The Ikhana unmanned aircraft system has been used by NASA last year to fight wildfires from the sky and this month to provide images of current Californian wildfires to authorities (link to NASA images). But Ikhana is also used to evaluate advanced sensing technology installed on its wings to improve its efficiency. The new sensors, which incorporate fiber optic sensing technology, are located side by side with traditional sensors. As said one NASA researcher, 'there are 3,000 sensors on Ikhana that are imperceptibly small because they're located on fibers approximately the diameter of a human hair.' But read more...
The sensors are so small that they're almost invisible. "Although the new sensors on the Ikhana, which are located on fibers that are the diameter of a human hair, are not visible, the sealant used to apply them can be seen in this view from above the wing." (Credit: NASA photo by Tony Landis) Here are two links to a larger version of this picture and to a Ikhana photo collection.
How these fiber optics sensors could improve aircraft efficiency? "The weight reduction that fiber optic sensors would make possible could reduce operating costs and improve fuel efficiency. The development also opens up new opportunities and applications that would not be achievable with conventional technology. For example, the new sensors could enable adaptive wing-shape control. 'Active wing-shape control represents the gleam in the eye of every aerodynamicist,' [said Lance Richards, Dryden's Advanced Structures and Measurement group lead.° '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.'"
And where are located these new sensors? "Six hair-like fibers located on the 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 fibers are so small that they have no significant effects on aerodynamics. The sensors eventually could be embedded within composite wings in future aircraft. To validate the new sensors' accuracy, the research team is comparing results obtained with the fiber optic wing shape sensors against those of 16 traditional strain gauges co-located on the wing alongside the new sensors."
These fiber optic sensor systems could also improve safety. "Another safety-related benefit of the lightweight fiber 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 fiber optic sensors to compensate for stresses on the airframe, helping prevent situations that might otherwise result in a loss of flight control."
For more information about this unmanned aircraft, please visit the Ikhana home page at NASA's Dryden Flight Research Center. And for more information about the fiber optic wing shape sensor system installed on Ikhana, here is a link to a recent Dryden news release, "Measuring up to the Gold Standard."
Sources: NASA Press release, July 14, 2008; and various websites
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