The take-off weight of our large Alouette III is relatively high, and we therefore decided to revise the linkage for the XL-C rotor head and the 3-blade rotor head in order to optimise the system to cope with the increased loads. The modified lever ratio allows for increased swashplate travels, resulting in greater precision of control combined with low actuating forces. The travels are only reduced to the actual required values directly at the blade holder.The bellcrank positions were chosen to ensure that all linkage pushrods run vertically, with the result that the linkage components are not subjected to lateral forces.Note that the revised system requires the swashplate to carry out all travels in the opposite direction to the usual configuration.3-blade rotor headfor 12 mm Ø rotor shaftfor models with take-off weights above 20 kg