SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop Instrumentation Test - Particle Size Measurements. Installation of 1D2D-X probe in the IRT. Probe supplied by Science Engineering Associates (SEA)

SFD (Subsonic Flight Demonstrator) of SLD (Super Large Drop) testing in IRT (Icing Research Tunnel). Drop size shown on computer from detection probe during test. Cloud drops imaged by probe displayed on computer screen

SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop) Instrumentation Test - Particle Size Measurement in the IRT (Icing Research Tunnel), June 8-11, 2026. Drop size shown on computer from Drop Sizing Probe seen in the IRT test section.

Ice collection seen on un-heated sections of the 1D2D-X ice drop detection probe in the test section of the IRT (Icing Research Tunnel). Drop Size Probe testing - SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop) Instrumentation Test in IRT (Icing Research Tunnel) – Particle Size Distribution Entry, June 8-11, 2026 Large Drop Testing in IRT

Ice collection seen on un-heated sections of the 1D2D-X ice drop detection probe in the test section of the IRT (Icing Research Tunnel). Drop Size Probe testing - SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop) Instrumentation Test in IRT (Icing Research Tunnel) – Particle Size Distribution Entry, June 8-11, 2026 Large Drop Testing in IRT

Ice collection seen on un-heated sections of the ice drop detection probe in the test section of the IRT (Icing Research Tunnel). Drop Size Probe testing - SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop) Instrumentation Test in IRT (Icing Research Tunnel) – Particle Size Distribution Entry, June 8-11, 2026

Installation of 1D2D-X probe in the IRT. Probe supplied by Science Engineering Associates (SEA). SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop Instrumentation Test - Particle Size Measurements. Particle Size Distribution Entry, June 8-11, 2026 Large Drop Testing in IRT

SFD (Subsonic Flight Demonstrator) test of SLD (Supercooled Large Drop) Instrumentation Test - Particle Size Measurements Testing in IRT (Icing Research Tunnel). Installation of probe in the IRT. Installation of 1D2D-X probe in the IRT. Probe supplied by Science Engineering Associates (SEA)

SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop) Instrumentation Test - Particle Size Measurement in the IRT (Icing Research Tunnel), June 8-11, 2026. Drop size shown on computer from Drop Sizing Probe seen in the IRT test section.

Ice collection seen on un-heated sections of the 1D2D-X ice drop detection probe in the test section of the IRT (Icing Research Tunnel). Drop Size Probe testing - SFD (Subsonic Flight Demonstrator) of SLD (Supercooled Large Drop) Instrumentation Test in IRT (Icing Research Tunnel) – Particle Size Distribution Entry, June 8-11, 2026 Large Drop Testing in IRT

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

A wood router cuts precise holes in plywood for temporary floorboards on Aug. 26, 2024, in the Experimental Fabrication Shop at NASA’s Armstrong Flight Research Center in Edwards, California. The flooring was designed for the X-66 experimental demonstrator aircraft.

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

NASA’s Sustainable Flight Demonstrator project completed wind tunnel tests on a Boeing-built X-66 full-span model during a 13-week campaign between January and March 2025. The tests were completed in the 11-Foot Transonic Unitary Plan Facility at NASA’s Ames Research Center in California’s Silicon Valley. The model underwent tests in expected flight conditions to obtain engineering data to help improve the aircraft’s design and flight simulators.

Eric Garza, an engineering technician in the Experimental Fabrication Shop at NASA’s Armstrong Flight Research Center in Edwards, California, observes a wood router cut holes for temporary floorboards on Aug. 26, 2024. The flooring was designed for the X-66 experimental demonstrator aircraft. 

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

A model of the X-66 aircraft with a wingspan of almost 6 feet was placed in the 12-Foot Low-Speed Wind Tunnel at NASA’s Langley Research Center in Hampton, Virginia on October 30, 2024. During the tests, the team captured measurements of forces such as lift and drag over many aerodynamic configurations and flight conditions.

Eric Garza, an engineering technician in the Experimental Fabrication Shop at NASA’s Armstrong Flight Research Center in Edwards, California, cuts plywood to size for temporary floorboards for the X-66 experimental demonstrator aircraft on Aug. 26, 2024.

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

A model of the X-66 aircraft with a wingspan of almost 6 feet was placed in the 12-Foot Low-Speed Wind Tunnel at NASA’s Langley Research Center in Hampton, Virginia on October 30, 2024. During the tests, the team captured measurements of forces such as lift and drag over many aerodynamic configurations and flight conditions.

Boeing’s MD-90 aircraft flies from Victorville California to Palmdale, California on August 15, 2023. This aircraft will be NASA’s future Sustainable Flight Demonstrator. Modifications to the aircraft will include changes to the fuselage and most notably the use of a transonic truss-braced wing.

The cockpit of an old MD-90 aircraft arrived at NASA’s Armstrong Flight Research Center in Edwards, California, in March 2024. Parts will be used to build a simulator for NASA’s X-66, the demonstration aircraft for the Sustainable Flight Demonstrator project.

The cockpit of an old MD-90 aircraft arrived at NASA’s Armstrong Flight Research Center in Edwards, California, in March 2024. Parts will be used to build a simulator for NASA’s X-66, the demonstration aircraft for the Sustainable Flight Demonstrator project.

NASA’s Sustainable Flight Demonstrator project concluded wind tunnel testing in the fall of 2024. Tests on a Boeing-built X-66 model were completed at NASA’s Ames Research Center in Silicon Valley, California, in the 11-Foot Transonic Unitary Plan Facility. Pressure points, which are drilled holes with data sensors attached, are installed along the edge of the wing and allow engineers to understand the characteristics of airflow and will influence the final design of the wing.

NASA’s Sustainable Flight Demonstrator project concluded wind tunnel testing in the fall of 2024. Tests on a Boeing-built X-66 model were completed at NASA’s Ames Research Center in California’s Silicon Valley in the 11-Foot Transonic Unitary Plan Facility. The model underwent tests representing expected flight conditions to obtain engineering information to influence design of the wing and provide data for flight simulators.

NASA research engineer Walter Hargis regulates the 15-foot Structural Wing Experiment Evaluating Truss-bracing model in the Flight Loads Laboratory at NASA’s Armstrong Flight Research Center in Edwards, California, on Tuesday, March 31, 2026. The model is part of NASA’s research to develop technologies for future ultra-efficient aircraft. 

Lab technicians Phil Tofts, Chris McLain, and Jeff Howell and NASA engineers Erin Anderson and Richard Larson prepare the 15-foot Structural Wing Experiment Evaluating Truss-bracing model in the Flight Loads Laboratory at NASA’s Armstrong Flight Research Center in Edwards, California, on Thursday, Dec. 11, 2025. The model is part of NASA’s research to develop technologies for future ultra-efficient aircraft. 

Lab technicians Jeff Howell, left and Chris Mount install the 15-foot Structural Wing Experiment Evaluating Truss-bracing model in the Flight Loads Lab at NASA’s Armstrong Flight Research Center in Edwards, California, Wednesday, February 11, 2026. The model is part of NASA’s research to develop technologies for future ultra-efficient aircraft.

The 15-foot Structural Wing Experiment Evaluating Truss-bracing test article is fully installed in the Flight Loads Laboratory at NASA’s Armstrong Flight Research Center in Edwards, California, on Wednesday, May 20, 2026. The model is part of NASA’s research to develop technologies for future ultra-efficient aircraft.