Today's Message Index:
----------------------
1. 12:03 AM - Re: ARC transponder connector? (jetboy)
2. 07:07 AM - running SD-8 without regulator (Bill Boyd)
3. 07:07 AM - Hot Wire Grid for Carb Heat (James H Nelson)
4. 08:14 AM - Re: Back-Up Battery ground (The multi-word answer) (Robert L. Nuckolls, III)
5. 08:14 AM - Re: Avionics cooler (Robert L. Nuckolls, III)
6. 08:22 AM - Re: running SD-8 without regulator (Robert L. Nuckolls, III)
7. 08:53 AM - Re: Re: Back-Up Battery ground (The multi-word answer) (Ernest Christley)
8. 09:10 AM - Re: Re: Back-Up Battery ground (The multi-word answer) (Robert L. Nuckolls, III)
9. 09:34 AM - Re: Avionics cooler (Carlos Trigo)
10. 10:06 AM - Re: Avionics cooler (Gilles Thesee)
11. 10:15 AM - Re: Avionics cooler (Robert L. Nuckolls, III)
12. 10:31 AM - switching from old to new (Michael T. Ice)
13. 10:31 AM - Re: Back-Up Battery (Carlos Trigo)
14. 01:53 PM - Re: Re: Back-Up Battery (C Smith)
15. 04:08 PM - Re: Back-Up Battery (Carlos Trigo)
16. 04:28 PM - Re: Avionics cooler (Carlos Trigo)
17. 04:38 PM - Re: Avionics cooler (Carlos Trigo)
18. 05:12 PM - Re: Re: Back-Up Battery (Robert L. Nuckolls, III)
19. 05:49 PM - Re: Re: Back-Up Battery (Ken)
20. 06:02 PM - Re: Re: Back-Up Battery (Ed Anderson)
21. 06:16 PM - Re: Avionics cooler (Speedy11@aol.com)
22. 06:26 PM - Re: "Broken and Garbled" (Additional data) (Speedy11@aol.com)
Message 1
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| Subject: | Re: ARC transponder connector? |
to make it clear pins 15,1 on the ssd120 go to gnd
pins 8,14 go to pin 9 on RT359A
Also I missed the +12v aircraft pwr goes to RT359 22
for 12V theres a jumper connecting pins 23, 8
By the look of the page I printed, it came off the aeroelectric connection data
Ralph
--------
Ralph - CH701 / 2200a
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=84945#84945
Message 2
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| Subject: | running SD-8 without regulator |
The next time I have the RV cowl off, I'd like to go ahead and install
the SD-8 dynamo, mostly to check for any interference issues with the
nearby P-mag (older style case). It may be awhile longer before I am
ready to tackle the larger task of mounting and wiring in all the
regulator and relay stuff to support the SD-8. Is there any potential
harm to operating this device with nothing at all attached to its
terminals? I'd think not, but I'd rather make sure.
-Bill B
Message 3
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| Subject: | Hot Wire Grid for Carb Heat |
Jim,
I had a 912S for several years. The engine can get carb ice.
There is a water heated jacket that attaches to the carburetor
immediately down stream of the carb. It actually attaches to the carb.
This jacket keeps the throttle plate from icing up. I think Rotax sell
it. It was originally designed and available from England. That unit
(2) will keep ice from forming period. You hook it up and forget it.
Forget the on / of valve and temp indicator as it is all stuff not
needed. It operates all the time the engine is running and producing hot
water. I added it to my Rotax to avoid having another control to mess
with and have ice build up and give me to much stress. Its worth the
added cost.
Jim Nelson
Message 4
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| Subject: | Re: Back-Up Battery ground (The multi-word answer) |
At 08:24 PM 12/26/2006 +0000, you wrote:
><trigo@mail.telepac.pt>
>
>Bob, Larry et all
>
>Please forget the reason why I may want to put the Avionics Back-Up
>battery in the tail, and please answer the electric questions:
> - Can I connect the (-) terminal of that battery to the tail's ground lug,
>which is isolated from the fuselage and is directly connected to the (-)
>terminal of the "Main" battery ?
Can't imagine what you're describing here. Ground the
battery to local structure.
> - Can I continue to use that same ground lug to connect the other grounds
>( from the tail light, the strobe beacon, and the elevator trim motor)
>there?
Ground these devices to local structure. You don't
need a "tail ground" in a metal airplane for items
located in the tail.
> - Isn't there any possibility of "ground loop"?
No.
Do you plan a "mini battery contactor" for this "mini-battery"?
Even thought it's a relatively small battery compared to
the ship's battery, it is capable of significant fault currents
and should be treated like any other battery with respect to
positive disconnection via local contactor.
It would be helpful if you could publish sketches of your
proposed wiring.
------******------
Now that there's a bit more time to consider the questions,
let's do a quick review of the techniques and rationale for
installing "backup" batteries:
When you use the phrase "backup" there is an implied
notion that what ever power supply is normally expected
to carry some load aboard the aircraft suffers a low order
of confidence that it will always be there to do its job.
For decades, we've willingly launched into the grey with
a dependence upon alternators and batteries with less than
stellar performance records. Certain essential radios were
similarly plagued with propensities for failure. These
demonstrable facts led us to adopt a variety of fall-back
plans that included dual radios, hand-held radios in the
flight bag, back-up batteries either installed or portable
that could be pressed into service should our worst nightmare
become a reality. It's also a certainty that public
perceptions of aviation and systems that support comfortable
flight are polluted with Hollywood's
The present state of the art in electrical system architecture
and quality of materials have demonstrated that modern
alternators and batteries are a factor of 10 better than
the devices we grew up with. Further, as members of the
OBAM aviation community, we've come to understand that with
some failure mode effects planning and the crafting of
practical preventative maintenance programs, we can
justify a high order of confidence in an aircraft
electrical system.
The classic idea of a "backup" power source has been
with us since day-one. The engine drive generator or
alternator is primary, the battery is a secondary energy
source. If we consider nothing beyond the classic
alternator/battery based electrical system, modern
components and reasonable preventative maintenance offers
great reliability.
With the popularity of all-electric panels on the
rise, many airplanes have an open pad on the engine
were a vacuum pump came off . . . and for a very small
$time$ and weight budget, we can enjoy a second
source of engine driven power with essentially
unlimited endurance.
If for whatever reason, a builder finds it useful
to add a second battery, a technique for adding a
battery to any system are illustrated in Z-30 of
http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf
Major features are an always-hot bus where feeders
from that bus are protected at 7A or less by fuses,
5A or less by breakers. The feeder between the battery
and its bus is kept short. The fat-wire between the
battery and the rest of the system is controlled
by some form of disconnect . . . either a contactor
where the battery is large and used to aid in cranking
an engine or perhaps a plastic, 20A relay where the
battery is small and not useful during engine cranking.
Of course, a small battery COULD be charged-only via
a low voltage drop diode (Schottky) in cases where
the battery is never expected to deliver energy back
to the charging system.
Let's explore the original questions that launched
this thread:
There was some concern about "ground loops" . . .
Ground loops are not created by the mis-application of
a battery ground. Ground loops are the mis-application
of grounds in TWO systems . . . the antagonist and
victim systems. For the most part, ground loops are
avoided by careful crafting of the wiring for potential
victims . . . so while battery charge/discharge
currents for the small stand-by battery under discussion
are a potential source for miniscule noise currents
carried on the battery's ground path, good grounding
practice for potential victims makes the ground-loop
question moot. So yes, the battery can share a ground
to the airframe with all other non-victim devices
that might also ground to that location.
If I understand correctly, this battery is being considered
as "useful ballast" and was not a high-priority
item in a failure mode effects analysis. This begs
the question as to why the ballast should become a battery
as opposed to a chunk of dead-lead. If the builder's
confidence level in the rest of the system is so low as
to make addition of this battery attractive, then I'll
suggest that some attention be paid to the rest of the
system first. Perhaps the perception of poor reliability
is not justified. If the goal is to simply make a piece
of necessary ballast "useful" I would suggest caution.
System complexity goes up which increases likelihood
of generating maintenance issues with the extra battery's
installation. I.e, you now have a piece of ballast with
an ongoing maintenance requirement for the lifetime of
the airplane. You also have battery disconnect and hot-bus
structures co-located in the tail with the battery.
Would it not be an improvement on the $time$ expensed
in the ownership of this airplane if the ballast were
"dead lead" as opposed to "useful"?
This presumes, of course, that all the appropriate homework
has been accomplished on the rest of the system that
drives real usefulness for this "backup" battery to zero.
In other words, if this battery has real value as a backup
energy source, does this not speak poorly of any efforts
to make the additional battery unnecessary in the first place?
Bob . . .
Message 5
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| Subject: | Re: Avionics cooler |
At 10:42 PM 1/1/2007 +0000, you wrote:
><trigo@mail.telepac.pt>
>
>Has anyone ever installed (even if not, I'd also like to hear your
>opinion) an avionics cooler, like this one from AmerI-King, in an OBAM
>airplane?
>What's your opinion on this?
>- Is it only necessary when you operate in hot climates?
Difficult to answer because so much is dependent upon"
how many radios are in your stack? . . . how well does
air circulate around them naturally? Does your cabin
heat outlet blow on the radios in cool weather?
The only solid answer to necessity for external cooling
is to conduct worst case conditions cooling tests with
thermocouples. This is impractical for the vast majority
of OBAM aircraft projects so the alternative is to
add blowers if there are any doubts as to the welfare
of tightly packed stacks of radios or any other electronics.
>- Which avionics do need this cooling? Xpdr, Comm radio, EFIS, GPS,
>Auto-Pilot controller?
In the early beginnings of the solid state radio days,
there was a common misconception that since transistor
radios ran cooler, that the need for forced air cooling
automatically went away.
Problem was that the parts associated with fabricating
any radio had about the same temperature limitations
whether used for vacuum tube or silicon radios. Further,
temperature rise within a radio was a function of WATT-DENSITY
or watts/cubic-in. While silicon radios dissipated fewer
watts internally, they were also MUCH more compact. It
was not unusual to find that some solid state radios
had worse internal hot-spots than did their vacuum
tube ancestors.
Whether or not any particular radio is vulnerable to
suffocation needs to come from the manufacturer. Instrument
panel mounted equipment for small aircraft would be qualified
under Category A1 for temperature/altitude. This is +55C
ambient and 15,000 feet. Check the devices you're installing
for their DO-160 qualification ratings.
Lots of older transponders and DME transceivers
were fitted with a dedicated blower duct attachment
right on the back of the radio and external cooling
required as part of the certified installation.
Except for the degree of circulation, a radio
behind the panel is breathing the same air as
you and +55 is really toasty!
It doesn't hurt to cool things but I'd be surprised
if any modern hunk of electronics will need it
in an OBAM light plane.
>- Is it mounted vertically, horizontally or either?
Cooling fans are not orientation sensitive . . .
>- Is it sufficient to use air from inside the cockpit as the source, or is
>it necessary to bring fresh air from the aircraft's exterior ?
Obviously, cooler is better . . . but be wary of external
air sources. We filled a few radios with rain water due
to poorly crafted duct drains when slip stream driven
droplets propagated all the way into the radios.
Unless your cooling air inlet is right next to your
cabin heat outlet, cabin ambient air is sufficient.
Recall that the effectiveness of cooling air has
more to do with motion than with temperature
differential. The most valuable task the cooling
air blower can serve is to CIRCULATE air at
almost any lower temperature.
>- Should it be ON everytime the avionics are ON, or should it have an
>independent On-Off switch? Is there any kind of thermostatic automatic switch
?
A switch (thermostatic or otherwise) not installed
is not going to require future maintenance or be forgotten
at a bad time. I'd recommend that cooling blowers be
powered from the main bus and come alive anytime the
airplane is powered up. I think that's what we do
with all avionics cooling in the big ships. If there's
a possibility that any radio is on, the blower(s) are
on too. No switches.
Bob . . .
Message 6
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| Subject: | Re: running SD-8 without regulator |
At 10:06 AM 1/2/2007 -0500, you wrote:
>
>The next time I have the RV cowl off, I'd like to go ahead and install
>the SD-8 dynamo, mostly to check for any interference issues with the
>nearby P-mag (older style case). It may be awhile longer before I am
>ready to tackle the larger task of mounting and wiring in all the
>regulator and relay stuff to support the SD-8. Is there any potential
>harm to operating this device with nothing at all attached to its
>terminals? I'd think not, but I'd rather make sure.
>
>-Bill B
No, there are no potential hazards to the alternator for
letting it run open-circuit.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 7
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| Subject: | Re: Back-Up Battery ground (The multi-word answer) |
Robert L. Nuckolls, III wrote:
>
> In other words, if this battery has real value as a backup
> energy source, does this not speak poorly of any efforts
> to make the additional battery unnecessary in the first place?
>
> Bob . . .
>
Not necessarily. With an electrically dependant, auto-conversion engine
you have ignition, control computers and fuel pumps which must all be
fed a healthy diet of electrons at somewhere around 15A. Even with the
'backup' battery, it would not be possible to burn through all the
usable fuel on board in case of an alternator failure. A 20Ah unit
would be marginal at best. The extra battery capacity in this case
carries very real benefits.
--
,|"|"|, Ernest Christley |
----===<{{(oQo)}}>===---- Dyke Delta Builder |
o| d |o http://ernest.isa-geek.org |
Message 8
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| Subject: | Re: Back-Up Battery ground (The multi-word answer) |
At 11:51 AM 1/2/2007 -0500, you wrote:
><echristley@nc.rr.com>
>
>Robert L. Nuckolls, III wrote:
>
>>
>> In other words, if this battery has real value as a backup
>> energy source, does this not speak poorly of any efforts
>> to make the additional battery unnecessary in the first place?
>>
>> Bob . . .
>Not necessarily. With an electrically dependant, auto-conversion engine
>you have ignition, control computers and fuel pumps which must all be fed
>a healthy diet of electrons at somewhere around 15A. Even with the
>'backup' battery, it would not be possible to burn through all the usable
>fuel on board in case of an alternator failure. A 20Ah unit would be
>marginal at best. The extra battery capacity in this case carries very
>real benefits.
Not the point. This is a 4.5 a.h. "backup" battery installed
in lieu of dead-lead as ballast. The question before us is
to ascribe value in having "ballast" assume lifetime requirements
for maintenance. This assumes the rest of the electrical system is
already blessed with load analysis, failure mode effects analysis and
preventative maintenance to insure that all other battery(ies)
will meet their intended purposes as sources of energy to back
up an alternator failure.
In other words, what is the return on investment for "useful"
ballast as opposed to "dead-lead."
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 9
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| Subject: | Re: Avionics cooler |
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>>- Is it only necessary when you operate in hot climates?
>
> Difficult to answer because so much is dependent upon"
> how many radios are in your stack? . . .
I will have 1 Comm Radio, 1 Transponder, 1 Garmin 296 and 1 Car radio/CD
player in the stack, plus 1 single display EFIS and the Auto-Pilot control
module.
> how well does air circulate around them naturally?
I believe (I'm not sure) that air will not circulate naturally, or very
little, behind my RV-9A panel.
> Does your cabin heat outlet blow on the radios in cool weather?
No. Besides the "normal" fresh air outlets, which are in the usual places in
side-by-side RV's, at the bottom corners of the panel, I will also have 2
separate heat outlets, situated right below the others, which will heat the
cabin, sourced from an hot coolant heater blower ( Eggenfellner Subaru
engine)
>>- Which avionics do need this cooling? Xpdr, Comm radio, EFIS, GPS,
>>Auto-Pilot controller?
>
> ......... Whether or not any particular radio is vulnerable to
> suffocation needs to come from the manufacturer. .....
> Check the devices you're installing for their DO-160 qualification
> ratings.
I will try to find that, however I am installing an ICOM A-200 (or perhaps,
if permitted by future income, a GARMIN SL-30) and a NARCO AT-160 (or a
GARMIN GTX-330, when mode S becomes mandatory in Europe).
>>- Is it mounted vertically, horizontally or either?
>
> Cooling fans are not orientation sensitive . . .
OK, if I install it, I will try to avoid puting it horizontally with the
inlet facing upwards, only to avoid the fan from throwing out dust or any
screw that could fall from the avionics :-)
>>- Is it sufficient to use air from inside the cockpit as the source, or is
>>it necessary to bring fresh air from the aircraft's exterior ?
>
> Obviously, cooler is better . . . but be wary of external
> air sources. We filled a few radios with rain water due
> to poorly crafted duct drains when slip stream driven
> droplets propagated all the way into the radios.
Yeah! Somebody else has already warned me against that possiblity
>>- Should it be ON everytime the avionics are ON, or should it have an
>>independent On-Off switch? Is there any kind of thermostatic automatic
>>switch ?
>
> A switch (thermostatic or otherwise) not installed
> is not going to require future maintenance or be forgotten
> at a bad time. I'd recommend that cooling blowers be
> powered from the main bus and come alive anytime the
> airplane is powered up. I think that's what we do
> with all avionics cooling in the big ships. If there's
> a possibility that any radio is on, the blower(s) are
> on too. No switches.
Not even to have the possibility to turn it Off in a
no-alternator-low-battery-power emergency situation?
Thanks
Carlos
Message 10
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| Subject: | Re: Avionics cooler |
>> I'd recommend that cooling blowers be
>> powered from the main bus and come alive anytime the
>> airplane is powered up....
>
> Not even to have the possibility to turn it Off in a
> no-alternator-low-battery-power emergency situation?
>
Carlos and all,
In that case, you'll be on E-bus only, so the fan will be off since it
is powered from the main power bus.
Or did you install no E-bus at all ?
Best wishes to all,
Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
Message 11
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| Subject: | Re: Avionics cooler |
At 05:28 PM 1/2/2007 +0000, you wrote:
><trigo@mail.telepac.pt>
>
>From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>
> <snip>
>
>>>- Should it be ON everytime the avionics are ON, or should it have an
>>>independent On-Off switch? Is there any kind of thermostatic automatic switch
?
>>
>> A switch (thermostatic or otherwise) not installed
>> is not going to require future maintenance or be forgotten
>> at a bad time. I'd recommend that cooling blowers be
>> powered from the main bus and come alive anytime the
>> airplane is powered up. I think that's what we do
>> with all avionics cooling in the big ships. If there's
>> a possibility that any radio is on, the blower(s) are
>> on too. No switches.
>
>Not even to have the possibility to turn it Off in a
>no-alternator-low-battery-power emergency situation?
If cooling is on the main bus and devices
needed for comfortable termination of flight
are on the e-bus, then cooling is one of those
loads automatically shed when the alternator
is inoperative.
Bob . . .
Message 12
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| Subject: | switching from old to new |
Hello,
I began wiring the RV-9 awhile back. I knew nothing about wiring, it terrified
me. I bought the Aeroelectric bible and the Z plans seemed like a maze into which
I spun out. So I did what I thought was the easy thing and bought the Van's
electric harness and all the switchable circuit breakers, the whole she-bang.
(Yeah, Yeah, I know, bad move.)
I installed the pre-made wire harness and while doing so continued to struggle
through reading the "book" and read posts to this list. Somewhere along the line
a little spark in the back of my brain began to grow into a light that allowed
me a tiny glimpse into what you folks are talking about.
Last weekend I finally got a bigger fire going and decided to can the Van's wire
harness (nothing wrong with that approach unless you want to modify) and do
the Z-11 Plan.
Here are the questions.
Are any of the switches that came with the Van's package any good for my new Z-11
plan?
Or is it better to buy all new switches and start fresh?
Any other words of wisdom, about wiring are greatly appreciated.
Blue Skies,
Mike Ice
Anchorage, Alaska
Message 13
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| Subject: | Re: Back-Up Battery |
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
> Now that there's a bit more time to consider the questions,
> let's do a quick review of the techniques and rationale for
> installing "backup" batteries:
>
> When you use the phrase "backup" there is an implied
> notion that what ever power supply is normally expected
> to carry some load aboard the aircraft suffers a low order
> of confidence that it will always be there to do its job.
>
> The classic idea of a "backup" power source has been
> with us since day-one. The engine drive generator or
> alternator is primary, the battery is a secondary energy
> source.
>
> With the popularity of all-electric panels on the
> rise,
I must say that my airplane will be double-electrically-dependant. I have a
Subaru electrically-dependant engine and an all-electric panel (well, I'll
still have 2 "steam-gauges": Altimeter and Airspeed Indicator). Since I have
no possibility of installing a second alternator or generator, and the
engine factory installation calls for 2 (equal) batteries, no wonder I am
thinking about a 3rd (small battery), also fuelled by the possibility of
having to put some wheight in the butt.
Opposite to your opinion, I think that, if I have to put some "dead" lead
down there, why not put some "live" lead (aka battery), which will do both
jobs? I believe it's a very good return on investment, like you love to say.
>
> There was some concern about "ground loops" . . .
> Ground loops are not created by the mis-application of
> a battery ground. Ground loops are the mis-application
> of grounds in TWO systems . . . the antagonist and
> victim systems. For the most part, ground loops are
> avoided by careful crafting of the wiring for potential
> victims . . . so while battery charge/discharge
> currents for the small stand-by battery under discussion
> are a potential source for miniscule noise currents
> carried on the battery's ground path, good grounding
> practice for potential victims makes the ground-loop
> question moot. So yes, the battery can share a ground
> to the airframe with all other non-victim devices
> that might also ground to that location.
>
OK, thanks. I think I already got the "ground loop" thing.
Carlos
Message 14
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| Subject: | Re: Back-Up Battery |
Subject: AeroElectric-List: Re: Back-Up Battery
<trigo@mail.telepac.pt>
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
> Now that there's a bit more time to consider the questions,
> let's do a quick review of the techniques and rationale for
> installing "backup" batteries:
>
> The classic idea of a "backup" power source has been
> with us since day-one. The engine drive generator or
> alternator is primary, the battery is a secondary energy
> source.
>
Opposite to your opinion, I think that, if I have to put some "dead" lead
down there, why not put some "live" lead (aka battery), which will do both
jobs? I believe it's a very good return on investment, like you love to say.
Maybe it needs to be presented in another way.
Carlos, the issues that (I think) Bob is trying to address is not so much
about dead vs. live weight but the utility of having a battery that is so
small in capacity to be of marginal "real" value. The battery will require
periodic maintenance, so you will need reasonable access. Will that access
then require additional modifications to the plans/airframe. Now, again look
at your return on the modification. Add to that the associated circuitry and
wiring.
Is this mounting engineering task worthy of 4.5 Ah?
Recently I was researching another issue regarding electrical code and
aircraft hangars and (can't remember if it was in FARs or NEC) came across
some rules that prohibit charging aircraft batteries installed in the
airframe. (that finally answered a nagging question I'd always had as to why
my external power connector was electrically isolated from the ships
battery).
The "back-up" system installed in the 182 is a substantial system. I don't
recall the exact AH capacity of the battery but it is physically at least as
large as the primary battery under the cowl. Therefore there is an access
panel on the tail for the purpose of servicing the battery and avionics rack
there. So the system in the Cessna is a substantial piece of engineering,
but also quite massive.
It appears from your descriptions that the battery would actually end up
being just added system AH capacity, not a true "back-up electrical power
source". The Cessna system will power the entire avionics system for a solid
45 min. There is a test circuit that is part of every preflight, in order to
verify that the system is charged and available (another piece of
engineering that a reliable back-up would reasonably require).
Now for the few pounds of weight needed for balance, does it still seem
reasonable to jump these hurdles? I guess there still are personal
considerations involved, an aversion to unitaskers, or having something that
is just weight on an airplane where dead weight just seems like a waste of
useful load. But honestly, YOUR efforts would be better spent on
construction of your aircraft. This is not sarcasm, or ridicule, but a
discussion of the merits of an effort. Back up systems are great, but they
entail a level of engineering/cost/maintenance that needs consideration
before proceeding.
Believe me, in my profession(machine tool manufacturing), we constantly look
for more efficiency and utility in our equipment, and in that quest I've
come up with a lot of ideas, not all of which stood up under scrutiny.
Fortunately there were others to look at my ideas and point out factors I
may not have been aware of, or looked at from another viewpoint. I'm
grateful that I was saved the embarrassment of having spent time and MONEY
on features of little practical use.
Bob is correct in that all of the contactors/protection needs to be
considered in your endeavor, some are regulatory as well as for your safety.
Craig Smith
Message 15
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| Subject: | Re: Back-Up Battery |
From: "C Smith" <pilot4profit@sbcglobal.net>
> The battery will require periodic maintenance, so you will need reasonable
> > access. Will that access then require additional modifications to the
> plans/airframe.
Not at all. It will be installed on the tail "deck" of the RV-9A, between
the 2 halfs of the horizontal stabilizer. I don't know if you are familiar
with it, but that zone is covered by a fiberglass fairing which makes the
aerodynamic transition between the H.S. and the vertical stabilizer, and is
attached with some 12 screws easily removable.
> Add to that the associated circuitry and wiring.
Very simple. Since I was "authorized" by the experts-on-duty to connect the
(-) terminal to the local ground, I will only have to squeeze in an AWG#14
wire from the tail to the instrument panel (in fact, I already did, in case
I decide for this battery), and connect it there to the avionics I decide to
have back-up power, and to the main battery, through a Diode, to take
charge.
> Is this mounting engineering task worthy of 4.5 Ah?
I don't know how to do the exact calculations, but I suppose that it will be
enough to power the Comm Radio, the Transponder, the EFIS and the Auto-pilot
(or some of these 4, depending on the pilot's decision) for the 45 min you
mentioned. Well maybe I should go for something a little larger (6 Ah ?),
providing it stays within the C.G. limits
> It appears from your descriptions that the battery would actually end up
> being just added system AH capacity, not a true "back-up electrical power
> source".
Not so, as you can see from the above descriptions. My idea is to use this
battery always at the start-up procedure, to initially power the EFIS (to
keep the battery used and to control its voltage), and from then, remain as
a pure back-up only for the avionics, in case of alternator-Off and the
engine-ignition-fuel pumps running only on the Main and/or Aux batteries.
> There is a test circuit that is part of every preflight, in order to
> verify that the system is charged and available (another piece of
> engineering that a reliable back-up would reasonably require).
Above answered
> Now for the few pounds of weight needed for balance, does it still seem
> reasonable to jump these hurdles?
Yes, it does to me. Does it already seem to you (no sarcasm here, I mean,
after my explanations) ?
> But honestly, YOUR efforts would be better spent on
> construction of your aircraft.
Don't worry, I'm not spending my efforts on this. Today I was riveting my
canopy
> Back up systems are great, but they entail a level of
> engineering/cost/maintenance that needs consideration before
> proceeding.
That's exactly the reason why I brought the subject to this knowleadgeble
forum ....
> Bob is correct in that all of the contactors/protection needs to be
> considered in your endeavor, some are regulatory as well as for your
> safety.
What I did was to install a 10 or 15A (I can't remember which) fuse on the
tail, at the positive wire, right "after" the (+) future battery terminal.
Isn't that enough protection?
Carlos
Message 16
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| Subject: | Re: Avionics cooler |
Bon soir Gilles
(Fait-il beaucoup de froid Grenoble?)
My system is based on the ExpBus, which in case you don't know, is a
premanufactured electric buss system (which, by the way, 'letric Bob doesn't
recommend).
But since my system has a Main Battery buss and an Aux Battery buss, I will
connect it to the Main, therefore it will also be OFF in case of an electric
emergency.
Carlos
----- Original Message -----
From: "Gilles Thesee" <Gilles.Thesee@ac-grenoble.fr>
Sent: Tuesday, January 02, 2007 6:06 PM
Subject: Re: AeroElectric-List: Avionics cooler
> <Gilles.Thesee@ac-grenoble.fr>
>
>
>>> I'd recommend that cooling blowers be
>>> powered from the main bus and come alive anytime the
>>> airplane is powered up....
>>
>> Not even to have the possibility to turn it Off in a
>> no-alternator-low-battery-power emergency situation?
>>
> Carlos and all,
>
> In that case, you'll be on E-bus only, so the fan will be off since it is
> powered from the main power bus.
> Or did you install no E-bus at all ?
>
> Best wishes to all,
>
> Regards,
> Gilles Thesee
> Grenoble, France
> http://contrails.free.fr
>
Message 17
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| Subject: | Re: Avionics cooler |
Tom S., James H., Charlie E., Bob N.
Thanks for your input. I will try to measure the panel back temperature with
all the avionics paraphernalia already working (which will only happen, very
conveniently, in the next summer) and I'll decide accordingly.
Carlos
Message 18
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| Subject: | Re: Back-Up Battery |
At 06:27 PM 1/2/2007 +0000, you wrote:
><trigo@mail.telepac.pt>
>
>From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>
>> Now that there's a bit more time to consider the questions,
>> let's do a quick review of the techniques and rationale for
>> installing "backup" batteries:
>>
>> When you use the phrase "backup" there is an implied
>> notion that what ever power supply is normally expected
>> to carry some load aboard the aircraft suffers a low order
>> of confidence that it will always be there to do its job.
>>
>> The classic idea of a "backup" power source has been
>> with us since day-one. The engine drive generator or
>> alternator is primary, the battery is a secondary energy
>> source.
>>
>> With the popularity of all-electric panels on the
>> rise,
>
>I must say that my airplane will be double-electrically-dependant. I have
>a Subaru electrically-dependant engine and an all-electric panel (well,
>I'll still have 2 "steam-gauges": Altimeter and Airspeed Indicator). Since
>I have no possibility of installing a second alternator or generator, and
>the engine factory installation calls for 2 (equal) batteries, no wonder I
>am thinking about a 3rd (small battery), also fuelled by the possibility
>of having to put some wheight in the butt.
>
>Opposite to your opinion, I think that, if I have to put some "dead" lead
>down there, why not put some "live" lead (aka battery), which will do both
>jobs? I believe it's a very good return on investment, like you love to say.
If you already have two batteries, how about moving one of them aft
to satisfy W&B requirements without having to add all the overhead
for installing and maintaining a third battery?
Only you can make the judgement as to whether the proposed, third,
itty-bitty battery offers a good return. But after years of
rubbing elbows with folks in the business, I know what reactions
we'd get if we add one more line item to the maintenance list
for continued air-worthiness . . . especially in view of the
relatively small benefits offered by a 4.5 a.h. device.
This is why I wanted to discuss it in more detail. I like it
if everyone monitoring the List understands all the ramifications
for such an installation and understand further that I would
recommend avoiding such an installation until all the alternatives
and cost of ownership issues have been evaluated. I.e., is there
a simpler way to get the job done?
Bob . . .
Message 19
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| Subject: | Re: Back-Up Battery |
>
>
> I don't know how to do the exact calculations, but I suppose that it
> will be enough to power the Comm Radio, the Transponder, the EFIS and
> the Auto-pilot (or some of these 4, depending on the pilot's decision)
> for the 45 min you mentioned. Well maybe I should go for something a
> little larger (6 Ah ?), providing it stays within the C.G. limits
Carlos
As a guess off the top of my head, consider that if you intend to draw
say 4 amps out of a 4.5 AH battery then you will only get about 2 AH or
30 minutes with a new fully charged battery. A battery has high internal
losses when working that hard. There are discharge charts available for
many batteries that will give you a better approximation.
If your main batteries are say 16 AH then they won't run the run the
engine for much more than 30 min. each if you are drawing nearly 15
amps. You'd likely do a bit better with the batteries paralled. Adding
another 4 amps to those main batteries will only shorten the engine
running by a few minutes. You might get more benefit per lb. from upping
one of the main batteries to 20 AH than from adding another 4.5 AH battery.
However your weight and balance is certainly another consideration if
not your main concern with this. Yet another
important consideration will be system management though. If you
are ever in the situation where the battery capacity is that critical I
would urge you to make the system as easy to operate as possible and
ideally zero management. I would not want to have to manage 3 batteries
in the heat of the moment... Sizing the third battery so that it always
runs your critical instruments (E bus) and will outlast the engine might
be worth considering.
Also there are many ways to power a second generator on a subaru if you
decide you want more electrical capacity. I've even seen accessories
driven off a small flat belt from the prop shaft. I used two small
multi-v belts off the oem pulley on my ej22 and also I directly drive a
vacuum pump off the pulley end of a camshaft.
Ken
Message 20
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| Subject: | Re: Back-Up Battery |
Having flown an "electric dependent" Mazda rotary powered installation since
1998, I understand the concern about not having enough electrons along if
the electron pump stops working. However, I do agree with Bob concerning
the very marginal benefit vs complexity of a third small battery. I started
out with a modification of one of Bob's excellent wiring diagrams and ended
up with an 60 amp alternator (with abnormal voltage - too high or too low
warning )with the crowbar circuit tripper for the alternator and a
voltmeter. I started with two 25 AH Concord RCG batteries totaling 44 lbs!.
I could have probably stayed airborn on just the starter motor {:>)
After flying for 4 years with this combination and only using the secondary
battery to help crank on cold mornings, I now fly my "all-electric" with one
680 Odyssey battery (which I swap out every 2 years regardless of its
condition). I have shed 30 lbs of battery weight and I believe that on the
east coast that the 30-45 minutes the 17 AH Odyssey will give me at minimum
current drain configuration should enable me to easily find a suitable
airport. My minimum current drain configuration is all but engine
electronics off, GPS on battery, radio on. I pull a CB so only one set of
spark plugs are firing (the rotary has two per chamber), only one pair of
fuel injectors are firing (plenty to keep me airborn) and only one fuel pump
is running.
I have learned the hard way that weight is the performance killer and have
spent years slowly getting my aircraft's weight reduced toward a norm for my
bird. I would strongly suggest following Bob's suggestion of moving one of
your two batteries toward the rear for the W&B and forgetting the third
battery.
FWIW
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda/index.html
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
Sent: Tuesday, January 02, 2007 8:10 PM
Subject: Re: AeroElectric-List: Re: Back-Up Battery
> <nuckollsr@cox.net>
>
> At 06:27 PM 1/2/2007 +0000, you wrote:
>
>><trigo@mail.telepac.pt>
>>
>>From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
>>
>>> Now that there's a bit more time to consider the questions,
>>> let's do a quick review of the techniques and rationale for
>>> installing "backup" batteries:
>>>
>>> When you use the phrase "backup" there is an implied
>>> notion that what ever power supply is normally expected
>>> to carry some load aboard the aircraft suffers a low order
>>> of confidence that it will always be there to do its job.
>>>
>>> The classic idea of a "backup" power source has been
>>> with us since day-one. The engine drive generator or
>>> alternator is primary, the battery is a secondary energy
>>> source.
>>>
>>> With the popularity of all-electric panels on the
>>> rise,
>>
>>I must say that my airplane will be double-electrically-dependant. I have
>>a Subaru electrically-dependant engine and an all-electric panel (well,
>>I'll still have 2 "steam-gauges": Altimeter and Airspeed Indicator). Since
>>I have no possibility of installing a second alternator or generator, and
>>the engine factory installation calls for 2 (equal) batteries, no wonder I
>>am thinking about a 3rd (small battery), also fuelled by the possibility
>>of having to put some wheight in the butt.
>>
>>Opposite to your opinion, I think that, if I have to put some "dead" lead
>>down there, why not put some "live" lead (aka battery), which will do both
>>jobs? I believe it's a very good return on investment, like you love to
>>say.
>
> If you already have two batteries, how about moving one of them aft
> to satisfy W&B requirements without having to add all the overhead
> for installing and maintaining a third battery?
>
> Only you can make the judgement as to whether the proposed, third,
> itty-bitty battery offers a good return. But after years of
> rubbing elbows with folks in the business, I know what reactions
> we'd get if we add one more line item to the maintenance list
> for continued air-worthiness . . . especially in view of the
> relatively small benefits offered by a 4.5 a.h. device.
>
> This is why I wanted to discuss it in more detail. I like it
> if everyone monitoring the List understands all the ramifications
> for such an installation and understand further that I would
> recommend avoiding such an installation until all the alternatives
> and cost of ownership issues have been evaluated. I.e., is there
> a simpler way to get the job done?
>
> Bob . . .
>
>
>
Message 21
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| Subject: | Re: Avionics cooler |
Has anyone ever installed (even if not, I'd also like to hear your opinion)
an avionics cooler
Carlos,
I have the same experience as Tom S. The avionics manufacturers said that
while a fan is not required, it will extend the life of the avionics. Also, a
local avionics expert advised me to install one. So, I'm listening to the
experts - despite the cost and weight.
As with Tom, mine will also cool the SL-30, transponder and EFIS using
ambient air. It will be on anytime the main bus has power. It will be mounted
behind the panel.
Stan Sutterfield
Do not archive
Message 22
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| Subject: | Re: "Broken and Garbled" (Additional data) |
Very cool info. I wasn't aware of those radios. I ordered a pair as soon as
I saw your posting. Thanks.
Stan Sutterfield
Do not archive
GMRS, FRS and a few other handy acronyms are used to describe a variety
of license free or easy license use of the radio spectrum for
personal communications.
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