Structural analysis and optimization of a tethered swept wing for airborne wind energy generation

Ashwin A. Candade*, Maximilian Ranneberg, Roland Schmehl

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)
73 Downloads (Pure)


In this paper, we present an aero-structural model of a tethered swept wing for airborne wind energy generation. The carbon composite wing has neither fuselage nor actuated aerodynamic control surfaces and is controlled entirely from the ground using three separate tethers. The computational model is efficient enough to be used for weight optimisation at the initial design stage. The main load-bearing wing component is a nontypical “D”-shaped wing-box, which is represented as a slender carbon composite shell and further idealised as a stack of two-dimensional cross section models arranged along an anisotropic one-dimensional beam model. This reduced 2+1D finite element model is then combined with a nonlinear vortex step method that determines the aerodynamic load. A bridle model is utilised to calculate the individual forces as a function of the aerodynamic load in the bridle lines that connect the main tether to the wing. The entire computational model is used to explore the influence of the bride on the D-box structure. Considering a reference D-box design along with a reference aerodynamic load case, the structural response is analysed for typical bridle configurations. Subsequently, an optimisation of the internal geometry and laminate fibre orientations is carried out using the structural computation models, for a fixed aerodynamic and bridle configuration. Aiming at a minimal weight of the wing structure, we find that for the typical load case of the system, an overall weight savings of approximately 20% can be achieved compared with the initial reference design.

Original languageEnglish
Pages (from-to)1006-1025
Number of pages20
JournalWind Energy
Issue number4
Early online date8 Jan 2020
Publication statusPublished - 1 Apr 2020

Bibliographical note

Erratum: In Candade et al,1 the authors would like to correct the affiliations of Maximilian Ranneberg2 and Roland Schmehl1.


  • airborne wind energy
  • EnerKíte
  • optimisation
  • structural modelling
  • EnerKite


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