PROPELLER BLADE AND AEROFOIL PROFILE OF BLADE (VERSIONS) Russian patent published in 2000 - IPC

FIELD: aircraft manufacture; manufacture of propeller blades of rotary-wing aircraft. SUBSTANCE: aerodynamic focuses of profiles of cross sections of blade lie in line having bent or broken shape in plan. These focuses are so located relative to elastic axis of blade that extended section is available in shank portion between unit of attachment of blade to propeller hub at relative radius of r = 0.55; on this section, they are extended forward along chord in direction towards leading edge of blade as compared with position of these focuses relative to elastic axis in center (in span) portion of blade locater at radii exceeding r=0.55. Difference in position relative to elastic line of aerodynamic focuses of profiles of shank sections of blade in this section and position of aerodynamic focuses of profiles of sections relative to elastic axis in center portion of blade ranges from 3 to 55% of lengths of chords of profiles of respective shank sections. Aerofoil profile of blade is characterized by connection of rounded-off leading edge and pointed or blunt trailing edge by smooth lines of contours of upper and lower surfaces. Maximum thickness of spar is located at distance of 35 to 50% of its chord at positive coefficient of moment and zero lift and position of aerodynamic at 18 to 22% of chord in working range of Mach numbers for effective arrangement of spar inside contour of profile. EFFECT: reduced amplitude of varying hinge moments of blade and power loads in control system of main rotor; improved aerodynamic characteristics in hovering and during horizontal flight. 10 cl, 12 dwg