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graybeard
Joined: 20 Sep 2011
Posts: 33
Location: Grants Pass, OR
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 Posted: Sat Jun 23, 2012 9:37 am Post subject: Electrical System Design |
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How important is it to maintain elevator trim system capability? I am planning to use a VP-X Sport for primary circuit protection, but the “get-down safely in case of alternator failure” mode will drop out the VP-X and provide essential power via back-up circuits fed directly from “always hot” battery busses. The system is designed for day/night capability. Right now it includes 2 PC625 batteries, paralleled for normal operation, but feeding separate busses which will support the essential load with master switches “off”. I will “belt and suspenders” the PFD with a Dynon back-up battery. My only concern is losing elevator trim capability, although there might be others I have not thought of. I am planning to keep the AP servos powered. The system is a bit more complex than I would like, but if it prevents a black cockpit at night it will be worth it.
Stan Loer
RV8 Very Slow QB
[quote][b]
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bifft(at)xmission.com
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| Posted: Sat Jun 23, 2012 12:36 pm Post subject: Electrical System Design |
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On Sat, 23 Jun 2012, stazel(at)cpros.com wrote:
| Quote: | How important is it to maintain elevator trim system capability? I am
[much snippage]
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If you lose elevator trim, pilot workload goes up, but as long as you
are paying attention, it shouldn't be that unsafe. You wouldn't be able
to let go of the stick at any but the trimmed speed, if you were trimmed
for cruise when you lost power (as would most likely be the case) stick
forces on landing would be a bit heavy. I'll leave how heavy to those
with flying RVs. Fatigue could become a factor if you had to fly a long
way out of trim. A trim runaway is the more dangerous condition
Brian Huffaker, DSWL (bifft(at)xmission.com)
RV-8A 80091 wiring electrical
1/4 Starduster II N23UT down for engine overhaul
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carl.froehlich(at)verizon
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| Posted: Sat Jun 23, 2012 4:21 pm Post subject: Electrical System Design |
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Weird.
Two PC625 batteries provide ample power for full IFR flight to fuel exhaustion (large loads such as landing lights, strobes, pitot heat excluded). Why would this system design in loss of trim for an alternator failure? The trim servo is perhaps a 100ma or so – nothing.
Carl
RV-8A (800 hrs)
RV-10 (13.5 hrs)
From: owner-rv8-list-server(at)matronics.com [mailto:owner-rv8-list-server(at)matronics.com] On Behalf Of stazel(at)cpros.com
Sent: Saturday, June 23, 2012 1:37 PM
To: rv8-list(at)matronics.com
Subject: Electrical System Design
How important is it to maintain elevator trim system capability? I am planning to use a VP-X Sport for primary circuit protection, but the “get-down safely in case of alternator failure” mode will drop out the VP-X and provide essential power via back-up circuits fed directly from “always hot” battery busses. The system is designed for day/night capability. Right now it includes 2 PC625 batteries, paralleled for normal operation, but feeding separate busses which will support the essential load with master switches “off”. I will “belt and suspenders” the PFD with a Dynon back-up battery. My only concern is losing elevator trim capability, although there might be others I have not thought of. I am planning to keep the AP servos powered. The system is a bit more complex than I would like, but if it prevents a black cockpit at night it will be worth it.
Stan Loer
RV8 Very Slow QB
| Quote: | | http://www.matronics.com/Navigator?RV8-List |
01234567
[quote][b]
| | - The Matronics RV8-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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