Message text written by "Lancair Mailing List"
>Thanks for all the good advice on my power budget and alternator sizing.
It
will take a little while to digest it all, but I still have a few weeks
before
I need to walk over to Bill Bainbridge's booth at Oshkosh and buy an
alternator.<

One of the common errors I see is under sizing the alternator.  On my 360
with a vacuum system, a 65amp alternator was just barely big enough using
the 80% rule for continuous loads. LNN issue 16 August/September 1995 goes
into great detail on how to size the alternator and gives several load
analysis examples which would be a great help.

The last thing you want is while flying into IFR and rain, having the pitot
tube draw more amps as it tries to keep the pitot tube up to temp  and
overloading the alternator tripping it off line.  At this point  only
essential bus items are powered, and that is an emergency in my book (no
auto pilot, and other nice to have instruments all gone).

If you are all electric, I doubt a 65 amp alternator would do the trick for
an IFR airplane. BTW, the battery should be able to power the essential
instruments for 30 minutes.

James B. Frantz
Proprietary Software Systems, Inc.
www.angle-of-attack.com
LFrantz@compuserve.com
(952) 474-4154