The Peregrine Falcon's Dive: On the Pull-Out Maneuver and Flight Control Through Wing-Morphing

During the pull-out maneuver, Peregrine falcons were observed to adopt a succession of specific flight configurations which are thought to offer an aerodynamic advantage over aerial prey. Analysis of the flight trajectory of a falcon in a controlled environment shows it experiencing load factors up to 3 and further predictions suggest this could be increased up to almost 10g during high-speed pull-out. This can be attributed to the high maneuverability promoted by lift-generating vortical structures over the wing. Wind-tunnel experiments on life-sized models in the different configurations together with high fidelity CFD Simulations(LES) show that deploying the hand-wing in a pull-out creates extra vortex-lift, similar to that of combat aircraft with delta wings. The aerodynamic forces and the position of aerodynamic center were calculated from the Simulations of the flow around the different configurations. This allowed for an analysis of the longitudinal static stability in the early pull-out phase, confirming that the falcon is flying unstably in pitch with a positive slope in the pitching moment and a trim angle of attack of about 5◦, possibly to maximize responsiveness. The hand-wings/primaries were seen to contribute to the augmented stability acting as ‘elevons’ would on a tailless blended-wing-body aircraft