Airborne Wind Energy

Aero-structural dynamics of kites

Roland Schmehl

12 December 2025

CC BY 4.0

Outline

Kitepower

Learning objectives

  • Characterize aero-elastic phenomena of hard-wing kites
  • Characterize aero-structural phenomena of soft-wing kites
  • Describe and compare the modelling approaches for the dynamics of soft kites

Basic considerations

Flight testing at Valkenburg airfield, 23 August 2012

Hard-wing kites

  • Designed as conventional aircraft structures
  • Supported by single tether attachment or a split into two bridle lines
  • Wing structure used to transmit the aerodynamic forces to the tether or few bridle lines
  • Static or dynamic deformation response of kite structure denoted as aero-elasticity
  • Typical aero-elastic phenomena are bending and twisting of the wing, or flutter
  • Controlled with aerodynamic control surfaces (exception EnerKíte)
  • Coupling with control dynamics denoted as aero-servo-elasticity

Soft-wing kites

  • Designed as morphing aerodynamic control surfaces
  • Supported by a more or less dense bridle line system, depending on type of wing
  • Wing deforms due to changing geometry of bridle line system
  • Controlled by rolling and (some concepts) twisting of wing
  • Wide variety of aero-structural phenomena

Deformation root causes

  • Changes in the bridle line geometry, leading to symmetric & asymmetric actuation
  • Aero-elastic effects, leading, for example, to billowing

Hard-wing kite deformation

Terminology

Wijnja et al. (2018)

Simulation model

Aerostructural model using ASWING
Wijnja et al. (2018)

Physical scale model rear view

Wijnja et al. (2018)

Physical scale model side view

Wijnja et al. (2018)

Wind tunnel test setup

Wind tunnel test

Aero-structural simulation

Soft kites

Kasper Masure, TU Delft / Vantage

Ram-air wing

Ram-air wing

Ram-air wing

Ram-air wing

LEI wing

FSI simulation of an LEI kite

Tom Lolies, https://fair.aero

References

Wijnja, J., Schmehl, R., De Breuker, R., Jensen, K., Vander Lind, D.: Aero-elastic analysis of a large airborne wind turbine. Journal of Guidance, Control and Dynamics. 41, 2374–2385 (2018). https://doi.org/10.2514/1.G001663

Questions?





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