The main purpose of a helicopter rotor blade spar is to combine flap-wise, edgewise, torsional and centrifugal loads to and from a central torque drive hub. As such, these spars are subjected to extreme operational loadings and, in the past, were made from strong, high density materials including the metals aluminium or titanium. However, more recently these materials have tended to be replaced by resins reinforced with glass or graphite fibres. These composites have the attraction of being more corrosion resistant and offering an advantageous strength-to-weight ratio, as well as better damage tolerance. A fibre-reinforced rotor blade for helicopters has been invented by Sikorsky Aircraft Corp. In US Patent 5 939 007, the company explains that the purpose of the current invention is to produce a composite spar having the optimal fibre orientation for enhanced torsional and axial strength, while also reducing the weight of the component. The construction is divided into regions and subregions in which the fibre reinforced resin laminates are selectively arranged. These are usually cross-ply laminates using high modulus fibres in a binding resin in a range of +-38 deg to about +-42 deg relative to the longitudinal axis. The spar also includes at least one unidirectional laminate in each of the upper and lower sidewalls interposed between these cross-plies. Each unidirectional laminate includes a combination of high and low modulus composite fibres oriented again substantially parallel with the longitudinal axis. Generally, the reinforcing fibres should have a tensile strength of about 4.55x1011 N/m2 and a modulus of about 8.683x1010 N/m2.


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    Title :

    Tougher rotor blades for Sikorsky helicopters are fibre-reinforced


    Additional title:

    Zähere Rotorblätter mit Faserverstärkung für Sikorsky-Hubschrauber


    Published in:

    Publication date :

    2000


    Size :

    3 Seiten, 1 Bild



    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English