Message-ID: <36D6530B.EAA86714@bigfoot.com>
Date: Thu, 25 Feb 1999 23:53:47 -0800
From: Bob Belshe <rab22@bigfoot.com>
To: Lancair.list@olsusa.com
Subject: VFR Auto Pilot
Mime-Version: 1.0

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Others have described their systems with HSIs and in-panel approach
qualified GPSs, so I though I would describe my "economy" system.

Components are a Navaid "wing leveler", a Garmin GPSMAP195, and a Garmin
power/data cable.  The Navaid has a "GPS Smart Coupler" built in, which
converts the NEMA digital output of the GPS into an analog signal.  The
GPS gets power from the airplane and automatically switches to its
internal battery when airplane power is off.  The digital data output
from the GPS connects to a tiny switch which takes about 1 square inch
of panel space.  A cable from the switch plugs in to the back of the
Navaid.  I also installed a switch which switches the tracking input
between the GPS and a panel mounted Loran.

The Navaid gyro/display replaced my old turn and bank, so takes no extra
space.  It has a LED display which simulates the turn needle and a ball
skid indicator.  The Navaid servo is a box which just fits under the
right seat of my 235/320.  It is easy to get at and was simple to
install in a plane that was already flying.  The GPSMAP195  sits on the
console next to the elevator trim handle.

This unit steers the plane as straight as a string, behaves well in
moderate turbulence, and frees me to just hold the altitude.  You can
put in multi-leg courses, and it will fly you anywhere.  

The trim knob on the Navaid controls parallel offset from the desired
course line, and it is fairly sensitive.  It does not anticipate turns,
so there is a little overshoot if the turn is over 20 degrees or so.  
Most, if not all, hand-held GPSs have the NEMA standard output so you
are not limited to the GPSMAP 195.

In addition to tracking a course line from the GPS, the Navaid has a
mode which uses the signal from the GPS to hold a heading.

Altitude hold would be great to have, but for the price and ease of
installation, I don't think you can do better than this.

Bob Belshe
N19BJ