Original Date: 10/14/1988
Revision Date: 01/18/2007
Information : Composite Rotor Blade Fabrication
Composite main rotor blade fabrication at Bell Helicopter Textron, Inc. (BHTI) varies with blade model, but all of the blades are final cured in closed cavity metal tooling. Although many of the main rotor blade manufacturing techniques used at BHTI are used throughout the industry, BHTI has developed and uses several unique manufacturing practices.
One practice is the use of prepreg roving for the automated winding of spar straps. This assures final blade balance and weight, and eliminates resin squeezeout during winding around hinge pins. Prepreg roving stock is analyzed when it is received from the supplier for resin and fiber content. In the winding step, rolls of prepreg roving are selected that together will yield the desired resin and fiber content in the final blade.
Another practice is the use of a styrofoam mandrel covered with a rubber bladder for final curing of main rotor blade spars. In this approach, molded styrofoam segments are fitted onto a stiff inner support rod, and are then covered with a rubber bladder. The bladder is pressurized during the cure process in order to provide internal pressure. The mandrel is easily removed from the cured spar due to the thermal contraction of the styrofoam during the cure.
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