Kite Energy Simulator

We have developed a kite energy simulator that’s able to model the physics of an airborne wind (kite) energy system. It’s useful for the development of new kite designs and to test new control algorithms. It’s the first simulator that’s able to run in a browser, which means it can be run instantly on almost any computer.

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Inspiration / Sources

The is tether is modeled using point masses and springs connecting them similarly to the method used in FreeKiteSim. It’s also described in the paper Fechner, Uwe, et al. “Dynamic model of a pumping kite power system.” Renewable Energy 83 (2015): 705-716. link

For the flight controller we decided to implement a quaternion based attitude controller which is quite close to the approach described in Fresk, Emil, and George Nikolakopoulos. “Full quaternion based attitude control for a quadrotor.” Control Conference (ECC), 2013 European. IEEE, 2013. link

Airfoil data

The simulation includes a 360 degree lift and drag function for the DU 96-W-180 wind turbine airfoil. Timmer, W. A. “Aerodynamic characteristics of wind turbine blade airfoils at high angles-of-attack.” 3rd EWEA Conference-Torque 2010: The Science of making Torque from Wind, Heraklion, Crete, Greece, 28-30 June 2010. European Wind Energy Association, 2010. link, lecture material with nicer graph

The simulation also includes 180 degree lift and drag functions for the NACA 0012 symmetric airfoil. Sheldahl, Robert E., and Paul C. Klimas. Aerodynamic characteristics of seven symmetrical airfoil sections through 180-degree angle of attack for use in aerodynamic analysis of vertical axis wind turbines. No. SAND-80-2114. Sandia National Labs., Albuquerque, NM (USA),

The data has been extracted from figures from the above articles.

Source code

The source code is available at It’s published under GNU General Public License v3.0. We want to encourage collaboration on the development of kite energy simulation codes. Major code refactoring should be expected.

Flight Modes

The current simulation includes 3 different flight modes: Hovering, Transition and Path following.

Hovering up to a specified starting point Hovering up to a specified starting point. The thrust from the four rotors is distributed in such a manner that the drone is able to stay upright and fly to the designated position

Transition from hovering to crosswind flight (quadcopter to kite/airplane mode) Transition from hovering to crosswind flight. Doing this maneuver the kite/drone accelerate up to flight speed and angle the main wing perpendicular to the wind

Crosswind flight - all lift is generated by the wings of the kite Now the kite will track the predetermined path using only the rudder of the kite to control it’s direction.