Today's Message Index:
----------------------
1. 09:57 AM - Re: Fuselinks & breakers (Robert L. Nuckolls, III)
2. 10:53 AM - Re: D.A.R question about fuse access (Robert L. Nuckolls, III)
3. 04:09 PM - Re: D.A.R question about fuse access (BobsV35B@aol.com)
4. 07:37 PM - p and retard leads (Jeff Peterson)
5. 08:38 PM - (Robert L. Nuckolls, III)
6. 08:43 PM - Re: p and retard leads (Kelly McMullen)
7. 09:05 PM - Air conditioning stuff for sale (DEAN PSIROPOULOS)
Message 1
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| Subject: | Re: Fuselinks & breakers |
At 12:15 PM 7/18/2009, you wrote:
>Bob, in several of your Z drawings, you show a fuselink in series
>with a breaker. For instance, Z-18. You also have a fuselink and a
>breaker separated only by a relay in Z-18RB.
>
>What is the rationale behind this seemingly redundant layout?
Fusible links are not to be confused or even placed
in the same class as breakers and the run-o-the-mill
plastic fuses. Not all that is offered as a "circuit
protective device" has the same design goals.
Fuses are VERY FAST acting devices compared to
thermal breakers. Fusible links and the ANN/ANL
"current limiters" are VERY SLOW compared to the
breakers and slower still compared to fuses.
In the cases you cited, the protective device upstream
of a crowbar ov protection system needs to be pilot
re-setable . . . but when combined with remotely
mounted fuse blocks, a "extension" of the main bus
bar up to the field breaker, the legacy design goals
call for some form of protection for the extended
bus that drives the one and only breaker. However,
it must be MUCH more robust protection than the breaker
itself. I.e., feeders protected with ANL limiters or
fusible links.
Fusible links and current limiters are SPECIAL,
robust forms of circuit protection which are NOT
interchangeable with fuses and breakers on distribution
feeders. They are recommended for use only in
situations described in the Z-figures.
I had a builder some years ago share his wiring diagram
with me concerning some other issues wherein he had
scattered a number of fusible links around the system.
Your car has one, maybe two fusible links. All other
circuit protection is breakers, fuses or polyfuses
specifically tailored to the protection task. Before
you do anything with links or limiters, let's talk about
it here on the list before you do it. Further, the
short answer to your question is that the buss extension
up to the breakers cited is classically protected by
some extra-robust device at the feeder end.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 2
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| Subject: | D.A.R question about fuse access |
>
>The nice thing about having internal batteries within the EFIS is that
>nothing changes while you scurry to either change the fuse or land and
>repair - even for the AP. If I couldn't isolate the problem by replacing
>the fuse - I'd just land. Kind-o-like the ole' circuit breaker theory -
>if it blows once you reset it. If it blows twice, you leave it.
But what is the likelihood that replacing a properly sized,
popped fuse will restore any system to functionality? If
it's anticipated that the wing leveler's services will ever
be critical to comfortable termination of flight, then
is not as essential as radio navigation or cockpit lighting?
Perhaps dual wing levelers are in order? I'd bet that a BIG
chunk of the accidents due to poor pilot visibility and/or
workload distractions for single-pilot IFR would have been
averted electrons had the stick. I'll suggest that most
IFR capable airframes would be better outfitted for ventures
into poor visibility if there were NO displays on the panel
and dual, heading-slaved wing levelers installed. The wing
levelers are probably lighter and more reliable than a suite
of panel mounted gyros and more capable than pilot's trying
to manage an airplane interleaved with other distractions/
duties in the cockpit . . . including the distraction of
fiddling with fuses -OR- breakers.
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 3
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| Subject: | Re: D.A.R question about fuse access |
Good Evening Bob,
I agree with your evaluation, but back when Mooney tried it, most pilots
didn't care for it. You would regularly find the interrupt button taped down
thus deactivating the system. I feel certain that some method could be made
to work and still be acceptable to the average pilot, but no one has, as
yet, figured out that method.
Had JFK jr just let his autopilot fly his airplane, we would probably have
a light plane pilot high in our government hierarchy by now.
'Tis a quandary indeed!
Happy Skies,
Old Bob
AKA
Bob Siegfried
LL22
Stearman N3977A
In a message dated 7/19/2009 12:53:57 P.M. Central Daylight Time,
nuckolls.bob@aeroelectric.com writes:
Perhaps dual wing levelers are in order? I'd bet that a BIG
chunk of the accidents due to poor pilot visibility and/or
workload distractions for single-pilot IFR would have been
averted electrons had the stick. I'll suggest that most
IFR capable airframes would be better outfitted for ventures
into poor visibility if there were NO displays on the panel
and dual, heading-slaved wing levelers installed. The wing
levelers are probably lighter and more reliable than a suite
of panel mounted gyros and more capable than pilot's trying
to manage an airplane interleaved with other distractions/
duties in the cockpit . . . including the distraction of
fiddling with fuses -OR- breakers.
**************Can love help you live longer? Find out now.
(http://personals.aol.c
om/articles/2009/02/18/longer-lives-through-relationships/?ncid=emlweuslove00000001)
Message 4
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| Subject: | p and retard leads |
I have an engine with bendix shower of sparks magnetos.
The mags have number S4LN-200 and S4LN-204.
I need 2 ea. p-leads and 1 ea. retard lead to hook this up.
I dont know whether I need the hex nut or round nut connector,
nor where I can get same.
--
Jeff Peterson
Message 5
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At 06:06 PM 7/19/2009, you wrote:
>Good Evening Bob,
>
>I agree with your evaluation, but back when Mooney tried it, most
>pilots didn't care for it. You would regularly find the interrupt
>button taped down thus deactivating the system. I feel certain that
>some method could be made to work and still be acceptable to the
>average pilot, but no one has, as yet, figured out that method.
Yeah . . . PC (positive control) by Brittain as I recall.
A totally pneumatic wing leveler that operated directly
though valves at the back of the turn-coordinator driving
"tomato juice can" servos. A truly elegant design for its
time. Just found that the system is still offered at:
http://www.brittainautopilots.com/
I liked it. You couldn't hurt it by direct over-ride while
engaged. No servos to smoke, no clutches to burn, no
engagement solenoids to burn out. This was TSO-C3a hardware
which tells us how far back that goes. I did a little white
paper for Cessna way back when that suggested large diaphragm
pneumatic force cartridges operated by pitot/static delta-P
and permanently rigged to ailerons. A simple reed valve system
driven from a turn-coordinator would drive a simple set
of electronics that consumed less than 1 watt of total power.
Three moving parts, no lubrication issues, etc. etc. But they
were the proud owners of ARC who was already offering a line
of autopilots that plagued with every failure mode that such
devices might offer . . .
>
>Had JFK jr just let his autopilot fly his airplane, we would
>probably have a light plane pilot high in our government hierarchy by now.
Hmmm . . . you can lead a horse to water. . .
All we can do as teachers/designers/suppliers is offer well
considered advice backed by a history of recipes for success. Dr.
Dee speaks of a human condition known as "cognitive dissonance"
http://en.wikipedia.org/wiki/Cognitive_dissonance
which we've all observed first hand: "I KNOW that
smoking is bad for me . . . but I (like/need/want)
to do it". We've all observed a pilot's worst ever
day in the cockpit that appeared to rise from a
dead-short-between-the-headphones. It's called the
"bell curve". For the very best among us, there MUST
be individuals who balance out the other end of the
curve.
>
>'Tis a quandary indeed!
Let us continue to strive for position on the upper
slope of that curve . . .
Bob . . .
---------------------------------------
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
---------------------------------------
Message 6
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| Subject: | Re: p and retard leads |
I have those mags on my Mooney. The P-leads take one size round
connector, the retard lead is a different size, so you can't mix them up.
Jeff Peterson wrote:
> I have an engine with bendix shower of sparks magnetos.
> The mags have number S4LN-200 and S4LN-204.
>
> I need 2 ea. p-leads and 1 ea. retard lead to hook this up.
>
>
> I dont know whether I need the hex nut or round nut connector,
> nor where I can get same.
>
> --
> Jeff Peterson
>
> *
>
>
> *
Message 7
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| Subject: | Air conditioning stuff for sale |
Don't know if any of you are contemplating an air conditioning system in
your airplane or have an old R-12 system in your airplane (or car) that
needs fixing but I may have what you need. Since I no longer own a vehicle
that uses R-12 refrigerant I have seven 12 ounce cans available for sale at
$35 dollars apiece (a repair shop now charges upwards of $100 a pound for
R-12, if they can locate some). I also have an R-12 manifold gauge set
(used to monitor the high and low pressures in an R-12 system while filling)
and a tap for the R-12 cans ($35.00 for both of these). Let me know if you
need any of these or, buy the whole ball of wax for $250.00.
Dean Psiropoulos
RV-6A N197DM
Prop removed for radiographic inspection.
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