Frequently Asked Questions

What is atmospheric in-flight icing?
Atmospheric icing is a term that describes special weather conditions that can lead to ice accumulation on an aircraft. If an aircraft encounters such conditions during flight, the process is called in-flight icing.

What conditions lead to icing?
Atmospheric icing occurs when meteorological conditions exist that allow for the existence of supercooled liquid droplets in the air. Such supercooled liquid droplets are typically found in clouds (in-cloud icing), but can also occur as freezing rain or freezing drizzle (precipitation icing)

What are supercooled droplets?
Supercooled means, that the droplets have a temperature below the freezing point, but remain in liquid form. This can happen when the droplets lack an ice nucleus (a small particle that acts as a “seed” starting crystallization). Droplets found in clouds are about the size of the width of human hair (15-80 micrometres) while precipitation droplets are much bigger, up to several millimeters in size.

Why is icing bad for UAVs?
When an unmanned aerial vehicle (UAV) flies through atmospheric icing conditions, ice starts to grow on the wings and propellers. As the ice grows, it alters the shape of these aerodynamic surfaces – which leads to flow disturbances. These disturbances reduce the ability of the aerodynamic surfaces to generate lift and thurst while also increasing the resistance (drag). This can quickly lead to hazardous situations where the aircraft cannot keep itself in the air.

How do researchers study UAV icing?
Researchers study UAV icing using a combination of numerical simulations, icing wind tunnel tests, and real flight tests. This multi-method approach helps them understand the physics behind icing, its effects on various UAV components, and how to develop effective anti-icing and de-icing solutions.

What is an icing wind tunnel?
An icing wind tunnel is a specialized facility that simulates real icing conditions in a controlled environment. It is equipped with a spray system to introduce water droplets into the airflow and cooling systems to supercool the droplets before they hit the test object (e.g., UAV components). These tunnels allow researchers to conduct experiments under various icing conditions without relying on actual flights.

How can UAVs be protected from icing?
Researchers are working on developing anti-icing and de-icing solutions to protect UAVs in icy conditions. These solutions may include specialized coatings, heating elements, or active systems that detect and remove ice as it forms. The effectiveness of these solutions is tested through numerical simulations, icing wind tunnel tests, and real flight tests.

Why is it important to study UAV icing?
Studying UAV icing is essential for ensuring the safe and reliable operation of UAVs in various weather conditions. As UAVs become increasingly important for tasks like weather monitoring, agriculture, and disaster response, understanding and mitigating icing risks will help improve their performance and safety for a wide range of applications.