NASA Evaluates Sensor Technology for Future Aircraft Efficiency

Tag : Lead Wires

EDWARDS, Calif. -- NASA is evaluating an advanced, fiberoptic-based sensing technology that could aid development of activecontrol of wing shape. Controlling a wing's shape in flight wouldallow it to take advantage of aerodynamics and improve overallaircraft efficiency.
The Fiber Optic Wing Shape Sensor system measures and displays theshape of the aircraft's wings in flight. The system also haspotential for improving aircraft safety when the technology is usedto monitor the aircraft structure.
Flight tests on NASA's Ikhana, a modified Predator B unmannedaircraft adapted for civilian research, are under way at NASA'sDryden Flight Research Center at Edwards Air Force Base inCalifornia. The effort represents one of the first comprehensiveflight validations of fiber optic sensor technology.
"Generations of aircraft and spacecraft could benefit from workwith the new sensors if the sensors perform in the sky as they havein the laboratory," said Lance Richards, Dryden's AdvancedStructures and Measurement group lead.
The weight reduction that fiber optic sensors would make possiblecould reduce operating costs and improve fuel efficiency. Thedevelopment also opens up new opportunities and applications thatwould 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 everyaerodynamicist," Richards said. "If the shape of the wing can bechanged in flight, then the efficiency and performance of theaircraft can be improved, from takeoff and landing to cruising andmaneuvering."
Six hair-like fibers located on the top surface of Ikhana's wingsprovide more than 2,000 strain measurements in real time. With acombined weight of less than two pounds, the fibers are so smallthat they have no significant effects on aerodynamics. The sensorseventually could be embedded within composite wings in futureaircraft.
To validate the new sensors' accuracy, the research team iscomparing results obtained with the fiber optic wing shape sensorsagainst those of 16 traditional strain gauges co-located on thewing alongside the new sensors.
"The sensors on Ikhana are imperceptibly small because they'relocated on fibers approximately the diameter of a human hair,"Richards explained. "You can get the information you need from thethousands of sensors on a few fibers without the weight andcomplexity of conventional sensors. Strain gauges, for example,require three copper lead wires for every sensor."
When using the fiber optic sensors, researchers do not requireanalytical models for determining strain and other measurements onthe aircraft because data derived with the sensors include all ofthe actual measurements being sought.
Another safety-related benefit of the lightweight fiber opticsensors is that thousands of sensors can be left on the aircraftduring its lifetime, gathering data on structural health andperformance. By knowing the stress levels at thousands of locationson the aircraft, designers can more optimally design structures andreduce weight while maintaining safety, Richards explained. The netresult could be a reduction in fuel costs and an increase in range.
Further, intelligent flight control software technology now beingdeveloped can incorporate structural monitoring data from the fiberoptic sensors to compensate for stresses on the airframe, helpingprevent situations that might otherwise result in a loss of flightcontrol.
By extension, the application of the technology to wind turbinescould improve their performance by making their blades moreefficient.
"An improvement of only a few percent equals a huge economicbenefit," Richards said. "The sensors could also be used to look atthe stress of structures, like bridges and dams, and possibilitiesextend to potential biomedical uses as well. The applications ofthis technology are mind-boggling."
NASA's Aeronautics Research Mission Directorate is supportingalgorithm and systems development, instrument and ground testvalidation of the new sensor system. For more information on NASA'saeronautics research, visit:
http://www.aeronautics.nasa.gov