Rapid Prototyping of Composite Aircraft Structures 931219

The faculty, staff and students of the Raspet Flight Research Laboratory (RFRL) have developed a rapid prototyping capability in a series of research aircraft and unmanned aircraft development projects. There has been a steady change in the technologies used to accomplish these tasks at the RFRL. The most recent development has been the utilization of computer graphics and a 5-axis gantry robot router to accelerate the design, moldmaking and parts trimming tasks. The composite structure fabrication processes at the RFRL have evolved from wet-lay-up to autoclave cure. Currently, the feasibility of the stitched composite material preform and resin transfer molding process is being explored.

The organizational structure of the RFRL rapid prototyping group has been found to be most important in accomplishing a vehicle development that is technically sound, safe, and reasonable in cost. A close, free interaction among all participants is encouraged since it is essential for correct decisions to be made in the limited time available. Experience shows it is essential for the project leader to be well versed in most aspects of aircraft design, fabrication, and testing. The structural configuration and layout must be established within the framework of concurrent engineering through detailed analysis and design optimization with the fabrication process and test plans as major considerations. Another requirement is to have a very rapid purchasing authority use overnight delivery if necessary to ensure that the materials and supplies are readily available to support the project.

The RFRL faculty adopted a plan to invest in advanced computing, automation, and composite processing equipment to enhance the rapid prototyping expertise that has been developed over the years. The recent RFRL experience with the National Aerospace Plane 50 ft. long mock-up student project and a 200 lb. unmanned vehicle airframe development project has shown that the combination of analysis and AUTOCAD 12 (an engineering drawing software), a powerful PC computer, the 5-axis gantry robot router, and the “one-shot” mold process technique can significantly improve the quality and reduce the cost associated with the construction. The use of a stitched composite material preform and the resin transfer mold process holds the promise to produce composite structures with reduced cost, improved crashworthiness, and improved quality. The incorporation of optimization techniques and concurrent engineering in the design holds the promise to produce certificated custom configuration aircraft at current mass production costs levels.