NASA is leveraging its expertise and enhancing its test facilities to help address a rare but persistent aviation hazard: icing that occurs when aircraft encounter unusually large, very cold water droplets in clouds.  

The problem, known as “supercooled large droplet icing,” occurs when aircraft fly through clouds containing unusually large drops of water that are very cold but remain liquid. When a plane passes through those drops, they can rapidly freeze to surfaces that are not protected from ice buildup.  

With a series of tests in the Icing Research Tunnel at Glenn Research Center in Cleveland, NASA researchers are helping U.S. industry better understand the phenomenon. 

Supercooled water is common in clouds – droplets can go below 32 degrees Farenheit but not freeze unless they encounter dust or other tiny particles around which they can crystalize. Aircraft are designed to encounter typical icing conditions where droplets range from 2 to 100 microns in diameter (for comparison, a human hair is about 70 microns wide). But in rarer cases, clouds can contain supercooled large drops up to 2,000 microns in diameter (if you’ve ever been caught in freezing rain, you’ve encountered these droplets at ground level). These much larger droplets can hit or splash to the aft of an aircraft, including areas behind conventional ice protection systems.  

The aviation industry relies on engineering tools to help design their aircraft. Current tools work well for typical clouds, but engineers have questions about how well they account for the physics of supercooled large drops. To help answer those questions, NASA is working to enhance the equipment it uses to generate and measure experimental clouds for testing in the Icing Research Tunnel.  

NASA researchers have experimented with brand new probes that help calibrate the sizes of the drops in the clouds the tunnel produces. The probes can “see” drops larger than 45 microns and perform a real-time analysis of their sizes. NASA will compare these results, a laborious technique of post-processing droplet size image data from the tunnel. The results will be mated to results from a different probe that measures droplets smaller than 45 microns. With this, the complete droplet size spectrum is known. 

The test campaign marks an important milestone for the Subsonic Flight Demonstrator project, part of NASA’s Research and Technology Mission Directorate. Detailed analysis of the collected data continues, and NASA’s project team will share results with the broader aerospace community once complete.

On Sept. 30, 1946, five National Advisory Committee of Aeronautics (NACA) engineers arrived at Muroc Army Airfield in California’s high desert to achieve supersonic flight for the first time. In less than two years, NACA flew the X-1 aircraft faster than the speed of sound, marking an important milestone in aviation history.

Fast forward 80 years, and that former NACA outpost is now NASA’s Armstrong Flight Research Center in Edwards, California, flying the X-59 supersonic X-plane in the same skies to demonstrate that supersonic flight doesn’t have to come with a boom.

Over Armstrong’s 80-year history, the center has supported milestone missions ranging from space shuttle landings to SR-71 flights, shaping the evolution of science, aeronautics, and space research.

This Southern California NASA center is poised to lead the next era of aeronautics and human spaceflight, advancing technologies that will define the future of flight.

Fast facts

• NASA Administrator Jared Isaacman recently named Armstrong as the agency’s Center of Excellence for Flight Test and Aircraft Operations, recognizing the center’s unmatched rigor in executing unique missions only NASA can fly.
• To support NASA’s Artemis missions and return to the Moon, Armstrong uses research aircraft such as a 737 for astronaut suit testing, the G-III for Artemis II heat-shield data collection, and an F/A-18 aircraft that tested the autopilot for the SLS (Space Launch System) rocket.
• NASA’s aeronautics centerpiece, the X-59, is undergoing rigorous testing and a series of flights at Armstrong to prepare for upcoming quiet supersonic demonstrations over U.S. communities.
• NASA Armstrong has transformed commercial and military aviation — from early supersonic flight research to digital fly-by-wire — and continues working with other government agencies, industry, and academia to make flying safer, more autonomous, and more efficient.
• The center plays a vital role in global science by flying aircraft like the ER-2, C-20A, and Gulfstream G-III/IV/V to collect critical data on wildfires, glacier melt, pollution, minerals, and more.

Behind these achievements are the engineers, pilots, technicians, and mission support teams who continue to push the boundaries of what’s possible.

For more about NASA Armstrong, visit:

https://www.nasa.gov/armstrong

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Dede Dinius / Teresa Whiting
Armstrong Flight Research Center, Edwards, California
661-276-3449
darin.l.dinius@nasa.gov / teresa.whiting@nasa.gov

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Long before they helped shape NASA’s future aerospace breakthroughs, Derek Abramson, Justin Hall, and Justin Link were in their garages and homes building radio‑controlled aircraft, testing new ideas, and flying their creations at hobby events. That early passion now fuels the work of NASA’s Dale Reed Subscale Flight Research Laboratory at the agency’s Armstrong Flight Research Center in Edwards, California.

At NASA Armstrong’s subscale flight lab, the team turns that lifelong enthusiasm into mission-focused innovation. The laboratory supports research that ranges from advanced navigation systems for future landings on the Moon and Mars to emerging aeronautics concepts that need quick, low-cost evaluation. NASA’s small, remotely piloted and autonomous aircraft allow engineers to explore ideas that could be difficult, risky or expensive to test at full scale.

Skilled team

Abramson, Hall, and Link play key roles in that work. Abramson serves as the laboratory’s chief engineer. Hall is the chief pilot. Link is a drone pilot. Together, they integrate emerging aerospace technologies with the lab’s subscale aircraft fleet and, when needed, design and build aircraft or flight experiments to evaluate new concepts.

Abramson’s expertise, built through service in the U.S. Navy and the aerospace industry, centers on technical oversight, management, and system design. Hall is known for creative approaches to problem solving and uses practical methods to address technical challenges and maintain flight safety. Link specializes in designing and fabricating research vehicles and draws on extensive hands-on experience to understand what works, and what does not, in flight. 

On weekends, the team often tinkers in their garages or hangars building radio-control aircraft, researching hobby trends, or exploring new technologies. You might see them flying their creations at hobby events or attending trade shows. Their passion for flight brought Abramson, Hall, and Link together years before they one-by-one joined NASA more than a decade ago, though each discovered that spark in a different way.

Early influences

Abramson’s interest began as a child with rubber-band powered stick and tissue aircraft and radio-controlled models. His early aviation pursuits led to his first solo flight while in high school and a pilot’s license. In the Navy, he worked on multiple aircraft, including EA-6B and the F-18, as an avionics technician. As an engineer, he supported the B-1 and CV-22 Osprey aircraft flight tests. As an intern at NASA Armstrong, he used his operational and engineering experience on remotely piloted and autonomous aircraft.

Hall’s interest grew after seeing historic aircraft including the Mach 3 SR-71 fly over his elementary school playground and watching Space Shuttle Challenger land from above his dad’s shoulders. He has built and flown model and remotely piloted aircraft for as long as he can remember. His reputation flying radio-controlled hobby aircraft at fly-ins and trade events led to an offer to fly subscale aircraft at NASA.

Link was five years old when he built balsa-wood aircraft with his dad and flew them in a field near their home. As he grew older, his hobby expanded to include radio-controlled cars, boats, helicopters, and aircraft. Aviation runs deep in Link’s family. His great grandfather served in the U.S. Army Air Corps, his grandfathers served in the U.S. Air Force, and his dad was an Air Force avionics technician. Link raced sailplanes, competed with scaled warbird aircraft, and was encouraged by family and friends to pursue an aviation profession. He has worked with large drones for more than 11 years, focusing on research and development, composite materials, and specialized fabrication methods.

Together, the team applies its experience and knowledge in rapid design, fabrication, integration and flight testing to bring new ideas to flight. Their work continues to support NASA’s missions across aeronautics, science, and exploration.