DARPA Aircraft Could Maneuver Using Only Pressurized Air

­The very nature of flight makes it both inefficient and precludes stealth, but DARPA is tinkering with an experimental aircraft that could mark the greatest paradigm change since the Wright brothers.

Most aircraft, both jet- and propeller-driven, use moving surfaces to control and maneuver the vehicle in flight. But DARPA’s Control of Revolutionary Aircraft with Novel Effectors (CRANE) program is experimenting with an active flow control (AFC) system that would use bursts of highly pressurized air to navigate planes in-flight.

By dispending with the traditional moving flight controls on the exterior of the wings and tail, stealth becomes that much easier.

As The Drive points out, “Designers of stealthy aircraft have to be mindful of any joints or other gaps between exposed surfaces, and try to generally keep them to a minimum, to ensure the radar cross-section remains as low as possible.”

And since traditional control surfaces cannot always be flush with the rest of the aircraft's external shape, designers need to formulate innovative solutions to enable stealth in the first place.

Eliminating those moving surfaces would also reduce overall weight and allow for greater maneuverability, especially in unmanned aircraft.

Concept art appears to show a single jet engine, possibly powering the pressurized air. And Aurora Flight Sciences has been busy testing its CRANE design.

"Using a 25% scale model, Aurora conducted tests over four weeks at a wind tunnel facility in San Diego, California…over 14,000 data points were collected, including 8,860 AFC control power points, forming the foundation for a flight-quality aerodynamic database to enable rapid execution in future program phases," Aurora noted last year.

That was part of Phase 1. Phase 2 will focus on design and development of flight software and controls, leading to a design review of an X-plane demonstrator.

From there, Phase 3 would include a test flight of a 7,000 pound demonstrator, with a 30-foot wingspan and the ability to reach speeds of up to Mach 0.7. That phase should happen some time in 2025.

“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  CRANE Program Manager Richard 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.”