What Type Rotor Head

[hilaw3]

Perhaps this question should be placed in the semi-rigid rotorhead post but I'll ask it here. When a helicopter is designed who, what or how is it determined what type of rotorhead (semi-rigid, fully articulated, etc.) will be used in the design?

[widgeon]

IMHO any finalized design is the result of many trade offs between performance, safety, reliability ,cost ( both initial and life cycle) and technological risk . The better final design will be where none of these elements has overwhelming influence . This applies equally to all elements of the helicopter ( rotor heads , blades , landing gear , power plant etc etc).

[Dave Jackson]

hilaw3,

"When a helicopter is designed who, what or how is it determined what type of rotorhead (semi-rigid, fully articulated, etc.) will be used in the design?"


This answer may appear slightly flippant, but I believe it is an honest one. The primary determining factor is the name of the manufacture. Every manufacture has invested considerable time and money in developing, refining and promoting their specific rotorhead design.

If a particular company had the resources and determination to develop a new rotorhead, they would base it on the proposed usage for the helicopter and the current level of applicable technology.

Dave J

[Nick Lappos]

Having been on the design team of several helicopters, the answer is a bit more complicated that Dave describes (although for some manufacturers, their quiver seems to have only one type of arrow, so dave is not totally off base!)

The biggest determinent is the mission, and the needed CG range (longitudinal and lateral), the maneuverability and the flight envelope (especially the negative G).

Almost nobody would develop a new helicopter with a conventional teetering rotor or a lubricated articulated rotor any more, unless the resources were very low, or the mission was very benign.

Most rotors now fall into two groups, the bearingless flex beam rotor, and the elastomeric bearing rotor, both really variations on the same theme.

Only marginal homebuilts use teetering rotors because the whole reason for their existence, low cost, determines that they keep an easily built, light weight rotor head design.