REFLECTOR: Load distrib

Sat Feb 26 11:31:52 CST 2005

See below in red.

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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Terrence Miles
Sent: Friday, February 25, 2005 11:39 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Load distrib

Y'all,

Great posts!!   Geez I am going to have to get and get trained in speed
reading!  Several have mentioned dual screen GRT's, but I didn't see mention
of dual AHRS.  So here's my two part question:

Q #1.  What are you guys doing for attitude/airspeed indicator back up when
AHRS goes bad?  

In our setup the GRT has it's own AHRS and Air Data Computer which is
separate from the Blue Mountain, which has the same.  They will be on
independent (under normal ops) busses.  I really got sold on the BM as a
high value multi-mode autopilot which just so happens to have PFD, HSI and
moving map functions (plus it has a Canard airplane symbol on the map).
Under normal ops I will fly PFD on the GRT's and use the HSI on the BM.  The
second display of GRT will be moving map with TIS from a GTX330 and then the
EIS6000 will be for engine info.

Q #2.  Craig, I am not familiar with the Blue Mt guts very much.  If you
have a dual, independent central air data computers (CADC) will you have
both your CADCs wired to your Essential bus?  Could you talk some more?    

See above.  They will be sharing a pitot tube and static system.  I have
considered putting normal round airspeed and altitude on the right of radio
stack just to make the FAA inspector happy come inspection time.  It also
gives the copilot that information right in front of them.  But as others
have indicated, we are starting to push the belts, suspenders, etc.  But I'm
a military avionics guy with lots of software experience and Murphy knows
how to fly.

My thinking at present is to create dual electrical power and distrib
sytems:   DC1 and DC2.  Alt1 and Alt2.  Batt1 and Batt2...with each system
having it's own main bus and each with it's own essential/critical bus.
What causes this thinking is how to distribute power to these backed-up
multi function EFIS rascals if I go w/o vacuum driven round dial stuff.  

I'll have three switches a MAIN bus OFF/ON/ALT.  A ESTL bus OFF/ON/ALT.  And
a XFEED OFF/AUTO/ON.  This allows independent busses and the ability to gang
together during "bad times".

Where's everybody mounting their EIS 6000's.  In pilot's eye view or
elsewhere?  

Terry

 : reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf
Of Craig and/or Denise Woolston
Sent: Friday, February 25, 2005 10:30 AM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: electrical sys design

John and I are going with a dual alternator/dual battery system also.  We
are going the dual screen GRT also.  Add to that the Blue Mountain G3 with
autopilot and we basically have dual everything except the engine.  My plan
is the 70amp alternator that came with our IO-550 and either the 7 or 20 amp
vacuum pump pad B&C.  The essential bus will have the radio, transponder, BM
EFIS, EIS.  The main bus everything else.  I want to know that both my
alternators are working before launching into the soup so both will be
"active" all the time.  We plan to use Bob's Low Voltage Module to auto
connect the Essential to the Main if the Essential alternator goes down.  We
will have a crossfeed switch OFF/AUTO/ON.  The AUTO will be Normal Ops so
there is no pilot work load during a failure.  If the ESSENTIAL does down,
then it will auto switch to the MAIN.  If the MAIN alternator goes down then
we get the Low Volt on MAIN and can when pilot work load dictates go to
forced XFEED.  The Low Volt Module will then flash if the load is too great,
so we can shed what we need to as appropriate.

Currently I'm thinking a 24ah for starting and the main bus and a 17ah or
smaller for the essential bus.  My thought is to always start on the 24 and
then 17 is only seeing starting operations on those cold mornings or hot
starts that go bad???  Plus there will be no voltage sag on the 17 under
normal start so the EIS will be available immediately.

My solution for the below is three annunciator, a LOW VOLT and then under it
a MAIN and ESTL, which will light as described above.  Plus the EIS is on
the ESSENTIAL bus so it will read that voltage and the GRT EFIS is on the
MAIN bus so it will read that one.  Which should trigger my other
annunciators a ENGINE and a EFIS.  I'll be looking at a fricking XMAS tree
which will be hard to miss.

Craig

XL-5FG in Palmdale,CA

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From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Terrence Miles
Sent: Thursday, February 24, 2005 6:14 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: electrical sys design

If it works out that way then I'll drop to a motorcycle batt with an ammeter
and voltmeter on the primary system  Then I understand that there is an aux
plug on the GRT EIS audio warning I could steal and/or maybe set abnormal
range gauge readings  to a master caution.   One problem w/ electrical
abnormals is you don't see 'em until the lights go out.

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