Flap Design Case Study

Abstract

The wing leading edge and trailing edge high lift system is essential for the low speed characteristics of the aircraft. Advanced CFRP technology can contribute to cost and weight savings on aircraft level as well as to improved low speed performance and added product value for the aircraft operator. In this case study, different CFRP flap design schemes and manufacturing technologies are discussed, pointing out the interdependence of CFRP material, design, manufacturing process and resulting part properties. Starting with the description of the reference flap design and the most relevant design targets, new solutions such as multi-spar and sandwich designs are characterised with their advantages and shortfalls. Advanced thermoset solutions (based on prepreg and resin infusion technology) and thermoplastic solutions (based on the tape laying technology) are included. Material and manufacturing as well as strength and stiffness aspects related to aerodynamic performance are analysed. In addition, wing integration challenges linked to new design schemes are discussed. Keywords High lift • Flap • Torsion box • Galvanic corrosion protection • Erosion protection • Shell sandwich • Multi-spar-design • Braided sleeve • Resin transfer moulding • Thermoplastic tape laying • Recurring cost • Non-recurring cost • Flap gap and overlap deformation • Flap wing integration General Procedure, Reference Design and Targets New flap design schemes, materials and manufacturing technologies have been extensively investigated in the course of the R&D program "ProHMS" [1]. The goal was to explore new technical solutions of high lift structure, systems and aerodynamics in order to improve the low speed characteristics of modern aircraft. These characteristics are very important for reducing the noise footprint, allowing steeper approach and descent, improving the takeoff performance, enabling landing on short runways, enabling a capacity growth of airports and for many other purposes. An overview of structural developments which was performed using the A320 as a reference can be seen in Fig. 7.1. In order to evaluate the cost-and weight-saving potentials of new technologies, detailed studies were performed for the outer flap.