Textron Corporation

Bell Helicopter Textron Inc.

Jing G Yen

Jan M Drees

Walter G Sonneborn

David A Popelka

A nodalized rotor system is provided for a multi-bladed helicopter. Equally spaced radial arms each have an inboard flapping section to accommodate beam-wise blade flapping and an outboard flex section to accommodate pitch changes. A blade is coupled to the end of each arm with a cuff and pitch horn rigidly connected to the blade and pivotally connected to its arm in the region of the flapping section. The blade has a concentration of weight over the section of blade extending from about 32% to 42% of the hub-blade radius of running weight four times the running weight at 50% of the hub-blade radius. Said blade has a reduced mass at outboard 30% of the hub-blade radius, at a level of 80% of the running weight at 50% of the hub-blade radius.

Nodalized 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.

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Arlington, TX, United States of America

Jing G Yen