Design, Test, and Acceptance Criteria for Helicopter Transparent Enclosures
Final rept. 27 Jan 1974-26 Jul 1976
UNITED TECHNOLOGIES CORP STRATFORD CT SIKORSKY AIRCRAFT DIV
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This report describes a series of analytical and experimental studies that were performed to develop and substantiate the design, acceptance, and test criteria for Army helicopter transparent enclosures. Primary emphasis was placed on structural substantiation methods and the airframe interface. Wind-shield endurance tests were performed in a manner intended to duplicate actual service conditions. Suitable instrumentation was used to determine critical loading combinations. A NASTRAN finite-element analysis was performed to demonstrate the applicability of this type of structural analysis for helicopter cockpits. The analysis showed the benefits of using NASTRAN to evaluate transparency stresses in curved panels, and stresses resulting from fuselage wracking. As abrasion has been the primary cause for helicopter transparency replacements, a series of tests were conducted to enable simulation of the various forms of abrasion in the laboratory. The tests were conducted on glass, acrylic, and polycarbonate the acrylic and polycarbonate materials were with and without abrasion-resistant hard coats. Ballistic tests were performed on a variety of transparent materials to quantify spall characteristics. The test data were compared to empirical relationships used to equate spall energy with probability of skin penetration.
- Manufacturing and Industrial Engineering and Control of Production Systems