Operating Handbook For Digiflight II SERIES AUTOPILOTS TRUTRAK FLIGHT SYSTEMS 1500 S. Old Missouri Road Springdale, AR 72764 Ph. 479-751-0250 Fax 479-751-3397 Toll Free: 866-TRUTRAK 866-(878-8725) www.TruTrakap.
1 Table of Contents General Information Introduction ............................................................... 2 Mode and Data Display ............................................. 3 Controls ..................................................................... 4 Initializing the Autopilot ........................................... 4 GPS Acquisition ....................................................... 5 Digiflight II Lateral Modes............................................................
2 General Introduction The TruTrak autopilot can be defined as being an orthogonal rate system. This means that gyroscopic rate sensors are installed so as to sense motion about each of the major axes (roll, yaw, and pitch). These sensors generate the fast signal responses necessary to create an autopilot with the best possible dynamic performance.
3 POWER UP—AIRCRAFT STATIONARY SEE INITIALIZING THE AUTOPILOT PAGE 4 area is used to show pitch trim. This display consists of four horizontal bars spaced vertically as the rungs on a ladder, and are made to move up or down when the aircraft is in need of being trimmed. In the upper left where direction is shown, a flashing indicator is present beneath NO FIX. When there is GPS serial data present but no position fix, this will be a flashing period.
4 Controls The Digiflight II series autopilot uses the simplest controls available. All programming is done via a rotary encoder knob and two buttons labeled MODE and ALT. The MODE button toggles between the default (TRK) mode and the GPSS mode (or GPS NAV mode if GPS steering is not available), as well as moves the cursor back to the SEL numerals. The ALT button engages altitude hold or moves the cursor to the SVS numerals. If in the GPSS mode, the ALT button will engage the GPSV mode, if it is available.
5 GPS Acquisition Beneath the word NO FIX a flashing period • will appear each time the GPS sends a message to the autopilot (once per second). This indicates the GPS is working but has not yet obtained a position fix. As long as the period is shown, the NO FIX display cannot transition to the TRK mode. When the GPS does obtain a fix, the period will be replaced by an asterisk *. This means that when a certain velocity is attained GPS OK will be replaced by TRK.
6 Altitude Hold Mode When the autopilot is engaged it will be in the basic lateral track mode, and will synchronize to the direction being flown at the time. The pitch servo will not be engaged at this time. To engage the altitude hold the aircraft must be at the desired altitude and be trimmed for level flight. After trimming the aircraft, to enter the altitude hold mode, simply press and release the ALT button.
7 Continue depressing the knob for 15 seconds to set the gyro center. Power Loss If there is a momentary loss of electrical power, the autopilot will disengage. The autopilot gyros may need to be manually re-initialized using the GYRO SET operation. Manually fly the aircraft in a straight line as steadily as possible, while holding in the knob for at least ten seconds after the words GYRO SET appear in the display. After approximately ten seconds have elapsed, release the knob.
8 systems or a GPS with vertical GPS steering outputs. Vertical Modes When the autopilot is engaged it will synchronize to the direction and vertical speed being flown at the time, the lower right section of the display shows SVS (selected vertical speed). To enter altitude hold at any time, push and release the ALT button two times. If an altitude change is desired, momentarily push and release the ALT button and the cursor will move over to the selected vertical speed.
9 enter GPSV hold, and the display will show as below: Once the VDI has been above the center by one dot for at least 5 seconds the GPSV mode will ARM, and the display will show: As the VDI passes through center, the autopilot will couple to the virtual glide slope, and the display will show that the autopilot is now coupled to the virtual glide slope as below: Missed approach Once the Glide Slope is coupled press any button to activate the Go Around mode.
10 commands a vertical speed climb in which the aircraft slows to the minimum airspeed, the aircraft will maintain that airspeed and will flash MIN AS on the display. Likewise if the pilot commands a vertical speed descent in which the aircraft accelerates to the maximum airspeed, the autopilot will not fly the selected vertical speed, but will maintain the maximum airspeed and flash MAX AS.
11 Digiflight Setup Procedure The setup consists of setting activity, torque, serial baud rate, bank angle setting, micro activity, minimum airspeed, maximum airspeed and static lag. To enter the lateral setup mode, press and hold the MODE button for approximately 3 seconds, until the first setup screen appears. The first setup screen shows the current value for the activity of the aileron servo, with an underline under the present setting of activity.
12 or Garmin protocol (moving map output). Once the desired baud rate or Garmin protocol has been selected, again press and release the ALT button to advance to the next setup screen. The unit will now show the next screen: The bank angle setting can be adjusted to suit the pilot. This setting controls how much bank the autopilot will command when in a turn. This will not change the flight dynamics of the system and any of the three settings will fly the aircraft equally well.
13 To configure the pitch portion of the autopilot push and hold the ALT button for 3 seconds. The first setup screen allows the pitch axis to be turned on or off. (NOT USED IN DII) The default of on will always be selected after a power cycle. To turn the pitch axis off, select off, and click the knob to exit.
14 The next screen in the setup procedure is the static lag setup screen. This setting should only be changed if autopilot tends to oscillate in pitch during altitude hold, due to lag in the static system. The display will show: Rotating the encoder knob will change the number as in previous setup screens. Having selected the desired value, press the ALT button to advance to the next setup screen.
TruTrak Flight Systems, Inc. (11/09) Printed in U.S.A.
