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