Operating Handbook For Digiflight SERIES AUTOPILOTS TRUTRAK FLIGHT SYSTEMS 1500 S. Old Missouri Road Springdale, AR 72764 Ph. 479-751-0250 Fax 479-751-3397 www.trutrakflightsystems.
1 Table of Contents General Information Introduction....................................................................... 2 Mode and Data Display................................................... 3 Controls .............................................................................. 4 Initializing the Autopilot................................................. 4 GPS Acquisition .............................................................. 5 Digiflight 100 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 Mode and Data Display area is used to show pitch trim. This display consists of three 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 between TRK or MAG and the numerals that follow. When there is GPS serial data present but no position fix, this will be a flashing period.
4 Controls The Digiflight series autopilot uses the simplest controls available. All programming is done via a rotary encoder knob and entered by depressing and then releasing the knob. This will be referred to hereafter as enter. There is a small button located to the left of the display. This button toggles between the default (TRK) mode and the GPS-S- mode (or GPS NAV mode if GPS steering is not available).
5 GPS Acquisition Between the word MAG and the three digit numeric display, a flashing period MAG•155 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 heading display cannot transition to the TRK mode. When the GPS does obtain a fix, the period will be replaced by an asterisk MAG*155. This means that when a certain velocity is attained MAG will be replaced by TRK.
6 display is slaved to a magnetic heading source contained within the programmer and TRK is replaced with MAG . This magnetic mode is only a backup and would seldom be needed; however, it does provide a means of selecting and maintaining a drift-free direction of flight. If the GPS-Ssignal source is functional, the GPS-Smode will remain functional. Gyro Set When the initializing has been done correctly, the gyros should already be centered at the time of take off.
7 programmed into the GPS. The autopilot must, however, overfly each way point prior to turning and intercepting the next course line. TRK+135 GPS NAV AP ON If the GPS-S- option has been added, pushing the small button to the left of the display will engage the GPS steering. In the GPS-S- mode the autopilot follows lateral steering or bank commands generated by a navigation system (EFIS or GPS).
which time the words GYRO SET will be displayed. MAG*180 GYRO SET Power Loss If there is a momentary loss of electrical power, the autopilot will disengage. The autopilot gyros must now be manually re-initialized using the GYRO SET operation. 8 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.
9 The lateral modes previously described are based on GPS track being present. When GPS is lost, the DG display is slaved to a magnetic heading source contained within the programmer, and TRK is replaced with MAG . This magnetic mode is only a backup and would seldom be needed; however, it does provide a means of selecting and maintaining a drift-free direction of flight. If the GPS-Ssignal source is functional, the GPS-Smode will remain functional.
10 fast trim it will be necessary to tap or pulse the trim button so that it will be slow enough to turn it off before going too far. When a reversal takes place, a slight tap in the opposite direction may be required to get the bars to stay off. Finally when the bars have been made to disappear and there has been no speed change, the bars can be ignored if they reappear in that it is known the aircraft is close to being in trim.
11 Any value between 0 and 12 may be chosen. In this example, the value of 1 will be selected. Activity should be set so as to not be exc essive in turbulence and yet sufficient to fly without hunting in still air. (Any lost motion or play between the servo and the control surface can cause hunting in still air). Once activity is set to the desired value, press and release the knob to confirm and enter the selected value into storage.
12 moved within the panel, or if new equipment is installed nearby. In order to skip this step, press and quickly release the encoder knob while N is selected. If calibration is desired, it must be done in the air on a day in which there is little wind or turbulence. The autopilot will turn the aircraft through a full circle, using the GPS signal as a reference to calibrate the internal magnetometers. The aircraft is turned, first to North, then East, then South, and finally West.
13 mode once again. Once in the setup mode, scroll though the various setup screens until the display shows: VRT ACTIVITY 8 VRT TORQUE 200 The first screen shows current values for the activity and torque of the aileron servo with an underline under the present setting of activity. A typical screen might show: VRT ACTIVITY 8 VRT TORQUE 200 Turn the encoder knob to set the activity level to the desired value for the particular aircraft. Any value between 0 and 12 may be chosen.
TruTrak Flight Systems, Inc. (2-03) Printed in U.S.A.
