NASA researchers recently subjected a novel, slender, and lightweight wing design to a rigorous series of stress tests to identify its structural limits. The results have provided encouraging insights into the wing’s potential, even when pushed beyond its intended operational parameters.
The test article, known as the 15-foot Structural Wing Experiment Evaluating Truss-bracing (SWEET-15), is part of NASA’s ongoing research into developing ultra-efficient future aircraft. This design features a long wing supported by an aerodynamic strut, building upon NASA’s previous Transonic Truss-Braced Wing concept.
The research team aims to determine if the SWEET-15’s architecture and lightweight structural composition could significantly reduce fuel consumption in commercial airliners. To achieve this, engineers first had to analyze how the structure responds to the intense forces encountered during actual flight.
The SWEET-15 design was made possible by integrating five advanced composite manufacturing and assembly technologies. Fabricated at NASA’s Langley Research Center in Hampton, Virginia, the 15-foot test article was subsequently transported to NASA’s Armstrong Flight Research Center in Edwards, California, for experimental testing.
During several months of testing, NASA engineers intentionally applied bending forces to the wing within the Flight Loads Laboratory at NASA Armstrong. To monitor the structure’s response as loads increased, a network of strain and load sensors, including fiber-optic technology, was embedded throughout the assembly.
Sensor data validated the predictions generated by NASA’s computer models. Initial findings indicate that the wing successfully withstood anticipated in-flight forces. These results have bolstered confidence in the new manufacturing techniques and assembly methods used for SWEET-15, which may serve as a blueprint for future efficient aircraft. The manufacturing process, developed at NASA Langley using the Integrated Structural Assembly of Advanced Composites robot, is designed to create lighter and more robust composite structures for aerospace applications.
The testing concluded with a deliberate “test-to-failure” phase, where engineers increased loads beyond design specifications to observe the exact point and nature of structural failure. The structure ultimately failed at approximately 127% of its design limit load, with visible damage occurring near the trailing edge of the wing and on the upper wing cover. This phase provided critical data on how the joints connecting the wing to its primary strut and secondary jury strut behave under loads exceeding the expected flight envelope.
This experiment represents the first time a representative composite truss-braced wing configuration has undergone this level of structural evaluation. The success of the project was driven by inter-center collaboration and the use of specialized agency resources, such as the Fiber Optic Sensing System used for aircraft and spacecraft data collection.
Prior to testing, engineers at NASA Langley were responsible for the design, analysis, manufacturing, and safety preparations required for the laboratory setup.
Researchers will now analyze the collected data to inform future airframe engineering and support NASA’s continuous development of more efficient aviation technologies.
This research is conducted through NASA’s Subsonic Flight Demonstrator project within the Research Technology Mission Directorate. The successful testing of these innovative components represents a significant milestone in NASA’s aeronautics research endeavors.