Distributed-Flap Layout Trade Study on a Highly Flexible Common Research Model

Abstract

The results of a layout trade study of a full-span, trailing-edge flap system for the NASA Common Research Model are presented. Previously developed analysis and design tools are used to determine the potential performance benefits of several flap layouts on a highly flexible version of the aircraft wing. The wing is first re-twisted for optimal aerodynamic performance at the design cruise condition while addressing aeroelastic effects. Several flap layouts are then installed on the new baseline wing. The deflection of each segment on all flap layouts is then optimized for aerodynamic performance at an overspeed flight condition to ascertain the effectiveness of each flap system. The results indicate that employing twosegment flaps greatly improves overspeed performance as compared to using no or just single-segment flaps. The study also showed that additional segments offer only incremental improvements in performance. The results also show that using only four spanwise flaps can produce meaningful performance gains. Overall, the trade study results suggest a simple distributed flap system (four spanwise flaps with two segments each) can reduce the drag of the Common Research Model by 13 counts at a Mach number that is 3.5% higher than the design cruise point.