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Evaluation of Scratch and Spall Resistant Windshields

A program was conducted to develop and assess materials configurations 
offering a potential improvement tc the scratching and spalling problems 
present in existing Amy helicopter windshields . 
Two prototype designs were fabricated for the UH-I helicopter, flight 
tested at Ft. Rucker, Alabama, and subjected to ballistic and bird impact 
tests while under flight-simulated conditions. The designs tested included 
an acrylic windshield (used as the standard), a monolithic polycarbonate 
windshield with an abrasion-resistant coating on both surfaces, and a glass- 
plastic composite using Chemcor and polycarbonate materials _ 
Flight test results demonstrated that the coated polycarbonate design 
can provide approximately 1200 service flight hours, or four times the 
average service life span of a typical acrylic windshield. Ballistic impact 
testing of the polycarbonate designs produced the best spall resistance 
(essentially no spall) , while the other configurations produced many dan- 
gerous fragments . Bird impact results graphically demonstrated that the 
polycarbonate prototype provided the superior resistance, i.e., resistance 
to bird strikes at speeds up to 120 knots while the standard acrylic wind- 
shield was incapable of defeating a bird strike at the IN-I cruising speed 
of 90 knots . 
In general, the superior mechanical properties and the flight worthi- 
ness of the coated polycarbonate configuration have been demonstrated.

This project was accomplished as part of the US Army Aviation Systems 
Command Manufacturing Technology program. The primary objective of 
this program is to develop, on a timely basis, manufacturing processes , 
techniques, and equipment for use in production of Army materiel. 
Coments are solicited on the potential utilization of the information 
contained herein as applied to present and/or future production pro- 
grams. Such coments should be sent to: US Army Aviation Systems 
comand, ATTN: DRSAV-EXT, P.o. Box 209, st. Louis, MO 63166.