DARPA moves forward on X-65

DARPA is working on the CRANE program, which aims to develop an innovative aircraft that utilizes active flow control (AFC) actuators instead of traditional external control surfaces for primary flight control. Aurora Flight Sciences has been chosen to build a full-scale X-plane called X-65 to demonstrate the feasibility of using AFC effectors for roll, pitch, and yaw control.

The X-65 has been designed to break away from the century-old paradigm of flight control and eliminate external moving parts, resulting in a reduction of weight and complexity, while improving performance. AFC effectors use jets of air from a pressurized source to shape the flow of air over the aircraft's surface, allowing it to manoeuvre without traditional control surfaces.

The X-65 is an unmanned aircraft with a 30-foot wingspan, capable of speeds up to Mach 0.7, and weighs over 7,000 pounds. The unique diamond-like wing shape is designed to maximize what can be learned about AFC in full-scale, real-world tests. The aircraft will have two sets of control actuators, traditional flaps and rudders, and AFC effectors embedded across all the lifting surfaces. This will minimize risk and maximize the program's insight into control effectiveness. The plane's performance with traditional control surfaces will serve as a baseline, and successive tests will selectively lock down moving surfaces, using AFC effectors instead.

The X-65 is a technology demonstrator, and its size, weight, and speed are similar to a military trainer aircraft, the flight test results are immediately relevant to real-world aircraft design. The X-65 is being built as a modular platform to allow it to live on as a test asset for DARPA and other agencies long after CRANE concludes.

Aurora Flight Sciences has already started fabricating the X-plane, and it is scheduled to be rolled out in early 2025, with the first flight planned for the summer of the same year. The AFC suite of technologies enables multiple opportunities for aircraft performance improvements, such as elimination of moving control surfaces, drag reduction and high angle of attack flight, thicker wings for structural efficiency and increased fuel capacity, and simplified high-lift systems.

The contract includes a Phase 3 option in which DARPA intends to fly a 7,000-pound X-plane that addresses the two primary technical hurdles of incorporation of AFC into a full-scale aircraft and reliance on it for controlled flight. Unique features of the demonstrator aircraft will include modular wing configurations that enable future integration of advanced technologies for flight testing either by DARPA or potential transition partners.

Overall, the CRANE program aims to evaluate a wide range of relevant technologies during the planned X-plane flight tests, building on the significant advancements made by the active flow control community over the past several decades. The X-65 is an exciting development in aerospace engineering, with the potential to revolutionize both military and commercial aircraft design in the future. “Thanks to a variety of innovative participants, the CRANE program has significantly advanced the state of the art of multiple active flow control technologies,” said Wlezien.

 “We are uniquely positioned to build on those achievements by evaluating a wide range of relevant technologies during our planned X-plane flight tests.”