"? 😁

LOL, the same old saying in China is "得寸进尺" (de cun jin chi) literally "Got (a) inch take (a) feet", although it's in traditional Chinese unit, 1 chinese inch=3 ¹⁄₃ cm and a Chinese feet=33 ¹⁄₃ cm (in recent value, it was changing throughout the history)

[HighBypass 2,339]

Nice, consistent use of 1/3 cms there! Also interesting is the fact that despite being across the other side of the planet and with wildly differing cultures, some sayings are extremely similar in phrasing and use. 🍻

[GHD 21]

On 9/24/2020 at 10:19 PM, Chock said:

 and nobody buys 2.25 kg of potatoes either, it's a five pound bag of spuds. 

I

I always ask for half a stone of potatoes.

 

[JRMurray 214]

7 hours ago, GHD said:

I always ask for half a stone of potatoes.

Funny, the concept of "stone" came up at the breakfast table this morning when my family started talking about metric versus Imperial (talk about synchronicity--the discussion was totally unprompted by me). We don't use stones in Canada at all ... seems to be British thing. 

[Penzoil3 480]

What do you use for gravel then?

2 hours ago, JRMurray said:

We don't use stones in Canada at all ... seems to be British thing. 

LOL

 Sue