Laboratory investigations of materials properties show that significant reductions in aero-engine weight and cost are possible by using fiberglass reinforced composite materials. These were first applied to fabrication of compressor blades by Rolls-Royce, Ltd. Since the conclusion of the research program coincided with a new design, in which the sole engine function was to support a VTO aircraft during transition, the composites were specified for low temperature components. This paper describes properties of such materials and explains the philosophy adopted in their application. Construction of related subassemblies are fully detailed.