Interestingly, Sikorsky also produced (perhaps) the most complex tail rotor of all with the Sikorsky S-56 (H-37). This tail rotor was fully articulated, complete with dampers!
The S-56 represented a collosal leap in Helicopter technology, when you consider how fast helicopters came from the R-4 and in such a short period of time.
This tail rotor even made it from the H-37 to the prototype CH-54 (Skycrane), although by the time it reached production it was a very simple tail rotor, (similar to the S61 but like the S61R, with oil lube). The CH-54 was an evolutionary derivative of the H-37, employing essentially the same rotor system (6 bladed instead of 5) and the defunct H-37 inventory became a common source of parts to keep the Cranes going over the years.
In the process of the evolution of the H-37, two major modifications were attempted. The first was the incorporation of a 6 bladed rotor system (same as the crane). The second may have been the most complex tail rotor arramgement in the history of the helicopter;
Twin Tail Rotors
The prototype XHR2S-1, USMC No. 133734, was modified to have a "V"-tail with two tail rotors. The original version using two four-bladed tail rotors first flew on March 2, 1956. Subsequently, two five-bladed tail rotors were flown on April 11, 1956. The rationale for this modification was to increase the center-of-gravity range and allow more indiscriminate loading. With two canted tail rotors, the individual tail rotor thrusts could be adjusted to provide both the required anti-torque thrust and different levels of lift. In this way, centers-of-gravity that were further forward or further aft could be compensated for by decreasing or increasing the combined tail rotor lift component by retaining the same anti-torque sideforce. The project was successful but never adopted for production. My guess is that the additional weight and power required were too high to make the system viable.
http://www.big-deuce.de/d_story05.htm
Does demonstrate that in the evolution of helicopters, virtually every possible design is considered and sometimes utilized.
Fortunately, perseverance may demonstrate that simplicity is a virtue!
(I suppose the most complex tail rotor must lie with the Boeing twin rotor products!)
[ 17 December 2001: Message edited by: Cyclic Hotline ]