Evaluation of a Distributed Variable-Camber Trailing-Edge Flap System at Preliminary Aircraft Design Stage

The economic pressure on airlines, as well as the increasing political and societal awareness of the climate crisis, require the most efficient aircraft operation possible. The majority of current aircraft wings have a fixed geometry and are consequently a compromise to enable operation at different flight conditions. One already identified possibility to improve the aircraft’s performance is to adjust the camber of its wings to the changing flight conditions during cruise by utilizing the existing trailing-edge flaps. This is referred to as variable camber (VC) with differential flap setting (DFS). Furthermore, new types of flap actuation systems have emerged in recent years with power-by-wire (PbW) actuators that have not yet been investigated for the use of VC with DFS on aircraft level. This paper aims to investigate the VC technology with DFS for a segmented trailing-edge system on overall aircraft level at the preliminary design stage, using the MICADO software. Statements are to be provided on the savings potential regarding jet fuel for different mission planning. In addition, an assessment shall clarify whether actuation on the basis of a central shaft system with interconnected gearboxes is reasonable, or whether PbW actuation is advantageous. The investigation is based on a commercial aircraft with a maximum take-off mass (MTOM) of 270 t. Different configurations of the trailing-edge flaps ranging from the common two-flap configuration up to a configuration with five trailing-edge devices are covered in order to give a holistic implementation recommendation including actuation and flap segmentation. The evaluation shows that all investigated applications of VC with DFS have a considerable potential for fuel savings. For the flap actuation, rotary electro-mechanical actuators are identified as the most promising variant for the PbW architecture. With regard to the reference aircraft with a conventional flap actuation system, the utilization of PbW actuators enable a significant reduction in system mass.