Designed by Lockheed Martin's Advanced Development Programs, known informally as the Skunk Works,[1] the aircraft was first revealed by Aviation Week,[2] and is intended to research active flutter suppression and gust-load alleviation technologies. The X-56A is based on Lockheed's earlier UAV work, showing influence from the Polecat, Sentinel and DarkStar UAVs. The program calls for the construction of two 7.5 feet (2.3 m)-long fuselages and a wingspan of 27.5 ft,[3] with four sets of wings being constructed for flight testing.[4]
The first X-56A unmanned aircraft was severely damaged in a crash shortly after takeoff from the dry lakebed at Edwards AFB, California, on 19 November 2015, on its first flexible-wing flight to test active flutter suppression. The aircraft had previously made 16 flights with stiff wings to prove its operating envelope.[7]
The second X-56A unmanned aircraft flew for the first time on 9 April 2015 while under operation by NASA.[8] The aircraft flew eight flights with the stiff wings to clear its operating envelope.[9] The vehicle then completed its first flight with the highly flexible wings on 31 August 2017.[10]
One instability mode, body freedom flutter, was shown to be actively suppressed by the digital flight control at 110 kn (200 km/h), within its normal flight envelope.
Slender, flexible and lighter low-drag wings would be enabled by flutter suppression.[11]
X-56B was destroyed in a crash on 9 July 2021 after suffering an "anomaly in flight".[12]
