TruTrak Altrak VS User Manual

Altrak Altitude Hold &

Altrak VS Altitude Hold

Installation & User Guide

8300-014 Rev B

TRUTRAK FLIGHT SYSTEMS

1500 S. Old Missouri Road

Springdale, AR 72764

Ph. 479-751-0250 Fax [phone]

www.trutrakap.com

Revision

Date Description

Page #

INSTALLATION MANUAL

For

Altrak VS & Altrak Altitude Hold

TABLE OF CONTENTS

Mechanical Considerations ...................................................................................... 1

RFI/EMI considerations ........................................................................................... 2

Altrak Programmer Mounting / Setup / Ground Test ............................................ 2

Altrak VS control panel installation ........................................................................ 3

Power Up ................................................................................................................... 3

Basic Altrak Operation ............................................................................................. 4

Altrak VS Operation................................................................................................. 5

Electrical Pin out ....................................................................................................... 6

Altrak Wiring Diagram ............................................................................................ 7

Altrak VS Wiring Diagram ...................................................................................... 8

Trouble Shooting ...................................................................................................... 9

Installation Diagram ................................................................................................11

Assembly Diagram ...................................................................................................12

RETURN MERCHANDISE POLICY AND PROCEDURE ... Error! Bookmark not

defined.

A

B 01/10/2009 New schematics & Installation notes 7 - 12

07/01/2008 Initial Release

Mechanical Considerations

The installation information in this section is extremely important and
must be clearly understood by the installer. Improper servo installation
or failure to observe and diagnose installation problems prior to flight
can result in extremely serious consequences, including loss of ability
to control the aircraft. If there are any questions on the part of the
installer it is mandatory to resolve these questions prior to flight of the
aircraft.

Most modern experimental aircraft use push-pull tubes to drive the primary controls. These tubes generally
have a total travel of 3" or less; therefore, it is best to connect the autopilot servo to the primary control by the
same method. This connection consists of an arm on the servo connected by a push-pull rod to the primary
control. Rod-end bearings are required on each end of the push-pull rod.

The servo arm must not rotate even near to the point called OVER CENTER, the point at which the
primary aircraft control would lock up. Some aircrafts mechanical primary control installations will not
allow this to occur and do not need the servo stops.

This is a condition that would result from the servo being back driven when the pilot operates the
controls, or from the servo itself driving the controls to a stop. To protect against this mechanical
stops are supplied with the servos. These stops are drilled so that they can be mounted at different
angles as required (18° intervals).

In addition to the proper use of the stop it is important to know the amount of travel on the primary
control that the servo can handle. With the push rod connected to the outer most hole (1 1/2") the
travel on the primary can not exceed 2 1/2", the intermediate hole 2 1/16", and the inner hole 1 5/8".

It is important to note that the servo travel should be very nearly the same in both directions. In most
cases this means that the servo arm needs to be perpendicular to the push rod but there are
exceptions such as the RV-4 and RV-8 installations.

There will be installations in which space does not permit the use of the stop. When this is done the
aircraft's primary control stops must be positive and care must be taken to be sure that the servo
drives the push rod the same distance in both directions, and that the travel limits of the servo arm
are not exceeded.

There are installations in which the travel of the push-pull tube exceeds the allowable 2 1/2". For such
installations, the drive can be applied to a bell crank at a radius point that moves the desired 2 1/2" of
maximum allowed travel in the outer most hole of the arm.

When there is no way to have a drive point of less than 2 1/2" or when the primary control is cable-driven it is
necessary to use the capstan-cable servo drive. When this is done the servo should be mounted so that the
1/16" diameter cable which wraps around the capstan when extended parallel to the primary cable is
approximately 3/16" from the primary cable. If the primary control travel does not exceed 5" the cable-locking
pin will be 180° away from the point at which the cable leaves the capstan. When the primary control is at the
neutral point this means the total cable wrap around the capstan is 360°. If the primary control travel is
greater than 5" the cable wrap is 720°and the pin is adjacent to the output point when the primary control is at
the neutral point. The cable clamps when properly installed will not slip and thus get loose, but it is desirable
to nico press or swedge a fitting onto the cable so as to provide added assurance that the cable will not
become slack. If the bridle cable is not sufficiently tight there will be lost motion in the autopilot drive. This
will result in hunting (oscillation).

TruTrak Flight System 1 Altrak Installation & User Guide
January 2009 8300-014 Rev B

RFI/EMI considerations

The autopilot programmer is shielded and does not generate any appreciable level of electromagnetic
interference. More over, the servo lines (except for power and ground) are low-current and cannot contribute
to RF interference. The servo power and ground lines do have switching currents through them, but so long
as there are no parallel runs of servo power and ground lines with such things as poorly-shielded antenna
lines or strobe light power lines, there is no need to shield the servo harnesses.

The autopilot itself has been internally protected from RF interference and has been tested under fairly
extreme conditions, such as close proximity to transmitting antennas. However, it is always good practice to
insure that such antennas are properly shielded and not routed directly over or under sensitive panel-mounted
electronic equipment. Most problems in this area are the result of improper RF shielding on transmitting
antennas, microphone cables, and the like. The most sensitive input to the autopilot is the Control Wheel
Switch input. This line should not be routed in parallel with transmitting antennas or other sources of known
RF interference. If necessary, it can be shielded with the shield connection to pin 15 of the autopilot
connector.

Altrak Programmer Mounting / Setup / Ground Test

Must be performed before first flight

After the servo is installed check to see which direction the servo turns to move the elevator up. If the servo
turns counter-clockwise (when looking at the servo arm or capstan) to drive the elevator up then no jumper is
necessary on the programmer. If the servo turns clockwise for elevator up then the pitch servo reverse
jumper must be installed. See Pin 4 on the wiring table for instructions on how to wire the pitch servo reverse
jumper.

The programmer has a static port located next to the connector. The static port can be connected to the
static system. For pressurized aircraft it is necessary that the static system be connected to the Altrak static
port. For most other aircraft the static connection is optional.

Before mounting the Altrak it should be tested for proper operation. After the servo installation and wiring are
complete and the Altrak programmer is plugged in, the test can be performed. When the Altrak is powered-up
it is necessary that the Altrak be stationary. The attitude of the programmer is not important during the
power-up phase. With the Altrak programmer secured turn on the master switch and avionics master so the
Altrak has power. During the power-up phase of operation (the first ten seconds that the Altrak has power)
the ALT button will flash. Next engage the Altrak by pressing the ALT button. With the THIS SIDE RIGHT
sticker facing you rotate the programmer module clockwise to simulate a nose down attitude. The servo
should cause the elevator to move up to correct for the simulated nose down attitude. Rotating the
programmer counter-clockwise should drive the elevator down.

Mounting the programmer module of the Altrak can be done in any location; the only requirement that must be
met is that the side of the unit label "This side right" must face the right side of the aircraft. This is also the
side that has six (6) screws on the surface. The rotational position is not important as long as the right side is
facing right. The side with the sticker also must be parallel with the direction of flight. The mounting holes on
the programmer are 1-1/2 inches apart, and are tapped for a 6-32 thread, use any screw length up to 1" in
length. The engage/disengage pushbutton which also serves as the enunciator can be mounted anywhere in
the panel.

The activity setting (activity is the amount of servo movement for a given amount of programmer movement)
in all RV type aircraft will be at medium activity setting. If more or less activity is required, it is necessary to
use a jumper as per the wiring diagram to change the activity setting.

MOVE TAIL UP AT LEAST A FOOT AND ELEVATOR MUST
MOVE UP AT SAME TIME. MOVE TAIL DOWN AT LEAST A
FOOT AND ELEVATOR MUST MOVE DOWN AT SAME TIME.

TruTrak Flight System 2 Altrak Installation & User Guide
January 2009 8300-014 Rev B

Altrak VS control panel installation

The Altrak VS comes with a reversible control panel, which can be mounted either horizontally or vertically.
The engage/disengage button requires a 5/8” diameter hole; the same size hole can be used for the mounting
of the VS control knob. A template for the two holes is included with this manual. When putting the knob on
the VS control potentiometer, the pointer must be pointing at the larger white mark on the control panel. This
is shown below for both the horizontal and vertical mounting orientations.

Power Up

When powering up the autopilot ensure that the aircraft is still

for 10 seconds.

The power up of the autopilot takes approximately ten seconds. During the power up cycle it is very
important that the aircraft be as still as possible for the initialization of the internal gyro. While the

autopilot is in the power up phase, the enunciator will flash rapidly for approximately ten seconds. Once the
power up phase is completed, the enunciator will remain unlit.

TruTrak Flight System 3 Altrak Installation & User Guide
January 2009 8300-014 Rev B