Thermsstructural and Material Considerations in the Design of the F-14 Aircraft Transparencies

Abstract

The evolution of the design is traced, along with in-service-dictated modifications, under the constraints of cost, weight, and schedule without sacrificing vital performance. Design requirements are given, along with the systems that affect the load and thermal environments. Tradeoffs between monolithic and multilaminate configurations are shown. Windshield and canopy temperature, thermal stress distributions, and distortions are presented. Transparency material ranking criteria are given. Predicted and in-flight measured canopy tem- perature correlations are shown. It is shown how various factors influenced the decision processes in arriving at a successful design. HE problem was to design, develop, and test a trans- parent cockpit enclosure for the F-14 aircraft that would combine high strength, light weight, maximum visibility, and minimum distortion within the entire flight envelope under all operating conditions. This paper presents the ther- mostructural and material aspects of the solution to that problem. The evolution of the transparency final design is traced, along with in-service-dictated modifications, through the various stages from the proposal through fleet deployment. Design concepts are described, and results of thermostructural analyses and tests are presented. Extremes in the operational and environmental conditions of the high-performance F-14 fighter have posed a host of problems to the transparency engineering and design teams. The problem faced on the F-14 was how best to meet tomorrow's challenge with yesterday's experience and today's capabilities. One of the more challenging tasks was to strike a proper balance between the functions to be performed by the transparencies and the constraints imposed by extraneous boundary conditions. Vital transparency performance was to be maximized under the constraints of mission severity, cost, weight, desired reliability, and schedule. Crucial decisions affecting overall design concepts had to be made early in the program because of abbreviated schedules. A decision that contributed significantly to the eventual success of the program was one concerning material selection. A decision had to be made whether to proceed with a conservative but highly reliable design, using an acrylic canopy and a flat glass windshield; or to proceed with a contoured windshield and a class of glamour materials whose claimed performance was not established experimentally. The decision was made to go conservative.