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Subject: RE: [FlyRotary] Re: Two Alternators?
Date: Tue, 24 Jan 2006 12:37:27 -0600
Message-ID: <87DBA06C9A5CB84B80439BA09D86E69E0378DAD6@MAIL01.austin.utexas.edu>
Thread-Topic: [FlyRotary] Re: Two Alternators?
Thread-Index: AcYhEbAE3p5UlF8JQje2piD25ZpMNAAANc+Q
From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Hi Doug,
I agree with your philosophy on flying with failed equipment.  In most
cases, I would head for the nearest airport.  But if something
insignificant, such as an instrument light burns out, you wouldn't
terminate the flight.  My electrical system is designed from the start
to operate normally on only one alternator.  With one adequately sized
alternator and two batteries, my system would be no different than Ed's,
except that I have an extra battery.  If the second alternator were to
fail, I would not fall out of the sky.  I would still have two healthy,
fully-charged batteries to power things for well over an hour, running
only flight critical items.  If/when the second alternator fails, that's
when I would head for the airport. =20

As a side note, I have all flight critical hardware on breakers, per
Ed's suggestion.

Mark S.
   =20

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Doug Mueller
Sent: Tuesday, January 24, 2006 12:07 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Two Alternators?

Hey Mark, I would like to encourage you as well as all other
builder/flyers to=20
have a different mind set. When an alternator should fail or any
electrical=20
problem exist regarding batt or alt, It is an emergency not an
opportunity. It=20
is just like any problem with cooling. (ie Water pressure loss or
Coolent temps=20
exceeded) I guarantee that this approach will save your life one day. We
can=20
not have these ideas sponing these go/go actions. The homebuilt
community=20
cant afford this type of advertisement, in a day an age when insurance=20
companies are looking to ditch insuring high risk mentality. It may be
an=20
oversight or a mistatement on your part but I implore all builder/flyers
that=20
the dual alternator/battery system is for redundency to get you to the=20
realestate safely not to make it to point B. :)

>=20
> From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
> Date: 2006/01/24 Tue AM 10:20:28 EST
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: Two Alternators?
>=20
> John,
>=20
> I forgot to answer your question.  Each battery is connected
> independently to its own alternator through an individual contactor.
If
> one alt fails, I can shut it off by opening the field (good argument
for
> external regulated alt) and close the x-feed contactor to connect both
> batteries in parallel.  So, a failed alternator should be a
non-event...
> just open the field on the failed alt, flip the x-feed switch and
> continue on to my destination.
>=20
> =20
>=20
> Mark S. =20
>=20
> =20
>=20
> ________________________________
>=20
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On
> Behalf Of John Slade
> Sent: Tuesday, January 24, 2006 8:00 AM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Re: Two Alternators?
>=20
> =20
>=20
> Mark,
>=20
> How do you charge the backup battery? A diode? Got a part number?
>=20
> I'm just switching a contactor right now, but I'd like to isolate the
> backup.
>=20
> Regards,
>=20
> John
>=20
> 	-----Original Message-----
> 	From: Rotary motors in aircraft
> [mailto:flyrotary@lancaironline.net]On Behalf Of Mark R Steitle
> 	Sent: Tuesday, January 24, 2006 8:21 AM
> 	To: Rotary motors in aircraft
> 	Subject: [FlyRotary] Re: Two Alternators?
>=20
> 	Doug,
>=20
> 	I have dual alternators and dual batteries per Aero-Electric
> Z-14 architecture.  I'm using the small 55amp ND units.  They weigh
> about half of what the Mazda alternator weighs, so I rationalized that
> there was very little weight penalty to using two alternators, but a
> significant safety improvement.  With an electrically dependent engine
> and all electric panel, I decided this was the way to go for me.  The
> cross-feed contactor connects both Odyssey batteries during starting,
so
> I am able to use smaller batteries than would be required to start the
> 3-rotor with only one battery.  Every annual, I plan on replacing the
> main battery, rotating the 1 year old main battery to the aux
position,
> and move the 2 year old aux battery to my Goldwing motorcycle.  That
way
> the main battery will be less than one year old, the aux battery will
be
> 1 - 2 years old, and the motorcycle battery will be 2-3 years old.
I'll
> send you a picture off-line. =20
>=20
> 	=20
>=20
> 	Mark S.=20
>=20
> 	=20
>=20
> =09
> ________________________________
>=20
>=20
> 	From: Rotary motors in aircraft
> [mailto:flyrotary@lancaironline.net] On Behalf Of DLOMHEIM@aol.com
> 	Sent: Tuesday, January 24, 2006 6:11 AM
> 	To: Rotary motors in aircraft
> 	Subject: [FlyRotary] Two Alternators?
>=20
> 	=20
>=20
> 	I am debating the future use of two batteries vs. two
> alternators and I was wondering if anyone in the group has mounted a
> second alternator and if so if they had any pictures of its mounting
> location, etc.
>=20
> 	=20
>=20
> 	Thanks for the information.
>=20
> 	=20
>=20
> 	Doug Lomheim    RV-9A / 13B
>=20
> 	OK City, OK
>=20
>=20
>=20

Doug Mueller
RX-6 13BT
N900DM
Boulder City(61B),Nevada


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