>From ARocket.
May be of interest to some:.



>>>Who would want to convert metric to English units?

There are no English units of note any more. Imperial is the 
closest you get :-).

> I have no problem with metric for dynamics... m/s make as 
> much sense
> as knots (for flight... I think miles/hr for cars, sigh, 
> and for those
> it's either miles/hr or km/hr, not m/s).
>
> But ask me to do materials stress analysis in pascals and 
> I break out
> the conversion tables.

> I was born a PSI guy...


NZ is wholly metricated. Officially.
Older minds swim in a variable mix.

I was born an LSD guy (and that has nothing to do with the 
fact that I remember the 60's).

Currency    Dollars and cents. LSD wholly excised. We had 
halfpennies at the start, the Farthings having gone not too 
long before I arrived. Plus thruppeny bits, shillings, 
half-crown and even guineas if you were posh.

Length:    km, m, mm fine. But feet and miles stand in 
readily. Inches are comfortable but gone as an engineering 
measure. "About 3 inches" still is comfortable.

Velocity:    kph and mph equally happy. Not knots.

Mass / force:    kg now 2nd nature. lbf comfortable. Stone 
gone.
Slugs were only ever found in the garden. And dyning is for 
dinnertime. Poundals were a dim undergrad atrocity which 
never made it into my real world.

Time:    Daze. Eternal now. The second is king and all the 
rest just convenient scaling factors.

I had great difficulty in China trying to use a GPS NEMA 
string to find the factory that I was sitting in because I 
had forgotten that GPS use an interesting 
degree.second.decimal second format (I think it is). Once 
you get that right and key it into wikipedia all is well. 
Long overdue for true decimal fractions of a degree at least 
if we can't quite convince ourselves to jump to grads or 
better. Radians are useful but we'll never be able to sell 
them to Joe Public.

Amps.        Amps.            (Yes I know its really 
"current")

Watts seem to have survived very well. And the intuitive 
link with Joules is "very helpful". Calories are more a 
mental conversion factor than a useful unit. BTU happen at 
the end of the calculation or the start, if needs be. They 
try not to happen in the middle.

Fuel economy:    mpg still the most intuitive (although the 
pump reads in litres and the odo in km.) litres/100km is the 
std measure here and I'm OK with that but an inverse 
compressing measure with increasing economy seems 
intuitively be the way to better portray such things. Some 
system do use km/l.

PCB design packages often work natively in inches which 
helps keep the imperial units alive.

Any formal design work gets done in MKSA  / ISO and 
converted to other units as/if required.

Remember the Gimli glider!!!!
(Not to mention certain spacecraft)


        Russell


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