Today's Message Index:
----------------------
1. 02:35 AM - Gauge wiring best practice (James Kilford)
2. 10:07 AM - The state of the industry (glen matejcek)
3. 10:28 AM - Re: Gauge wiring best practice (Robert L. Nuckolls, III)
4. 11:30 AM - Interesting tid-bits from history of herding electrons. (Robert L. Nuckolls, III)
5. 12:58 PM - Re: Interesting tid-bits from history of herding electrons. ()
6. 10:27 PM - Tri State Logic help needed (rparigoris)
Message 1
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Subject: | Gauge wiring best practice |
Greetings to all,
I've bought a number of UMA's delightful 1-1/4" custom-marked engine
instruments (CHT, EGT, fuel pressure, oil pressure, oil temp. etc.)
and I'm about to start wiring them in to my plane project (Jodel D150
with Lycoming O-235). I've a couple of questions about best practices
and I wonder if you can help.
I would like to make the panel easily disconnectable, and I'm going to
be using something like Tyco AMP MATE-N-LOK connectors for connecting
other things to the panel. (These are multi-way locking connectors,
with crimped pins, supporting various wire gauges -- 10-30AWG at
least).
To connect the UMA instruments, I figure I can go one of two ways:
1) wire each UMA-supplied DB9 connector straight through to the power
bus, ground bus, and sender. The downside is that I'd have to screw /
unscrew many connectors to disconnect the 8 or so UMA instruments,
which might be quick tricky behind the panel.
2) wire all the DB9 connectors to a multi-way MATE-N-LOK plug behind
the panel, and then wire a MATE-N-LOK socket to the various sensors
and whatnot. This would give me the big advantage of being able to
disconnect all engine instruments in one connector.
I don't see any downside to this, but any input would be greatly appreciated.
Secondly, I note that each of the instruments requires a 12V supply
and a ground. Can all these engine instruments be connected together
at the instrument panel and then run to the power bus and ground bus
in two "big" wires, or should I run two separate wires back for each
instrument?
The 12V feeds could be linked together, with the risk of one engine
instrument going u/s knocking out all the others, but this seems like
a smallish risk. Or perhaps I could do a combo approach -- a few
feeds each feeding a couple or three instruments. Any thoughts about
this from you seasoned flyers would be great.
Also, I've read what it says about grounding, etc., in the
Aeroelectric Connection, and the possibility for errors because of
resistance through different ground paths. However, I find that the
UMA instruments have in general four connections: +12V, GND, sensor
+ve, sensor -ve, all connected via a DB-9 socket. Does this mean that
the sensor input has a sort of privileged design because it has its
own ground going direct the instrument? The two grounds could be
connected internally I guess, but I can't work out what difference
that would make!
Very many thanks in anticipation of your advice.
James
Message 2
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Subject: | The state of the industry |
Off topic warning; Everyone else hit delete!
And, Do not archive.
Good morning, Old Bob,
You needn't worry about the nomex undies, not from this quarter.
I will say though, our careers have taken very different paths. I suspect
your military career was over and you were in the left seat before I was
born ;-P
but that does not alter the reality that I and my coworkers lived. Then
again, not all of them lived.
Like many of a later generation / iteration, I've witnessed unprecedented
growth, the transition from non-union to union, and the failure of a couple
major carriers first hand. Then there were the corporate and fractional
gigs.
While there are plenty of conscientious operators out there, not all
operators are created equal. With the turn over and growth rates at some
carriers at different points in history, folks have gone from CFI to
captain in a year's time or less. This creates potential for crewmembers
not being exposed to all they could while still in a mentoring environment.
If a carrier can't quite bring itself to ensure that it's crews are
equipped to operate in the prevailing conditions, someone else needs to.
During his testimony before congress after the debacle in NY, Randy Babbitt
indicated that he was going to pursue better and more diversified training
for air carrier pilots while lowering the total time requirement for the
ATP. Less quantity, more quality. So far, it sounds like some common
sense might get infused into our system. I suspect that the proposed
changes will have zero impact on the syllabus at your alma mater, but it
would have required adding quite a bit of new material at my first carrier.
I also suspect that you will agree that Randy hardly qualifies as a
"sideliner".
Like you, I don't profess to have the answers, but I do know a few things
that don't work. Principal among those is leaving the fox to guard the
chicken coop. Corporate culture is the most powerful element at work here,
and ever since deregulation the biggest motivator for carriers, by far, has
been "Flying Cheap".
glen matejcek
aerobubba@earthlink.net
> Good Morning glen,
>
> Yes this IS way off topic, but I will make a comment anyway. <G>
>
> I agree with both sides of this argument.
>
> The vast majority of our young and new aviators are competent serious
> students of the art and it is a very safe mode of transportation.
>
> However there are a few that slip through the cracks.
>
> The low pay, lousy working conditions, and lack of respect afforded to
> professional pilots certainly does not promote improvement.
>
> The current level of safety was obtained during the days when a pilot
could
> expect to stay with one carrier for an entire career. There was a
strong
> union that worked hard to address safety issues and to maintain
> professional standards. The pay and working conditions were definitely
secondary
> goals.
>
> The atmosphere was such that those who made the various cuts worked hard
to
> maintain the overall level of proficiency.
>
> And cuts there were!
>
> We often talk about folks "washing out" of military training. That term
is
> rarely used in civilian life.
>
> At least ninety percent of our pilots were military trained and that
> evaluation philosophy was carried over into civilian flying. It was not
just
>
> the instructors and evaluators that made decisions on who stayed and who
went
>
> on to other endeavors, it was the pilots on the line who trained and
> evaluated the newcomers.
>
> There were twenty-eight highly qualified pilots in my new hire class.
Seven
> of those left the group during our six week training course. That was
> about average. Some classes had as many as half leave the program. I
don't
> know of any class when all participants were accepted.
>
> All pilots were subject to very strict scrutiny for the first year.
Anyone
> could be released for any reason. Out of the twenty-one that made it
> through training school, another five of my class left during that first
year.
>
> Captains were required to file a report on every copilot that flew with
them
> until the copilot had three years on the line.
>
> There was no recourse for those who were released during the first year.
>
> After three years of flying copilot, each pilot was sent to captain
> upgrading. It had nothing to do with actually flying as captain, it was
strictly
>
> an evaluation point in his (There were no females involved!) career.
While
> the applicant did get an ATP and a type rating from the course, the more
> serious part was the evaluation by a board of senior pilots as to
whether or
> not the applicant would make a good captain.
>
> If the applicant was marginal, but showed promise, he would be sent back
to
> the line for a six month period and assigned to fly with captains who
were
> felt to have the knack of bringing out the best in young aviators. A
> second chance at "Captain Upgrading" was then given.
>
> The result was that at the end of four years, a pilot had been pretty
> heavily monitored, knew that he had the capabilities needed, and had
gained the
>
> respect of his peers.
>
> The lack of stability and the idea that full evaluation is made by the
> check pilots and not by the line pilots has been a negative factor that
has led
>
> to what we now see. Folks slip through the cracks who would have been
> weeded out in the more stable environment of yesteryear
>
> The idea that any set of rules will make a difference is ridiculous. It
is
> a stable environment combined with constant peer evaluation that makes
the
> very best aviator.
>
> Requiring a minimum amount of flying time is a typical bureaucratic
answer
> that makes for a good sound bite but has no validity at all. Some of our
> early washouts were very high time pilots and some of our very best long
term
>
> aviators had only a couple hundred hours when they first sat in that
right
> seat.
>
> It is the attitude that counts the most!
>
> I sure DO NOT have an answer, but I think we aviators need to be the ones
> who make the decisions, not a bunch of ivory tower sideliners.
>
> Flame away at will my friends, but that is the way I see it!
>
> Happy Skies,
>
> Old Bob
> (soloed 64 years ago this month)
>
> Do Not Archive
>
>
> In a message dated 5/27/2010 6:44:10 A.M. Central Daylight Time,
> aerobubba@earthlink.net writes:
>
> --> AeroElectric-List message posted by: "glen matejcek"
> <aerobubba@earthlink.net>
>
> AMEN.
>
> glen matejcek
> aerobubba@earthlink.net
>
> > Subject: AeroElectric-List: Whither Aviation OFF TOPIC
> >
> > Now to the point:
> > I suggest you dial in "Flying Cheap" on PBS - I watched an article
> > on typing "PBS Buffalo - flying cheap" into Google. Perhaps there are
> better
> > ways unknown to me. The title is typically bad grammar, but the
content
> is
> > revealing.
>
>
> Do not archiv
>
Message 3
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Subject: | Re: Gauge wiring best practice |
I would like to make the panel easily disconnectable, and I'm going to
be using something like Tyco AMP MATE-N-LOK connectors for connecting
other things to the panel. (These are multi-way locking connectors,
with crimped pins, supporting various wire gauges -- 10-30AWG at
least).
Keep in mind that every connector interface adds three new
joints to every wire. Running lots of electro-goodies through a
single connector adds a single point of failure for all
those electro-goodies.
To connect the UMA instruments, I figure I can go one of two ways:
1) wire each UMA-supplied DB9 connector straight through to the power
bus, ground bus, and sender. The downside is that I'd have to screw /
unscrew many connectors to disconnect the 8 or so UMA instruments,
which might be quick tricky behind the panel.
2) wire all the DB9 connectors to a multi-way MATE-N-LOK plug behind
the panel, and then wire a MATE-N-LOK socket to the various sensors
and whatnot. This would give me the big advantage of being able to
disconnect all engine instruments in one connector.
I don't see any downside to this, but any input would be greatly appreciated.
You can do this . . . but you'll never find it done
on production aircraft either commercial or military.
It's a little-value-added activity that does add
significant cost-of-ownership and reduces reliability.
You can replace the stock jack-screws with devices
having extended handles designed for access with
the bare fingers.
It's a fact that the majority of d-sub connectors come with
short, slotted-head 4-40 jack screws that are EXCEEDINGLY
difficult to work with in confined spaces traversed by wire
bundles. Theres a host of fingers-only, d-sub retention
systems including Positronics V-series and mil-spec slide
locks. There's also a handy but seldom offered wire-bale-
and-clip that used to be VERY popular on printer connectors.
These are easy to incorporate into new products were you want
to order thousands . . . but unfortunately, they're not
often found as catalog items.
The computer world has offered a variety of extended jack-screw
handles, most of which can be operated with the bare fingers.
My personal choice is the DIY extended jackscrew fabricated
from a piece of 4-40 screw and 3/16" hex threaded spacer.
See:
http://tinyurl.com/34nrdd5
When accessed with the nifty miniature nut-driver from
Xcelite (or similar) one can get a better feel of just
how tight the screw is when replacing it . . . and
it's a light-year away from the inconvenience of
stock, slot-head jack-screws.
Secondly, I note that each of the instruments requires a 12V supply
and a ground. Can all these engine instruments be connected together
at the instrument panel and then run to the power bus and ground bus
in two "big" wires, or should I run two separate wires back for each
instrument?
Failure-tolerant design suggests that every electro-whizzie
be treated as a separate system . . . i.e. no single failure
affects more than one system. Just how much your personal
design goals tolerate risks for merging systems is up to
you. What you propose will FUNCTION as expected as long
as everything is working right.
Also, I've read what it says about grounding, etc., in the
AeroElectric Connection, and the possibility for errors because of
resistance through different ground paths. However, I find that the
UMA instruments have in general four connections: +12V, GND, sensor
+ve, sensor -ve, all connected via a DB-9 socket. Does this mean that
the sensor input has a sort of privileged design because it has its
own ground going direct the instrument? The two grounds could be
connected internally I guess, but I can't work out what difference
that would make!
Probably no functional differences. However, it's
been my observation over the years that spending a lot
of time adding complexity for some perceived future
convenience has a poor return on investment. Suggest
you 'enhance' the stock jack-screws and wire each
instrument as a stand-alone system while minimizing
features shared with other systems.
Bob . . .
Message 4
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Subject: | Interesting tid-bits from history of herding electrons. |
While working on a little research project I ran across a
couple of repositories that speak to the simple-ideas of
yesteryear.
This work on aircraft electrical systems is dated (1979) but
the physics that makes things work is well explained and
amply demonstrated. Some of the AeroElectric List community
may find this both interesting and re-enforcement of
understanding.
http://tinyurl.com/3296ed9
This website doesn't have much to do with aviation except
that it's a certainty that many pieces of "artistic"
glass depicted were foundations for airborne communications
and navigation equipment dating back to the first Army Air Corps
airborne radio experiments in the early 1920s.
http://electricstuff.co.uk/
Bob . . .
Message 5
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Subject: | Interesting tid-bits from history of herding electrons. |
Do Not Archive
Bob,
Wow - a splendid reference. I'm going to run through just as soon as I
retire J
Have a great weekend everyone.
Glenn E. Long
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Robert L. Nuckolls, III
Sent: Friday, May 28, 2010 2:31 PM
Subject: AeroElectric-List: Interesting tid-bits from history of herding
electrons.
While working on a little research project I ran across a
couple of repositories that speak to the simple-ideas of
yesteryear.
This work on aircraft electrical systems is dated (1979) but
the physics that makes things work is well explained and
amply demonstrated. Some of the AeroElectric List community
may find this both interesting and re-enforcement of
understanding.
http://tinyurl.com/3296ed9
This website doesn't have much to do with aviation except
that it's a certainty that many pieces of "artistic"
glass depicted were foundations for airborne communications
and navigation equipment dating back to the first Army Air Corps
airborne radio experiments in the early 1920s.
http://electricstuff.co.uk/
Bob . . .
Message 6
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Subject: | Tri State Logic help needed |
Trying to wire stick grip to control Airmaster electric constant prop manual control
(jog to course or fine) we came to realization we are one wire short on
connector.
Thus it would save a lot of time and effort if I could use Tri State Logic for
a solution.
I could easily have one wire with three states using my SPTT switch on stick.
1) Infinite resistance (not connected to anything) when switch is in neutral
2)+12V when pushing momentary switch forward
3) (-) ground when pushing momentary switch back
My goals:
** Have 2) +12V energize a 5 amp relay which runs prop Course
** Have 3) (-) energize a 5 amp relay which runs prop Fine
** Have 1) NOT energize either Course or Fine relay
Any help and or ideas greatly appreciated.
I think I would rather use relays compared to solid state because I just don't
know what is going on inside the constant speed controller, and relay contacts
can easily replicate resistance compared to supplied switch.
I am OK with failure mode of circuit and relays because I plan to replicate for
each stick (2).
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=299239#299239
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