Windshield Weight Reduction through the Use of High Strength Glass and Polyurethane Interlayers,
MCDONNELL AIRCRAFT CO ST LOUIS MO
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Polyurethane interlayers were developed during the 1970s and are a potential replacement material for the polyvinyl butyral interlayer, specified in MIL-G-25871, for laminated glass. In addition to the interlayer, higher strength glass has become available through the advancement of manufacturing techniques for thermally tempering glass that appears to be an improvement over thermally tempered glass, specified in MIL-G-25667. Through minor modifications, current laminated glass windshields could be redesigned to utilize these new materials. Potentially, the resultant effect could be a weight reduction or an improvement for aircraft cold dispatch capabilities. To fully quality a redesigned windshield for commercial aircraft, testing and analysis is required to meet FAA requirements for bird impact, fail-safe, environmental anti-ice and defog, and optical qualities. To utilize these new materials, full-size windshield specimens interchangeable with the DC-10KC-10 were tested successfully to the FAR 25 requirements. The weight difference between the production windshields versus the lighter weight windshields was 17.5 pounds nominal.