| 摘要 |
<p>The quiet tail rotor (QTR) blade (20) for helicopters provides reduced noise levels and increased thrust efficiency and includes a first segment (24) for connecting the QTR blade (20) to a helicopter tail rotor hub and an outboard segment (26), integral with the first segment (24), having a configuration that reduces high speed impulsive noise and blade vortex interaction noise and provides increased thrust efficiency. The outboard segment (26) includes an inboard segment (28) integral with the first segment (24) and a swept, tapered tip segment (30) integral with the inboard segment (28). The inboard segment (28) has a constant chord and a predetermined constant airfoil section profile defined by constant upper and lower surface contours. The predetermined constant airfoil section profile has a t/c ratio greater than about twelve percent of the chord at any station. The swept, tapered tip segment (30) has a variable chord and a predetermined airfoil section profile defined by constant upper and lower surface contours. The predetermined airfoil section profile has a t/c ratio less than about nine percent of the chord at any station. The swept, tapered tip segment (30) includes a rearwardly swept, straight leading edge having a sweep angle in the range of about 30 DEG to about 45 DEG , and preferably about 45 DEG . <IMAGE></p> |
