The response of the thrust and induced velocity of a helicopter rotor due to a rapid change of collective blade-pitch has been experimentally determined. The results are compared with calculations based on the concept of an "apparent additional mass" of air influenced by the rotor disk. The thrust overshoot following a rapid pitch change disappears less than 15/Ω second after the pitch reaches its final value. Any appreciable difference among the time histories of the thrust variation in various flight conditions can not be observed. The calculated results show good coincidence with the test results when the apparent additional mass associated with the rotor disk is assumed to be equal to that of the impervious disk.
東京大学宇宙航空研究所報告 9 (2_C), 725-732, 1973-06