Progress of active flow control aircraft adopting rudderless flight control and STOL

Abstract Active flow control aircraft (AFCA) represent a significant development direction in next-generation aircraft design. Among them, rudderless flight control (RFC) and short takeoff and landing (STOL) are gaining widespread attentions and are gradually applied as disruptive technologies of next-generation aircraft, displaying marked strategic and engineering value. In 2020, DARPA launched “Control of Revolutionary Aircraft with Novel Effectors” (CRANE) project, where active flow control (AFC) was incorporated as a critical dimension of overall design with the goal of developing the next-generation AFCA. The full-scale demonstrator of CRANE was officially named X-65 in 2023. Two of the critical technologies being validated are RFC and STOL. This article reviews the developing process of typical AFCA adopting above technologies and provides an outlook on the futural development tendency. AFCA adopting STOL developed earlier, and comprehensive evaluations and flight tests have already been conducted on full-scale commercial and military aircraft, demonstrating a high level of technological maturity. In contrast, AFCA adopting RFC developed later and have so far undergone flight tests only on small-scale UAVs, needing further evaluation on full-scale aircraft. Future research hotspots and challenges of AFCA will contain AFC implementation scheme combining the bleed air system and synthetic jet actuators, full-envelope high-efficiency AFC technology, coordination control of multiple AFC technologies, flight dynamics modeling of AFCA, redundant high-reliability flight control, high-stealth heavy-payload wide-speed-range large-airspace flight platform, and aircraft overall design integrating AFC.