Fluid reaction surfaces (i.e. – impellers) – Specific blade structure – Radial flow devices
Patent
1990-12-20
1992-08-11
Denion, Thomas E.
Fluid reaction surfaces (i.e., impellers)
Specific blade structure
Radial flow devices
416228, 416238, 416DIG2, 416DIG5, B63H 126
Patent
active
051374277
ABSTRACT:
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..
REFERENCES:
patent: 3721507 (1973-03-01), Monteleone
patent: 4012172 (1977-03-01), Schwaar et al.
patent: 4142837 (1979-03-01), de Simone
patent: 4569633 (1986-02-01), Flemming, Jr.
patent: 4880355 (1989-11-01), Vuillet et al.
patent: 5035577 (1991-07-01), Damongeot
Denion Thomas E.
Radke Terrance J.
United Technologies Corporation
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