Fig. 1—Measurement of the aerodynamic properties of an aircraft wing, Inter-digitated electrodes with a linear center of pressure spatial weighting, Prototype carbon nanotube center of pressure sensor
Fig. 2—Testing spatially-weighted sensors in the Morpheus Lab
Fig. 3—Spatially distributed lift and drag sensors
Fig. 4—Simple demo of the spatially distributed conformal pressure sensors
Fig. 5—On-board one of the lab aircraft looking out the right wing
Conformal aerodynamic sensors have been developed for the LDC program that can provide direct measurement of the aerodynamic properties of an aircraft wing, such as the lift, drag, and center of pressure. These sensors implement smart materials, such as piezo-resistive inks and quantum-tunneling composites, on spatially shaded sensor apertures that are designed to extract desired aerodynamic properties from the flow on an aircraft wing by on-board integration of the distributed pressures.
Developing conformal sensors to measure aerodynamic properties involves designing the sensor electrode, selecting the appropriate sensing material, and prototyping the proposed sensor designs. Spatial weighting techniques are used to determine the electrode shapes needed to measure specific aerodynamic properties. This research has patented a revolutionary method by which the electrode shape can be determined that will measure the lift and drag on a span section of an aircraft wing, resulting from the pressure distribution, with a single transducer. Research is underway to determine the appropriate sensor material to be used for this project. Poly-vinylidene Flouride, or PVDF, a carbon-nanotube composite material sensor, specifically developed for this program by NASA LaRC, a Quantum Tunneling Composite (QTC), and piezo-resistive ink are among some of the materials being tested. Recent testing of these materials and electrode shapes, including some in-flight testing, has revealed excellent pressure response of these materials, with some consideration required for temperature effects.
Fig. 4 displays a simple demo of the spatially distributed conformal pressure sensors that provide the aerodynamic feedback for the Lift Distribution Control algorithms. The conformal pressure sensor is sampled by a microprocessor and provides direct feedback to a control flap in this simple demo.
Fig. 5 shows a video from on-board one of the lab aircraft looking out the right wing. Some early prototypes of the conformal sensors were installed on this wing for preliminary testing.