Higher Performance and Low Noise Characteristics of the Sikorsky S-76D Helicopter

The current paper discusses the performance and acoustic progression of S-76® helicopter designs from earlier models to the newly certificated S-76D™ helicopter. Supporting this progression has been extensive model scale and full scale rotor testing, analytical modeling and aircraft level testing, as well as advances in manufacturing capabilities and enabling technologies such as active vibration control that can expand the rotor design envelope. The S-76D™ helicopter simultaneously achieves higher performance with low Flyover, Takeoff and Approach noise characteristics providing significant reductions in certification noise levels. In addition to the S-76DT™ noise certification test results, potential additional noise reductions via dual rotor speed operation are discussed and comparisons with other noise reduction technologies are provided. Finally, a discussion of the potential for further design and technology based noise reductions is presented.