Flight Turbulence: Cancelled!

Our Chair of Flight Mechanics and Control recently hosted an exciting wind tunnel measurement campaign in collaboration with the Vienna-based start-up Turbulence Solutions. The company developed an innovative active gust cancelling system which improves aircraft stability and passenger comfort during turbulent flight conditions. This cutting-edge technology uses an automatically controlled flap to counteract the additional lift caused by turbulence-induced changes in the angle of attack.

The system relies on real-time data from an aircraft-integrated multi-hole probe, which measures incoming airflow. Based on this data, the flap is dynamically deflected by a self-designed flight controller in order to neutralize the effects of turbulence, ensuring smoother flight conditions. To enhance and refine this system, Turbulence Solutions brought their UAV (unmanned aerial vehicle) into our facilities.

Our wind tunnel was equipped with a specifically designed gust generator for this campaign. This device, consisting of five synchronously controlled vanes mounted on the wind tunnel nozzle, was capable of producing gusts with frequencies of up to 4 Hz and amplitudes of 10 degrees. This setup allowed for precise simulation of turbulent conditions, providing an ideal environment for testing the gust cancelling system.

The data acquisition setup was a unique combination of synchronized measurement devices for us. A 6-component force balance, where the UAV is mounted on. The pitch and roll angle were electrically adjustable. The flow was externally measured with a X-type two-wire constant-temperature-anemometer (CTA probe) that was also used to quantify the gust generators wake field before the UAV installation. The aircraft was equipped with an integrated multi-hole pressure probe for local flow angle and magnitude. The gust generator position was also recorded. Finally, the general wind tunnel data, which is inflow velocity, density and temperature should never miss. All measurement devices acquired data with a rate of at least 200 Hz and a synchronizing accuracy of just 1 sample, which equals 5ms.

The data evaluation is not finished yet, but a reduction of the aircrafts lift response on the turbulence is already visible in the raw data. This is equal to a reduced turbulence perception of a pilot or passengers. This campaign is therefore already considered a success and for us and Turbulence solutions, this is a step forward in the interdisciplinary field of experimental aerodynamics and flight control applied on UAVs.