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Re: [PSUBS-MAILIST] Design depth
On 12/10/2010 9:20 AM, Les & Anna wrote:
Just a couple of thoughts, as with Doctors talking with their trained
terminology, likewise, Engineers and the like, to those not in the field
it does sound complicated,
inherently increased by those same professionals not having that other
specialized field of knowing how to impart that knowledge.
In some cases, professional jargon is deliberately overcomplicated to
exclude lay persons. In others, serviceable terms understandable to
laymen are set aside in favor of those understandable to other
professionals speaking other languages. Medicine is an example: a
Russian doctor often has less trouble understanding an English doctor's
diagnosis than does his English patient.
Anything that one doesn't understand is by definition complicated. When
somebody speaks a foreign language, it always sounds as if he's talking
very fast whether that is so or not. The only remedy is to learn the
language.
It is all in the way it is presented .....as a suggestion; would it not
be simpler to give an example of a simple workable format and then the
related maths to confirm how it was established so that individuals can
reverse engineer a simple format to assist them to understand the
principles, maths and calculations easier, to apply to for more
complicated formats.
There are limits to the degree to which a problem can be simplified.
More on that below.
i.e.. A simple example if you like, to help them visualize and get an
indication of exactly what is involved.
eg. If someone in the club, engineering orientated, could, for the
exercise, apply this to;
a simple cylinder say 1200mm diameter x 4meter long, no tapers
include two normal round end capsno other orifices
An example of simplification that isn't. Intuitively, hemispherical end
caps on a cylinder should give the simplest structural solution and the
lowest stress. They don't. The stress state where the caps meet the
cylinder is very complicated and very high. The optimal structural shape
is different and requires some grasp of higher math to comprehend.
What this does for the layperson is give them a perception of size,
shape, steel dimensions, weight etc.of what they should be considering
,which also acts
as a reasonable check to their later calculations with tapers and other
shapes, and conning towers, considering dynamic loads etc.
I'm not sure this is so. I think it would tend to give a false sense of
security, instead, and lead to possibly fatal errors.
In my consulting work I often run into people who try to scale up a
model airplane, say, to full size and think that anything that works at
one scale will work at another. The first time I encountered this I was
floored; I had been immersed in dimensional analysis for so long that I
forgot this was not the normal condition of Mankind. Explaining dynamic
scaling laws doesn't always work, and you just have to let reality prove
itself. That's okay if it's a model airplane, or if the only consequence
of error is that a ducted fan's thrust doesn't meet expectations; if
your life is at stake, it's probably unacceptable.
They then have an idea of what expectations should be for the
environment they are calculating for .........*a base line if you like*.
Baselines are only useful if the person using it has a grasp of the
correct process for proceeding from that baseline to the scale of his
project. Unfortunately, that is "complicated"...and crucial.
How much volume a 1000litres of liquid takes up,the weight of a 1000
> litres of liquid etc.
A thousand liters has a volume of...1000 liters! The liter is a unit of
volume, after all. Everybody outside the USA should have learned in
Elementary School that it equals 1/1000 of a cubic meter, and that the
volume was chosen such that one liter of pure water weighs one kilogram.
the size and weight of appropriate batteries etc.
Here is one area where a repertoire can be useful and not misleading.
Such data are routinely used in weight-sensitive applications like
aircraft - there is even a Society of Aeronautical Weight Engineers
(SAWE) that publishes tables of typical weights for various items. I
have some excerpts from their old lists that include such exotics as
kapok insulation, corkboard and so forth for estimating the weight of
cabin furniture.
One psubs FAQ topic could be Weights and Volumes and include entries
ranging from formulas used for first-order estimates to actual weights
of specific apparatus, by brand and model.
Best to all,
Marc de Piolenc
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