Wind -Dynamic wind load is created by a line connected to the center of the wind pressure on the model, and controlled dynamically by a servomotor. A spring is connected to the pulling line to smoothen the impact, and to improve the achieved spectrum.

The servomotor works in a closed loop with a load cell continuously correcting (at 200Hz MS) for the differences between the measured and the target loads.

The figure below shows the performance of the achieved wind spectrum when compared to the target wind spectrum.

Wind Generation  - Specific wind spectra can also be created using Wind Spectral Load Generator (WSLG)., which is normally mounted on top of the model. The WSLG consists of a motor and two blades. The motor is rotating at a constant speed, 4000-RPM. A servomotor controls the pitch angle of the blade, and by varying the blades’ angle the dynamic wind load can be generated.
The WSLG is instrumented with two load cells to measure the generated wind load. These measurements are used to compare the specified and the actual spectra.
Wind can also be generated by placement of six 3 foot diameter fans each driven by a one horsepower AC motor.  All of which are controlled by a parametric AC motor speed controller.