Impact Studies with Reduced Size Aircraft Stabiliser Demonstrators Including Hybrid Laminar Flow Control Technology

Impact with large-scale projectiles like birds needs analyses at full-scale. The reason is
that the impact behaviour can yet not be scaled from small-size demonstrators.
The impact studies presented here aim to analyse hybrid laminar flow control (HLFC)
structures for stabilizer or wing leading edges. To mature HLFC technology, impact
requirements need to be incorporated during the design phase and have to be fulfilled
during the certification process. Therefore, simulation methodologies play an important
role to integrate impact designs in an early design stage.
Within a project where HLFC is applied on the horizontal stabiliser, several design and
manufacturing tests are conducted. A reduced-size demonstrator with a short span
width but a full cross-section was selected for manufacturing and design purposes.
The reduced-size demonstrator has been selected as a mean for impact studies based on
earlier simulation and experimental studies. A symmetric vertical stabiliser design of
similar size was used to build up a simulation model of an asymmetric horizontal
stabiliser design. In several steps, this demonstrator was already verified experimentally
by a soft body impact. It was proven that both the design and the design methodology
including the demonstrator size was applicable.
During the design process of the current horizontal stabiliser HLFC design, structural and
manufacturing details were analysed with respect to consequences on the impact
behaviour. The structural analyses with respect to impact were performed with explicit
finite element and particle flow simulation tools. It is envisaged to subject this
demonstrator also to impact testing in order to gather important validation data for the
used impact simulation tools.
The boundary conditions of the two approaches are similar. However, the HLFC principle
is designed different. The current design of the asymmetric demonstrator for a
horizontal stabiliser leading edge incorporating a chambered HLFC approach was
simulated under soft body impact. It proves sufficient resistance against impact loading.
At a later stage, it will be impact tested for validation purposes, too.