Date: Thu, 25 Feb 1999 10:39:55 -0500
From: Lynda Frantz <LFrantz@compuserve.com>
Subject: Auto Pilot vs. wing leveler
Sender: Lynda Frantz <LFrantz@compuserve.com>
To: "INTERNET:lancair.list@olsusa.com" <lancair.list@olsusa.com>
Message-ID: <199902251040_MC2-6BCB-6C6C@compuserve.com>
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Message text written by INTERNET:lancair.list@olsusa.com
>Does anyone have an autopilot system that really holds the course and
flight plan that is error sourced to the GPS?  Most seem to work well
when holding a course set by the DG, so maybe an HSI is an integral part.<

I have the STEC-40 in my Lancair -360.  It is much more than a wing
leveler.  It gets its input from the HSI and the HSI CDI gets its input
from either the ILS localizer, VOR radial or the GPS.  Consequently
the autopilot will track great circle routes, intercept and track radials,
and intercept and track localizers.

One of the highlights during my 25 hour test flying was shooting the
first ILS to a low approach at 180  knots with the auto pilot in LOC
to St. Paul.  Upon executing the pre arranged missed procedure I
simply selected GPS mode, pushed the GPS direct to button, pushed the
LOC autopilot button and the aircraft turned to the great circle route
direct to the missed approach fix.  As I pulled up to the assigned missed
approach altitute the controller said "Nice Job, what kind of cruise
speeds do you get?"  I couldn't help but reply, "I'm  just coasting" and
headed back to my designated test base with a ground speed of 230 knots. 

I have a push button that when pushed in is lit on one side indicating
VOR NAV and when out is lit on the other side indicating GPS NAV.  When
I select an ILS frequency on the NAV receiver the CDI of the HSI uses LOC
info regardless of the push button position but the annunciation is
correct.  Yup, I went a bit crazy.

For single pilot IFR flying in my Lancair 360, I consider the single
axis autopilot a must to bring the IFR work load down to acceptable
levels.  Of course I also have the heading bug on the HSI connected to
the autopilot.

I get a little wing walk above 170 knots indicated if the aileron is not
perfectly in trim.

Jim Frantz
Lancair Network News
Jim@angle-of-attack.com