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ohioip(at)yahoo.com Guest
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Posted: Sun Dec 14, 2008 6:49 pm Post subject: Need for Start-Up Protection |
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Bob-
My apologies for my previous digest post. That was only my second post, so I'm still learning the ropes! I'm more of a listener than a talker.
With regard to your questions, I would like to provide you with specific details, test data and analyses of the products and the airframes that I alluded to, but I do not wish to "throw" the OEM avionics mfr. or the airframers "under the bus" to support what is, in the end, nothing more than my personal design philosophy. Besides, such a discussion would inevitably devolve into a narrowly-focused critique relating to specific situations rather than a discussion of the merits of a general design philosophy (i.e., whether or not to incorporate an avionics master switch).
In a way, I believe you made my point for me. You stated that your livelihood includes investigating "unanticipated characteristics" and failures to meet design goals. It is well-known that such characteristics and design failures are often not discovered until a product is fielded and problems arise in service. I personally prefer to assume the system-reliability risk of of an avionics master switch as a safeguard against such potential issues, even if the extent of the risk of equipment damage is unquantified.
And for the record, I was not trying to "persuade" anyone, instill "fear" of "imagined" issues, nor prove you wrong. I apologize if I did not clearly convey my thoughts. I was merely stating that there are two schools of thought on the subject, both having (IMHO) valid points, and sharing why I elected to utilize an avionics master switch.
Bob, I feel I must share with you that the tenor of your response has made me more hesitant to express my thoughts in the future. I'm telling you this not as a complaint, but rather as honest feedback.
Best Regards,
Mike
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nuckolls.bob(at)aeroelect Guest
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Posted: Sun Dec 14, 2008 11:05 pm Post subject: Need for Start-Up Protection |
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At 08:49 PM 12/14/2008, you wrote:
Quote: |
Bob-
My apologies for my previous digest post. That was only my second
post, so I'm still learning the ropes! I'm more of a listener than a talker.
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No problem . . . just a gentle nudge . . .
Quote: | With regard to your questions, I would like to provide you with
specific details, test data and analyses of the products and the
airframes that I alluded to, but I do not wish to "throw" the OEM
avionics mfr. or the airframers "under the bus" to support what is,
in the end, nothing more than my personal design
philosophy. Besides, such a discussion would inevitably devolve
into a narrowly-focused critique relating to specific situations
rather than a discussion of the merits of a general design
philosophy (i.e., whether or not to incorporate an avionics master switch).
In a way, I believe you made my point for me. You stated that your
livelihood includes investigating "unanticipated characteristics"
and failures to meet design goals. It is well-known that such
characteristics and design failures are often not discovered until a
product is fielded and problems arise in service. I personally
prefer to assume the system-reliability risk of of an avionics
master switch as a safeguard against such potential issues, even if
the extent of the risk of equipment damage is unquantified.
And for the record, I was not trying to "persuade" anyone, instill
"fear" of "imagined" issues, nor prove you wrong. I apologize if I
did not clearly convey my thoughts. I was merely stating that there
are two schools of thought on the subject, both having (IMHO) valid
points, and sharing why I elected to utilize an avionics master switch.
Bob, I feel I must share with you that the tenor of your response
has made me more hesitant to express my thoughts in the future. I'm
telling you this not as a complaint, but rather as honest feedback.
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Point taken and many have expressed similar feelings.
Please understand that my role here is illuminator
of physics and a random access repository for repeatable
experiments that have served aviation well for longer
than my own decades of participation in the craft.
I'm not happy to be proven wrong . . . because it brings
forward an error in my thinking (and teaching) that begs
immediate rectification. So while not delighted to discover
errors, I am grateful when it happens. So please don't read
emotions or intent into my words that is not specifically
expressed . . . I know this is difficult with only the
printed word for communication.
Alternative "schools of thought" are not useful teaching
tools unless they are part of a revelation of simple-ideas,
data gathered, and demonstrated repeatable experiments.
For example, it was suggested recently that Transorbs be
used downstream of a fuse or breaker to protect some
appliance from an over voltage condition. This idea
has surfaced here on the list in times past and was shown
to be in error after the capabilities of Transorbs
(designed to stand off low energy spikes) was shown
insufficient to stand off a high energy ov event with
an additional expectation of opening the up-stream
circuit breaker.
I asked the individual to recommend a part number of
Transorb for this purpose. I intended to show
an energy analysis for the n'th time that would
tell us how this part could not be expected to
block stresses it was being asked to protect
against . . . stresses that either don't exist
or are easily managed by tried-and-true recipes
for success.
My mission here is to assist 1800 readers (mostly
neophyte builders) in making decisions based
on the collective experiences of myself and many
others who have made a living in this business
for decades. Any 'push back' you might perceived
about your feelings on the topic was not an attempt
to persuade you of anything. It was intended to
remind everyone that there are reasons to do things
based on logic, science and repeatable experiments
. . . and there are reasons to do things because
they make us feel better. I have no personal interest
in anyone's informed decision for any feature
they choose to incorporate in their project. However,
I will do my best to assist them in BEING INFORMED.
My customers don't pay my exorbitant fees to
feel better. They expect (and I offer) the best I
know how to do based on data and experiences I
have at my disposal. I'll be pleased to update
that advice when offered new data. Yeah, there
ARE fielded products that missed established
design goals. But is it our duty as consumers to
discover those errors and kick them back up
the supply chain . . . or should we modify our
behavior (and our designs) to accommodate the
POSSIBILITIES so that poor designs get pampered/
tolerated and perhaps never discovered?
I'm sorry if you don't share my faith in the
skill and integrity of myself and fellow engineers
to do our homework. But folks are paying
me/us good fees because we do our homework and
pretty much expect our associates in the field
to do their homework too. The consequences for
missing the mark should be levied on US and
not upon the consumers of our work-product.
Now, we're probably making this more complicated
than it needs to be. Let's do the reversed
hypothetical: How would you modify a starter/
alternator/battery combination such that it
could be predicted to produce stresses that
exceed industry design goals for the accessories
powered by the system? If you're feeling
good for accommodating potential "accidents of
design" that produce a non-compliant condition
. . . how much of a problem is it to purposefully
design a non-compliant system?
What would you propose we hammer, bend, break
or otherwise modify some component to produce
a system that's hazardous to its appliances?
I think this is exercise useful to demonstrate
that no PURPOSEFUL way exists that demonstrates
or mimics anyone's ACCIDENT. In other words, it's
so easy to do this one right that worrying about
doing it wrong is unworthy of concern.
As I mentioned earlier, I've never asked any
customer of mine to turn off my gizmo to protect
it from anything the airplane can be expected
to throw at it. I've never had a customer bring
me a box of smoked junk because I missed the
design goal. It's not a big deal.
Bob . . .
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