23.4. The rotorhead

There are two types of rotorhead designs commonly used on R/C helicopters:

A flapping head allows each rotor blade to flap, lead/lag, and feather independently. This is accomplished by having having three hinges per blade:

This is typically used on helicopters with more than two blades, but some two-bladed helis such as the Corona use this.

A seesaw head typically has the blade grips for two blades connected by a feathering shaft. This feathering is rigid and only allows the two blades to seesaw as a single unit, e.g. when one blade rises, the other is forced to sink. The two blades will still feather and lead/lag independently, however.

Most R/C helicopters use this system, including the ECO 8, Logo 10, Shogun, T-rex, etc.