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!

Overview

The SK-720 can greatly simplify your heli’s setup, by eliminating the flybar mechanics, tail gyro, and with the use of satellite receivers (not included), the receiver core and associated wiring as well.

But more than just a flybarless system, the SK-720 is a complete 6-degree of freedom inertial flight control system. So what does that mean for you?

Fast Performance

For 3D pilots, the SK-720 integrates the yaw and cyclic gyros, giving rock-solid piro maneuvers and tail control that benefit from knowing what the collective stick is doing. Flybarless flight gives you more power with less bogging, and a locked-in control feel that is far superior to traditional flybar flight.

Improved Stability

For beginners or those learning 3D, the SK-720’s built-in 3-axis accelerometer means you can set it to self-level, like a coaxial heli. This feature can be turned on full time, dialed down as your skills improve, or set to bail you out at the flick of a switch. Plus, a flybarless heli has greater stability than a heli with a flybar, and with fewer parts, is easier to repair. Small 450 size helis become as stable as 90-size helis. The SK-720 will allow every new pilot's first R/C helicopter to be flybarless.

Flight Logging

For all pilots, the SK720’s built-in flight logging lets you record and play back your flights in a simulator-like display on your PC (like a black-box recorder). Both the heli’s motion and the stick positions are displayed, letting you learn exactly where you can improve your skills – or why you crashed. The playback software can also be used as a diagnostic tool, warning you of voltage dropouts and high vibration, while marking where in the flight they occurred.

Helis Big & Small

For pilots flying micro-helis, the SK-720 will greatly simplify and lighten your machine. It also has a special small-heli tail gyro mode to give good holding power even on 250-size helis.

If you fly larger helis, the SK-720 includes a heavy-duty external power bus that’s good for 25 continuous amps, and helps to isolate vibration from the gyro itself. The bus allows for high voltage servos, low voltage servos, or a combination of both, and includes 16 gauge cabling to connect directly to a 2-cell lipo battery.

Easy Setup

The PC setup software has wizards to guide you through setting up your first flybarless heli in just minutes – making it easier to set up an SK-720 machine than a heli with a traditional flybar!

The setup software or optional SK-LCD terminal lets more advanced users fully tune their heli for max performance. And it's easy to upgrade the firmware at home so you'll benefit from any future product improvements with just a click of your mouse.

Future upgrades will include a GPS accessory for more precise xyz positions in the flight logs, as well as abilities entirely new to the hobby.

Features

• Easy set up for first-time users
• Flybarless stabilization with piro-compensation
• Built-in tail gyro, supporting most all tail servos by name in the setup software
• Supports use as a 9-channel receiver core when used with 2.4 GHz
  satellite receivers (two dedicated Sat-RX ports)
• Works with Digital or Analog swash servos
• Suitable for 120, 135/140, and 90 degree eCCPM, as well as mCCPM swashplates
• Works with 2,3,4, or 5 blades, with phase trim adjustable to +-90°
• Swash Ring anti-binding algorithm
• Internal swash mixing, for accurate control
• Supports radios with either 1024 or 2048 servo steps, and 22ms or 11ms frame rates
• Can also be used with traditional R/C receivers
• Expansion port for future accessories such as GPS
• 38 x 30 x 14 mm, 17 grams
• 8.5 volt capable
• Optional 25 amp external power bus (included) for larger than 50-size and nitro helis (15 grams). Make brownouts a thing of the past!
• 3-axis accelerometer + 3 gyros, allowing self-leveling
• High-power 32 bit processor (for future upgradeability)
• Expansion port for GPS or a third sat-receiver
• Up to 10 servos (one tail servo, 4 digital swash servos, and 5 analog servos)
• Port for a remote indicator LED , which you can mount outside of the canopy
• Built in micro-SD card (2 GB flight-data logging)
• Built in USB mass storage device - Connect the unit to your computer without having to install drivers
• Flight data logs can be played back on your PC with analysis of tuning and heli health
• Compatible with the Skookum SK-LCD terminal
• Existing SK360 setup files can be easily up-converted for the new unit

SK-720 Flybarless System : Software Update

Here you can Download the installer package for:

Rev 1.10 SK720 Setup Software
Rev 1.10 SK720 Playback Utility
Rev 1.10 SK720 Manual

If you want to try out the flight log playback software, you can download one of Alvin Chai's flight logs. Note, the SK720 can't directly record position without a GPS accessory (we're working on it!), so XYZ positions are only estimates.

For Existing SK-720 Owners:

The new setup software includes a web-based firmware update tool for your unit, under the utility menu in the software. But before updating, please read the release notes!

SK-720 Software Rev 1.10 - RELEASE NOTES

* The setup software currently tells you to format your SK720 first (as of June 22, 2010). This is not needed unless there are more than about a dozen files on the unit's flash drive. If you do decide to format it, be sure to use the method under the utility menu, do not use windows explorer.

* If you have a 4-servo swash, you must re-arrange the servo leads to match the SK720's manual & label. The 1.00 rev of the firmware had them swapped.

* If you have a servo that uses 960us frames (Hitec or Logitech), the center point has been changed slightly. You will have to adjust the trim on the Tail Servo tab.

* DO NOT plug an RPM sensor into port IO-C without first turning the sensor option on in your setup and re-booting the unit. Otherwise, there is some risk of burning the sensor out if IO-C is still sending a servo signal. Note,the "Eagle Tree" sensors seem to have their red and black leads switched vs the industry standard.

* The SK-720's self-leveling feature IS NOT AUTO HOVER. That would require an external position sensor, which we plan to release at a later date. Also, at the present time the system is optimized to get the heli close to upright under a wide range of conditions, not to keep it perfectly level with only conservative flying. The self-level feature will turn itself off if the vibration level is too high for more than about 5 seconds, which on an otherwise smooth heli can still happen during hard climb outs or max-roll-rate maneuvers (due to blade stall, such as when you hear the blades barking). Its weakest area is flying fast turns with near-max collective, as the combination of high G's and periods of high vibration can cause errors in its sense of up.

Changes to the Setup Software for rev 1.10:

* Improved setup wizards
* Improved method of setting gyro orientation, which catches some user errors in setup
* Firmware updates for SK720 are easy, and happen over the web
* Several additional tail servos have been added
* Under the View menu, you can check the last flight's vibration level (also available via the LCD terminal)
* RPM sensor option for flight logging
* Added "blur piros" option to the tail banks
* Some other minor bug fixes

Changes to the Playback Software for rev 1.10:

* More reliable and accurate playback
* Displays RPM, if an RPM sensor is used
* Displays which Cyclic and Tail bank is in use

Changes to the Firmware for rev 1.10:

* Self-leveling is activated
* More reliable, smoother startup for tail and throttle channels
* Smoother binding for Dx7se and 9 channel spektrum radios
* If there is an in-flight brownout or reset, it gets flying again faster
* Improvement to tail stability in hover
* More consistent piro rates
* Better hold ability for the tail
* Better bounding on tail servo motion
* "Blur Piros" option, so at 100% rudder the heli will piro at almost 3 revs/second.
* Slight change in center for 960us pulse tail servos (HITEC AND LOGITECH)
* Servo outputs for 4-servo swashes consistent with manual and label
* RPM capture to flight logs, via Port IO-C, that works with most sensors (see manual re Eagle Tree Sensors)
* Improvements to logging, so it's more reliable
* Flight logs should be saved even after a crash where electrical power is lost
* Logging quality improved
* Ability to set up the unit via USB even with the SD card inoperable or removed
* Fixed a bug where the unit could fail to start up if there are a large number of files in the SD card's root directory
* More reliable LCD firmware updating using the SK720
* Lowered risk of setup file being corrupted
* Improved the SD-card reformat method
* Error flags are more consistent