Abstract:This study investigates the aerodynamics of the falcon Falco peregrinus while diving. During a dive peregrines can reach velocities of more than 320 km h−1. Unfortunately, in freely roaming falcons, these high velocities prohibit a precise determination of flight parameters such as velocity and acceleration as well as body shape and wing contour. Therefore, individual F. peregrinus were trained to dive in front of a vertical dam with a height of 60 m. The presence of a well-defined background allowed us to rec… Show more
“…The angle of attack for the investigated flight situation was determined in a previous study by Ponitz et al (2014) [18] for the equilibrium condition at the maximum diving speed and is set to 5 α = . Figure 6 shows a schematic vector diagram of the acting lift and drag forces on the falcon as well as the angle of attack in relation to the reference line of the falcon model which is built between the falcons tip and tail.…”
Section: Resultsmentioning
confidence: 99%
“…The numerical simulation in this study is based on the specific diving flight condition which is gained from a previous study by [18]. A peregrine falcon was trained to dive from a dam wall and the dive was captured with a stereo high-speed camera system to reconstruct the 3-D flight path.…”
Section: Dam Wall Diving Flights Of Real Falconsmentioning
confidence: 99%
“…where u is the free stream velocity, I is the turbulence intensity ( 0.04% I = , from experiments [18]) and l is the length scale ( )…”
Section: Numerical Set-upmentioning
confidence: 99%
“…Therefore, we investigated different wing configurations (opened wings and cupped wings extension [9]) of the peregrine falcon during diving flight. Both geometries are gained from a previous study by Ponitz et al (2014) [18] at maximum diving velocities from a dam wall dive. The present study investigates the influence of the geometry change of the extended cupped wings configuration via numerical simulations.…”
During a dive peregrine falcons can reach velocities of more than 320 km/h and makes themselves the fastest animals in the world. The aerodynamic mechanisms involved are not fully understood yet and the search for a conclusive answer to this fact motivates the three-dimensional (3-D) flow study. Especially the cupped wing configuration which is a unique feature of the wing shape in falcon peregrine dive is our focus herein. In particular, the flow in the gap between the main body and the cupped wing is studied to understand how this flow interacts with the body and to what extend it affects the integral forces of lift and drag. Characteristic shapes of the wings while diving are studied with regard to their aerodynamics using computational fluid dynamics (CFD). The results of the numerical simulations via ICEM CFD and OpenFOAM show predominant flow structures around the body surface and in the wake of the falcon model such as a pair of body vortices and tip vortices. The drag for the cupped wing profile is reduced in relation to the configuration of opened wings (without cupped-like profile) while lift is increased. The purpose of this study is primarily the basic research of the aerodynamic mechanisms during the falcon's diving flight. The results could be important for maintaining good maneuverability at high speeds in the aviation sector.
“…The angle of attack for the investigated flight situation was determined in a previous study by Ponitz et al (2014) [18] for the equilibrium condition at the maximum diving speed and is set to 5 α = . Figure 6 shows a schematic vector diagram of the acting lift and drag forces on the falcon as well as the angle of attack in relation to the reference line of the falcon model which is built between the falcons tip and tail.…”
Section: Resultsmentioning
confidence: 99%
“…The numerical simulation in this study is based on the specific diving flight condition which is gained from a previous study by [18]. A peregrine falcon was trained to dive from a dam wall and the dive was captured with a stereo high-speed camera system to reconstruct the 3-D flight path.…”
Section: Dam Wall Diving Flights Of Real Falconsmentioning
confidence: 99%
“…where u is the free stream velocity, I is the turbulence intensity ( 0.04% I = , from experiments [18]) and l is the length scale ( )…”
Section: Numerical Set-upmentioning
confidence: 99%
“…Therefore, we investigated different wing configurations (opened wings and cupped wings extension [9]) of the peregrine falcon during diving flight. Both geometries are gained from a previous study by Ponitz et al (2014) [18] at maximum diving velocities from a dam wall dive. The present study investigates the influence of the geometry change of the extended cupped wings configuration via numerical simulations.…”
During a dive peregrine falcons can reach velocities of more than 320 km/h and makes themselves the fastest animals in the world. The aerodynamic mechanisms involved are not fully understood yet and the search for a conclusive answer to this fact motivates the three-dimensional (3-D) flow study. Especially the cupped wing configuration which is a unique feature of the wing shape in falcon peregrine dive is our focus herein. In particular, the flow in the gap between the main body and the cupped wing is studied to understand how this flow interacts with the body and to what extend it affects the integral forces of lift and drag. Characteristic shapes of the wings while diving are studied with regard to their aerodynamics using computational fluid dynamics (CFD). The results of the numerical simulations via ICEM CFD and OpenFOAM show predominant flow structures around the body surface and in the wake of the falcon model such as a pair of body vortices and tip vortices. The drag for the cupped wing profile is reduced in relation to the configuration of opened wings (without cupped-like profile) while lift is increased. The purpose of this study is primarily the basic research of the aerodynamic mechanisms during the falcon's diving flight. The results could be important for maintaining good maneuverability at high speeds in the aviation sector.
“…However, the improvements diminish when the flaps are mounted with an angle greater than of .Fig. 1
a Frontal and b side view of a falcon with popped-up feathers (taken from the measurement campaign documented in Ponitz et al [18])
…”
During the flight of birds, it is often possible to notice that some of the primaries and covert feathers on the upper side of the wing pop-up under critical flight conditions, such as the landing approach or when stalking their prey (see Fig. 1) . It is often conjectured that the feathers pop up plays an aerodynamic role by limiting the spread of flow separation . A combined experimental and numerical study was conducted to shed some light on the physical mechanism determining the feathers self actuation and their effective role in controlling the flow field in nominally stalled conditions. In particular, we have considered a NACA0020 aerofoil, equipped with a flexible flap at low chord Reynolds numbers. A parametric study has been conducted on the effects of the length, natural frequency, and position of the flap. A configuration with a single flap hinged on the suction side at 70 % of the chord size c (from the leading edge), with a length of matching the shedding frequency of vortices at stall condition has been found to be optimum in delivering maximum aerodynamic efficiency and lift gains. Flow evolution both during a ramp-up motion (incidence angle from to with a reduced frequency of , being the free stream velocity magnitude), and at a static stalled condition () were analysed with and without the flap. A significant increase of the mean lift after a ramp-up manoeuvre is observed in presence of the flap. Stall dynamics (i.e., lift overshoot and oscillations) are altered and the simulations reveal a periodic re-generation cycle composed of a leading edge vortex that lift the flap during his passage, and an ejection generated by the relaxing of the flap in its equilibrium position. The flap movement in turns avoid the interaction between leading and trailing edge vortices when lift up and push the trailing edge vortex downstream when relaxing back. This cyclic behaviour is clearly shown by the periodic variation of the lift about the average value, and also from the periodic motion of the flap. A comparison with the experiments shows a similar but somewhat higher non-dimensional frequency of the flap oscillation. By assuming that the cycle frequency scales inversely with the boundary layer thickness, one can explain the higher frequencies observed in the experiments which were run at a Reynolds number about one order of magnitude higher than in the simulations. In addition, in experiments the periodic re-generation cycle decays after 3–4 periods ultimately leading to the full stall of the aerofoil. In contrast, the 2D simulations show that the cycle can become self-sustained without any decay when the flap parameters are accurately tuned.
The family Falconidae has contrasting behaviors on its flight within the subfamilies. Falcons are primarily aerial predators requiring accuracy, high speed, and controlled movements during flight. Caracaras are generalists that seek food while walking and their flight is characterized as slow and erratic. We aimed to explore the muscle mass of the primary wing muscles in several species of Falconinae and to identify possible differences related to the role that these muscles perform during flight. We studied 34 wing muscles in 11 specimens of five species of falcons. The percentage of each muscle with respect to body mass was calculated as well as the total wing muscle mass. The search for differences between muscles of falcons and caracaras was analyzed using Bayesian statistical inference. Published data from Polyborinae were used for comparison. Five muscles were significantly different between both subfamilies mm. latissimus dorsi pars caudalis, biceps brachii, extensor carpi radialis, flexor digitorum superficialis, and extensor digitorum communis. The first two muscles were larger in Polyborinae, which could be useful to achieve more strength and stabilization. In falcons the last three muscles listed were larger, which might be associated with their fast and acrobatic flight. Variations in certain muscles generate, in turn, differences in function, which is reflected in their type of flight and its use. These findings reinforce the modular character of the locomotor system of birds whereby the regions involved in locomotion can have morphological peculiarities according to their lifestyle.
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