NASA Tests Droplet Probes for Aviation Icing Hazards

NASA Tests Droplet Probes to Study Aviation Icing Hazards in Cleveland Wind Tunnel

Trials at Glenn Research Center measure supercooled water droplets that can freeze onto unprotected aircraft surfaces.

NASA conducted testing at the Icing Research Tunnel at Glenn Research Center in Cleveland to investigate supercooled large droplet icing. The trials evaluated new probes that detect droplets larger than 45 microns in real time, supporting the Subsonic Flight Demonstrator project under NASA's Research and Technology Mission Directorate by measuring conditions where liquid water freezes rapidly onto unprotected aircraft surfaces.

Key facts

Drop Size Probe testing took place on June 8-11, 2026, in the Icing Research Tunnel at NASA's Glenn Research Center in Cleveland.

The campaign marks a milestone for the Subsonic Flight Demonstrator project under NASA's Research and Technology Mission Directorate.

Supercooled large droplet icing occurs when liquid water drops colder than 32 degrees Fahrenheit freeze rapidly onto unprotected aircraft surfaces.

Standard aircraft icing conditions involve droplets from 2 to 100 microns, whereas supercooled large droplets can reach up to 2,000 microns.

The tested probes detect droplets larger than 45 microns in real time and combine with data from a secondary probe measuring droplets under 45 microns to cover the entire size spectrum.

NASA conducted testing at its Icing Research Tunnel at the Glenn Research Center in Cleveland to investigate supercooled large droplet icing. The Drop Size Probe testing, held from June 8 to June 11, 2026, marks a project milestone for the Subsonic Flight Demonstrator under the agency's Research and Technology Mission Directorate.

Supercooled large droplet icing occurs when aircraft encounter liquid water drops colder than 32 degrees Fahrenheit that freeze rapidly onto unprotected surfaces. While typical aircraft icing conditions involve droplets ranging from 2 to 100 microns in diameter, supercooled large drops can reach up to 2,000 microns.

Measuring the Size Spectrum

During the tests in the Icing Research Tunnel, researchers evaluated new probes capable of detecting and analyzing droplets larger than 45 microns in real time. Data from these probes will be combined with readings from another probe that measures droplets under 45 microns to cover the complete size spectrum.

By combining both instruments, researchers can evaluate the full range of droplet sizes simulated inside the tunnel. The campaign provides data for the Subsonic Flight Demonstrator project as NASA continues research into the conditions that create severe icing hazards for aircraft.

Frequently asked questions

What is supercooled large droplet icing?

It is an aviation hazard that occurs when aircraft encounter liquid water drops colder than 32 degrees Fahrenheit that freeze rapidly upon hitting unprotected exterior surfaces.

How large are supercooled large droplets compared to typical icing droplets?

Typical aircraft icing conditions involve droplets between 2 and 100 microns in diameter, while supercooled large droplets can reach up to 2,000 microns.

What did the probe tests in Cleveland evaluate?

Researchers tested sensors capable of detecting and analyzing droplets larger than 45 microns in real time. Combined with a probe measuring droplets under 45 microns, the instruments capture the full droplet size spectrum.