Great cooling numbers on your flight testing...........Good to hear that after all the trials and tribulations you have been through that you are gaining confidence in your installation..............
The electrical system info may be somewhat dated as you said so everyone has to evaluate for themselves if current equipment failure rates are within their personal tolerance limits..........Most of us
are dealing with 1986-1995 era alternators with unknown mileage/hours on them..........I have had
failures on these alternators in automobiles............Some times just the diode array but once the internal
regulator............As luck would have it the failure was an "Open" that time so did not have a runaway
voltage condition..............So as I said each of us has to make their own decision on this subject.............
If nothing else this link provides a very comprehensive explanation of the charging system and excellent
troubleshooting information for even the most electrically challenged of our little group.............IMHO
-------------- Original message from "Mike Wills" <rv-4mike@cox.net>: --------------
Hi Kelly,
Thanks for the link. Some interesting info, but... What is lacking is any sort of statistical info to indicate that this is a real problem. I'm not convinced that using a Cherokee as an example system is all that applicable. And I dont know how old this article is, but gather it is pretty old given the reference to problems with alternator failures in cars resulting in nothing more than burning out lights. I'd venture to say that for virtually any car built since the mid 80s, a runaway alternator output would result in far more than a few burnt out lights.
Since virtually all cars these days use internal solid state regulators, if these things were prone to failure, and since a runway over volt failure on any modern car would likely toast some pretty expensive electronics, I'd expect a fair number of really expensive repairs, warranty issues, etc.... My conclusion is that this type of failure is actually quite rare, but if you can point to relevant statistical data that says otherwise, I'm all ears.
Some folks are more risk averse than others and a 1 in a million possibility is enough to justify making a change. But sooner or later you have to stop engineering for every possible risk no matter how remote the failure mode and just get on with it.
Meanwhile, the important points I take from this reference are, dont overload your alternator, ensure that the field is de-energized while cranking the engine, and keep it cool.
Off topic, another 1.2 hours closer to completing my Phase 1. This was the first flight that after I landed I didnt have anything on my list to fix before the next flight. 95 degrees OAT at takeoff today and the oil temp got to 200 at the top of the climb to 5000' but backed off to 192 after I leveled. H2O temp never above 180. Starting to gain some confidence in it. Oh, and I have a DNA muffler on order. Should have it by next weekend but may put off installing it so I can fly some more.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Sunday, August 30, 2009 1:21 PM
Subject: [FlyRotary] FW: More Charging Circuit Info
Group,
I am still on the bandwagon about modifying our flying alternators for an external
regulator as noted in my past posts...........After supplying group member Tim Holt &
also the group with info how to modify the Mazda alternator I remembered the link
below which explains in language even the electrically challenged among us will be
able to understand...............This info may have been already seen by some of you
but I believe all of us should file it and also copy it to have available when wiring
our aircraft electrical systems.............IMHO!!..........
--
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold
-------------- Forwarded Message: --------------
From: "Kelly Troyer" <keltro@att.net>
To: tntholt23@bellsouth.net (Timothy Holt)
Subject: More Charging Circuit Info
Date: Sun, 30 Aug 2009 20:06:30 +0000
Tim,
For your informaton here is additional justification in my opinion for going to an external
regulator in our aircraft and having the ability to either automaticly or manualy cut power
to the field windings in case of a shorted regulator............Note that solid state regulators
tend to fail "Shorted" about 50% of the time and all current internal regulators are solid
state.............Link Below..................."Nuff Said" !!...............IMHO
--
Kelly Troyer