The US Defense Advanced Research Projects Agency (DARPA) has awarded contracts to Aurora Flight Sciences, Lockheed Martin and Georgia Tech Research Corporation to work on its Control of Revolutionary Aircraft with Novel Effectors (CRANE) programme, which aims to demonstrate an aircraft design based on active flow control (AFC), an area not fully explored compared with traditional flight controls. The goal is to demonstrate significant efficiency benefits deriving from AFC, as well as improvements in aircraft cost, weight, performance and reliability.
“The performers are looking at using active flow control very early in the design scope. That’s the differentiating piece that hasn’t been done before,” explained Alexander Walan, CRANE Program Manager in DARPA’s Tactical Technology Office. “AFC has been explored at a component level, but not as an integral piece of aircraft design. By altering the design approach, CRANE seeks to maximize the chance of a successful X-plane development while also integrating AFC into the aircraft’s stability and control.”
Phase 0 is a long conceptual design phase to give performers time to evaluate flow control options before solidifying their demonstration approaches. Phase 0 awards will comprise multiple conceptual design trades, active flow control component testing, multi-domain analysis and optimisation, concept down-selection and a conceptual design review.
Over the past two decades, the term AFC has described a wide range of fluid dynamic control approaches. For the CRANE programme, AFC is defined as the on-demand addition of energy into a boundary layer for maintaining, recovering, or improving vehicle aerodynamic performance. CRANE is excluding already proven techniques that use large external moving surfaces, mechanical vectoring of engine jet exhaust, or other traditional moving aerodynamic control devices.
CRANE performers are expected to maximize use of commercial-off-the-shelf-parts and components for non-flight control subsystems to reduce programme risk outside of unique configurations and AFC technologies.
“Active flow control technology has matured at the component level to the point where a potential leap forward in aircraft technology is possible […] We see an opportunity with CRANE to open up the future design space for both defense and civilian applications,” stated Walan.