Rotor blade assembly with high pitching moment airfoil section for a rotary wing aircraft
AssigneeSikorsky Aircraft Corporation
InventorsRobert Moffitt, James E. Duh, Charles Berezin
Life of this patent
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Abstract
A main rotor blade assembly with a high negative pitching moment airfoil section having a pitching moment coefficient beyond (more negative than) −0.035 at Mach Numbers below 0.80 and a blade taper of 1:5 or greater.. The main rotor blade preferably limits blade torsional bending and an aft loaded tip airfoils to approximately ‘no more’ than that of conventional effective rotor blade designs based on conventional tip airfoil sections.
Claims37
A main rotor blade assembly comprising:
- an inboard section, an intermediate section outboard of said inboard section, and an outboard section outboard of said intermediate section, said outboard section includes an airfoil section having over an entire length a pitching moment coefficient more negative than −0.035 at Mach numbers below 0.80 and a chord taper section having a taper ratio of at least 3:1, said airfoil section and said chord taper section each extends to a distal end of a blade tip.
A main rotor blade assembly for a rotary wing aircraft comprising:
- an inboard section, an intermediate section outboard of said inboard section, and an outboard section outboard of said intermediate section, said outboard section comprises an airfoil section having over an entire length a pitching moment coefficient more negative than −0.035 at mach numbers below 0.80 and a chord taper section having a taper ratio of at least 3 to 1, said chord taper section defined relative to an inboard tapered blade chord dimension of said chord taper section divided by a smaller outboard tapered blade chord dimension of said chord taper section, said inboard tapered blade chord dimension generally equivalent to a maximum blade chord dimension of said intermediate section, said airfoil section and said chord taper section each extends to a distal end of a blade tip.
A method of fabricating a rotary-wing aircraft main rotor blade comprising the steps of:
- providing the main rotor blade with an inboard section, an intermediate section outboard of said inboard section, and an outboard section outboard of said intermediate section said outboard section comprising an outer airfoil section having over an entire length a pitching moment coefficient more negative than −0.035 at Mach numbers below 0.80 over a prescribed length, said airfoil section extends to a distal end of a blade tip;
- and
- tapering a blade chord of the main rotor blade over at least a portion of the prescribed length to define a chord taper section with a taper ratio of at least 3:1 of the outboard section, the chord taper section defined relative to an inboard tapered blade chord dimension of the chord taper section divided by a smaller outboard tapered blade chord dimension of the chord taper section, the inboard tapered blade chord dimension generally equivalent to a maximum blade chord dimension of the intermediate section and said outboard tapered blade chord dimension located at the distal end of the blade tip.
A main rotor blade assembly comprising:
- an inboard section, an intermediate section outboard of said inboard section, and an outboard section outboard of said intermediate section, said outboard section comprising an airfoil section having over an entire length a pitching moment coefficient more negative than −0.035 at Mach numbers below 0.80 and a chord taper section at least partially overlapping said airfoil section and having a taper ratio of at least 3:1.
Dependencies are inferred from the claim text.