Rotary aircraft passively stable in hover

A method for passively stabilizing a rotary aircraft in hover, the aircraft including a hub having a central axis and a plurality of blades coupled with the hub spaced around the hub, each of the blades extending at least generally outwardly from the hub and being fixed in pitch with respect to the hubs, the blades being configured to generate lift in a common lift direction of the central axis when the hub and blades are rotated together in a given rotational direction around the central axis, the method comprising the steps of:

• rotating the hub and blades sufficiently quickly so as to support the aircraft in hover with the blades generating at least a major proportion of the lift supporting the aircraft;
• and
• generating sufficient lift along an outer periphery of the rotating blades directed transversely outwardly at acute angles to both the lift direction and a plane of rotation perpendicular to the direction to maintain a center of the lift generated by the aircraft along the central axis while hovering in a cross-wind.

A method for passively stabilizing a rotary aircraft in hover, the rotor including a hub having a central axis and a plurality of blades coupled with the hub spaced around the hub, each of the blades extending at least generally outwardly from the hub and being fixed in pitch with respect to the hub, the blades being configured to generate lift in a common lift direction of the central axis when the hub and blades are rotated together in a given rotational direction around the central axis, the method comprising the steps of:

• providing enough blade outer tips turned sufficiently transversely away from a plane of rotation perpendicular to the central axis and from the common lift direction and sufficiently turned with respect to tangents to radii from the central axis towards each turned tip to generate with the turned outer tips lift forces transverse to the central axis tending to stabilize the aircraft in hover in a cross wind;
• and
• rotating the hub and blades sufficiently quickly so as to support the aircraft in hover with the blades generating at least a major proportion of the lift supporting the aircraft.