Gyro Differences

The first type of gyro is the piezoelectric gyro which uses a quickly vibrating crystal. As the crystal vibrates, an applied rotational force will cause disturbances in it’s wobble which create a small, but measurable electric current proportional to the rate at which the gyro is rotated.

A disadvantage of piezoelectric gyros systems is that they’re very temperature sensitive and going from hot to cold or vice versa will cause them to act erratically. Most have built in temperature protection circuits, but they’re not perfect, so if you’re going to take a gyro from warm your car and fly in cold weather, give it 10 or 15 minutes to adjust before flying.


The second and most modern type of gyro is the MEMS or Micro Electric-Mechanical System gyro.

MEMS are molecule sized machines that are fabricated on top of a piece of silicon, along with the electronics to interface to them. They vibrate at a high rate just like the piezoelectric gyro and as the gyro rotates, so does the displacement of the mass and the signal generated by the gyro.
Besides the different makeups and types of gyros, there are two primary ways that gyro’s operate, rate and heading hold mode.



Rate Gyros

Rate gyro’s are often used in scale RC helicopters because they lend themselves to a more realistic flying experience, while heading hold gyros are used by almost everyone else because they make flying easier.
The only time that we will use rate mode on the gyro is when we are setting it up. The reason for this, is that the servo will always go back to center when you release the stick.

Heading Hold Gyros

Heading hold or heading lock gyros are a conceptually simple extension of rate gyros.
In a heading hold gyro, a built microprocessor that keeps track of and remembers how far the helicopter has turned from its set position. Based on the deflection from the set position, the gyro will control the rudder servo such that the gyro returns the helicopter to the set position.

Therefore, as you increase the throttle or headspeed of your heli, the head holding gyro will counter the main rotors thrust automatically keeping your heli’s tail in its original position.

Heading hold gyros are very popular and pretty much standard among RC helicopter pilots for that very reason – they’ll hold your tail in a constant position no matter what you’re doing as long as you don’t input a rudder command, even if you’re doing 3D aerobatics or flying in a strong wind.

With a head holding gyro, the rudder signal from your transmitter no longer directly controls the tail – it simply tells the gyro how many degrees to turn per second. It will also reset the gyros stored position to the new position you move your heli to.

In conclusion, only purchase a head holding gyro unless you are wanting to go scale. And even then, learn on a head holding gyro first, then progress onto the scale heli's and rate mode gyros.