Rotary‐Wing Aircraft: The Final Article of a Series Summarizing the Current State of Knowledge Available to Purchase

IN last month's article, the simple case of an articulated rotating system in which the whole mass is concentrated at a single point is discussed. An approximate method will now be described of obtaining the natural vibrations of a two‐bladed rotor in which the drag hinges are inclined downwardly and outwardly. This approximation requires the solution of fourth degree equations. Later a more accurate method is considered in which eighth degree equations have to be solved, and it will be seen that an accurate analysis of a three‐bladed rotor would be extremely laborious owing to the increased number of variables and therefore of simultaneous differential equations.