Makers of RC electric helicopters are constantly upgrading the components of even their most basic craft, in an effort to outdo the competition. This makes life confusing for newcomers to electric helicopters who are just getting to grips with the basics.
For example, what is a Heading Hold Gyro - and how does it differ from a Piezo-Electric one? It helps if you understand the job a gyro has to do; which means understanding how tail rotors work.
Non co-axial RC Helicopters have a tail rotor to counteract the torque, or body spin, that the main blades produce. The tail rotor must be adjustable, and this is done by changing its pitch or motor speed.
Adjusting the tail rotor (pitch or RPM) of Electric Helicopters allows pilots to apply yaw; in other words, to allow rotation of the craft about the tail axis. Say you’re heading in a westerly direction, but then want to fly south. Adjusting the yaw allows the heli to pivot and face in the new direction. However, there are many other applications for 3D flying and, evidently, the best RC electric helicopters are the ones with the best tail control…
Tail rotors are of two main designs:
- Fixed pitch motor driven. These have their own independent motor. Rotor adjustments are made by the pilot adjusting the ESC (electronic speed controller) of this motor.
- Variable pitch belt-driven. The rotor pitch is altered via servos controlled by the pilot. Power is supplied via a belt and gearing system connected to the main motor.
Both motor driven and belt driven Electric Helicopters employ tail gyros. These help balance the chopper by detecting outside forces, e.g. directional wind changes, and counterbalancing them. Only the most basic, indoor RC Helicopters lack a gyro.
Typically, a tail gyro will be of piezoelectric design. This means it generates an electrical signal in response to vibratory or other unwanted tail movement, and adjusts the rotor inputs accordingly. Thus, RC Helicopters with built-in gyros will respond as the pilot wants them to, unaffected by outside influences. The sensitivity of the gyro can be adjusted depending on the pilot’s ability or the flying conditions.
Heading Hold/Lock Gyros are a more advanced form of gyro with a “memory” function. A basic PEG works on each individual tail fluctuation. A Heading Lock memorises all the varying rotor speeds and then applies the best solution overall. They are excellent for bad weather flying, or for Electric Helicopters that are used in advanced 3D aerobatics.