Controlling a wing's shape in flight would allow it to take advantage of aerodynamics and improve overall aircraft efficiency.
The Fibre Optic Wing Shape Sensor system measures and displays the shape of the aircraft's wings in flight and also has potential for improving aircraft safety when used to monitor the aircraft structure, NASA said.
Flight tests on NASA's Ikhana, an unmanned aircraft adapted for civilian research, are under way at Dryden Flight Research Centre in California.
The effort represents one of the first comprehensive flight validations of fibre optic sensor technology.
"Generations of aircraft and spacecraft could benefit from work with the new sensors if they perform in the sky as they have in the laboratory," said Lance Richards, Dryden's Advanced Structures and Measurement group head.
The weight reduction that fibre optic sensors would make possible could reduce operating costs and improve fuel efficiency, besides opening up new applications like enabling adaptive wing-shape control.
"Active wing-shape control represents the gleam in the eye of every aerodynamicist," Richards said.
"If the shape of the wing can be changed in flight, then the efficiency and performance of the aircraft can be improved, from takeoff and landing to cruising and maneuvering."
Six hair-like fibres located on top surface of Ikhana's wings provide more than 2,000 strain measurements in real time.
With a combined weight of less than two pounds, the fibres have no significant effects on aerodynamics.
The sensors eventually could be embedded within composite wings in future aircraft, NASA said.
To validate the new sensors' accuracy, the research team is comparing results obtained with fibre optic wing shape sensors against those of 16 traditional strain gauges co-located on the wing alongside the new sensors.
"The sensors on Ikhana are imperceptibly small because they're located on fibres approximately the diameter of a human hair," Richards explained.
"You can get the information you need from the thousands of sensors on a few fibres without the weight and complexity of conventional sensors."
Another safety-related benefit of the lightweight fibre optic sensors is that thousands of sensors can be left on the aircraft during its lifetime, gathering data on structural health and performance.
By knowing the stress levels at thousands of locations on the aircraft, designers can more optimally design structures and reduce weight while maintaining safety, Richards explained.
The net result could be a reduction in fuel costs and an increase in range.
Further, intelligent flight control software technology now being developed can incorporate structural monitoring data from the fibreoptic sensors to compensate for stresses on the airframe, helping prevent situations that might otherwise result in a loss of flight control, NASA said.
By extension, the application of the technology to wind turbines could improve their performance by making their blades more efficient.
"The sensors could also be used to look at the stress of structures, like bridges and dams, and possibilities extend to potential biomedical uses as well. The applications of this technology are mind-boggling," Richards said.
