X-65: A New Era in Aircraft Control from DARPA

Assembly and Design Features

The experimental unmanned aerial vehicle X-65, developed by DARPA, is being assembled at Aurora Flight Sciences, a Boeing subsidiary, in Bridgeport, West Virginia. Currently, the fuselage is being constructed and will soon be fitted with a unique diamond-shaped wing.

Innovative Control Approach

The X-65 stands out not only for its futuristic appearance, with unconventional angles and wing shape, but also for its fundamentally new control method. Unlike traditional aircraft that use rudders, flaps, and ailerons, the X-65 employs an Active Flow Control (AFC) system. Instead of moving control surfaces, 14 special nozzles in the wings and tail emit precisely controlled jets of air. This creates virtual control surfaces, allowing real-time changes to the aircraft’s aerodynamic characteristics.

Advantages of Abandoning Classic Elements

Traditional mechanical control systems add weight, complexity, and cost to an aircraft, and also introduce additional aerodynamic drag due to gaps, hinges, and protruding elements. The use of AFC eliminates these drawbacks, making the structure lighter, more efficient, and less detectable by radar thanks to fewer reflective angles.

How AFC Works

The AFC system can instantly increase lift on one side of the wing to induce roll, or alter airflow behind the tail to control pitch and yaw. AFC can also boost lift by acting on the wing’s leading edge, which is especially important for challenging aerodynamic conditions.

Why a Diamond-Shaped Wing?

The diamond-shaped wing was chosen as the optimal configuration for testing under the CRANE program. This design, with straight edges and varying sweep angles, allows for the creation of diverse airflow patterns over the wing surface. However, such a wing is particularly prone to flow separation, and the AFC system is specifically intended to compensate for this and create virtual control surfaces.

Safety and Modularity

Since the X-65 is an experimental platform, it is also equipped with conventional movable control surfaces, which DARPA refers to as “training wheels.” These provide extra safety during early test phases and allow for comparison of flight characteristics with and without AFC. During testing, the aircraft will reach transonic speeds, and the new system is expected to improve the diamond wing’s efficiency at low speeds and high angles of attack—regimes where traditional solutions are less effective.

Flexibility for Future Research

The X-65 features interchangeable modular components, enabling it to serve as a platform for further research after the CRANE program concludes. This modularity allows engineers to test different nozzle configurations and refine the AFC system.

Plans and Outlook

Due to technical challenges, the project is behind schedule, and the first X-65 flight is now planned for late 2027. Larry Wirsing, Vice President of Aircraft Development at Aurora Flight Sciences, noted that the X-65 will become a long-term test asset, and the technologies and flight data obtained will be valuable for future projects and research missions.