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Al,
That wasnt from me, that was from the weblink
Kelly sent. I simply quoted it. I dont know if it is true or false, but I do
know that at least one of my previous cars opened the alternator field any time
the starter was engaged. It is my understanding that this is typical of car
ignition switches though I dont know if its necessary or just a
holdover.
My approach is to leave the field
de-energized during cranking, energize it after the engine starts, and then
energize the non-essential equipment bus. My RV is a very simple day VFR
airplane so even when everything is turned on the electrical load is pretty
low.
I couldnt be much happier with the cooling.
95 is about as hot as it ever gets here. Oil temp did not limit my climb
performance - I chose to level at 5000 to avoid conflicts with airliner traffic.
At some point I will investigate the cowl flap option but first just want to get
in some flight time and figure out how to consistently land this thing
well.
The DNA muffler arrived today. Looks like its
actually going to be a pretty easy swap with my existing muffler so i may get it
installed before the next flight.
Mike Wills
RV-4 N144MW
----- Original Message -----
Sent: Monday, August 31, 2009 12:18
PM
Subject: [FlyRotary] Re: FW: More
Charging Circuit Info
From
Mike - …..ensure that the field is de-energized
while cranking the engine.
And I will
respectfully disagree with that – at least until somebody can prove me wrong.
The output current is a function of rpm as well as what the voltage
regulator is demanding. From what I can find, I conclude that
alternators typically won’t put out their rated current until they get
spinning about 1500 – 2000 rpm, or more (which is usually about double engine
rpm). So there is no risk of damaging the rectifier diodes at cranking
speed.
I’m going to guess
that it is a worse shock to the electronics if the field is suddenly turned on
at higher rpm when the regulator is on full demand – although I don’t think
it’s an issue.
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.
Contrary to our
friend George’s faint praiseJ, I’d say your
temps are excellent. If it does that well at OAT of 95 F; then
your next thing will be to think about adjustable cowl flap to reduce
cooling drag at cruise on a cooler day.
Al
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