Helicopter Gyro: Tail Gyros, Flybarless Units and Setup
A helicopter gyro is an electronic sensor unit that keeps an RC helicopter stable. On older and simpler helicopters, a tail gyro holds the heading so the tail doesn’t swing with every torque change. On modern collective-pitch helicopters, a 3-axis flybarless (FBL) controller stabilises the tail and the main rotor, replacing the mechanical flybar and often adding rescue and self-levelling modes. Toy helicopters have small built-in gyros. Correct mounting, direction and gain settings are what make a helicopter fly well.
By Kyle HilsonUpdated: October 20263 min read
Types of gyros
| Type | Stabilises | Used on |
|---|---|---|
| Built-in toy gyro | Yaw (heading), sometimes all axes | Coaxial and toy helis |
| Tail (heading-hold) gyro | Yaw | Flybar helicopters |
| Flybarless controller | Roll, pitch, yaw | Modern collective-pitch helis |
| FBL with rescue/attitude | All axes plus self-levelling | Beginners and 3D pilots |
How it works
The gyro measures rotation rates many times per second. On the tail, when torque from the main rotor tries to turn the helicopter, the gyro adjusts the tail rotor pitch to hold the heading. In heading-hold mode, the helicopter keeps pointing the same way until you move the rudder stick. A flybarless controller does the same on all three axes, correcting the swashplate to keep the rotor stable, which replaced the mechanical flybar described in what is a flybar.
Setup steps
- Mount the gyro/FBL unit firmly on the frame, aligned with the axes, using the supplied vibration-damping pad.
- Route wires so they can’t pull on the unit.
- Follow the setup wizard: servo types, swash type, directions, limits.
- Check correction directions: rotate the helicopter by hand and watch surfaces move to oppose it.
- Set gain on a transmitter channel; start at the recommended value.
- Hover and adjust: raise gain until slight wagging, then reduce a little.
Common problems
- Tail wags: gain too high or loose tail linkage.
- Tail drifts: gain too low or not in heading-hold mode.
- Helicopter tips on take-off: wrong correction direction; check before flying.
- Random twitches: vibration reaching the gyro; balance blades and check mounts.
- Gyro won’t initialise: helicopter moved during start-up.
Choosing a good gyro
For modern collective-pitch helicopters, choose a well-supported flybarless unit with good software, rescue mode if you want a safety net, and support for your receiver type. For flybar helicopters, a quality heading-hold tail gyro with a fast digital tail servo makes a big difference. Plane gyros work on similar principles; see RC plane gyros.
Vibration matters
Gyros are sensitive to vibration. Balanced blades, straight shafts and good bearings keep the signal clean. Many FBL units have vibration analysis tools; use them after builds and crashes.
Rescue and attitude modes
Many flybarless units offer a rescue function: flick a switch and the helicopter returns to a level, upright hover (or climbs away), whatever attitude it was in. Some also offer an attitude or “beginner” mode that limits tilt and self-levels when the sticks are centred. These modes help when learning and save many crashes, but they need correct setup and enough height to work. Test rescue at a safe height before relying on it, and remember it can’t fix mechanical failures.
After any crash, check that the gyro unit is still firmly mounted and aligned, and re-run the direction check before the next flight.
FAQ
What does a helicopter gyro do?
It senses rotation and corrects the controls to keep the helicopter stable.
What is heading hold?
A mode where the tail holds its direction until you command a turn.
Do I need a flybarless unit?
For modern collective-pitch helis, yes.
Why does my tail wag?
Gain too high or a loose tail linkage.
More on this topic: the complete RC Helicopters guide covers the basics behind this article.
About 20 years in RC. Mostly boats in the NAVIGA Mini Eco Expert class, with many self-made parts; also a King Motor Baja 5B, a home-built electric plane, home-built nitro planes he has flown, and an RC helicopter. More about SwellRC
