The subscale X-56 UAV is the latest aircraft at NASA Armstrong to be instrumented with FOS technology. NASA is using FOS to investigate challenges associated with highly flexible, lightweight wings. In contrast to stiff, rigid wings found on commercial aircraft today, X-56 is outfitted with long, very high-aspect ratio wings which often flex significantly during flight. The use of more flexible wings is considered essential to next generation, fuel efficient aircraft. Commercial aircraft currently do not employ wings of this nature due to their susceptibility to the highly destructive aeroelastic instability known as flutter. NASA is utilizing FOS data to identify the onset of flutter and drive active flutter suppression systems.