Peregrine Falcon’s Dive: Pullout Maneuver and Flight Control Through Wing Morphing

Abstract

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.

Aerofoil Flow Sensing Using On-Board Optical Tracking of Flexible Pillar Sensors

“…This is important when considering the high flexibility of such natural fliers in comparison to the relatively rigid airframes of current aircraft and their associated complex flight dynamics models [4]. Even in high-speed flight, mechanoreceptors on fast fliers have the ability to scale with flow conditions to a high level of sensitivity [5], which is critical during high-speed stoops where small changes to angle of attack (AoA) can have significant effects on lift generation and flight stability [6].…”

A Polymorphing Wing Capable of Span Extension and Variable Pitch

“…Morphing aircraft is a promising technology that can help in mitigating the adverse effects of flight and meet the FlightPath 2050 goals. In addition, morphing wings can increase maximum lift, reduce drag [2,3] and vibrations, improve flight performance within a certain airspeed range [4], and enhance aeroelastic performance [5,6] and aircraft maneuverability [7,8]. By definition, a morphing aircraft continuously adjusts its geometry to enhance flight performance, control authority, and multi-mission capability.…”

Detecting aerofoil separation pre-cursors using on-board optical tracking of flexible pillar sensors

“…Investigations of biological inspired sensors have shown a variety of natural fliers using wing receptors to detect temporal flow and pressure changes, in addition to variations of amplitude for signals of the same frequency for executive decision making in flight control and stabilisation [1]. Even in high-speed flight, mechanoreceptors on fast-fliers have the ability to scale with flow conditions to a high level of sensitivity [2], which is critical during high-speed stoops where small changes to angle of attack can have significant effects on lift generation and flight stability [3].…”