HELICOPTER ROTOR BLADE Russian patent published in 2015 - IPC B64C27/467 

FIELD: aircraft engineering.

SUBSTANCE: blade comprises root part, aerodynamically shaped parts and tip. In the range of relative radii from 0.5R to (0.95-0.98)R aerofoils feature permanent relative depth making 0.10-0.095 of chord profile. Radii of rounding of top and bottom parts of profile tip feature the ratios of about 1:3. Aerofoils at relative radii 0.4, 0.3 and 0.2 feature variable relative depth consecutively increasing at every said relative radius by about 1/4 of profile relative depth at relative radius 0.5. Tip in plan is composed of elliptic curve while its aerofoil is composed by arcs of ellipses tangentially inscribed in outline of adjacent aerofoil cross-sections. Blade geometrical twist makes approximately 7 degrees while blade finned part starts from relative radius 0.13-0.15R.

EFFECT: better aerodynamics, higher safety at rotor spinup and stoppage.

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