AEROELASTIC CHALLENGES IN THE AIRCRAFT DESIGN PROCESS

Aeroelastic effects influence the aircraft design process at many points. One of the most important constraints within the design process of flexible aircraft is to avoid aeroelastic instability for all combinations of speed and altitude encompassed by the flight envelope. This constraint affects both the structural design and the aerodynamic design, impacting the calculated aircraft performance. Aeroelastic effects also include the estimation of initial design loads used as input in order to size the components and are therefore critical for the aircraft design process. However, during initial design stages, not all parameters that are required to perform correct loads or aeroelastic instability analyses are available. This lack of information on the aeroelastic effects imposes technical and financial risks both for the suppliers as well as the Original Equipment Manufacturer (OEM). It is therefore of significant importance to understand the aeroelastic behaviour of the aircraft concept during all design phases and to avoid major changes in the detailed design phase which bring along additional costs. This holds true both for the design of next generation aircraft concepts, for example strut-braced wings with increased wing’s slenderness, as well as newly designed conventional aircraft components. The latter is often a major challenge for tier one and two suppliers that do not have an overview of the total aircraft system which is needed to understand the aeroelastic behaviour. Their component optimization process affects the aeroelastic behaviour of the entire aircraft system and is therefore critical when included in the overall design. This paper discusses a methodology developed by the Netherlands Aerospace Centre (NLR) to estimate design loads and access the aeroelastic instability on aerodynamic aircraft components with different levels of fidelity and different turnaround times. This methodology mitigates the risk of ‘invalid’ designs and large changes in the next design phases and thereby avoids large modifications and additional costs.