LARGE COCURE COMPOSITE STRUCTURE DEVELOPMENT FOR COMANCHE AIRFRAME

The design to cost targets for the next generation of composite aircraft requires a significant reduction in fabrication costs. These types of aircraft bring with them additional complexity due to new technical requirements. To achieve these goals Sikorsky Aircraft formed a multi- disciplined concurrent engineering team (CET). The primary objective of the team was to successfully produce a series of low cost, high quality composite components with a repeatable process. These components are all configured to be representative of airframe structure for the Comanche helicopter. The program utilizes a CATIA system which allows the transfer of information to all personnel and organization involved in the design effort. This paper and presentation discusses all phases of a highly successful integrated development effort initiated in 1989 and concluded in 1991. The aim of this effort is to reduce the manufacturing cost of composite primary airframe structure while improving quality. The program is discussed through all phases from: risk reduction reduced scale design and development, full scale design, tooling development, hardware fabrication, tests, and application to the lessons learn to the Comanche design. Primarily outlined are the development and principles for fabricating large autoclave cocured structures and trading this development with a concurrent development of a comparable "built up" approach assembled structure. Both approaches took advantage of a new tooling methodology which combines conformal caul locators with reusable bagging systems and conventional female tooling. Discussed in depth, are how this tooling approach for molding large composite structures, in conjunction with conventionally fabricated parts developed process and cost data for most of the types of composite structure anticipated in the Comanche aircraft. In addition this program considers the following: the feasibility of machining and fixturing techniques for trimming, drilling and qualifying composite components. This paper and presentation is concluded with a review of these techniques, lessons learned, and their application to the design of large cocured structures for the RAH-66 Comanche.