REFLECTOR: Electrical system

Don Johnston numa at comcast.net
Thu Jul 4 20:47:45 CDT 2013


"I am wired using the VPX-Pro, controlled via the GRT 10.1(Dual AHARS, back
up battery)."

That's pretty much the same setup that I'm currently wiring up...

I was told that the backup battery from GRT is for 12v systems only.   What
backup battery are you using?

On Thu, Jul 4, 2013 at 8:05 PM, Lawrence Epstein <ljepstein at hotmail.com>wrote:

> Never saw that article. Good reading (
> http://www.aeroelectric.com/articles/richter/response_1.pdf).
>
> Reiff-
> I am not flying yet. I am wired using the VPX-Pro, controlled via the GRT
> 10.1(Dual AHARS, back up battery). 28V 1 battery. 1 alternator.
> my backup is a Dynon 100 EFIS with it's own AHARS/backup battery. Thinking
> here is I have 3 independent sources of attitude information from 2
> different systems. My hope is that the GRT and Dynon have different
> known/unknown failure modes.
>
> Larry
>
>
> On Thu, Jul 4, 2013 at 7:48 PM, Chris Barber <cbarber at texasattorney.net>wrote:
>
>>  Reiff,
>>
>>  Just as a basis of comparison, Bob Knuckles, on his Aeroelectric.comsite, does a point by point critique of Richter's paper. IMAO, he attempts
>> to educate and explain the various factors. The write up is available on
>> the site and may provide insight so you may make a more well informed
>> choice.
>>
>>  Just FYI.
>>
>>  Chris
>> Houston
>>
>> Sent from my iPhone 5
>>
>> On Jul 4, 2013, at 15:07, "Reiff Lorenz" <Reiff at Lorenz.com> wrote:
>>
>>   ** **
>>
>> Larry,****
>>
>> ** **
>>
>> Thanks for the link. Just read through the whole thing.****
>>
>> ** **
>>
>> Did you follow this advice? One battery, one alternator, 24 volts? Do you
>> have any backup systems, like vacuum pump instruments or in-EFIS batteries?
>> What about electronic ignition?****
>>
>> ** **
>>
>> I'm fascinated to hear what other builders are doing. It's a big help
>> when considering the options for my installation.****
>>
>> ** **
>>
>> Thanks!****
>>
>> ** **
>>
>> Reiff****
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> *From:* reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org<reflector-bounces at tvbf.org>]
>> *On Behalf Of *Lawrence Epstein
>> *Sent:* Thursday, July 4, 2013 1:52 PM
>> *To:* Velocity Aircraft Owners and Builders list
>> *Subject:* Re: REFLECTOR: Reflector Digest, Vol 100, Issue 10****
>>
>> ** **
>>
>> I strongly recommend the following reference for aircraft
>> wiring/electrical systems:****
>>
>> ** **
>>
>> http://www.eaa.org/experimenter/articles/0903_aircraft_wiring.pdf****
>>
>> ** **
>>
>> Granted, it is written by Greg Richter (BMA), but it goes through a
>> logical analysis of what sort of redundancy is necessary and where. He
>> addresses back up batteries (no need if you are 24 V) on page 5 and 2nd
>> alternator ("overkill") on page 6.****
>>
>> ** **
>>
>> Lots of good stuff here.****
>>
>> ** **
>>
>> On Thu, Jul 4, 2013 at 11:15 AM, Patrick Sieders <pjsieders at comcast.net>
>> wrote:****
>>
>>  Brooke and Dave,
>>
>> You all have a point in simplicity. On backup systems however, I disagree.
>>
>> Many production airplanes had backup systems : electrical and suction
>> instruments.
>>
>> These days we are all leaning/using electrical EFIS screens etc. So to
>> have another backup alternator in lieu of the old vacuumpump is just common
>> sense.
>>
>> Take it from a guy flying an electric airliner, being told we always will
>> have instruments(i.e. EFIS SCREENS) to look at.. I have met Murphy in IMC...
>>
>> Patrick sieders
>>
>>
>> ****
>>  ------------------------------
>>
>> *From: *Dave T Nelson <dtnelson at us.ibm.com>
>> *Sent: *July 04, 2013 10:09
>> *To: *reflector at tvbf.org
>> *Subject: *Re: REFLECTOR: Reflector Digest, Vol 100, Issue 10****
>>
>> Brooke - well said, Sir!
>>
>> The comparison to other no redundancy systems (like your entire airframe)
>> is spot on, and reinforces my philosophy - stay away from complexity, and
>> build it really, really well - but just once.  Adding all the stuff I hear
>> about is adding extra weight, complexity, and failure modes.
>>
>> How many Cessnas, Pipers, Beechcrafts, Mooneys, etc., are lost due to the
>> lack of an extra alternator?  An extra battery?  Where you see a store
>> bought airplane accident due to an electrical failure, it's pretty much
>> always due to smoke or fire in the cockpit... How much extra risk are you
>> adding for that kind of problem with all of your additional redundant
>> systems?
>>
>> Take great care in building, but build it once and keep it simple.
>>
>> Dave
>>
>> Dave T. Nelson
>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>> Program Director, ISC ECAT NPI & Test Engineering
>>
>> ----- Message from Brooke Wolf <bwolf1 at tds.net> on Wed, 3 Jul 2013
>> 21:32:32 -0400 ----- ****
>>
>> *To:*****
>>
>> reflector at tvbf.org****
>>
>> *Subject:*****
>>
>> REFLECTOR: Electrical system****
>>
>> Reiff
>>
>> As we go through the mental gymnastics of 2 alternators or 2 batteries or
>> primary busses or essential busses or main busses or emergency busses or
>> battery busses and redundancy galore, let us not forget we have only one
>> engine.  Safety and associated redundancies should balance.  Just food of
>> thought.
>>
>> Brooke
>>
>> On Jul 3, 2013, at 4:11 PM, reflector-request at tvbf.org wrote:****
>>
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>> Today's Topics:
>>
>>  1. Re:  Electrical system (Jack Prock)
>>
>> *From: *"Jack Prock" <jackprock at wavecable.com>
>> *Subject: Re: REFLECTOR: Electrical system*
>> *Date: *July 3, 2013 4:10:30 PM EDT
>> *To: *"Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>> *Reply-To: *Velocity Aircraft Owners and Builders list <
>> reflector at tvbf.org>
>>
>>
>> Reiff,
>>
>> The only thing that I would add is that you start your engine using the
>> battery, but fly using your alternator(s).  If you were going
>> to decide between having a duplicate of one OR the other, I would go with
>> a duplicate alternator.
>>
>> If the battery goes out, you can’t start... get jumper cables, start the
>> engine, you’re on your way... just like a car. (assuming 12 volt system )
>>
>> If your single alternator goes out, you run on your battery(s) until
>> it/they die (while you look for a place to land)...
>> at night... over mountains, not a good scenario!!  Other backups will
>> help... but the pucker factor goes way up when
>> (almost) everything goes dark!
>>
>> The consequences of one, far outweigh the consequences of the other.
>>
>> That is just my opinion... and just like assholes, everyone has one!!
>>
>> Jack
>>
>> *From:* Reiff Lorenz <Reiff at lorenz.com>
>> *Sent:* Wednesday, July 03, 2013 12:24 PM
>> *To:* Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> *Subject:* Re: REFLECTOR: Electrical system
>>
>>
>> Terry,
>>
>> Thank you for all the details. This is all very helpful. I like your
>> suggestion about the heat-shrink labeling, even though it's expensive. For
>> planning/drawing software I'm leaning toward Visio. (Turbo-CAD does have
>> some good features, too.)
>>
>> I'm still working on the right tradeoff between redundancy and
>> complexity. Lots of suggestions from other builders to do 2 batteries.
>> Others say 1 battery and 2 alternators. Andy Millin sent me his diagram and
>> he's got 3 batteries! The Vertical power system simplifies some of this.
>> They have multiple configurations for dual batteries and/or dual
>> alternators and/or ground power plugs, but it's still not as easy as
>> connecting everything to one box.
>>
>> Builder Bill Stockman lives near me. He's retro-fitting his long-wing SE
>> with a Vertical Power system and a Garmin G3X. I'm hoping to be able to
>> help him and learn about wiring a VP system in the process.
>>
>> I may have similar W&B issues to what you describe. I'm a skinny guy and
>> don't want to have trim issues, but I also want to take some of my larger
>> friends in the front seat (6'3 & 260 lbs.)  Maybe there's some middle
>> ground between the two extremes?
>>
>> Looking forward to talking to you at Oshkosh!
>>
>> Reiff
>>
>>
>> *From:* reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org<reflector-bounces at tvbf.org>]
>> *On Behalf Of *Terry Miles*
>> Sent:* Tuesday, July 2, 2013 11:46 PM*
>> To:* Velocity Aircraft Owners and Builders list*
>> Subject:* Re: REFLECTOR: Electrical system
>>
>> Wow.  Dave, that is a very nice summary.  I did all of my wiring...every
>> inch, every connector, every everything.  I would repeat a lot of what you
>> offered, if asked, and that is:  keep track of wire size to fit the current
>> load, secure stuff properly so it cannot rub against anything,  (I used
>> that black wax lace stuff.  Yank on every connector after you make it to
>> test it.   Check every BNC you make for continuity and twist it around a
>> little before you declare it sound.   If you make 25 pin connectors
>> becareful with pin crimps, and especially the outboard most pins when you
>> go to secure the entire bundle.  (You can google how to tied the knots.)  I
>> read all the Nuckols stuff faithfully as I educated myself and choose
>> against the double alternators, but I do have a pair of Odessey 925
>> batteries located forward of the carnard bulkhead in the RG and have not
>> had water issues so far.   The main distribution is after of the carnard
>> bulkhead.   I did the 2 batts in part for wgt and bal since I am 150 pounds
>> and heard stories of trim issues.  While it is another discussion,  the
>> decision for one or two batts was and always will be debatable.  It might
>> have been better for me to use removable ballast since I cannot take
>> anybody much over 200 lbs and put them in the front seat.  My inflight draw
>> is about 4 amps, much much different from days gone by.  I will run out of
>> gas before I every run out of batt power.  I replace one batt every 18
>> months to two years.
>>
>> Making wire streams (I like that term) would have been some good advice
>> for me.  I didn't do that and actually installed the wiring a little at a
>> time and added a lot of after the fact stuff....and I do have a lot of
>> loose single wires going hither and yon (sp?) back and forth from port to
>> starboard behind the instrument panel.  I used auto fusing mostly but do
>> have about a dozen in view aircraft grade CB's for stuff I want to know
>> about...ignition, transponder, hydro pump and gear control gizmo...stuff
>> like that.  There are also decisions about putting more than one component
>> into a single fuse/breaker.
>>
>> I bought a $300 plus wire labeling system that uses heat shrink.  The dam
>> heat shrink refills were about 35 cents an inch, but I thought that was
>> money well spent, as well as being able to work at a base level with
>> turbo-cad to do the drawings since I experienced endless edits in that
>> department from my first paper drawings.
>>
>> If you do your own wiring, I would call Dave first since he offered.  I
>> am only a Saturday afternoon electrician-avionics tech, but I can certainly
>> add my name if you want an opinion about doing your own harness and/or
>> tacking the job of installing all of the avionics and doing those 2
>> gazillion settings on your own.  Being able to buy both an AHRS and an
>> autopilot from the same vendor is a big plus not available to me.  I have
>> GRT stuff and I like it.  Besides buying mil spec wire, buying high grade
>> teflon tape is a good idea too.
>>
>> Terry****
>>  ------------------------------
>>
>> To: reflector at tvbf.org
>> From: dtnelson at us.ibm.com
>> Date: Sun, 30 Jun 2013 10:36:59 -0500
>> Subject: Re: REFLECTOR: Electrical system
>>
>> Hi Reiff,
>>
>> The power and ground bus bars I'm talking about is behind the canard
>> bulkhead in the area behind the panel - not forward of the bulkhead and
>> exposed.
>>
>> In general, for exposed connections, the worry wouldn't be failure due to
>> shorting from the water, it'd be corrosion.  In general, galvanic corrosion
>> should be considered, but can be easily controlled with HW store
>> electrician's grease.  The relays and connections that I do have on the
>> forward (exposed) side of my bulkhead all have a dab of that stuff (main
>> contactor, hydraulic pump relays, battery connections, etc.).
>>
>> I've never seen galvanic corrosion on my homemade brass bus bars & the
>> bimetal ring connectors I've used.
>>
>> I've seen the other comments re. use of two alternators, etc. I agree
>> with the guidance from Richard Gentil - if you've got an electrical problem
>> you're going to want to land and fix it anyway.  Keeping your system as
>> simple as possible and building your simple system with reliability in mind
>> makes much more sense to me than trying to add all kinds of redundancy...
>> which just gives Murphy more opportunities to ruin your day.  I'd think
>> really hard before installing a system with two alternators, two batteries,
>> all kinds of switching relays, lots of extra wiring... failure points...
>> and things to go wrong.
>>
>> My two cents.
>>
>> Dave
>>
>> Dave T. Nelson
>> T/L 553-4327, Voice 507-253-4327, Fax 507-253-3648
>> Program Director, ISC ECAT NPI & Test Engineering
>>
>> Dave,
>>
>> Terrific advice! Thanks for all the help.
>>
>> Did you cover the power buss with anything? Is there any concern of
>> having a "naked" power buss in the nose? I have an RG, so I'm imagining the
>> entire inside of the nose will get wet if I take off or land in the rain.
>>
>> I really appreciate all the info!
>>
>> Reiff
>>
>> *
>> From:* reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org<reflector-bounces at tvbf.org>]
>> *On Behalf Of *Dave T Nelson*
>> Sent:* Saturday, June 29, 2013 1:12 PM*
>> To:* reflector at tvbf.org*
>> Subject:* Re: REFLECTOR: Electrical system
>>
>> This is an excellent area for KISS.... Keep It SIMPLE!
>>
>> In my installation, I used two connection blocks in the area behind the
>> instrument panel for both 12V and ground (4 total), one of each flavor on
>> the left and on the right.  I made them myself by soldering brass screws
>> into a brass plate.  I then used ring terminals on the wire ends.  The
>> terminals are then held tight with MS21042 nuts.  The idea is to avoid
>> having to have wires seeking 12V or ground from having to cross the whole
>> panel from the left side to the right (or vise-versa).  The ground system
>> should be simple - everything has only one grounding point (to avoid ground
>> loops).  On both power and ground, the buss bars are powered (or grounded)
>> via two wires for redundancy.
>>
>> I used switch circuit breakers instead of switches with separate circuit
>> breakers (or fuses).  I wouldn't recommend that... I've had a couple of
>> them fail.
>>
>> I used circuit breakers instead of fuses.  My reasoning was that I want
>> to be able to see at a glance if one had popped (hard to do with a fuse).
>>  I wish I'd used the type that allow you to pull the end of the circuit
>> breaker to switch a circuit off.
>>
>> Don't buy used circuit breakers!
>>
>> Use real aviation grade wire, not Radioshack junk.
>>
>> I used, carefully and religiously, a wire size chart.  I've seen many,
>> many installations where folks use wire of way to low of a gauge (too thick
>> and heavy).  You'll be surprised how often you can use 20 or even 22 gauge
>> based on the current requirements.  Make sure the wiring chart you use is
>> for bundled wire, not single strand.  Make sure you use the right size
>> terminal for each wire.
>>
>> I sized the circuit breakers for the load, not for the wire carrying
>> capacity.  There has been some debate on this, as Nuckolls would size the
>> fuse/circuit breaker for the wire, not the load.  IMHO I'm trying to
>> protect the expensive load (radio), and the wire will always****
>>
>>
>>
>> [The entire original message is not included]****
>>
>>
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