Skookum SK720 User Manual

Flybarless system

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SK720
User Manual and Setup Guide
The SK-720 replaces the tail gyro, mechanical flybar, and
receiver on your R/C Helicopter. Other features include flight
logging with playback, optional-self leveling, and more to come!
This unit is ideal for pilots from beginner to 3D expert.
Go flybarless!
Flybarless
System
Rev 1.00
SK720 User Manual & Setup Guide

Table of Contents

1
Introduction ...........................................................................3
2
Package Contents.................................................................4
3
Getting Started ......................................................................5
4
Safety .....................................................................................6
5
Setup Overview .....................................................................7
6
Mounting the Gyro................................................................9
7
Helicopter Airframe Setup .................................................11
8
Connections ........................................................................13
9
Modes, Indicators, and Power-Up.....................................16
10 Installing the Windows Setup Software ...........................17
11 Gyro Setup Using the USB Interface ................................21
12 How to Check Cyclic Pitch & Phasing..............................29
13 After Setup: Final Check!...................................................31
14 Flight with the SK720 Gyro ................................................32
15 Using the Self-Leveling / Bailout option...........................33
16 Basic Tuning .......................................................................35
17 Advanced Tuning for 3D Pilots .........................................36
20 Trouble Shooting Guide.....................................................51
Appendix A: Specifications ......................................................54
Appendix B: Firmware Upgrades .............................................55
©2010 Skookum Robotics, Ltd
2

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Summary of Contents for Skookum SK720

  • Page 1: Table Of Contents

    11 Gyro Setup Using the USB Interface ........21 12 How to Check Cyclic Pitch & Phasing......29 13 After Setup: Final Check!...........31 14 Flight with the SK720 Gyro ..........32 15 Using the Self-Leveling / Bailout option......33 16 Basic Tuning ...............35 17 Advanced Tuning for 3D Pilots .........36 18 Replaying Flight Recorder Logs in the 3D Viewer ..39...
  • Page 2: Introduction

    Introduction Your gyro package includes: The SK720 Digital Flybar is a high performance yet compact and lightweight pitch, roll, and yaw stabilizer for radio controlled (R/C) helicopters. It replaces the traditional flybar (stabilizer bar) mechanism and tail gyro while saving power, SK720 Gyro unit •...
  • Page 3: Getting Started

    An R/C helicopter is not a toy and can cause serious injury to people or damage The SK720 has a standard mini USB port located on the back of the unit. to property. Use of this gyro places a flight control computer (the gyro unit) Connect your new SK720 to your PC using the included USB cable.
  • Page 4: Setup Overview

    . Reference Step 7 in Setup Overview Chapter 11 of this manual. You will need to complete the following steps before you can fly your SK720 10) Fly and trim. equipped helicopter. 1) Set up a new helicopter model on your transmitter.
  • Page 5: Mounting The Gyro

    Xtremelink receivers. If you plan to use the SK720’s self-levelling / bailout feature, it’s better to mount the unit close to your heli’s center of gravity. Also, the lower the vibration levels on your heli are, the better self-levelling / bailout will work.
  • Page 6: Helicopter Airframe Setup

    90 degrees to the blades (for 2- after the SK720 has been configured for your servos. Your servos could be bladed rotors), the phase angle will need to be adjusted. See the diagram below: damaged by an incorrect configuration.
  • Page 7: Connections

    Gain / Bank Select EXT-LED The SK720 supports one or two satellite receivers. Either port A or port B can be used if you are using only one satellite receiver. With the SK720’s power off, Note that only one port needs to supply power to the device, so only the signal connect satellite receivers to the ports marked “Sat A”...
  • Page 8: Modes, Indicators, And Power-Up

    PC by a USB cable or connected to an SK-LCD Terminal. While the SK720 is in setup mode, it will do the control mixing for the helicopter but it will not provide any stabilizing action. This enables mechanical setup and servo trimming.
  • Page 9: Installing The Windows Setup Software

    For reference only: The latest version of Microsoft’s .NET runtime library must be installed on your computer for the SK720 configuration software to work. Leaving the “Check for Microsoft .NET Runtime” option enabled will allow the installation program to test whether you have the required runtime library installed on your computer.
  • Page 10 Figure 10.3 – SK720 Configuration Program Installation Folder Screen After installing and starting the SK720 setup software on your computer, plug your SK720 into any available USB port using the supplied USB cable. The setup software will automatically detect the gyro. The Connected indicator in the setup software should turn green, and the gyro’s serial number and firmware revision...
  • Page 11: Gyro Setup Using The Usb Interface

    CAUTION: Do not connect the swashplate or tail servos to the gyro until not you will be using satellite receivers. after the SK720 has been configured for your servos. Your servos could be damaged by an incorrect configuration. Note: The PC Setup Software has built-in Wizards to guide you through these set up steps as a first-time user.
  • Page 12 Now make sure the heli’s motor is off and then reconnect the SK720 to • your PC. On the Control tab, click Set Throttle Failsafe and follow the instructions that appear.
  • Page 13 • Figure 11.6 – Check for Correct Tail Rotor Blade Movement Windows SK720 setup software. Select “By Name” and find the model of tail servo on your heli in the Servo Name drop-down list. If the tail blade pitch response is not correct, reverse it by clicking on the •...
  • Page 14 0, 100% equal +100 and 0% equal –100. Use values greater than 50% for one bank and less than 50% for the other. Alternatively, disable the gyro gain menu and set the gain channel end points per the method described above. ©2010 Skookum Robotics, Ltd ©2010 Skookum Robotics, Ltd...
  • Page 15: How To Check Cyclic Pitch & Phasing

    SK-LCD Terminal or to a computer Note: this will give you normal phasing (90 degree lead); multi-bladed rotors using a USB cable. A slowly flashing green LED on the SK720 indicates that may fly better with some positive phase trim.
  • Page 16: After Setup: Final Check

    5) Select throttle hold mode and then set zero collective pitch. Check that the swashplate moves to give zero blade pitch. Note: When you use “Auto-tune Bell Gains” or Log Files, the SK720 has to be 6) Set full up collective pitch. Check that the swashplate moves to give sure the helicopter is on the ground before saving to its memory.
  • Page 17: Using The Self-Leveling / Bailout Option

    Ideally, the vibration level should stay below 7 during playback. If you use the SK720’s self-leveling / bailout option, there are a few things to be aware of: The lower your helicopter’s vibration level, the better it will work. Tune •...
  • Page 18: Basic Tuning

    • swash should be level. Adjust the individual servo centers or the 1) As a starting point, for most helis adjust the gains for the SK720 to about linkages as required. 50% for the Cyclic gain and 50% for the tail gain. But for very small helis, start with 40% for the Cyclic gain, and 30% for the tail gain.
  • Page 19 For each of those banks, fly the helicopter as you normally would for at least Hiller Decay to 200%, and hover the helicopter hands-off, both nose-out and four flights. Use the SK720 setup software to disable self-tuning once the nose-in. If it consistently drifts to its right, left, forward or back, adjust the gains stop changing much.
  • Page 20: Replaying Flight Recorder Logs In The 3D Viewer

    Start the 3D viewer by selecting Replay Flight Log in the File menu of the SK720 setup software. You will be shown a dialog box similar to that shown in Figure 18.1 below.
  • Page 21: Setup Software & Advanced Features Guide

    The main window of the setup software is broken down into three areas: Format MicroSD Card: This option will permanently erase the contents of your SK720 mass storage device. Be sure to back up any important files (such as the The menu bar provides access to the program’s features and functions •...
  • Page 22 SK720 setup software window as shown in Figure 19.3 below. SK720. Control Tab The Control tab is found in the Offline Setup Values region of the main SK720 setup software window, as shown in Figure 19.2 below. Figure 19.3 – SK720 Setup Software Swashplate Tab Swashplate Type: Select your swashplate and mechanical mixing type.
  • Page 23 Tail Servo Tab The Tail Servo tab is found in the Offline Setup Values region of the main SK720 setup software window as shown in Figure 19.5 below. Figure 19.4 – SK720 Setup Software Swash Servos Tab Servo Type: Digital uses higher frame rates than analog servos can handle which, along with their better holding power, improves performance.
  • Page 24 SK720 setup software window as shown in Figure 19.6 below. The tab that is currently active is denoted by the blue bar. Switch the active tab using your Lock Cyclic Gain: This allows you to lock in the value for overall cyclic gain, transmitter’s gain/bank channel.
  • Page 25 Collec to Tail: Feeds in tail pitch to directly compensate for torque changes due to changes in collective pitch. Normally 15% to 30%. Increase this value if the The two Tail tabs are found in the Offline Setup Values region of the main SK720 helicopter’s tail twitches to the right during climb outs.
  • Page 26: Trouble Shooting Guide

    Symptom Problem & Solution and pitch, or tilts at one it is mounted on good damping tape The SK720 stays in initialization The heli must be stationary and not particular rpm. and doesn’t contact the frame. Also mode (LED stays red, won’t go vibrating for the unit to initialize.
  • Page 27: Appendix A: Specifications

    Aileron, and Yaw axes. Check that the Dimensions 39x30x14mm as it slows down). Gets worse SK720 gyro is mounted correctly. Also with higher Hiller gains. check rotor head phasing. Weight (without cables) 18 grams...
  • Page 28: Appendix B: Firmware Upgrades

    Skookum Robotics Ltd warrants this product against any defects in materials or 3) Connect the SK720 unit to your PC with a USB cable and ensure that workmanship for a period of 90 days from the purchase date. This warranty is the status indicator in the upper left corner of the GUI shows green and limited to the original purchaser.

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