Textron Corporation

Walter G Sonneborn

Cecil E Covington

Wesley L Cresap

David E Snyder

Jan M Drees

Jing G Yen

Charles W Hughes

Keith W Harvey

A control for a helicopter tail rotor where inboard twist sections on opposite sides of a central hub section are adjacent to pitch horns mounted outboard the margins of the twist sections and extend to a negative delta.sub.3 connection point located at the virtual bending axis of each twist section. The rotor teeters on the tail mast with the span axis of the rotor at an angle of the order of 30.degree. to 45.degree. from the teetering axis.

Twist control for helicopter tail rotor pitch change

A helicopter rotor hub assembly (10) in which a blade grip (30) extends inboard of a yoke (14) and transfers centrifugal forces to the yoke (14) through a spherical elastomeric bearing (38). Pitch change of the grip (30) and blade (32) is accommodated by the spherical elastomeric bearing (38) which also acts as the pivot point for lead-lag motion of the blade (32) and grip (30). A lead-lag damper (22) is located inboard of the elastomeric bearing (38) and is connected between one end of the grip (30) spaced away from the lead-lag pivot and the yoke (14) for damping the lead-lag motion between the grip (30) and yoke (14).

Soft inplane helicopter rotor

A method and system which isolates two-per-rev hub spring moment vibrations while providing control power during zero-g flight in a two-bladed teetering rotor helicopter. Hub spring structure is connected between the rotor and the pylon to resist rotor flapping about the teeter axis and thus provide control during zero-g flight. To isolate from the fusilage the hub spring moment two-per-rev vibrations, the rotor is coupled to the pylon below the rotor center of gravity at a distance related to both the hub spring rates and the in-plane frequency of the helicopter blades.

Hub spring moment isolation in underslung two-bladed teetering rotor

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Fort Worth, TX, United States of America

Walter G Sonneborn