results
Simulation Results Reel-Out testing at Maasvlakte, NL
Overview of reel-out runs per wind speed
The test scenario:
- the kite is parked at zenith (keep it still above your head while in equilibrium)
- then it is steered to the left and takes a dive
- then it is steered towards the planned figure-of-eight that promises the highest power
- it flies figures of eight and reels out
The initial tether length is 150 m, the final length 380 m. The wind speed is the ground wind speed, measured at a height of 6 m, using a vertical wind profile law combining the exponential and logarithmic laws, matched to measurements at a near-shore site in Maasvlakte, NL. A ground-station with 20 kW nominal power and 30 kW peak power is assumed. The nominal reel-out speed is 3.5 m/s, the maximum force 8400 N.
| date | time | v_wind | power_ratio | total_time | rt_factor | opt_requests | opts_installed | av_power | min_power | max_power | min_force | av_force | max_force | v_ro_min | v_ro_av | v_ro_max | av_depower | rms_error | success_criteria |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026-09-20 | 22:38:14 | 3.5 | 0.95 | 358 | 2.55 | 6 | 5 | 725 | 196 | 1759 | 529 | 787 | 1360 | 0.32 | 0.87 | 1.35 | 0.295 | 0.79 | all 10 passed |
| 2026-09-21 | 23:42:55 | 4 | 1.04 | 161.3 | 2.6 | 5 | 5 | 1578 | 832 | 2593 | 886 | 1198 | 1737 | 0.84 | 1.31 | 1.56 | 0.283 | 0.69 | all 10 passed |
| 2026-09-21 | 23:52:33 | 5 | 1.01 | 128.9 | 2.82 | 5 | 5 | 3779 | 2655 | 4757 | 1464 | 2064 | 3023 | 1.16 | 1.83 | 2.18 | 0.275 | 0.59 | all 10 passed |
| 2026-09-22 | 00:33:39 | 6 | 1.01 | 193.1 | 3.19 | 6 | 6 | 7339 | 5290 | 8528 | 2716 | 3229 | 4311 | 1.68 | 2.27 | 2.58 | 0.269 | 0.58 | all 10 passed |
| 2026-09-22 | 00:37:23 | 7 | 1 | 80.8 | 3.55 | 6 | 6 | 12238 | 9177 | 14705 | 3870 | 4553 | 5503 | 1.96 | 2.69 | 3.08 | 0.266 | 0.69 | all 10 passed |
| 2026-09-21 | 23:47:20 | 8 | 0.99 | 97.6 | 2.64 | 5 | 5 | 18627 | 13689 | 22077 | 5008 | 5962 | 6639 | 2.53 | 3.12 | 3.45 | 0.265 | 0.85 | all 10 passed |
| 2026-09-21 | 22:18:41 | 8.25 | 0.97 | 90 | 2.77 | 4 | 4 | 19779 | 15296 | 24311 | 4896 | 6180 | 7101 | 2.65 | 3.19 | 3.49 | 0.267 | 0.96 | all 10 passed |
| 2026-09-21 | 22:12:02 | 8.5 | 0.96 | 86.3 | 2.87 | 4 | 4 | 20836 | 15528 | 25771 | 5266 | 6377 | 7428 | 2.64 | 3.25 | 3.54 | 0.268 | 0.96 | all 10 passed |
| 2026-09-21 | 20:05:41 | 9 | 0.89 | 54 | 4.83 | 4 | 4 | 20939 | 13606 | 27833 | 5248 | 6403 | 8282 | 2.59 | 3.25 | 3.64 | 0.277 | 1.14 | all 10 passed |
| 2026-09-21 | 23:21:29 | 10 | 0.82 | 65.6 | 3.11 | 3 | 3 | 20226 | 16009 | 26098 | 5652 | 6424 | 7587 | 2.61 | 3.14 | 3.63 | 0.294 | 1.22 | all 10 passed |
| 2026-09-21 | 23:17:22 | 11 | 0.86 | 74.2 | 3.27 | 4 | 4 | 19187 | 14037 | 24089 | 4994 | 6101 | 7274 | 2.45 | 3.15 | 3.63 | 0.319 | 1.13 | all 10 passed |
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The average mechanical power during reel-out, the force, and the speed are shown in the following plot. At about 9 m/s the maximal force of 8400 N is reached. From this wind speed onwards the force is limited by increasing the depower settings.
The optimal trajectory of the kite, the shape of the figure of eight, depends on the tether length and on the wind speed. Below, use the slider to adjust the ground wind speed, and see the shape of the desired and actual trajectory the kite flies. For each figure-of-eight, the AWETrim quasi-static optimizer calculated the optimal trajectory.
The same run in 3D: the flown path in the world frame, coloured by the mechanical winch power, with the ground track underneath and the straight line to the ground station. Drag to rotate, scroll to zoom. Note that at 3 m/s no run was performed and the run at 3.5 m/s is shown instead.
The time series below show, for the same wind speed selected above, the cross-track error, elevation, course/heading tracking, steering, tether force and length, reel-out speed, depower, and the entry state machine over the whole run. The first subplot, `d ', shows the distance between the actual and planned trajectory in degrees.
The plots below show, for the same wind speed selected above, the tether force, reel-out speed and mechanical power over the whole run, and the cumulative mechanical energy.
The plots below show, for the same wind speed selected above, the angle of attack (at the wing centre and the span mean), the wing and effective lift-to-drag ratio, and the apparent wind and kite speed over the whole run.
Acknowledgements
This work has been supported by the MERIDIONAL project, which receives funding from the European Union’s Horizon Europe Program under the grant agreement no. 101084216. The opinions expressed in this document reflect only the author’s view and reflects in no way the European Commission’s opinions. The European Commission is not responsible for any use that may be made of the information it contains.
These results were achieved using the following research software:
- SimpleKiteControllers.jl, path-following kite control software by Uwe Fechner, Delft, 2026
- AWETrim was used to provide optimal flight paths, depending on the inflow conditions, written by Oriol Canyon, Delft, 2026
- V3Kite.jl was used as detailed, validated kite model of the V3 kite of TU Delft. It was developed by Jelle Poland, Rotterdam, The Netherlands and Bart van de Lint, Delft, The Netherlands, 2026