Messerschmitt-boelkow-blohm Gesellschaft MIT Beschraenkter Haftung

Messerschmitt-boelkow-blohm Gmbh

Gerald Kuntze-Fechner

Michael Hahn

Otmar Friedberger

A helicopter rotor with foldable blades has, in the hub and blade roots, holes for mounting the blade roots to the rotor hub with connecting bolts passing through these holes in the operating position of the blades. Additionally, at least one blade of two blades and the hub have aligned holes for holding the respective foldable blade in a folded position, whereby one of the regular connecting bolts passes through the aligned holes, which are located as close as possible to the pivoting point connecting a pitch angle control rod to a pitch angle control sleeve.

Rotor, especially for rotary wing aircraft

In order to avoid a negative coupling between blade lead-lag movements and lade angle adjustment movements in a helicopter rotor, the angle (.beta.) between a control rod (5) for the blade angle adjustment and an effective damping plane (M) of the rotor is increased as compared to the respective angle in conventional rotors. This increase of the angle (.beta.) is accomplished by arranging a damping device (9) having the effective plane (M) for suppressing blade lead-lag movements in such a way on a blade angle control sleeve (4), that the effective plane (M) of the damping device (9) encloses an angle (.alpha.) with the lead-lag plane of the rotor.

Rotor structure, especially for a rotary wing aircraft

A rotor for a rotary wing aircraft has two damping structures on the outs of the blade angle adjustment sleeve. Each damping structure is a sandwich of an elastomeric layer between two stiff cover layers. A two-armed strut passes through the blade neck and is connected at its center in a pivoting manner to the blade root. The threaded outer ends of the two-armed struts pass through the respective sandwich for yieldingly connecting the radially inner end of the blade angle adjustment sleeve to the blade root. By tightening nuts on the threaded strut arms the elastomeric layer may be compressed. Thus, the damping structure performs, in addition to the damping function, a connecting function for the blade angle adjustment sleeve.

Rotor structure, especially for rotary wing aircraft

A rotor, especially for rotary wing aircraft, has a rotor hub (1) with one r more torsionally stiff rotor hub arms (1.1) projecting radially outwardly. A rotor blade (2) having a blade root (2.1), a blade wing section (2.3), and a torsionally flexible blade neck (2.2) is attached by bolts (3) to each rotor hub arm (1.1). A torsionally rigid blade angle control sleeve (5) extends without contact along each blade neck (2.2) and is rigidly connected at its radially outer end to the blade wing section (2.3) and is movably connected at the radially inner end to the blade root (2.1). In order to isolate the blade control from any blade flapping movements, and to reduce the distance between the flapping hinge point and the rotor hub (1), the rotor hub arm (1.1) is flat in a direction perpendicular to the blade rotation plane and is more flexible to blade flapping movements than the blade neck (2.2) is. The blade root (2.1) is in the form of a yoke or fork for attachment to the rotor hub arm (1.1), whereby the two shanks or prongs (2.1.1) of the yoke or fork form the base for the movable support of the blade control sleeve (5).

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Bad Wiessee, Germany

Gerald Kuntze-Fechner