TruTrak Sorcerer User Manual

Operating Handbook

For

SORCERER AUTOPILOT

TRUTRAK FLIGHT SYSTEMS

1500 S. Old Missouri Road

Springdale, AR 72764

Ph. 479-751-0250 Fax [phone]

www.TruTrakap.com

Table of Contents

Operating Instructions

General Introduction ................................................. 3

Autopilot Power-up ................................................... 4

Mode and Data Display ............................................. 4

Controls .................................................................... 9

Lateral Modes ........................................................... 9

GPS Steering/GPS Nav Mode ................................... 9

NAV/Loc Course Mode ............................................ 10

Reverse Course Mode ............................................... 11

Gyro Back-Up Mode ................................................. 11

Yaw Damper............................................................. 12

Vertical Modes ......................................................... 12

Altitude Hold Mode .................................................. 13

Vertical GPS Steering Mode ..................................... 13

Barometer Set ........................................................... 13

Altitude Select Mode ................................................ 14

Stopping the Transition to a Selected Altitude ........... 15

VNAV Mode ............................................................ 15

Minimum Airspeed ................................................... 15

Maximum Airspeed .................................................. 16

Additional Operating Instructions

Initializing the Autopilot ........................................... 16

GPS Acquisition ....................................................... 16

Altitude Select with AP Off....................................... 17

Gyro Set ................................................................... 17

Engaging the Autopilot ............................................. 17

Setting Pitch Trim ..................................................... 17

Power Loss ............................................................... 18

GPSS Missed Approach Function.............................. 18

Setup Procedure

Lateral Setup............................................................. 5

Pitch Setup ............................................................... 7

3

General Introduction

The TruTrak autopilot can be defined as being an orthogonal rate system.
This means that gyroscopic rate sensors sense motion about each of the
major axes (roll, pitch and yaw). These sensors generate the fast signal
responses necessary to create an autopilot with the best possible dynamic
performance.
To fly an aircraft well about the axis controlled by the ailerons, velocity
of aileron movement must be directly proportional to the rate of roll for small
movement. This means that aileron position corrections do not lag behind
motion of the craft about the roll axis. Aileron control systems that use a
turn coordinator, which senses twice as much azimuth as roll rate, cannot do
this. Instead, yaw disturbances in turbulence cause undesired aileron
movement. In some aircraft this effect is so severe that the controls may
even momentarily move in the wrong direction.
The goal at TruTrak is to create systems with the very best dynamic
performance available—systems that do not need to be disengaged in
turbulence, but instead provide function when needed most.
The complete TruTrak autopilot system combines all the electronic and
sensing elements needed for the roll and pitch functions within a single
panel-mounted programmer/computer package. A rate-gyro-controlled yaw
damper can be added to the system.
Basic directional control is provided by digital selection of a GPS track.
This replaces heading selection on the DG and eliminates drift as well as
crosswind correction. In the GPS steering mode of operation, the system
responds to digital guidance information to fly a complex navigation
program.
The vertical portion of the system contains a digital altimeter and
associated altitude selector with selectable increments as small as fifty feet.
Altitude transitions can be made by airspeed, vertical speed, or horizontal
distance (VNAV) selection. If an upward vertical speed is selected which is
beyond the capability of the aircraft, there will be no stall. Instead, the
autopilot will cause the aircraft to climb at a pre-set minimum safe airspeed.
This is the only known system to provide this safety feature.
For any set of features all TruTrak computers are identical. Servos
likewise are identical in velocity response. Servos do differ according to
total torque required. By providing setup functions in the programmer for
system activity and torque, one TruTrak programmer-servo combination can
fly any aircraft.
As a starting point in understanding how to operate the TruTrak system,
the following describes the presentation of data, the operating controls, and
the procedures for selecting modes of operation.

4

Autopilot Power Up

The autopilot master switch should be in the off position when the
engine is started. Aircraft electrical systems can generate voltage
transients during an engine start and like other avionics systems, the
autopilot should not be subjected unnecessarily to these conditions.
After start up, turn on the autopilot master switch and keep the aircraft
stationary as the internal gyros are initialized. This takes approximately
ten seconds during which time the display will show the words PWR UP
in the lower right. When initializing is complete PWR UP will change
to AP OFF.

Mode and Data Display

The display shows operating modes and associated data. It is also
used to display setup mode screens and their values. When displaying
operating modes, the left side shows lateral data and the right side shows
vertical data. NO GPS will be displayed in the top left of the display
when no GPS signal is detected. A flashing period will appear when a
GPS signal is detected, but no position information is available. The
words NO FIX will be displayed. Once GPS position data becomes valid
a flashing asterisk will appear and the display will show GPS OK. If
GPS flight plan information is being received over the serial channel or if
GPS steering information is being received, a flashing plus sign will be
shown in place of the asterisk.

The upper left display is labeled TRK, showing the electronic DG
slaved to GPS track. When the GPS track is not available, TRK will be
replaced by BANK. This means the autopilot is using its internal gyros
for bank angle control. The lower left display labeled SEL shows the
selected GPS ground track when in the standard track mode. When in
the gyro mode, the lower left shows the current selected bank angle. The
upper right display shows altitude or selected altitude, and the lower right
display shows either selected vertical speed or selected airspeed.

Underlined numbers indicate a value that can be adjusted by rotating
the knob. A sample of the display is shown below.

5

Sorcerer Setup Procedure

In the Sorcerer setup screens, pressing VS UP on the rocker switch
will advance the page to the next setup screen. Pressing VS DN will
return to the previous screen. All values are changed by rotating the
knob. Pressing the knob will exit the setup mode.

Lateral Setup

To enter the lateral setup mode, press and hold the TRK button for
two or more seconds until the first setup screen appears. This screen
shows the current value for the LAT ACTIVITY. Any value between 0
and 24 may be chosen. In this example, the value of 3 is selected. The
higher the number is set, the faster the servo moves the control system.
Too low of a setting will cause hunting, too high of a setting will cause
hunting and the servo to be overactive and jitter. (Any lost motion or play
between the servo and the control surface can cause hunting in still air).

The next setup screen is for adjusting LAT TORQUE. This determines
how much torque the roll servo is allowed to apply with 12 being the
maximum. A default value of 12 is set at the factory but may need to be
modified to suit a particular aircraft or pilot. Trutrak recommends a
setting of 12 for all aircraft. If the torque setting is too low the AP may
not be able to control the aircraft in all flight conditions. This could
cause the aircraft to drift off selected track.

The next screen shows the RS-232 input BAUD rate setting. The
default setting is 9600. Consult the Sorcerer installation manual for
information on how to setup some GPS receivers to properly
communicate with the Sorcerer AP.

6

The next screen shows the BANK ANGLE adjustment. It is
adjustable to LOW, MED, or HI. This will limit the AP bank angle to
approximately 13°, 18°, and 24° respectively. This setting has no effect
on the GPSS mode. It only affects GPS TRK and GPS NAV modes.

The next screen is the MICROACTIVITY. This setting is used
in cable controlled systems to remove any slack or lost motion
introduced by the cables. This setting should be left at zero unless
advised by the factory.

Advance to the next setup screen. This is the GPSS GAIN
setting. This setting should be left at 16 unless advised by the factory.

The next setup screen is SPEECH. This setting turns the speech
annunciation on and off. If the speech is turned off, the autopilot will
give a series of alerter tones for important information. If the speech is
turned on, there will be a voice annunciation for important information.

The next setup screen is for AUDIO LEVEL. While this screen is
displayed, the autopilot will send an audio tone to the audio system.
Adjust the value between 0 and 16 for the desired volume.

The next screen is the EXT DG/HSI selection. Use the knob to
select either Y (yes) or N (no) depending on whether an external DG or
HSI is connected to the system. Leave setting at N for Garmin G3X.

The next screen is the YAW DAMPER selection. Select Y (yes)
or N (no) to indicate whether or not a yaw damper is present. If N is