Today's Message Index:
----------------------
1. 03:53 AM - Re: Heathrow 787 lithium event (Henador Titzoff)
2. 07:10 AM - Re: Re: two com radios (Bob Verwey)
3. 08:41 AM - Re: Heathrow 787 lithium event (Robert L. Nuckolls, III)
4. 09:15 AM - Re: Multi-hop wire sizing? (donjohnston)
5. 10:06 AM - Re: 14V or 28V (Jeff Luckey)
6. 10:09 AM - Re: Re: Multi-hop wire sizing? (Robert L. Nuckolls, III)
7. 10:23 AM - Re: 14V or 28V (Carlos Trigo)
8. 10:29 AM - Re: Multi-hop wire sizing? (donjohnston)
9. 10:34 AM - Re: Re: Multi-hop wire sizing? (Bill Putney)
10. 10:37 AM - Re: 14V or 28V (Eric M. Jones)
11. 10:56 AM - Re: 14V or 28V (Jeff Luckey)
12. 11:08 AM - Re: Re: 14V or 28V (Carlos Trigo)
13. 11:17 AM - Re: 14V / 28V converter (Carlos Trigo)
14. 11:41 AM - Re: 14V or 28V (Dj Merrill)
15. 11:57 AM - Re: 14V / 28V converter (Jeff Luckey)
16. 01:15 PM - Re: Re: 14V or 28V (Tim Andres)
17. 01:33 PM - Re: 14V or 28V (Eric M. Jones)
18. 01:33 PM - Re: Multi-hop wire sizing? (donjohnston)
19. 02:12 PM - Re: Re: 14V or 28V (Robert L. Nuckolls, III)
20. 02:20 PM - Re: Re: Multi-hop wire sizing? (Robert L. Nuckolls, III)
21. 02:41 PM - Re: Re: 14V or 28V (GERRY VAN%20DYK)
22. 04:30 PM - Re: 14V / 28V converter (Bill Putney)
23. 05:06 PM - Re: Re: Multi-hop wire sizing? (Bill Putney)
24. 05:13 PM - Re: Re: Multi-hop wire sizing? (Bill Putney)
25. 08:43 PM - FAR 23 and airplanes of any stripe (Robert L. Nuckolls, III)
26. 11:43 PM - Re: FAR 23 and airplanes of any stripe (Bill Putney)
Message 1
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Subject: | Re: Heathrow 787 lithium event |
Bob, I believe the FAA is requiring that all 787 ELTs be inspected as a sam
pling of a larger population in order to derive statistical data, then regr
oup and do what's in section Interim Action:=0A=0A---- "This AD is
considered to be interim action. Because the fire occurred on a =0A--
--- Model 787-8 airplane, required actions in this AD are focused on
Honeywell=0A- - - fixed ELTs installed on that model. However, we ack
nowledge that ELTs are=0A- - - installed on various other aircraft; t
herefore, continued investigation is=0A- - - required. Once final act
ion has been identified, we might consider further=0A- - - rulemaking
." =0A=0AIt just seems odd that this particular model ELT decided to burn u
p on a DreamLiner and so far, two of its worse problems involve lithium bat
teries. Maybe the DreamLiner has more vibration at specific frequencies tha
n other planes, and the ELT is spec'ed incorrected?- All I know is it's e
asier to blame the little guy than the big guy, especially when it involves
big corporations and/or government. It won't be long before this airplane
is called the BadDreamLiner.=0A=0AYes, I'm glad I fly OBAM, but it's mostly
because of the TSA and all the security hassles we're subjected to. I don'
t mind being frisked by a good looking babe, but most of them are Fugly! I
asked one if the TSA paid all the bills, and she said "no, I also work nigh
ts at a masochist masseuse parlor. Here's my business card."=0A=0A-=0AHen
ador Titzoff=0A=0A=0A________________________________=0A From: "Robert L. N
uckolls, III" <nuckolls.bob@aeroelectric.com>=0ATo: aeroelectric-list@matro
nics.com =0ASent: Monday, July 29, 2013 12:54 AM=0ASubject: Re: AeroElectri
c-List: Heathrow 787 lithium event=0A =0A=0A=0AAt 07:48 PM 7/28/2013, you w
rote:=0A=0AThe DreamLiner has had its share=0Aof glaring problems.- If a
pinched wire was the root cause of=0Afailure, then I attribute this to poor
workmanship.- This is a very=0Abad attribute for a new, high tech airlin
er, possibly leading to other=0Afailures.- What else lurks inside that ca
rcass?=0A>=0A>Last thing I need is the stench of dilithium crystals boiling
under my=0Abutt.=0A-- Yes but . . . it seems this 'pinched wire' is IN
SIDE=0Athe=0A-- ELT. The FAA issued an AD against the airframe=0A=0Ahtt
p://tinyurl.com/mekmrzd=0A=0A-- stating . . .=0A=0A"We are issuing this
AD=0Ato prevent a fire in the aft crown of the airplane, or to=0Adetect an
d correct discrepancies within the ELT that could cause such a=0Afire." -
- -------=0A=0A- . . .which I find a little odd. If the
suspected=0A- root cause is located inside a TSO'ed appliance=0A- then
I would have thought the AD would have been=0A- written against that appl
iance.=0A=0A- There are approximately 6000 of this ELT in=0A- service b
ut the AD only investigates those installed=0A- on the 787 and then in ve
ry unspecific terms except=0A- to =0A=0A"Inspect the Honeywell fixed ELT
=0Afor discrepancies, and do all applicable corrective actions=0Abefore fur
ther flight, using a method approved in accordance with the=0Aprocedures sp
ecified in=0Aparagraph (h) of this AD."=0A=0A- Not sure I understand how
this works . . .=0A- perhaps every ELT installed on a 787=0A- receives
proper 'corrective action', gets=0A- re-installed and all is right with t
he=0A- universe?- Seems there's a few thousands=0A- yet to be inspect
ed/corrected. . . oh,=0A- perhaps another AD, this time against the=0A-
ELT.=0A=0A- In the mean time, how would you like to=0A- be Honeywell l
ooking at financing the fixing=0A- of a smoked 787 and doing inspect/repa
ir/replace=0A- on a boatload of ELTs?=0A=0A- Aren't you glad you fly an
=====
Message 2
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Subject: | Re: two com radios |
Todd, thanks for the heads up on an issue I would never have considered
from that point of view!
Just wrestling with the whole 2 comms/intercom problem at the moment. You
just made it easier!
Bob Verwey
A35 Bonanza ZU-DLW
Safari ZU- AJF
On 27 July 2013 20:15, toddheffley <public@toddheffley.com> wrote:
> public@toddheffley.com>
>
> John
>
> I wonder if you have considered an alternative solution to a installed
> second com?
>
> My experience with hand crafted audio control systems has been 100%
> negative,,,, meaning poorly thought out, no documentation, making repair a
> puzzling endeavor.
>
> My favorite set up for a VFR/CrossCountry/LightIFR aircraft is:
>
> ONE com. The best quality you can afford. CI122 antenna on the belly,
> Meaning a REAL antenna, not just a cheapy 1/4 wave stick, not a internal
> antenna. Best practices on coax termination and so forth. Carefully think
> through Bob's well documented Zdiagrams to give the unit the bast chance of
> rock solid power + some type of Plan B power.
>
> A intercom correctly installed with the direct Mic/Phone jacks wired, as
> well as the Pilot/Copilot/Pax mic/phone jacks. NAT is my favorite, but
> that is because I am a snob.
>
> My point is, put most of you eggs in that basket and make that basket
> FIRST RATE.
>
> Secondly, a backup com system that is a REAL backup.
>
> Meaning, a handheld radio, SOLIDLY afix the panel or side wall. Separate
> mic and phone jacks wired ONLY to the handheld. A DEDICATED 2nd com antenna
> hooked directly to the handheld.
>
> FRESH batteries, and/or Fresh spare batteries in the flight bag.
>
> This approach gets rid of the audio panel, a single point of failure, and
> divides the cost of the second com in half.
>
> I recommend this after YEARS of working on light aircraft with poorly
> maintained, 2nd rate avionics.
>
> Best wishes for you and your project.
>
> Todd
>
> --------
> WWW.toddheffley.com
> www.theinterconnectco.com for lighting products
> AV-TS.com for Jet Aircraft Test Equipment
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=405436#405436
>
>
Message 3
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Subject: | Re: Heathrow 787 lithium event |
At 05:52 AM 7/29/2013, you wrote:
Bob, I believe the FAA is requiring that all 787 ELTs be inspected as
a sampling of a larger population in order to derive statistical
data, then regroup and do what's in section Interim Action:
It may well be . . . but it seems that a
mandatory service bulletin from Boeing would
do the same thing.
It just seems odd that this particular model ELT decided to burn up
on a DreamLiner and so far, two of its worse problems involve lithium
batteries. Maybe the DreamLiner has more vibration at specific
frequencies than other planes, and the ELT is spec'ed
incorrected? All I know is it's easier to blame the little guy than
the big guy, especially when it involves big corporations and/or
government. It won't be long before this airplane is called the BadDreamLiner.
The difference between failures in the ship's
system batteries and the ELT battery is profound.
Root cause for the system batteries was internal
to the battery and was not particularly unique
to the lithium chemistry . . . all battery
technologies have suffered separator development
and quality control problems at one time or
another.
The 'simple failure' that occurred within the
battery was elevated in consequence by the chemistry
that really likes to burn.
The failure in the ELT seems to be a quality control
issue with the routing of wires outside the batteries
during assembly. Again, the 'simple failure' was
elevated to $high$ miseries by the energetic failure
mode of the lithium batteries . . . but in this
case, the batteries themselves were performing as
designed and qualified onto the product.
In the first case, we have a failure to meet design
goals in a product with hazardous failure modes. In
the second case, the failure seems to reside with
first line supervision in manufacturing and quality
control of a mature product. The first case is
not excusable but understandable. The second case
(assuming present suppositions are proven true)
boggles the mind.
Yes, I'm glad I fly OBAM, but it's mostly because of the TSA and all
the security hassles we're subjected to. I don't mind being frisked
by a good looking babe, but most of them are Fugly! I asked one if
the TSA paid all the bills, and she said "no, I also work nights at a
masochist masseuse parlor. Here's my business card."
Understand. And I hope my comments were not mis-interpreted
by anyone to mean that my global view of hazard for
the air transport industry was pessimistic. Those
guys could loose an airplane a day and still be
statistically safer than personal automobile.
I am concerned that questions of suitability to task,
meeting system design goals and having the will
and means to react quickly to serious problems
is bring impeded by an increasing load of no-value-
added 'activity' dictated by bureaucratic organization
and policy/procedures taking its toll on skills/
common-sense.
For the moment at least, we're largely free of such
impediments in the OBAM aviation world.
Bob . . .
Message 4
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Subject: | Re: Multi-hop wire sizing? |
Thanks for the reply.
But I still am unclear on something.
Let me try a different example.
The alternator (50a) B lead will connect to the battery side of the starter contactor
on the firewall. That wire will be about 4' long. When I size that wire,
do I only consider the 4' distance and ignore the larger wire to the battery?
(In which the alternator wire can be 12AWG)
Or do I consider the length from the alternator to the battery. (In which case
I'm looking at 8AWG).
Sorry if I'm not making my question clear. [Embarassed]
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405574#405574
Message 5
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|
You have to be careful when selecting power converters of this type.- =0A
=0ABe aware of the power requirements.- If the radio in question only dra
ws 2 amps at transmit then that's 48 watts of power, P = IE (watts = am
ps x volts) that the converter must deliver when you key the mic.- The on
e referenced is only 13 watts and would be inadequate.=0A=0A=0A=0A_________
_______________________=0A From: R. curtis <mrspudandcompany@verizon.net>
=0ATo: aeroelectric-list@matronics.com =0ASent: Sunday, July 28, 2013 5:15
AM=0ASubject: Re: AeroElectric-List: 14V or 28V=0A =0A=0A--> AeroElectric-L
ist message posted by: "R. curtis" <mrspudandcompany@verizon.net>=0A=0A=0A>
Still didn't get any answer about the second part of my initial query.=0A>
How about keeping the 14V system and using a 14/28 voltage converter to fe
ed=0A> the radio?=0A=0A=0A- - - You could use something like this.
- Just make sure that you=0A- - - size it to supply enough 24 volt
power for your needs.=0A- - - This will connect to your 12 volt sys
tem and supply 24 volts=0A- - - to your radios.=0A=0A- - - ht
tp://aconinc.com/index.php?route=product/product&path=1_12400_12402&pro
duct_id=136=0A=0A- - - Using this would mean that there is no othe
r mod required=0A- - - to your aircraft electrical system thus maint
aining a standard=0A- - - 12 volt system.=0A=0A- - - Roger
=0A=0A--=0A=0ADo you have a slow PC? Try a Free scan http://www.spamfighter
- - - - - - - - - - - - - - -Matt Dralle, List
======
Message 6
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Subject: | Re: Multi-hop wire sizing? |
At 11:15 AM 7/29/2013, you wrote:
>
>Thanks for the reply.
>
>But I still am unclear on something.
>
>Let me try a different example.
>
>The alternator (50a) B lead will connect to the battery side of the
>starter contactor on the firewall. That wire will be about 4' long.
>When I size that wire, do I only consider the 4' distance and ignore
>the larger wire to the battery? (In which the alternator wire can be 12AWG)
Yes, that wire is not part of the cranking system
and is rated for continuous duty operation at some
current level and ambient temperature.
So the alternator b-lead is sized to the alternator's
output. Don't know where you got 12AWG . . . 6 AWG
is closer to appropriate.
>Or do I consider the length from the alternator to the battery. (In
>which case I'm looking at 8AWG).
???? distance is not a factor here on these short runs.
It's temperature rise over ambient when subjected
to the design currents.
>Sorry if I'm not making my question clear. [Embarassed]
I'm sorry I didn't pick up on your concerns. We're
getting wrapped around the axles of minute details
that most venues have put aside with conservative
selection as opposed to spending $time$ on slicing
and dicing the options. I'd go to local weld shop
where I know you can get 4AWG welding cable . . .
and put a hunk of that nice flexible stuff in for
a b-lead feeder. If they stock 6AWG, cool, use
that.
But once that wire ties into the battery/starter
feeders for cranking, all the slicing and dicing for continuous
duty service is replaced with meeting design goals.
Goals in intermittent duty service where supply
voltage, load current and energy demands levied
by engine characteristics and pilot skills
stack up to suggest much fatter wires.
Wires so fat as to be insignificant
players in the voltage drop issues for the
continuous duty studies driven by a load
analysis.
If it were my airplane with 30' of cranking
loop, I'd go with 2AWG. B-lead at 4AWG. If
you've got a hydraulic gear pump, then you
MIGHT drop to 6AWG for that feeder but if
it is short and 4AWG was all the local shop
had in stock, make that 4AWG too.
The problems your wrestling with have legacy
solutions borne more of field experience and
practice than of finely tuned analysis.
Bob . . .
Message 7
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Jeff
Thanks for calling my attention.
In that case, I suppose the adequate should be this one
http://aconinc.com/index.php?route=product/product
<http://aconinc.com/index.php?route=product/product&path=1_12400_12406&produ
ct_id=436> &path=1_12400_12406&product_id=436
or this one
http://aconinc.com/index.php?route=product/product
<http://aconinc.com/index.php?route=product/product&path=1_12800_12807&produ
ct_id=531> &path=1_12800_12807&product_id=531
Is that so?
Carlos
De: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:04
Para: aeroelectric-list@matronics.com
Assunto: Re: AeroElectric-List: 14V or 28V
You have to be careful when selecting power converters of this type.
Be aware of the power requirements. If the radio in question only draws 2
amps at transmit then that's 48 watts of power, P = IE (watts = amps x
volts) that the converter must deliver when you key the mic. The one
referenced is only 13 watts and would be inadequate.
_____
From: R. curtis <mrspudandcompany@verizon.net
<mailto:mrspudandcompany@verizon.net> >
Sent: Sunday, July 28, 2013 5:15 AM
Subject: Re: AeroElectric-List: 14V or 28V
<mrspudandcompany@verizon.net <mailto:mrspudandcompany@verizon.net> >
> Still didn't get any answer about the second part of my initial query.
> How about keeping the 14V system and using a 14/28 voltage converter to
feed
> the radio?
You could use something like this. Just make sure that you
size it to supply enough 24 volt power for your needs.
This will connect to your 12 volt system and supply 24 volts
to your radios.
http://aconinc.com/index.php?route=product/product
<http://aconinc.com/index.php?route=product/product&path=1_12400_12402&produ
ct_id=136> &path=1_12400_12402&product_id=136
Using this would mean that there is no other mod required
to your aircraft electrical system thus maintaining a standard
12 volt system.
Roger
--
Do you have a slow PC? Try a Free scan
http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
<br =======================
Message 8
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Subject: | Re: Multi-hop wire sizing? |
>
> Yes, that wire is not part of the cranking system
> and is rated for continuous duty operation at some
> current level and ambient temperature.
Thanks! That's what I was looking for.
>
> So the alternator b-lead is sized to the alternator's
> output. Don't know where you got 12AWG . . . 6 AWG
> is closer to appropriate.
The chart in AC43-13 indicates that 28v over ~10' at 50a works out to 12AWG.
I've got some pretty tight ducts for wire and I'm trying to conserve space as much
as possible and at the same time meet the electron moving requirements.
The hydraulic pump is only about 18" from the battery and draws ~25a. So I'm thinking
of running 14AWG there.
Thanks again,
Don
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405581#405581
Message 9
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Subject: | Re: Multi-hop wire sizing? |
So...
1) I'd say that a 12 AWG wire is a little on the light side for 50A.
Should be a 6 or 8 AWG according to AC 43.13-1B.
b) I would recommend a 50A circuit breaker (push-pull or toggle) between
the alternator and the battery side of the starter relay that can be
operated by the pilot. It's bad when an alternator dies (open) and
doesn't charge when in flight. It's much worse when an alternator dies
(shorted) and starts draining the battery as fast as it can. In my
airplane, their is a wire from the battery side of the starter solenoid
to the master bus (where all the circuit breakers are) and the
alternator is just another one on that bus. Of course there is also a 5A
breaker for the "field" (really goes to the regulator and then to the
rotor in the alternator).
III) In all cases you first look at AC 43.13-1B
(http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861)
Table 11-9 to find the minimum size wire you need. This is the wire's
maximum capacity regardless of length. It is based on the heat generated
as the current flows though the wire's internal resistance (you know
current * resistance per foot = watts of heat per foot). Select the wire
the size dictated by the load and wire temperature rating. For a 50A
circuit you need an 8 or 6 AWG wire depending on the temperature rating.
Then, use AC 43.13-1B Figure 11-3 to determine the larger size wire
needed if a longer wire run would have too much voltage drop for the
circuit. Length is the round trip circuit so if you're using the
airframe in a well bonded aluminum airplane the ground return is pretty
much ignored. If you've got a nav light at the tip of a fiberglass wing,
you have to calculate the length including the hot wire out to the load
and the ground return wire length back.
Note to self: I really have to connect the engine to the airframe (or
ground bus in a composite aircraft) with at least as big a wire as I
used for the starter. Bolts through the engine shock mounts don't count.
Bill
On 7/29/13 9:15 AM, donjohnston wrote:
>
> Thanks for the reply.
>
> But I still am unclear on something.
>
> Let me try a different example.
>
> The alternator (50a) B lead will connect to the battery side of the starter contactor
on the firewall. That wire will be about 4' long. When I size that wire,
do I only consider the 4' distance and ignore the larger wire to the battery?
(In which the alternator wire can be 12AWG)
>
> Or do I consider the length from the alternator to the battery. (In which case
I'm looking at 8AWG).
>
> Sorry if I'm not making my question clear. [Embarassed]
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=405574#405574
>
>
Message 10
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|
BTW: The presumption that a 28V radio has greater transmitting power than a 12V
radio is, in principle, untrue.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405583#405583
Message 11
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Carlos,=0A=0AYou should start with the spec sheet of the radio that you wan
t to use to determine its current draw.- Then you can use the formula I p
rovided to calc the required power.- I would then select a power converte
r that gives you a significant safety margin of power; perhaps at least 20
percent greater power than your calculation indicates.=0A=0ALet's hope some
one on this List has done this before and can recommend a device that they
have used successfully.=0A=0A=0A=0A=0A________________________________=0A F
rom: Carlos Trigo <trigo@mail.telepac.pt>=0ATo: aeroelectric-list@matronics
.com =0ASent: Monday, July 29, 2013 10:21 AM=0ASubject: RE: AeroElectric-Li
st: 14V or 28V=0A =0A=0A=0AJeff=0A-=0AThanks for calling my attention.=0A
In that case, I suppose the adequate should be this one=0A-=0Ahttp://acon
inc.com/index.php?route=product/product&path=1_12400_12406&product_id
=436=0A-=0Aor this one =0A-=0Ahttp://aconinc.com/index.php?route=pr
oduct/product&path=1_12800_12807&product_id=531=0A-=0AIs that so?=0AC
arlos =0A-=0A-=0ADe:owner-aeroelectric-list-server@matronics.com [mailt
o:owner-aeroelectric-list-server@matronics.com] Em nome de Jeff Luckey=0AEn
viada: 29 de julho de 2013 18:04=0APara: aeroelectric-list@matronics.com=0A
Assunto: Re: AeroElectric-List: 14V or 28V=0A-=0AYou have to be careful w
hen selecting power converters of this type.- =0A=0ABe aware of the power
requirements.- If the radio in question only draws 2 amps at transmit th
en that's 48 watts of power, P = IE (watts = amps x volts) that the con
verter must deliver when you key the mic.- The one referenced is only 13
watts and would be inadequate.=0A-=0A=0A________________________________
=0A=0AFrom:R. curtis <mrspudandcompany@verizon.net>=0ATo: aeroelectric-list
@matronics.com =0ASent: Sunday, July 28, 2013 5:15 AM=0ASubject: Re: AeroEl
urtis" <mrspudandcompany@verizon.net>=0A=0A=0A> Still didn't get any answer
about the second part of my initial query.=0A> How about keeping the 14V s
ystem and using a 14/28 voltage converter to feed=0A> the radio?=0A=0A=0A
- - - You could use something like this.- Just make sure that you
=0A- - - size it to supply enough 24 volt power for your needs.=0A-
- - This will connect to your 12 volt system and supply 24 volts=0A-
- - to your radios.=0A=0A- - - http://aconinc.com/index.php?rout
e=product/product&path=1_12400_12402&product_id=136=0A=0A- - -
Using this would mean that there is no other mod required=0A- - - to
your aircraft electrical system thus maintaining a standard=0A- - - 1
2 volt system.=0A=0A- - - Roger =0A=0A--=0A=0ADo you have a slow PC?
Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen=0A=0A
=0A<br- - - - - - - - - - -========
=================0A=0A=0A=0A=0A=0A-=0A-
=0Ahttp://www.matronics.com/Navigator?AeroElectric-List=0Ahttp://forums.mat
=============
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Eric
Would you please elaborate a little bit on your opinion?
But do it for an electron-idiot guy, please...
Carlos
-----Mensagem original-----
De: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] Em nome de Eric M.
Jones
Enviada: 29 de julho de 2013 18:38
Para: aeroelectric-list@matronics.com
Assunto: AeroElectric-List: Re: 14V or 28V
--> <emjones@charter.net>
BTW: The presumption that a 28V radio has greater transmitting power than a
12V radio is, in principle, untrue.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405583#405583
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Subject: | 14V / 28V converter |
Well, the spec sheet of the TRIG radio mentions 2.4A when transmitting, so I
suppose that a 50W converter will still not be enough.
By the way, what would happen if I put an under rated converter, would it
fry after a couple of radio transmissions?
Carlos
De: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:55
Para: aeroelectric-list@matronics.com
Assunto: Re: AeroElectric-List: 14V or 28V
Carlos,
You should start with the spec sheet of the radio that you want to use to
determine its current draw. Then you can use the formula I provided to calc
the required power. I would then select a power converter that gives you a
significant safety margin of power; perhaps at least 20 percent greater
power than your calculation indicates.
Let's hope someone on this List has done this before and can recommend a
device that they have used successfully.
_____
From: Carlos Trigo < <mailto:trigo@mail.telepac.pt> trigo@mail.telepac.pt>
aeroelectric-list@matronics.com
Sent: Monday, July 29, 2013 10:21 AM
Subject: RE: AeroElectric-List: 14V or 28V
Jeff
Thanks for calling my attention.
In that case, I suppose the adequate should be this one
<http://aconinc.com/index.php?route=product/product&path=1_12400_12406&produ
ct_id=436>
http://aconinc.com/index.php?route=product/product&path=1_12400_12406&produc
t_id=436
or this one
<http://aconinc.com/index.php?route=product/product&path=1_12800_12807&produ
ct_id=531>
http://aconinc.com/index.php?route=product/product&path=1_12800_12807&produc
t_id=531
Is that so?
Carlos
De: <mailto:owner-aeroelectric-list-server@matronics.com>
owner-aeroelectric-list-server@matronics.com [
<mailto:owner-aeroelectric-list-server@matronics.com>
mailto:owner-aeroelectric-list-server@matronics.com] Em nome de Jeff Luckey
Enviada: 29 de julho de 2013 18:04
Para: <mailto:aeroelectric-list@matronics.com>
aeroelectric-list@matronics.com
Assunto: Re: AeroElectric-List: 14V or 28V
You have to be careful when selecting power converters of this type.
Be aware of the power requirements. If the radio in question only draws 2
amps at transmit then that's 48 watts of power, P = IE (watts = amps x
volts) that the converter must deliver when you key the mic. The one
referenced is only 13 watts and would be inadequate.
_____
From: R. curtis < <mailto:mrspudandcompany@verizon.net>
mrspudandcompany@verizon.net>
aeroelectric-list@matronics.com
Sent: Sunday, July 28, 2013 5:15 AM
Subject: Re: AeroElectric-List: 14V or 28V
<mrspudandcompany@verizon.net <mailto:mrspudandcompany@verizon.net> >
> Still didn't get any answer about the second part of my initial query.
> How about keeping the 14V system and using a 14/28 voltage converter to
feed
> the radio?
You could use something like this. Just make sure that you
size it to supply enough 24 volt power for your needs.
This will connect to your 12 volt system and supply 24 volts
to your radios.
http://aconinc.com/index.php?route=product/product
<http://aconinc.com/index.php?route=product/product&path=1_12400_12402&produ
ct_id=136> &path=1_12400_12402&product_id=136
Using this would mean that there is no other mod required
to your aircraft electrical system thus maintaining a standard
12 volt system.
Roger
--
Do you have a slow PC? Try a Free scan
http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
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> Would you please elaborate a little bit on your opinion?
> But do it for an electron-idiot guy, please...
I'm not Eric, but I'll chime in. VHF radio transmissions are line of
site. For the most part, if you can see it, you can "hear" it via radio.
Several years ago I climbed to the top of a mountain which was about 1
mile ASL. A friend of mine was ~80 miles away in a direct line, on the
ground at maybe 200 ASL. We both had handheld radios, and were talking
to each other. He was using 1/2 of a watt, I was using 1/4 of a watt
(the lowest power setting of the radios). There was barely any
discernible difference between 5 watts (the maximum setting), and the
low power settings that we were using.
In general, for the typical distances that we are communicating in our
airplanes, combined with the height above ground, it just doesn't matter
if the radio is 8 watts or 16 watts. The signal is only going to go as
far as line of site under normal conditions (ie, no weird atmospheric
"skip" happening).
In other words, under typical circumstances, you are not going to be
transmitting any farther using 16 watts than you are at 8 watts.
-Dj
--
Dj Merrill - N1JOV - VP EAA Chapter 87
Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/
Glastar Flyer N866RH - http://deej.net/glastar/
Message 15
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Subject: | Re: 14V / 28V converter |
=0A=0ABy the way, what would happen if I put an under rated converter, woul
d it fry after a couple of radio transmissions?=0A=0ALots of bad things:=0A
1. Transmitted signal would be weak or non-existant=0A2. Possible damage to
radio due to brown-out condition=0A3. You might fry the power supply or it
may have built-in overload protection and simply shut-off=0A=0A4. you migh
t induce total plutonic reversal and cause a rift in the space-time continu
um (oh, wait - that's only if you "cross the streams";)=0A=0A=0A=0A________
________________________=0A From: Carlos Trigo <trigo@mail.telepac.pt>=0ATo
: aeroelectric-list@matronics.com =0ASent: Monday, July 29, 2013 11:15 AM
=0ASubject: RE: AeroElectric-List: 14V / 28V converter=0A =0A=0A=0AWell, th
e spec sheet of the TRIG radio mentions 2.4A when transmitting, so I suppos
e that a 50W converter will still not be enough=0A=C2-=0ABy the
way, what would happen if I put an under rated converter, would it fry afte
r a couple of radio transmissions?=0A=C2-=0ACarlos=C2- =0A=C2-=0A=C2
-=0ADe:owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroele
ctric-list-server@matronics.com] Em nome de Jeff Luckey=0AEnviada: 29 de ju
lho de 2013 18:55=0APara: aeroelectric-list@matronics.com=0AAssunto: Re: Ae
roElectric-List: 14V or 28V=0A=C2-=0ACarlos,=0A=0AYou should start with t
he spec sheet of the radio that you want to use to determine its current dr
aw.=C2- Then you can use the formula I provided to calc the required powe
r.=C2- I would then select a power converter that gives you a significant
safety margin of power; perhaps at least 20 percent greater power than you
r calculation indicates.=0A=0ALet's hope someone on this List has done this
before and can recommend a device that they have used successfully.=0A=C2
-=0A=C2-=0A=0A________________________________=0A=0AFrom:Carlos Trigo <
trigo@mail.telepac.pt>=0ATo: aeroelectric-list@matronics.com=0ASent: Monday
, July 29, 2013 10:21 AM=0ASubject: RE: AeroElectric-List: 14V or 28V=0A=C2
-=0AJeff=0A=C2-=0AThanks for calling my attention.=0AIn that case, I su
ppose the adequate should be this one=0A=C2-=0Ahttp://aconinc.com/index.p
hp?route=product/product&path=1_12400_12406&product_id=436=0A=C2-
=0Aor this one =0A=C2-=0Ahttp://aconinc.com/index.php?route=product/pro
duct&path=1_12800_12807&product_id=531=0A=C2-=0AIs that so?=0ACarlos
=0A=C2-=0A=C2-=0ADe:owner-aeroelectric-list-server@matronics.com[mailto
:owner-aeroelectric-list-server@matronics.com] Em nome de Jeff Luckey=0AEnv
iada: 29 de julho de 2013 18:04=0APara: aeroelectric-list@matronics.com=0AA
ssunto: Re: AeroElectric-List: 14V or 28V=0A=C2-=0AYou have to be careful
when selecting power converters of this type.=C2- =0A=0ABe aware of the
power requirements.=C2- If the radio in question only draws 2 amps at tra
nsmit then that's 48 watts of power, P = IE (watts = amps x volts) that
the converter must deliver when you key the mic.=C2- The one referenced
is only 13 watts and would be inadequate.=0A=C2-=0A=0A___________________
_____________=0A=0AFrom:R. curtis <mrspudandcompany@verizon.net>=0ATo: aero
electric-list@matronics.com=0ASent: Sunday, July 28, 2013 5:15 AM=0ASubject
: Re: AeroElectric-List: 14V or 28V=0A=0A--> AeroElectric-List message post
ed by: "R. curtis" <mrspudandcompany@verizon.net>=0A=0A=0A> Still didn't ge
t any answer about the second part of my initial query.=0A> How about keepi
ng the 14V system and using a 14/28 voltage converter to feed=0A> the radio
?=0A=0A=0A=C2- =C2- =C2- You could use something like this.=C2- Jus
t make sure that you=0A=C2- =C2- =C2- size it to supply enough 24 vol
t power for your needs.=0A=C2- =C2- =C2- This will connect to your 12
volt system and supply 24 volts=0A=C2- =C2- =C2- to your radios.=0A
=0A=C2- =C2- =C2- http://aconinc.com/index.php?route=product/produc
t&path=1_12400_12402&product_id=136=0A=0A=C2- =C2- =C2- Using thi
s would mean that there is no other mod required=0A=C2- =C2- =C2- to
your aircraft electrical system thus maintaining a standard=0A=C2- =C2-
=C2- 12 volt system.=0A=0A=C2- =C2- =C2- Roger =0A=0A--=0A=0ADo yo
u have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter
?cid=sigen=0A=0A=0A<br=C2- =C2- =C2- =C2- =C2- =C2- =C2-
=C2- =C2- =C2- =C2-================
=========0A=0A=0A=0A=0A=C2-=0A=C2-=0A=C2-=0Ahttp://ww
w.matronics.com/Navigator?AeroElectric-List=0Ahttp://forums.matronics.com
=0Ahttp://www.matronics.com/contribution=0A=C2-=0A=C2- --> http://www.m
atronics.com/con=================0A=0A=0Aht
tp://www.matronics.com/Navigator?AeroElectric-List=0Ahttp://forums.matronic
=========
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Not arguing with that, but I believe the 430AW model is 28 volts only and is the
one with the 16 watt transmitter.
Tim
Sent from my iPad
On Jul 29, 2013, at 11:37 AM, "Eric M. Jones" <emjones@charter.net> wrote:
>
> BTW: The presumption that a 28V radio has greater transmitting power than a 12V
radio is, in principle, untrue.
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=405583#405583
>
>
>
>
>
>
>
>
>
>
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Yes, Watts is Watts, but the input voltage is irrelevant, and usually there isn't
much hardware-dependent on a particular voltage that the manufacturer won't
have another voltage available. But keeping the 28V radio and having an up-converter
is a bad use of money, an increase in noise and weight, a decrease in
reliability.
Eric's Rule #1: 1) Sell what you don't want on Ebay. 2) Buy the appropriate unit.
Eric's Rule #2: 99% of everything electrical on Earth comes in a 12V model.
GNS-430AW is 14/28 V operation.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405607#405607
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Subject: | Re: Multi-hop wire sizing? |
> 1) I'd say that a 12 AWG wire is a little on the light side for 50A.
> Should be a 6 or 8 AWG according to AC 43.13-1B.
My interpretation of figure 11-2 from 43-13-1B shows 12AWG. Are you sure you're
looking at the 28v column?
> b) I would recommend a 50A circuit breaker (push-pull or toggle) between the
alternator and the battery side of the starter relay that can be
> operated by the pilot. It's bad when an alternator dies (open) and
> doesn't charge when in flight. It's much worse when an alternator dies
> (shorted) and starts draining the battery as fast as it can. In my
> airplane, their is a wire from the battery side of the starter solenoid
> to the master bus (where all the circuit breakers are) and the
> alternator is just another one on that bus. Of course there is also a 5A
> breaker for the "field" (really goes to the regulator and then to the
> rotor in the alternator).
>
Excellent point. But with that configuration, it doesn't make sense to put the
starter contactor on the firewall because I'll still need to run the alternator
wire all the way up to the front anyway. I was planning on an ANL50 for protection.
> III) In all cases you first look at AC 43.13-1B
> (http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861)
> Table 11-9 to find the minimum size wire you need. This is the wire's
> maximum capacity regardless of length. It is based on the heat generated
> as the current flows though the wire's internal resistance (you know
> current * resistance per foot = watts of heat per foot). Select the wire
> the size dictated by the load and wire temperature rating. For a 50A
> circuit you need an 8 or 6 AWG wire depending on the temperature rating.
I'll look into that.
> Then, use AC 43.13-1B Figure 11-3 to determine the larger size wire
> needed if a longer wire run would have too much voltage drop for the
> circuit. Length is the round trip circuit so if you're using the
> airframe in a well bonded aluminum airplane the ground return is pretty
> much ignored. If you've got a nav light at the tip of a fiberglass wing,
> you have to calculate the length including the hot wire out to the load
> and the ground return wire length back.
Figure 11-3 in my copy is for intermittent load.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=405608#405608
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At 03:32 PM 7/29/2013, you wrote:
>
>Yes, Watts is Watts, but the input voltage is irrelevant, and
>usually there isn't much hardware-dependent on a particular voltage
>that the manufacturer won't have another voltage available.
Most of the time. Garmin had several products that
would run on 14/28 for the 'smart side' but needed
28v for full power out of the transmitter . . . but
it was still a quite useful output at 14v.
I'd have to dig back in my files to identify the radio
I did install drawings for on the AGATE program
at Beech but it had that characteristic.
Bob . . .
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Subject: | Re: Multi-hop wire sizing? |
At 12:33 PM 7/29/2013, you wrote:
>
>So...
>
>1) I'd say that a 12 AWG wire is a little on the light side for 50A.
>Should be a 6 or 8 AWG according to AC 43.13-1B.
>
>b) I would recommend a 50A circuit breaker (push-pull or toggle)
>between the alternator and the battery side of the starter relay
>that can be operated by the pilot.
Crew accessible b-lead breakers have pretty much gone
the way of the ADF and LORAN receivers.
B-lead protection moved out to the firewall on Bonanzas
about 35-30 years ago.
Emacs!
Not sure what the philosophy is for current
single engine production. I'll have to see
if I still know anyone at Cessna or Piper.
Bob . . .
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Just happened to be looking at the 400 series installation manual this afternoon.
Pate 1.4.2 "General Specifications" says:
Input Voltage range - all unites (main connector) 10 to 33.2 VDC
Input Voltage range GNC 420W, GNS 430W (Com Connector) - 11 to 33 VDC
Input Voltage range GNC 420AW, GNS 430AW (Com Connector) - 24.1 to 33 VDC
GNC 420W, GNC 420AW (Main Connector) 1.2A@28VDC (max) 2.5A@14VDC (max)
GNS 430W, GNS 430AW (Main Connector) 1.2A@28VDC (max) 2.5A@14VDC (max)
(amongst other specs)
Evidently the 420AW / 430AW units are 24/28V on the com side but full voltage range
on the main connector.
Gerry
----- Original Message -----
From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
Sent: Monday, July 29, 2013 3:11:29 PM
Subject: Re: AeroElectric-List: Re: 14V or 28V
At 03:32 PM 7/29/2013, you wrote:
>
>Yes, Watts is Watts, but the input voltage is irrelevant, and
>usually there isn't much hardware-dependent on a particular voltage
>that the manufacturer won't have another voltage available.
Most of the time. Garmin had several products that
would run on 14/28 for the 'smart side' but needed
28v for full power out of the transmitter . . . but
it was still a quite useful output at 14v.
I'd have to dig back in my files to identify the radio
I did install drawings for on the AGATE program
at Beech but it had that characteristic.
Bob . . .
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Subject: | Re: 14V / 28V converter |
So, it depends. Assume the wattage rating is the output wattage and not
the input wattage (being charitable here). A 50W converter is designed
to put out 1.8A at 28V. It probably operates over an 11V-15V input
range. So if it's 80% efficient it would use about 62W of power to make
the 50W on the output. A designer has to figure that at 11V input the
transistors that switch the DC have to be good for something more than
5.7A. At 15V They only need to do 4.2A and something slightly less than
that at the nominal 14V. What usually happens is that these inverters
use pulse duty cycle of these input transistors to do the raw regulation
of the output voltage. Once the maximum duty cycle is reached the power
in the circuit is at maximum and if more current is required the voltage
has to fall.
The bad news is that the power supply in the transceiver is also a
switch mode one (cause they're smaller, cheaper and lighter than
anything else) so it wants to keep the voltages inside the radio at the
designed conditions. So as the input voltage falls, it increases it's
duty cycle which draws more current at the input. I think you can see
where this is headed.
If the radio is designed well, it will blow an internal fuse or self
protect and shut down (probably requiring an avionics bus power cycle to
reset it). If it's pourly designed the radio's power supply will let the
internal voltages fall below the designed values making the transmitter
frequency unstable and creating all kinds of other interference products
in the transmitter. My guess that would be caught in the FCC independent
lab testing and it wouldn't get certified. So probably the power supply
in the radio is designed right.
You're asking that the converter operate at 130% of it's rated power?
Most designers cut some slack in their designs so you could get away
with a little. Most sales/marketing people want the numbers to sound big
though. So, if they say it's a 50W converter, that might be the input
power. If the converter is 80% efficient, that's 40W on the output.
About 1.4A and your radio is then 170% of the rated load. 70% is way to
expensive to design in for manufacturing slack. Of course your converter
may have used it's manufacturing slack in manufacturing...
I have had some sad experiences with one US manufacturers radio that
simply burn up the internal power supply in the radio in response to too
low an input voltage. It use to be that making the new engineers design
the power supplies was the thing to do because it was the least fun.
If you could figure out a way to limit the current in the converter, you
could charge a very small 28V battery from the converter and since the
transmitter duty cycle is low you'd just transmit using the battery
power to bridge the time you're transmitting and the battery would
charge back up using surplus capacity when the radio is in receive.
Or you could get the 14V Trig radio that puts out 6W instead of 12W.
That's an insignificant (-3dB) power decrease and oh so much simpler a
solution. A better antenna will make that much difference. If you were
in outer space the 12W would go twice as far but most of us don't travel
in outer space and we get over the horizon before we run out of power.
There is no limitation on the size of the transmitter based on input
voltage. I have a VHF ham radio that will deliver 100W and it runs on my
13V car battery. Draws a lot of amps doing it though. The power supply
inside the radio takes care of making the RF parts happy at whatever
power level is desired.
Bill
On 7/29/13 11:15 AM, Carlos Trigo wrote:
>
> Well, the spec sheet of the TRIG radio mentions 2.4A when
> transmitting, so I suppose that a 50W converter will still not be
> enough...
>
> By the way, what would happen if I put an under rated converter, would
> it fry after a couple of radio transmissions?
>
> Carlos
>
> *De:*owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] *Em nome de
> *Jeff Luckey
> *Enviada:* 29 de julho de 2013 18:55
> *Para:* aeroelectric-list@matronics.com
> *Assunto:* Re: AeroElectric-List: 14V or 28V
>
> Carlos,
>
> You should start with the spec sheet of the radio that you want to use
> to determine its current draw. Then you can use the formula I
> provided to calc the required power. I would then select a power
> converter that gives you a significant safety margin of power; perhaps
> at least 20 percent greater power than your calculation indicates.
>
> Let's hope someone on this List has done this before and can recommend
> a device that they have used successfully.
>
> ------------------------------------------------------------------------
>
> *From:*Carlos Trigo <trigo@mail.telepac.pt <mailto:trigo@mail.telepac.pt>>
> *To:* aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> *Sent:* Monday, July 29, 2013 10:21 AM
> *Subject:* RE: AeroElectric-List: 14V or 28V
>
> Jeff
>
> Thanks for calling my attention.
>
> In that case, I suppose the adequate should be this one
>
> http://aconinc.com/index.php?route=product/product&path=1_12400_12406&product_id=436
>
> or this one
>
> http://aconinc.com/index.php?route=product/product&path=1_12800_12807&product_id=531
>
> Is that so?
>
> Carlos
>
> *De:*owner-aeroelectric-list-server@matronics.com
> <mailto:owner-aeroelectric-list-server@matronics.com>[mailto:owner-aeroelectric-list-server@matronics.com]
> *Em nome de *Jeff Luckey
> *Enviada:* 29 de julho de 2013 18:04
> *Para:* aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> *Assunto:* Re: AeroElectric-List: 14V or 28V
>
> You have to be careful when selecting power converters of this type.
>
> Be aware of the power requirements. If the radio in question only
> draws 2 amps at transmit then that's 48 watts of power, P = IE (watts
> = amps x volts) that the converter must deliver when you key the mic.
> The one referenced is only 13 watts and would be inadequate.
>
> ------------------------------------------------------------------------
>
> *From:*R. curtis <mrspudandcompany@verizon.net
> <mailto:mrspudandcompany@verizon.net>>
> *To:* aeroelectric-list@matronics.com
> <mailto:aeroelectric-list@matronics.com>
> *Sent:* Sunday, July 28, 2013 5:15 AM
> *Subject:* Re: AeroElectric-List: 14V or 28V
>
>
> <mrspudandcompany@verizon.net <mailto:mrspudandcompany@verizon.net>>
>
>
> > Still didn't get any answer about the second part of my initial query.
> > How about keeping the 14V system and using a 14/28 voltage converter
> to feed
> > the radio?
>
>
> You could use something like this. Just make sure that you
> size it to supply enough 24 volt power for your needs.
> This will connect to your 12 volt system and supply 24 volts
> to your radios.
>
> http://aconinc.com/index.php?route=product/product&path=1_12400_12402&product_id=136
>
> Using this would mean that there is no other mod required
> to your aircraft electrical system thus maintaining a standard
> 12 volt system.
>
> Roger
>
> --
>
> Do you have a slow PC? Try a Free scan
> http://www.spamfighter.com/SLOW-PCfighter?cid=sigen
>
>
> <br =======================
>
>
> * *
> * *
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Message 23
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Subject: | Re: Multi-hop wire sizing? |
On 7/29/13 1:32 PM, donjohnston wrote:
>
>
>> 1) I'd say that a 12 AWG wire is a little on the light side for 50A.
>> Should be a 6 or 8 AWG according to AC 43.13-1B.
> My interpretation of figure 11-2 from 43-13-1B shows 12AWG. Are you sure you're
looking at the 28v column?
In that table voltage is irrelevant. It's the maximum current a wire of
a selected gauge (based on the internal resistance of the wire and the
amount of heat rise allowed) can safely handle. Could be 1V or 1000V. If
a piece of wire (of some length) has 1 ohm of resistance. 1 amp passed
through that wire will create 1 volt of drop across it and 1 watt of
heat. If the surface of the wire can dissipate that heat and stay below
the designed temperature it's safe. If the wire is operating in a
1,000,000 volt circuit with 1 amp flowing though it it's still going to
have 1 volt of drop across it creating the same 1 watt of heat.
>
>> b) I would recommend a 50A circuit breaker (push-pull or toggle) between the
alternator and the battery side of the starter relay that can be
>> operated by the pilot. It's bad when an alternator dies (open) and
>> doesn't charge when in flight. It's much worse when an alternator dies
>> (shorted) and starts draining the battery as fast as it can. In my
>> airplane, their is a wire from the battery side of the starter solenoid
>> to the master bus (where all the circuit breakers are) and the
>> alternator is just another one on that bus. Of course there is also a 5A
>> breaker for the "field" (really goes to the regulator and then to the
>> rotor in the alternator).
>>
> Excellent point. But with that configuration, it doesn't make sense to put the
starter contactor on the firewall because I'll still need to run the alternator
wire all the way up to the front anyway. I was planning on an ANL50 for protection.
I'd put the starter contactor as close to where the other loads are as
possible. If you have the battery in the back for W&B considerations
you're going to have to run a heavy gauge cable to the starter in the
front. Put the contactor on the firewall then everything gets to take
advantage of this big heavy wire when you're not cranking.
I realize that you aren't required to build to Part 23 standards but
some of them do make sense. Part 23 requires that circuit protection
devices for loads critical to safety of flight be resettable or
replaceable by the flight crew while in flight. What stuff are you
powering with the alternator you'd like to have if you're flying VFR on
top at night over Nevada somewhere? How would you fly and replace an
NL50 fuse? Where would you put it so it would be handy? Carrying a spare
NL50? That's required too (in Part 23).
>
>
>> III) In all cases you first look at AC 43.13-1B
>> (http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/99861)
>> Table 11-9 to find the minimum size wire you need. This is the wire's
>> maximum capacity regardless of length. It is based on the heat generated
>> as the current flows though the wire's internal resistance (you know
>> current * resistance per foot = watts of heat per foot). Select the wire
>> the size dictated by the load and wire temperature rating. For a 50A
>> circuit you need an 8 or 6 AWG wire depending on the temperature rating.
>
> I'll look into that.
>
>
>> Then, use AC 43.13-1B Figure 11-3 to determine the larger size wire
>> needed if a longer wire run would have too much voltage drop for the
>> circuit. Length is the round trip circuit so if you're using the
>> airframe in a well bonded aluminum airplane the ground return is pretty
>> much ignored. If you've got a nav light at the tip of a fiberglass wing,
>> you have to calculate the length including the hot wire out to the load
>> and the ground return wire length back.
> Figure 11-3 in my copy is for intermittent load.
Yes, you're right. It's probably safer to design the alternator circuit
for continuous duty. If you design to Part 23 your loads should never
exceed 80% of generating capacity. This was really hard to do before
there were LED and HID landing lights. Old tube radios really wolfed
down the juice too.
This table (Figure 11-2) really sets the allowable voltage drop over the
length of the wire. In a circuit where wire size is dominated by current
carrying capacity like the relatively short alternator wire, this table
doesn't dictate wire size. If the alternator is mounted on the front of
the engine, it could be 8-12 wire feet to get to the circuit protection
device and another 4-6 wire feet to get back to the battery side of the
starter contactor. Worst case that's between 12' and 20' and of wire
(always use the next line up on the chart) and that says an 8 AWG wire.
Then is it an 8 AWG or a 6 AWG? Depends on the thermal rating of the wire.
Bill
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=405608#405608
>
>
Message 24
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Subject: | Re: Multi-hop wire sizing? |
Message 25
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Subject: | FAR 23 and airplanes of any stripe |
Excellent point. But with that configuration, it doesn't make sense
to put the starter contactor on the firewall because I'll still need
to run the alternator wire all the way up to the front anyway. I was
planning on an ANL50 for protection.
Why? Did I miss something in the deliberations?
I'd put the starter contactor as close to where the other loads are
as possible. If you have the battery in the back for W&B
considerations you're going to have to run a heavy gauge cable to the
starter in the front. Put the contactor on the firewall then
everything gets to take advantage of this big heavy wire when you're
not cranking.
Okay, refresh my memory. I thought we were talking
about a canard pusher with battery in nose.
I realize that you aren't required to build to Part 23 standards but
some of them do make sense. Part 23 requires that circuit protection
devices for loads critical to safety of flight be resettable or
replaceable by the flight crew while in flight. What stuff are you
powering with the alternator you'd like to have if you're flying VFR
on top at night over Nevada somewhere? How would you fly and replace
an NL50 fuse? Where would you put it so it would be handy? Carrying a
spare NL50? That's required too (in Part 23).
Actually it is not. The relevant paragraph is here:
Sec. 23.1357 Circuit protective devices.
(a) Protective devices, such as fuses or circuit breakers, must be
installed in all electrical circuits other than--
(1) Main circuits of starter motors used during starting only; and
(2) Circuits in which no hazard is presented by their omission.
(b) A protective device for a circuit essential to flight safety may not be
used to protect any other circuit.
(c) Each resettable circuit protective device ("trip free" device in which
the tripping mechanism cannot be overridden by the operating control) must be
designed so that--
(1) A manual operation is required to restore service after tripping; and
(2) If an overload or circuit fault exists, the device will open the
circuit regardless of the position of the operating control.
(d) If the ability to reset a circuit breaker or replace a fuse is
essential to safety in flight, that circuit breaker or fuse must be so
located and identified that it can be readily reset or replaced in flight.
(e) For fuses identified as replaceable in flight--
(1) There must be one spare of each rating or 50 percent spare fuses of
each rating, whichever is greater; and
(2) The spare fuse(s) must be readily accessible to any required pilot.
1357.d speaks to 'essential to safety in flight' . . . okay suppose
you have a breaker that protects the only radio on the panel and you're
anticipating a launch into the murk. How many things in that radio can
'break' and render the radio inop? Don't know but you can bet
it's a bunch.
What is the likelihood that ANY kind of radio killing event will cause
the breaker to operate yet be 'clear' in some manner that
allows the breaker
to be reset?
Once a circuit protective device operates, the very high probability
assumption is that the powered device is no longer available
irrespective of root cause for the trip. At the same time, a
tripped breaker suggests that the device did it's job to prevent
electrically induced fire or wire damage. Once the breaker or fuse
has operated, do you really want to give it a second chance of
doing more damage?
Pilots in the big iron birds are told to leave popped breakers
alone . . . but if you're feeling lucky . . . reset one time only.
Failure tolerant design goals say that probability for comfortable
termination of flight is greatly enhanced if EVERY device
has a no-sweat backup. This includes the alternator. This
is the operating philosophy that birthed the e-bus about 20 years
ago. It's the philosophy that birthed Z-13/8 shortly thereafter.
That same philosophy is satisfied by having battery powered hand-helds
in the flight bag.
http://tinyurl.com/d5mrjgh
In other words, with careful management of known energy
requirements, it's no big deal to have greater electrical
endurance than fuel endurance. Hence, all things electric are
relieved of their sweat-breaking criticality and there's no
good reason to fiddle with any circuit progective device
in flight.
Yes, you're right. It's probably safer to design the alternator
circuit for continuous duty. If you design to Part 23 your loads
should never exceed 80% of generating capacity. This was really hard
to do before there were LED and HID landing lights. Old tube radios
really wolfed down the juice too.
The 80% rule was never intended to de-rate an
engine driven power source. It was intended to
wall off head-room for battery recharge in
some nominal period of time after takeoff . . .
no hard numbers here but 60-90 minutes has been
the rule of thumb . . . and is obviously driven
by the sized of the battery.
In fact, it's the dead-battery recharge scenario
that drove a number tense events for pilots. I've
often referred to the type-certificated, 60A B-lead
breaker on tens of thousands of airplanes fitted with
60A alternators as, "the breaker designed to nuisance trip."
A cold alternator recharging a dead battery will
put out significantly more than its nameplate rating.
I jump started a Cherokee 140 out of 1K1 and about
15 minutes out, the panel went black. B-lead breaker
was popped but resetting it did not bring the alternator
back. I'm guessing that the alternator load-dump
zorked something.
In any case, I finished the leg on hand-helds,
put a charger on the battery in Sallisaw and
flew home battery-only with minimal loads backed
up by hand-held. A no-sweat trip.
Your b-lead protection would do well to emulate
Beech and many others by switching to current
limiters (VERY robust fuses) on the firewall.
These DO NOT nuisance trip but will perform
intended functions for shorted diodes.
In spite of this level of robustness, there are
still many things that can take the alternator down
that a pilot is ill-advised to mess with while
in flight. Plans-B, C and even D outweigh a box
full of tools any day.
See Chapters 10 and 17 in the 'Connection. Also
articles at:
http://tinyurl.com/mpdjsef
http://tinyurl.com/mthp9u4
http://tinyurl.com/nxgdccs
http://tinyurl.com/7lhbbah
This table (Figure 11-2) really sets the allowable voltage drop over
the length of the wire. In a circuit where wire size is dominated by
current carrying capacity like the relatively short alternator wire,
this table doesn't dictate wire size. If the alternator is mounted on
the front of the engine, it could be 8-12 wire feet to get to the
circuit protection device and another 4-6 wire feet to get back to
the battery side of the starter contactor. Worst case that's between
12' and 20' and of wire (always use the next line up on the chart)
and that says an 8 AWG wire. Then is it an 8 AWG or a 6 AWG? Depends
on the thermal rating of the wire.
Circuit protection is classically installed as
close to the source of hazardous energy as practical. In
the case of the canard pusher with front mounted
battery, the current limiter would be mounted as
close to the starter contactor as practical and
the starter feeder used to take alternator energy
forward to the battery and bus structure.
Every "must" and "shall" in FAR23.1357 is easily
put to bed by well considered, failure tolerant
design. The most powerful failure tolerant design
goal says, "No single item in the electrical system
is necessary for me to comfortably terminate flight
at airport of intended destination without breaking
a sweat (or punching a circuit breaker back in)."
Too many stories like this have graced the pages
of the flying-rags . . .
http://tinyurl.com/kqo7jx8
. . .and for the most part, serve to illustrate how
little most pilots know about how their airplane's
systems really work. The sad thing is that the vast
majority of these stories should have played out
much differently . . . were in fact so ho-hum that
it wasn't worth writing for the magazine.
This my friends is what the 'Connection and these
forums are all about . . . A quest for ho-hum flying
where the most exciting features of a flight are
fantastic scenes viewed out the window.
Bob . . .
Message 26
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|
Subject: | Re: FAR 23 and airplanes of any stripe |
Damn Bob, you're so right! Why didn't I suggest that. Just charge the batter
y at every stop and do away with the alternator all together. :)
By the way, a 15 minute overload in the Cherokee probably falls outside the d
efinition of a "Nuisance Trip". And if you'd opened the breaker on the input
to the regulator you probably would have been able to reset the Over Voltag
e Protection circuit in the regulator and get the alternator back on line. J
ust a guess that when the output breaker opened the output voltage spiked an
d the OVP latched. Have to remove all the power to it to get it to reset. Bu
t you probably knew that.
You're right I did miss the pusher configuration part. You da man!
Bill
Sent from my iPad
On Jul 29, 2013, at 8:42 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroele
ctric.com> wrote:
> Excellent point. But with that configuration, it doesn't make sense to put
the starter contactor on the firewall because I'll still need to run the al
ternator wire all the way up to the front anyway. I was planning on an ANL5
0 for protection.
>
> Why? Did I miss something in the deliberations?
>
> I'd put the starter contactor as close to where the other loads are as pos
sible. If you have the battery in the back for W&B considerations you're goi
ng to have to run a heavy gauge cable to the starter in the front. Put the c
ontactor on the firewall then everything gets to take advantage of this big h
eavy wire when you're not cranking.
>
> Okay, refresh my memory. I thought we were talking
> about a canard pusher with battery in nose.
>
> I realize that you aren't required to build to Part 23 standards but some o
f them do make sense. Part 23 requires that circuit protection devices for l
oads critical to safety of flight be resettable or replaceable by the flight
crew while in flight. What stuff are you powering with the alternator you'd
like to have if you're flying VFR on top at night over Nevada somewhere? Ho
w would you fly and replace an NL50 fuse? Where would you put it so it would
be handy? Carrying a spare NL50? That's required too (in Part 23).
>
> Actually it is not. The relevant paragraph is here:
>
> Sec. 23.1357 Circuit protective devices.
> (a) Protective devices, such as fuses or circuit breakers, must be
> installed in all electrical circuits other than--
>
> (1) Main circuits of starter motors used during starting only; and
> (2) Circuits in which no hazard is presented by their omission.
>
> (b) A protective device for a circuit essential to flight safety may not b
e
> used to protect any other circuit.
> (c) Each resettable circuit protective device ("trip free" device in which
> the tripping mechanism cannot be overridden by the operating control) must
be
> designed so that--
>
> (1) A manual operation is required to restore service after tripping; and
> (2) If an overload or circuit fault exists, the device will open the
> circuit regardless of the position of the operating control.
>
> (d) If the ability to reset a circuit breaker or replace a fuse is
> essential to safety in flight, that circuit breaker or fuse must be so
> located and identified that it can be readily reset or replaced in flight.
> (e) For fuses identified as replaceable in flight--
>
> (1) There must be one spare of each rating or 50 percent spare fuses of
> each rating, whichever is greater; and
> (2) The spare fuse(s) must be readily accessible to any required pilot.
>
>
> 1357.d speaks to 'essential to safety in flight' . . . okay suppose
> you have a breaker that protects the only radio on the panel and you'
re
> anticipating a launch into the murk. How many things in that radio ca
n
> 'break' and render the radio inop? Don't know but you can bet it's a b
unch.
> What is the likelihood that ANY kind of radio killing event will caus
e
> the breaker to operate yet be 'clear' in some manner that allows the b
reaker
> to be reset?
>
> Once a circuit protective device operates, the very high probability
> assumption is that the powered device is no longer available
> irrespective of root cause for the trip. At the same time, a
> tripped breaker suggests that the device did it's job to prevent
> electrically induced fire or wire damage. Once the breaker or fuse
> has operated, do you really want to give it a second chance of
> doing more damage?
>
> Pilots in the big iron birds are told to leave popped breakers
> alone . . . but if you're feeling lucky . . . reset one time only.
>
> Failure tolerant design goals say that probability for comfortable
> termination of flight is greatly enhanced if EVERY device
> has a no-sweat backup. This includes the alternator. This
> is the operating philosophy that birthed the e-bus about 20 years
> ago. It's the philosophy that birthed Z-13/8 shortly thereafter.
> That same philosophy is satisfied by having battery powered hand-held
s
> in the flight bag.
>
> http://tinyurl.com/d5mrjgh
>
> In other words, with careful management of known energy
> requirements, it's no big deal to have greater electrical
> endurance than fuel endurance. Hence, all things electric are
> relieved of their sweat-breaking criticality and there's no
> good reason to fiddle with any circuit progective device
> in flight.
>
> Yes, you're right. It's probably safer to design the alternator circuit fo
r continuous duty. If you design to Part 23 your loads should never exceed 8
0% of generating capacity. This was really hard to do before there were LED a
nd HID landing lights. Old tube radios really wolfed down the juice too.
>
> The 80% rule was never intended to de-rate an
> engine driven power source. It was intended to
> wall off head-room for battery recharge in
> some nominal period of time after takeoff . . .
> no hard numbers here but 60-90 minutes has been
> the rule of thumb . . . and is obviously driven
> by the sized of the battery.
>
> In fact, it's the dead-battery recharge scenario
> that drove a number tense events for pilots. I've
> often referred to the type-certificated, 60A B-lead
> breaker on tens of thousands of airplanes fitted with
> 60A alternators as, "the breaker designed to nuisance trip."
>
> A cold alternator recharging a dead battery will
> put out significantly more than its nameplate rating.
> I jump started a Cherokee 140 out of 1K1 and about
> 15 minutes out, the panel went black. B-lead breaker
> was popped but resetting it did not bring the alternator
> back. I'm guessing that the alternator load-dump
> zorked something.
>
> In any case, I finished the leg on hand-helds,
> put a charger on the battery in Sallisaw and
> flew home battery-only with minimal loads backed
> up by hand-held. A no-sweat trip.
>
> Your b-lead protection would do well to emulate
> Beech and many others by switching to current
> limiters (VERY robust fuses) on the firewall.
> These DO NOT nuisance trip but will perform
> intended functions for shorted diodes.
>
> In spite of this level of robustness, there are
> still many things that can take the alternator down
> that a pilot is ill-advised to mess with while
> in flight. Plans-B, C and even D outweigh a box
> full of tools any day.
>
> See Chapters 10 and 17 in the 'Connection. Also
> articles at:
>
> http://tinyurl.com/mpdjsef
>
> http://tinyurl.com/mthp9u4
>
> http://tinyurl.com/nxgdccs
>
> http://tinyurl.com/7lhbbah
>
>
> This table (Figure 11-2) really sets the allowable voltage drop over the l
ength of the wire. In a circuit where wire size is dominated by current carr
ying capacity like the relatively short alternator wire, this table doesn't d
ictate wire size. If the alternator is mounted on the front of the engine, i
t could be 8-12 wire feet to get to the circuit protection device and anothe
r 4-6 wire feet to get back to the battery side of the starter contactor. Wo
rst case that's between 12' and 20' and of wire (always use the next line up
on the chart) and that says an 8 AWG wire. Then is it an 8 AWG or a 6 AWG? D
epends on the thermal rating of the wire.
>
> Circuit protection is classically installed as
> close to the source of hazardous energy as practical. In
> the case of the canard pusher with front mounted
> battery, the current limiter would be mounted as
> close to the starter contactor as practical and
> the starter feeder used to take alternator energy
> forward to the battery and bus structure.
>
> Every "must" and "shall" in FAR23.1357 is easily
> put to bed by well considered, failure tolerant
> design. The most powerful failure tolerant design
> goal says, "No single item in the electrical system
> is necessary for me to comfortably terminate flight
> at airport of intended destination without breaking
> a sweat (or punching a circuit breaker back in)."
>
> Too many stories like this have graced the pages
> of the flying-rags . . .
>
> http://tinyurl.com/kqo7jx8
>
> . . .and for the most part, serve to illustrate how
> little most pilots know about how their airplane's
> systems really work. The sad thing is that the vast
> majority of these stories should have played out
> much differently . . . were in fact so ho-hum that
> it wasn't worth writing for the magazine.
>
> This my friends is what the 'Connection and these
> forums are all about . . . A quest for ho-hum flying
> where the most exciting features of a flight are
> fantastic scenes viewed out the window.
>
> Bob . . .
>
>
>
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=========
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=========
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=========
>
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