A Review of Rotor Icing Evaluation Methods

Rotor icing evaluations by various helicopter manufacturers and government agencies have been conducted over the past 20-25 years utilizing a variety of simulated icing test facilities (i.e., Hover Spray Rig, Rotor Whirl Towers, Environmental Cold Chamber, In-Flight Tankers, Icing Wind Tunnels). Each of these facilities requires interpretation of the test results to relate the rotor ice accretion and shedding to normal operations in natural icing conditions. Because of major differences between rotor systems (i.e., rigid, articulated, teetering, etc.), airfoil profiles, rotor size, planform variations and blade construction, the icing test experience with any specific rotor system is difficult to use as a basis for a generalized evaluation of rotor icing.This paper addresses the evaluation of icing in terms of available airfoil ice data and the current ability to evaluate ice accumulation as a function of the complex flow environment of helicopter rotors. The simulated icing techniques used for rotor icing and ice protection systems evaluation are discussed along with ice protection systems and concepts. Rotor icing evaluation conclusions based on current technology are presented.