Under icing conditions

helicopter rotor is prone to icing.The rotor icing menaces the safety of the helicopter seriously

so the blade must be protected from icing.Through the analysis of external heat fluxes

the critical velocity was calculated for a given blade at ultimate state of icing when surface temperature was 0℃.The protected range along spanwise was then determined to be 0～95% form blade root to tip.By calculating the droplet impinging characteristic

the protected range along chordwise form the leading edge was then determined to be 12% along the upper surface and 33% along the lower surface.On the basis of the results

the configuration and structure of the heating system for a rotor blade can be designed.