High impact strength transparent enclosure

Claim 1

A HIGH IMPACT STRENGTH WINDSHIELD CONSTRUCTION FOR COCKPIT ENCLOSURE ON AIRCRAFT OR THE LIKE COMPRISING, INNER AND OUTER RESILIENT LAYERS OF TRANSPARENT MATERIAL, A RIGID LAYER OF TRANSPARENT MATERIAL INTERPOSED BETWEEN THE INNER AND OUTER RESILIENT LAYERS AND LAMINATED THERETO FORMING A UNITARY NON-HOMOGENEOUS STRUCTURE, THE MARGINAL EDGES OF SAID INNER AND OUTER RESILIENT LAYERS BEING SUBSTANTIALLY COTERMINOUS AND FORMING AN ATTACHING FLANGE FOR THE WINDSHIELD, AND RIGID SURFACE STABILIZING LAYERS OF TRANSPARENT MATERIAL LAMINATED TO THE INNER AND OUTER RESILIENT LAYERS TO MINIMIZE OPTICAL DISTORTION, THE SURFACE STAILIZING LAYER LAMINATED TO SAID INNER RESILIENT LAYER BEING THINNER THAN THE OTHER LAYERS AND HAVING A THICKNESS PROVIDING A MASS WEIGHT PER UNIT AREA LESS THAN THAT REQUIRED FOR SELF DELAMINATION UNDER THE MAXIMUM ANTICIPATED IMPACT LOADS, THE LAST MENTIONED SURFACE STABILIZING LAYER HAVING ITS MARGINAL EDGE TERMINATING SHORT OF SAID ATTACHING FLANGE ON SAID RESILIENT LAYERS AND BEING HELD IN PLACE ONLY BY THE SURFACE BOND BETWEEN THE STABILIZING LAYER AND THE RESILIENT LAYER WHEREBY THE STABILIZING LAYER IS ISOLATED FROM THE EDGEWISE ENCLOSURE SUPPORTING LOADS.