Wing-tail coordination balances efficient cruising and maneuvering flight in an avian-inspired flapping robot

Birds modulate wing-tail morphology to balance maneuvering capability and cruise efficiency, but fully replicating this mechanism in bio-inspired aerial robots increases actuator redundancy and control complexity. Here we present NPU-Sparrow, a micro flapping-wing robot that integrates a linkage-driven morphing tail with flapping wing incidence-angle control. Combining aerodynamic modeling, wind tunnel measurements and outdoor flight tests, we show that the negative-lift tail reconciles cruise stability with maneuvering performance through role reversal: it provides longitudinal static stability at low angles of attack, but becomes an auxiliary lifting surface above 13°. This low-degree-of-freedom strategy expands the level-flight speed envelope to 4.5-13.2 m s^-1, achieves a peak roll rate of 375° s^-1, reduces steady-turn radius by 20.4% and enables loops and barrel rolls. In this work, we show that translating avian wing-tail coordination into modelable engineering variables provides a route towards agile and efficient flapping-wing robots.