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An outboard region of a helicopter rotor blade of aerofoil cross section has a thickness to chord ratio not greater than twelve percent and an inboard region has a thickness to chord ratio greater than twelve percent. Preferably, the thickness to chord ratio of the inboard region is greater than eig

An outboard region of a helicopter rotor blade of aerofoil cross section has a thickness to chord ratio not greater than twelve percent and an inboard region has a thickness to chord ratio greater than twelve percent. Preferably, the thickness to chord ratio of the inboard region is greater than eighteen percent and may increase towards the root end to about twenty four percent. The inboard region may extend outwardly to a position not exceeding sixty percent of an operating radius of the rotor blade.

대표청구항 ▼

A helicopter rotor including a plurality of rotor blades attached to a rotor hub for rotation about an axis, each rotor blade having a root end for attachment to the rotor hub, a tip end and a central portion of aerofoil cross section having a thickness dimension and a substantially constant chord d

A helicopter rotor including a plurality of rotor blades attached to a rotor hub for rotation about an axis, each rotor blade having a root end for attachment to the rotor hub, a tip end and a central portion of aerofoil cross section having a thickness dimension and a substantially constant chord dimension and extending between the root and tip ends to define a blade span, wherein an inboard region of the central portion has a thickness to chord ratio greater than twelve percent, an upper surface aft of about a fifty percent chord of lower curvature than a corresponding lower surface and a positive basic pitching moment coefficient.