Kim D., Song K., Kee Y., Kim J., Joo G.

The helicopter produces lift and control force by rotating main rotor. A main rotor system is a major vibration source for helicopter as it flights in hover and forward condition. This vibration makes pilots and passengers uncomfortable and also the fatigue life of helicopter airframe shortened. So, low vibration design approach for rotor of helicopter is usually adopted in early study phase or preliminary design phase. Generally, there are two main approach methodologies to reduce helicopter vibration to be applied. The first approach method is to reduce the original vibration source by low vibration blade design. The second approach method is to apply anti-vibration device to helicopter. In early design phase, the first methodology is more recommended to reduce vibratory source since it has no additional weight penalty and no power penalty. On the other hand, the second methodology is usually applied at the latter stage of development due to its weight and power penalty. One of vibration reduction method from vibration source is well-matched mass and stiffness distribution which is especially linearly tapered along rotor radial direction In this paper, low-vibration blade design approach was introduced. The first approaching concept to apply tapered mass distribution method was adopted to reduce blade vibration. Blade section design was done by using CORDAS which was developed in KARI. After design of full size low vibration blade, the small-scaled blade was design and tested to verify low vibratory characteristics by using KARI GSRTS. The test result for small-scaled low vibration blade was compared with that of the existing benchmarking small-scaled blade. The improvement of vibration reduction was achieved about 10%~20%.