ZeroExperience
Aerospace
As title asks.
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Do you want to switch to SI units? 8
- Thread starter ZeroExperience
- Start date
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1
- #61
Sorry Hurricanes, I'm not convinced it is rubbish.
I was brought up with both, I tend to find imperial easier to visualize.
I was brought up with both, I tend to find imperial easier to visualize.
Posting guidelines faq731-376 (probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484
What is Engineering anyway: faq1088-1484
MiketheEngineer
Structural
Gimli glider is quite true. The pilot asked for XXX amount of gallons but instead got XXX amounts of liters. So he got about 26% of the fuel he requested.
Why he didn't believe his fuel gauges - God only knows - but us pilots are infallible.
And yes - they did glide it to an abandoned airstrip where a bunch of teenagers were staging impromptu drag races. Fortunately, one of them saw the plane on short final and got everyone off the runway - just in time. I believe he broke the nose wheel over running the end the rather short runway - it was designed for private aircraft.
Second story:
We have a manufactured piece - that is not critically precise (used in construction) but it was originally dimensioned in metric and fabricated in a "metric" country. Then re-dimensioned in Imperial and built in US and this went back a forth for say a dozen years. Guess what? The newer ones are about 1/4'' or 6mm different in length from the original because of all the transitioning of dimensions back and forth!! Makes my life simple - NOT
Why he didn't believe his fuel gauges - God only knows - but us pilots are infallible.
And yes - they did glide it to an abandoned airstrip where a bunch of teenagers were staging impromptu drag races. Fortunately, one of them saw the plane on short final and got everyone off the runway - just in time. I believe he broke the nose wheel over running the end the rather short runway - it was designed for private aircraft.
Second story:
We have a manufactured piece - that is not critically precise (used in construction) but it was originally dimensioned in metric and fabricated in a "metric" country. Then re-dimensioned in Imperial and built in US and this went back a forth for say a dozen years. Guess what? The newer ones are about 1/4'' or 6mm different in length from the original because of all the transitioning of dimensions back and forth!! Makes my life simple - NOT
JohnRBaker
Mechanical
And don't forget about that Mars mission that NASA lost a few years ago when one sub-contractor manufactured it's components based on the Metric system while the company that wrote the software that controlled it assumed that the specs they had been given were in Imperial units, what they had always worked in previously. POP goes a few million in tax-payer dollars.
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
UG/NX Museum:
To an Engineer, the glass is twice as big as it needs to be.
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
UG/NX Museum:
To an Engineer, the glass is twice as big as it needs to be.
Thanks Steve for the gas leak estimate. I listened to the broadcast again and the speaker did not say per hour or per day, just 25-30 cubic tons. The speaker was Dr. Simon Boxall, an oceanographer and oil pollution expert. I don't think he was speaking on behalf of Total.
HAZOP at
HAZOP at
dwallace1971
Aerospace
We could always go back to the base 12 system of the Egyptians.
"On the human scale, the laws of Newtonian Physics are non-negotiable"
"On the human scale, the laws of Newtonian Physics are non-negotiable"
patprimmer
New member
Well Total probably did not want to admit liability to an actual amount so he deliberately gave a nonsense figure that sounded like a real amount to the unwashed masses.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
SomptingGuy
Automotive
Base 12 is a nice idea, but would require a revolution in basic microprocessor technology to make real, native use of it.
- Steve
- Steve
Hurricanes
Mechanical
What I find weird with Imperial, is the same unit is sometimes used for different measures. I am currenly looking at an old piperack drawing (chiseled out of stone, back when dinosaurs roamed the earth) and the steam line is denoted as 110 pound steam. So pounds for mass, force and pressure? Crazy talk.
patprimmer
New member
I did not know the Egyptians used a base 12 system. Live and learn, particularly on here.
You can still only halve twice before you get into fractions.
As to intuitive nature.
Generally but not always, metric is easier to remember and work with as units line up better and where mostly though through to be easy to work with when created, however nature does not always co-operate and things eventually get to a point where there is no option but to incorporate an awkward constant.
It is always more in intuitive to use the units we are most familiar with, hence my use of kph for driving my road car with a kph speedometer and kph speed limits. I learned to barefoot water ski and ski jump and slalom in the mph days, and I still call for mph from the boat driver as I know in mph how hard the water feels under my ski or foot.
With building standards, I still mostly think in imperial as the modules and tooling never changed. A 4 by 2 was still a 4 by 2, the name just changed to 100 by 50, but as it was still a 4 by 2 it stayed that way in the mind. 1/2" pipe is still 1/2" not 12.5mm and 4" pipe is still 4", but 90mm pipe is 90mm pipe as I never used an imperial version as a std size. Sure when I buy 4" pipe I know it might be called 100mm.
As for pressure, a force per unit area is a lot more intuitive than a straight up number that needs to be interpreted in the mind.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
You can still only halve twice before you get into fractions.
As to intuitive nature.
Generally but not always, metric is easier to remember and work with as units line up better and where mostly though through to be easy to work with when created, however nature does not always co-operate and things eventually get to a point where there is no option but to incorporate an awkward constant.
It is always more in intuitive to use the units we are most familiar with, hence my use of kph for driving my road car with a kph speedometer and kph speed limits. I learned to barefoot water ski and ski jump and slalom in the mph days, and I still call for mph from the boat driver as I know in mph how hard the water feels under my ski or foot.
With building standards, I still mostly think in imperial as the modules and tooling never changed. A 4 by 2 was still a 4 by 2, the name just changed to 100 by 50, but as it was still a 4 by 2 it stayed that way in the mind. 1/2" pipe is still 1/2" not 12.5mm and 4" pipe is still 4", but 90mm pipe is 90mm pipe as I never used an imperial version as a std size. Sure when I buy 4" pipe I know it might be called 100mm.
As for pressure, a force per unit area is a lot more intuitive than a straight up number that needs to be interpreted in the mind.
Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
for site rules
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1
- #72
SI is a billion times easier to teach, because your units almost always work out. Pair that with the tendency in modern textbooks to represent any sort of flux as a little dot over the symbol of the quantity that's "fluxing," and it really makes a lot of sense.
All that sense goes out the window once you leave college and start dealing with the versions of the equations the old timers are using, and the design regulations are using.
I hate teaching in anything other than SI, because SI is built from the ground up to make sense. I hate engineering in anything other than imperial because imperial is what's been done before.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -
I am eternally gratefully to my college adviser who also happened to teach most of the upper level courses I took. He forced us to solve all problems in units first, and he forced us to use imperial. It was a godsend to figure it all out then and have confidence in using the wacky and sometimes unintuitive units now. (People look at me blankly when I tell them they've forgotten their slinch's.)
When the future's architectured
By a carnival of idiots on show
You'd better lie low
When the future's architectured
By a carnival of idiots on show
You'd better lie low
JohnRBaker
Mechanical
Hey drawoh, weren't these guys into feeling the lumps on your head in order to diagnose all sorts of physical disorders and mental weaknesses?
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
UG/NX Museum:
To an Engineer, the glass is twice as big as it needs to be.
John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
UG/NX Museum:
To an Engineer, the glass is twice as big as it needs to be.
Hurricanes
Mechanical
beej67,
"I hate teaching in anything other than SI, because SI is built from the ground up to make sense. I hate engineering in anything other than imperial because imperial is what's been done before."
I guess that's where here (Australia) is different. I am not sure when metric ticked over here, 1960s I think, going by old drawings, but it is pretty rare to come across anything in Imperial units.
The worst I have to deal with is converting lengths and pipe sizes to metric. Usually that has already been done for me on updated revisions of old drawings though.
A 24NB pipe means nothing to me, but DN600, ah, I can see what that looks like in my head.
"I hate teaching in anything other than SI, because SI is built from the ground up to make sense. I hate engineering in anything other than imperial because imperial is what's been done before."
I guess that's where here (Australia) is different. I am not sure when metric ticked over here, 1960s I think, going by old drawings, but it is pretty rare to come across anything in Imperial units.
The worst I have to deal with is converting lengths and pipe sizes to metric. Usually that has already been done for me on updated revisions of old drawings though.
A 24NB pipe means nothing to me, but DN600, ah, I can see what that looks like in my head.
moltenmetal
Chemical
The plane with the leaking fuel tank also glided safely to a landing in the Azores. That too was a Canadian one.
I'm with those who think it has to do with what you're raised with, and what your typical labour force works in. Despite being officially SI since I was a kid, Canada's tradesmen still work in feet and inches. That the plywood is now 19mm instead of 3/4" etc. doesn't bother them a bit.
As to pipe sizes, they might as well be called George and Bob: they are sized based on a table of ODs and wall thicknesses which have precious little to do with either their DN/PN or NPS "dimensions".
I'm with those who think it has to do with what you're raised with, and what your typical labour force works in. Despite being officially SI since I was a kid, Canada's tradesmen still work in feet and inches. That the plywood is now 19mm instead of 3/4" etc. doesn't bother them a bit.
As to pipe sizes, they might as well be called George and Bob: they are sized based on a table of ODs and wall thicknesses which have precious little to do with either their DN/PN or NPS "dimensions".
I'm sure if I lived and practiced overseas my whole life, and everything in the industry around me was in SI, I'd have zero reservations about SI.
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East -
I just ran into these conversion units the hard way this week.
I had a 3/4" gate valve strip out on a coldwater supply line.
No problem I just go get the same make and model of valve, remove the top and install it, Right? Wrong, the maker has moved his production to China. The new valve now has metric threads that do not fit. So I ended up dismantling by de- soldering a bunch of copper tubes and re-installing the new gate valve assembly into the line.
A 5 minute job turned into a 2 hour job.
Don't you just love SI units.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
I had a 3/4" gate valve strip out on a coldwater supply line.
No problem I just go get the same make and model of valve, remove the top and install it, Right? Wrong, the maker has moved his production to China. The new valve now has metric threads that do not fit. So I ended up dismantling by de- soldering a bunch of copper tubes and re-installing the new gate valve assembly into the line.
A 5 minute job turned into a 2 hour job.
Don't you just love SI units.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
SomptingGuy
Automotive
"Don't you just love SI units."
Yep. Like almost all of the modern World.
- Steve
Yep. Like almost all of the modern World.
- Steve
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