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Navaid Devices AP-1 Manual

Autopilot w/gps coupler and s-2 servo
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AP-1 AUTOPILOT
W/GPS COUPLER AND
S-2 SERVO
N A V A I D D E V I C E S , I N C .
6 4 1 N o r t h M a r k e t S t r e e t
C h a t t a n o o g a , T N 3 7 4 0 5
P h o n e : ( 4 2 3 ) 2 6 7 - 3 3 1 1
F A X : ( 4 2 3 ) 7 5 6 - 6 1 5 4

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Summary of Contents for Navaid Devices AP-1

  • Page 1 AP-1 AUTOPILOT W/GPS COUPLER AND S-2 SERVO N A V A I D D E V I C E S , I N C . 6 4 1 N o r t h M a r k e t S t r e e t...
  • Page 3 INTRODUCTION Thank you for buying a Navaid Devices autopilot. We appreciate your business, and we will support you in whatever way we can to make sure you get years of service from our product. We are quite confident that, after you read and follow the installation and checkout instructions contained in this manual, your autopilot will become one of your most valued flying tools.
  • Page 4 1. THREE POSITION MODE SWITCH RIGHT: Wing Leveler Mode. Keeps wings level by reference to the built-in gyro. In this mode you can fly level, turn left, or turn right with the TURN CONTROL, item 5. MIDDLE: Turn coordinator. This position lets you fly without the autopilot, but with the turn coordinator working.
  • Page 5 Of course you will mount the AP-1 control unit in full view, and wire it with a circuit breaker/switch (not supplied) to the power buss.
  • Page 6 INSTALLATION OF SERVO ACTUATOR - S2 CRANK ARM The S-2 crank arm servo is easier to install than the capstan version and is suitable for all but the largest homebuilt aircraft with heavy aileron loading. Because most installations use the crank arm servo, information specific to the capstan servo is found in Appendix The S-2 crank arm servo uses a pushrod terminated by rod end bearings to link the servo arm to the aircraft's aileron control system.

  • Page 7: Servo Mounting Hardware

    SERVO MOUNTING HARDWARE The installation kit that Navaid offers for the Varieze, LongEZ. and Cozy is shown in Fig. 2. INSTALLATION KIT FOR RUTAN EZs Fig. 2 Kits for other aircraft at least consist of a pushrod (cut to proper length by the user) and a suitably sized rod end bearing for connecting to the airplane.
  • Page 8 NOTE: A longer crank radius dictates a correspondingly longer radius at the drive end. The ailerons must travel from aileron stop to aileron stop within the range of movement allowed by the servo stops that limit crank arm rotation. The mounting place must be strong and rigid-conceivably a lateral force of up to 50 pounds could be encountered.
  • Page 9 WIRING DIAGRAM FOR HAND-HELD GPS AND AP-1 WITH GPS COUPLER WIRING DIAGRAM Fig. 3 - 7 -...
  • Page 10 12 volts and cause improper operation. See Fig. 1 for a view of the AP-1 controls. Flip the Mode Switch on the AP-1 to the right for Wing Leveler mode and turn on the aircraft master switch. The gyro should start to wind up, and the servo should crank to a stop somewhere.
  • Page 11 1) There is a nylon gear on the back end of the output shaft that engages another gear on the feedback pot shaft. Loosen the set screw that secures the gear on the output shaft, then slide it back so that it no longer engages its mating gear. 2) There is a U shaped gear engage rocker arm that the solenoid normally pulls up to engage the gear train.

  • Page 12: Install The Servo Pushrod

    Point the indicator straight up to put it tin the dead zone. Center the TRIM CONTROL and TRIM RANGE trimpot. Now the AP-1 should think the airplane is flying straight and level, and the servo is locked into the position that it would hold for neutral aileron.
  • Page 13 Use the supplied braided shield twin lead for the LORAN signal; do not use foil shield. If you need extra, call Navaid Devices. Ground the shield on only one end (Fig. 3 shows grounding at the AP-1 end). This shielded wiring is necessary only if you are connecting to a LORAN—it prevents the gyro motor from lowering the signal to noise ratio.
  • Page 14 CDI. Usually they are labeled '+ Left' and '+ Right', and they are to be connected to the corresponding AP-1 terminals. If the labeling is ambiguous, as it is on at least one fairly popular radio, just connect both wires without worrying about polarity and check it out in flight test.

  • Page 15: Circuit Breaker/Switch

    Set the TURN CONTROL to midrange and make sure it is in the center dead zone. To do this, set the AP-1 to WL mode (flip Mode Switch right) and slowly rotate the TURN CONTROL from stop to stop at a constant speed. You will hear the servo pause as the knob passes through the dead zone.
  • Page 16 TEST FLIGHT AND CALIBRATION Take off, get some altitude, and set up a level cruise. If you have cockpit adjustable trim, set it as necessary to achieve straight line flight. Flip the Mode Switch rightward to the Wing Leveler position. The autopilot should take control.

  • Page 17: Track Mode

    If the TRIM RANGE trimpot does not have sufficient range, reset it to midrange. Then use the TURN CONTROL to make the airplane fly straight. Leave everything as is, turn the autopilot off, and land the airplane. When the airplane is on the ground and the Wing Leveler is engaged again, the ailerons will go to the correct level flight position.
  • Page 18 The purpose in the delay in switching to Track mode is to allow the charge on some capacitors in the AP-1 to stabilize. If the switch is made as soon as the needle is centered, the machine will "remember" that the needle was off, "think" that it must correct, and bank the airplane off course.
  • Page 19 USER SELECTABLE GPS / LORAN SIGNAL GAIN The standard error signal voltage for driving a CDI, which is also used for the autopilot, is 150 mV at 5 miles off course (cross track error) for a GPS or LORAN. Some receivers also have user selectable tracking gain that can be set to give a 150 mV error signal at 1.25 miles off course, and it may be called APPROACH MODE instead of CRUISE.

  • Page 20: Calibrating The Display

    Obviously, putting in a fix at low speed can adversely affect high-speed response, and vice versa. It may be necessary to accept a compromise. CALIBRATING THE DISPLAY For your information, the RIGHT and LEFT CAL trimpots affect nothing but the number of bars lit for a given rate of turn.

  • Page 21: Common Problems And Questions

    THIS IS A VFR AUTOPILOT Please remember that th& Navaid autopilot is not recommended for use in IFR conditions. The components used in the kit are probably as reliable as any, but the system has not been through the test regime that would be required of a type accepted piece of equipment.
  • Page 22 LORAN, or flies a different radial toward the VOR, just adjust the trim knob. Trim toward the needle deflection. B) Verify that a tracking signal is present at the input to the AP-1. The receiver could be broken, or the signal wiring could be faulty (open, shorted to ground, or reversed).
  • Page 23 If there is no signal at the AP-1, check to see if the shield, which is grounded at the AP-1, could be shorted to either conductor. You may not be able to see it if this is the case, but an ohmmeter will read zero resistance between the shorted signal wire and the shield.
  • Page 24 AP-1. We hope to find a resistor value that increases the AP-1 gain enough to make it work off of the GPS or LORAN signal, but unfortunately this will probably destroy the machine's ability to track the VOR.
  • Page 25 The gyro should start to wind up, and the servo should crank to a stop somewhere. Set the SPAN trimpot fully clockwise. Rotate the TURN CONTROL on the AP-1 for a right turn, and note the direction of capstan rotation. When the cable is installed, this rotation must deflect the ailerons for a right roll.
  • Page 26 ROTATION RANGE OF THE S-2 CAPSTAN If the limit-to-limit cable travel is greater than 3.5 inches, it is possible to confuse the autopilot by turning it on when the stick is fully deflected, in which case the servo cranks the wrong way into the aileron stop. There is a way to avoid this possibility, but at the cost of reduced resolution which might adversely affect tracking performance.
  • Page 27 - A.3 -...
  • Page 28 Apply power to the autopilot and adjust the GYRO NULL trimpot until the meter seems to average a zero reading. Even with the AP-1 held rock steady, it is normal for the reading to bounce around several tens of millivolts, so don't expect to get a perfect reading of zero, especially if you have a very sensitive meter.

  • Page 29: Installation Check

    LED is on top, and the word "HEADING" is on the right side. Wire the NMEA 0183 output of your GPS receiver to pin 8 on the AP-1 main connector. Plug the telephone-type cable into the appropriate jacks in the back of the AP-1 and the mode switch.
  • Page 30 Put a course into the GPS receiver. Enable the NMEA 183 output from the receiver. Fly the aircraft to place it on course and on the correct heading. Enable the AP-1 in wing- leveler mode, and use the trim knob to ensure straight-and-level flight.
  • Page 31 To set the course width: 1. Hold the Course/Heading switch either to the left or right when you turn on the autopilot. You must keep the switch engaged until the LEDs stop their normal turn-on flashing sequence. 2. There is no indication that you have entered set mode. 3.
  • Page 32 1) Electrical transients during start-up may damage the integrated circuits in the autopilot. Therefore please provide a means for applying electrical power only after the engine is started. Attach the positive (B+) power lead from the AP-1 to your avionics master, a separate switch and fuse, or a breaker / switch.

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