А как быть с этим?:
"ROTORHEAD DESIGN
Given the critical role of the rotorhead, incorporating refinements into rotorhead designs is typically an evolutionary process, unlike the occasional flashes of brilliance that characterize the development of most other components. The term "evolutionary" implies the subtle nature of these refinements, often leaving the designer/manufacturer eager to display them to the public but reluctant to reveal them to the competition. So please bear with us for the relative brevity of this section.
SPORT COPTER has somewhat larger rotorheads than other comparable machines because they were designed for substantially higher loads. The large size is fairly obvious when you are standing next to one of our machines. But when you have the opportunity, you might care to get on a step-ladder and check out one of our rivals' rotorheads. If you do, you won't find any of the features described here:
First, all SPORT COPTER rotorhead components have built-in, replaceable bumper-stops (made of a new broad-temperature polymer) which protect all moving parts from each other as they reach the limits of their respective movement-arcs. The components of other rotorheads simply mash into one another when they reach their arc-limits, leaving dents, scoring and an occasional crack.
Second, the rotorhead itself is actually shock-isolated from the aircraft by a compression-type shock-mount for the longitudinal pivot. This isolation is achieved within the longitudinal carry-through by means of specially-formed polymer and Teflon bushings, compressed and mounted with machined stainless steel retainers, caps and bolts. This results in a significant reduction in shock and vibration transfer between the rotor and the rest of the aircraft. Both the bumper/limit-stops and the rotorhead isolation are intelligently engineered features found in no other gyrocopters, but in time they will almost certainly become accepted design standards throughout the industry."
sportcopter.com/Info/TechnicalInformation/tabid/131/Default.aspx
Это текст с сайта Спорткоптера, в котором в двух словах объясняется для чего туда вставлены полимерные втулки. Это сделано для того, чтобы свести к минимуму вибрации и повреждения сочлененных деталей. И ни слова о шарнирах. Так что, как бы это не было печально, шарниров там нет.