Dear Feedback editor,
Could you pass this on to Graeme Fletcher, please.
Thankyou,
Pat Naughtin
Geelong, Australia
Dear Graeme Fletcher,
A friend passed on a copy of your article 'Figuring horsepower a confusing
process' by Graeme Fletcher from the DRIVING section (Pg. C10) of the
Times
Colonist (Victoria, British Columbia) dated May 20, 2005 Friday.
I was enthralled by the mental gymnastics you needed to wade your way
through the multi-headed issue of horsepowers. That's right I used the
plural horsepowers because there have always been several of them. Not
only
are there several definitions of horsepower there are also many different
ways of testing the horsepower of any machine.
Russ Rowlett in 'A Dictionary of Units of Measurement' (University of
North
Carolina at Chapel Hill) see http://www.unc.edu/~rowlett/units/dictH.html
suggests politely that 'Slightly different values have been used in
certain
industries' to cover the reality that various industries have routinely
changed the definition of the horsepower to suit their individual
purposes.
Because there is a range of definitions and a range of test methods an
engineer is able to select from a range of horsepowers and a range of
horsepower test methods until they find a combinations of these that shows
their product in its most favorable light. ('Peak horsepower' in vacuum
cleaners is, I believe, currently popular in Canada). Accurate and precise
information for the public is often placed a long last behind the need for
obfuscation such as this.
As you correctly pointed out, this process began with James Watt
falsifying
his experimental results when he described the '33,000 foot-pounds of work
every minute' horsepower. My understanding of his motivations were that he
chose the strongest horses from his district to raise weights in a well,
through a measured distance, while he timed the event. At the end of this
experiment � as he could not be sure that the horses in his district were
the strongest available in the whole of England � he simply did what
engineers have always done � he added a safety factor (of about half and
to
a nice rounded number).
The ultimate solution to the whole horsepowers mess is simply to reject
all
the different horsepowers in favor of watts, kilowatts, and megawatts.
These
are defined accurately and precisely, they work well where they are used
e.g. the motor car, truck, and bus industry and all electrical industries
in
Australia, and they soon become accepted by the community as soon as they
develop some comparative figures to help with their individual change of
mindset.
To paraphrase your final paragraph:
What's the watts
If all manufacturers used the new standardized test to arrive at an
engine's
actual output (in kilowatts), comparing performance numbers and specs
would
be so much easier -- comparing kilowatts to kilowatts is just as easy as
comparing apples with apples.
Cheers,
Pat Naughtin
Geelong, Australia
61 3 5241 2008
[EMAIL PROTECTED]
http://www.metricationmatters.com
P.S. You might be amused by a piece that I wrote to an anti-metric
journalist in the USA. Go to
http://www.metricationmatters.com/articles.html
and scroll down to find 'Don't use metric'
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