Interdisciplinary Landing Gear Layout for Large Transport Aircraft

Abstract

One major task of an aircraft landing gear is the absorption of vertical energy which will mostly result either from the landing impact of from overrunning bumps and other ground irregularities. The necessity to limit the applied landing gear loads at the high stroke velocities at touch-down leads to damping characteristics which provide only lillte damping action at less vehement movements. Aircraft with high fuselage flexibility are therefore prone to vibration and resonance phenomena. The vonventional approach of developing the landing gear separetely from the airframe with only simple models to represent the aircraft ground dynamic properties seems no longer appropriate. Multibody system simulationis proposed as the basic software tool of an interdisciplinary development process which takes into account the elastic interaction between the aircraft components. The multibody system technique is aimed towards the simulation of the dynamics of a technical system in its entity, thus forming a core element of computer aided engineering software. Bi-directional interfaces to other software packages allow the integration of modeling and analysis data from a broad range of engineering disciplines. A case study demonstrates the optimization of a large transport aircraft landing gear layout in a multidisciplinary design environment. The aim is to improve the aircraft ride comfort on uneven runways without loss of landing impact absorbing qualities. Two landing gear concepts are considered: a conventional passive landing gear and a semi-active landing gear.