Today's Message Index:
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1. 10:37 AM - Electrical System Design ()
2. 01:36 PM - Re: Electrical System Design (Brian Huffaker)
3. 05:21 PM - Re: Electrical System Design (Carl Froehlich)
Message 1
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| 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
=9Cget-down safely in case of alternator failure=9D mode
will drop out the VP-X and provide essential power via back-up circuits
fed directly from =9Calways hot=9D 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
=9Coff=9D. I will =9Cbelt and suspenders=9D 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
Message 2
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| Subject: | Re: Electrical System Design |
On Sat, 23 Jun 2012, stazel@cpros.com wrote:
> How important is it to maintain elevator trim system capability? I am
[much snippage]
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@xmission.com)
RV-8A 80091 wiring electrical
1/4 Starduster II N23UT down for engine overhaul
Message 3
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| Subject: | Electrical System Design |
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 =93
nothing.
Carl
RV-8A (800 hrs)
RV-10 (13.5 hrs)
From: owner-rv8-list-server@matronics.com
[mailto:owner-rv8-list-server@matronics.com] On Behalf Of
stazel@cpros.com
Sent: Saturday, June 23, 2012 1:37 PM
Subject: RV8-List: 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
=9Cget-down safely in case of alternator failure=9D mode
will drop out the VP-X and provide essential power via back-up circuits
fed directly from =9Calways hot=9D 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
=9Coff=9D. I will =9Cbelt and suspenders=9D 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
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