How future aircraft can benefit from a steerable main landing gear for crosswind operations

Abstract

Many unconventional configurations for future aircraft, such as aircraft with very high aspect ratio wings or blended wing bodies, suffer from adverse flying characteristics for crosswind operations. Although the reasons for such undesirable behavior are different, coming from either tight geometric limitations, such as small bank angle allowances close to ground, or unfavorable flying qualities in the lateral motion, the consequences are challenging characteristics for take-off or landing under crosswind. In the presented study, a crosswind landing assistance system that makes use of a steerable main landing gear was designed and demonstrated in simulator trials. With such a system, the so-called de-crab maneuver is obsolete and the aircraft can touch down in crabbed motion. During roll-out on ground, the de-crab is performed automatically and the aircraft is kept on the runway centerline. A special concept for manual steering during this automatic de-crab on ground is introduced in the paper. The system is demonstrated in an A320 full-flight simulator with airline pilots, showing a good performance of the system and satisfactory pilot acceptance. The simulation results also show that the side forces acting on the landing gears could be reduced significantly with steerable main landing gears. This raises the hope that with such a system, the landing gear could possibly be designed lighter, saving at least some of the additional weight and cost for the necessary steering actuators of the main landing gear.