Review of the Performance of Swept Tip Helicopter Main Rotor Blades and an Analysis of Aeroacoustical Effects

摘要

The performance and effects of swept tip main rotor blades were studied, showing that the use of sweepback on the tips is advantageous. Although it is difficult to separate the effects of sweepback from the effects of other aerodynamic variables, there is sufficient evidence to justify the use of sweepback at the design stage and for post-design modification to improve the overall performance of a helicopter. Research into advanced planforms produced tips which show significant improvements in model and flight testing by utilizing a combination of variables in addition to sweepback. Sweepback on blade tips modifies the acoustic flow fields to yield benefits in rotational and broadband noise levels.