Gust load alleviation for a long-range aircraft with and without anticipation

Abstract

This paper presents an overview of the DLR activities on active load alleviation in the CleanSky Smart Fixed Wing Aircraft project. The investigations followed two main research directions: the multi-objective, multimodel, structured controller design for the feedback load alleviation part and the use of Doppler LIDAR technologies for gust/turbulence anticipation. On this latter topic, the prior work made in the AWIATOR European FP6 project constituted a reference in terms of demonstrations and the objective was not to repeat these previous investigations with a real sensor in flight test but to develop new ideas for the exploitation of the Doppler LIDAR measurements for gust alleviation purposes. Very fruitful exchanges between industry partners and research organizations took place during this project and all the work presented in this paper has been made using a generic long-range benchmark provided by Airbus on the basis of the XRF-1 model.

Performance Enhancement of Gust Load Alleviation Systems for Flexible Aircraft using H∞Optimal Control with Preview

“…This paper focuses rather on the question of the optimal exploitation of the previewed disturbance, and does not tackle the question of how to obtain this information in practice. This preview control approach proposed here can be seen as a direct extension of [17][18][19][20] in which the controllers were sub-optimally manually tuned based on the designer's understanding of flight mechanics and aeroelasticity.…”

“…Consequently, the orientation of DLR's research activities on gust alleviation moved from the design of gust alleviation systems that are based on classical sensors (such as in the OLGA or the LARS systems) to the investigation of the potential performance enhancement that would result from the use of more advanced/futuristic sensors. The previous work that had been performed in these directions, especially during the AWIATOR project, led in particular to the GCS [11] and the GLA [12][13][14] systems, and to also consider the use of Doppler LIDAR sensors for determination of wind ahead of the aircraft for load alleviation purposes [11][12][13][14][15][16][17][18][19][20].…”

Investigations of passive wing technologies for load reduction

“…In the third phase, the developed technologies were applied on a second aircraft, the so-called "new short range" (NSR) concept, see Sect. 4, which was used for extending the aeroelastic tailoring process by the introduction of CFD-based aerodynamics into the process. Finally, an assessment of the influence of passive load alleviation schemes on fatigue-relevant loads was performed, see Sect.…”

“…Regan [3] lists a number of examples for active manoeuvre and gust control on series aircraft; however, for commercial aircraft it is difficult to obtain technical information concerning the exact implementation of the systems. At DLR, research on active load control was performed on the ATTAS aircraft since the 1990s [4]. A wellknown set of investigations is also the Active Aeroelastic Wing (AAW) flight research program, a joint US Air Force/ NASA program [5].…”

Editorial for the CEAS Aeronautical Journal special edition on Smart Fixed Wing Aircraft, WP 1.2 “Load Control”

“…In a second block, active load alleviation strategies are discussed. Fezans, Jost, and Deiler show DLR work on "Gust Load Alleviation for a Long-range Aircraft with and without Anticipation" [7], i.e. preview of the disturbance by means of a LIDAR system.…”