Whats the most unique engineering unit you've encountered? 5

[JGard1985]

For fun, what is the most unique engineering unit you've encountered in your years?

Some considerations:
[ul]
[li]Name[/li]
[li]Units that mixing and matching english and metric[/li]
[li]Usefulness & practicality[/li]
[/ul]

My two first nominations:
[ul]
[li]KW/foot: A mix & match of english & metric, its used in the commercial nuclear power industry. The unit is a of measure of the amount of energy produced in metric, per linear foot of fuel rod. The calculation is important for evaluating the heat transfer capacity to the water in the reactor. Too much energy will result in fuel clad damage, compromising the integrity of the first fission barrier [/li]
[li]slinch: The slinch is an english unit of mass equal to 1 lbf*sec^2/in. (Think Weight divided by 386.6in/sec^2) In my opinion it has almost no practical application except for use in the mass input for english-unit based Finite Element Models.[/li]
[/ul]

Excited to hear your nominees

Jeff
Pipe Stress Analysis
Finite Element Analysis

http://www.xceed-eng.com

 

[dik]

drawoh... that's 21.7 times as dumb...

Dik

 

[dik]

Hokie:

and either a Face Cord or a Bush Cord, or a Logger's Cord?

Dik

 

[dik]

zeusfaber:

jar from Leyden Jar perhaps?

Dik

 

[dik]

drawoh:

I remember approaching the Mayor of the Town of Lindsay (now, City of Kawartha Lakes) about 20 years ago and asking him if I could get a sack and have Home Hardware there donate a bunch of hammers and if we could have a 'Sack of Hammers' award for the most deserving Councilman... he was not pleased...

Dik

 

[hokie66]

Many of you probably know, but an acre is 10 square chains, a chain being 66 ft in length, and there are 100 links in a chain. Probably an early acknowledgment that 10 is a simpler number to work with than 12.

Another interesting area unit is the perch. 40 perches = 1/4 acre, a common size housing block in a lot of countries.

 

[CheckerHater]

Barrel of monkeys?

"For every expert there is an equal and opposite expert"
Arthur C. Clarke Profiles of the future

 

[JGard1985]

Yes chains, flashback to surveying for a minute!

Jeff
Pipe Stress Analysis
Finite Element Analysis

http://www.xceed-eng.com

 

[berkshire]

Here is a detailed explaination of the chains roods perches system.

B.E.

http://rootsweb.ancestry.com/~engwahs/area.htm

You are judged not by what you know, but by what you can do.

 

[zeusfaber]

jar from Leyden Jar perhaps?

I think so. So far as I know, they used to tune the early shipborne wireless sets by wiring additional leyden jars into circuit (increasing the capacitance by a jar or two at a time).

A.

 

[dik]

zeusfaber... didn't know that, thanks. Other than a novelty, I didn't think Leyden Jars had a real use.

Dik

 

[berkshire]

Zeusfaber,
I found a reference to that in my dad's Hand book of wireless telegraphy.
It basically said," The Jar is now obsolete as the service unit, having been replaced by the Farad and its sub multiples."
It never said whether or not that was a direct substitution.
B.E.

You are judged not by what you know, but by what you can do.

 

[Compositepro]

From Wikipedia:
A jar was an early unit of capacitance once used by the British Royal Navy. The term originated as the capacitance of a Leyden jar. Its value is such that one farad is9×108 jars and one jar is 1111 picofarads.

 

[dik]

berkshire:

I didn't know that Leyden Jars were used outside of school physics labs... if they are around, they could be historic collectables. I've got an old Roentgen tube from decades back and a couple of chunks of cable samples, the latter from a project. My only electrical part collection.

 

[berkshire]

DIK,
Is that old under sea cable?
B.E.

You are judged not by what you know, but by what you can do.

 

[dik]

It's for direct buried; I don't know if it can be submerged other than some groundwater. The project had 4 runs of it (one spare) x 4 kilometers @ $75 per foot going to 6 - 400,000 lb transformers... Oil containment for each was 1-1/2 rail tanker cars. The one electrical engineer brought back a 'sackful' of samples and I managed to scrounge a couple. Prior to that, my largest conductor size was half the diameter and I thought that was huge.

It's new material.. outer poly sheath, spiral wound copper grounding 'cage', a semi-conductor, insulation, a semi-conductor and the copper conductor.

Dik

 

[hendersdc]

Not an engineering unit but I have had the good fortune to use the term "in the event of catastrophic milkshake failure" during a project presentation.

 

[EdStainless]

Berk and JG,
And that is why my front property stakes are actually 66' from the center of the street.
I have had to explain that to a number of people over the years.
In the mid-west most roads have 122' RoW, it was just easier that way.

In metallurgy we don't have many invented units, just use whatever is handy.
Until recently when paper editors got mean about it you would see a paper with strength in ksi, grain size in microns, atomic spacing in angstroms, and density in g/cc. Since you weren't doing math between units it didn't really matter.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[CostasV]

A traditional unit for measuring fields in Greece, before WWII, was called "zevgaria" meaning "pair of", and as you can imagine it means the area that a pair of oxen or horses can plow in a day. It was equal to anything between 2000 and 4000 m2, with most usual 2500 m2.

The Dictionary of Units of Measurement has plenty of information for other strange uom.

 

[drawoh]

CostasV,

In Saxon England, fields were measured in hides. I believe this was the field an ox could plough in one day.

--
JHG

 

[MikeHalloran]

<peeve>
The common unit for liquid flow resistance, Cv, is often stated as if it were dimensionless.
It is not.
Its units are:

gpm/square root(psid)

The square root function is often omitted in textbook definitions, and is misleading as commonly stated because 1 is its own square root, so it takes a while to figure out how to compute a Cv from a given pressure drop other than 1 psi and a corresponding flow.

</peeve>

Engine manufacturers who work in metric units will often supply Cv's metric inverse equivalent (less scaling constants):

mbar/(m^3/h)^2

for use in pressure drop calculations.
I don't know of a convenient name, but it is occasionally useful, if uncommon here in The Colonies.
I think I have seen it labeled as K or maybe F.


In my spreadsheets, I use
K=68.9476/0.05159/Cv^2
to convert from one to another.





Mike Halloran
Pembroke Pines, FL, USA