Designing composite structures for optimum in-service performance with reference to the Firefly aircraft and the Jetstream baggage pod

Abstract

When designing high-quality composites that are optimized for cost, weight and durability, the advantages and disadvantages of the materials used must be considered. This paper will discuss problems expected in the life of a composite structure, as well as the airworthiness certification of composites. In the last 20 years of Slingsby composite design and manufacture, no noteworthy in-service problems have occurred. The emphasis in this paper will therefore be on how potential in-service problems are covered by careful design and testing.

The discussion of in-service performance of composites will concentrate on Slingsby Aviation's experience with the design, testing and manufacture of the Firefly all-composite aircraft. The Firefly is a two-seat aerobatic training aircraft manufactured using glass fibre and hand wet lay-up techniques.

Reference will also be made to Slingsby test data relating to the performance of glass/Kevlar/Nomex honeycomb structures. This type of structure is used in the ventral baggage pod for the Jetstream 41 aircraft.