Aircraft rotor blade with passive tuned tab

US4514143A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventor

• Thomas Campbell · Concord, US

Key dates

• Filing date: Apr 28, 1983
• Grant date: Apr 30, 1985
• Expiry date: Apr 28, 2003

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S416/50
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

A structure (10) for reducing vibratory airloading in a rotor blade (12) with a leading edge (14) and a trailing edge (16) includes a cut-out portion (18) at the trailing edge. A substantially wedge shaped cross-section, inertially deflectable tab (20), also having a leading edge (22) and a trailing edge (24) is pivotally mounted in the cut-out portion. The trailing edge (24) of the tab (20) may move above and below the rotor blade (12). A torsion strap (26 or 64) applies force against the tab (20) when the trailing edge (24) of the tab (20) is above and below the rotor blade (12). A restraining member (92) is slidably movable along the torsion strap (64) to vary torsional biasing force supplied by the torsion bar (64) to the tab (20). A plurality of movable weights (82) positioned between plates (84) and (86) vary a center of gravity of the tab (20). Skin (74) of the tab (20) is formed from unidirectional graphite and fiberglass layers. Sliders (54 and 56), coupled with a pinned degree of freedom at rod (58) eliminate bending of tab (20) under edgewise blade deflection.