Lockheed Martin X-56

Lore & Background

The X-56A is based on Lockheed's earlier UAV work, showing influence from the Polecat, Sentinel and DarkStar UAVs. The program called for the construction of two 7.5-foot-long fuselages and a wingspan of 27.5 feet, with four sets of wings built for flight testing. The aircraft first flew on 26 July 2013 from Edwards Air Force Base, with twenty flights planned on behalf of the Air Force Research Laboratory before handover to NASA for further testing.

The first X-56A was severely damaged in a crash shortly after takeoff from the dry lakebed at Edwards AFB on 19 November 2015, on its first flexible-wing flight to test active flutter suppression. That aircraft had previously made 16 flights with stiff wings to prove its operating envelope. The second X-56A flew for the first time on 9 April 2015 while under operation by NASA, completing eight flights with stiff wings to clear its operating envelope, then its first flight with highly flexible wings on 31 August 2017.

One instability mode, body freedom flutter, was shown to be actively suppressed by the digital flight control at 110 knots, within its normal flight envelope. The X-56B was destroyed in a crash on 9 July 2021 after suffering an anomaly in flight.

Reader's Guide

The X-56 program's significance lies in its focused research into active flutter suppression and gust-load alleviation, technologies critical for future High-Altitude Long Endurance (HALE) military reconnaissance aircraft. By demonstrating that body freedom flutter could be actively suppressed by digital flight control at 110 knots within the normal flight envelope, the program provided practical validation of concepts that could enable lighter, more flexible wing structures in future UAVs. The modular design, with interchangeable fuselages and multiple wing sets, allowed systematic testing of stiff and flexible configurations. The program's progression from Air Force Research Laboratory oversight to NASA operation reflects a typical transition from military development to broader aeronautical research. The crashes of both the first X-56A and the later X-56B underscore the inherent risks of testing novel flight control technologies, particularly those involving highly flexible wings and active flutter suppression. Despite these setbacks, the successful suppression of body freedom flutter represents a tangible step toward the HALE reconnaissance platforms the X-56 was designed to inform.

Did You Know?

• The X-56 was designed by Lockheed Martin's Skunk Works.
• The first X-56A crashed on its first flexible-wing flight on 19 November 2015.