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Birds of Prey: Dynamics of Flight
 

Birds of Prey: Dynamics of Flight

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Birds of Prey: Dynamics of Flight presented by Michael P. Jones, DVM, at the Tennessee STEM Leadership Academy on June 27, 2012.

Birds of Prey: Dynamics of Flight presented by Michael P. Jones, DVM, at the Tennessee STEM Leadership Academy on June 27, 2012.

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    Birds of Prey: Dynamics of Flight Birds of Prey: Dynamics of Flight Presentation Transcript

    • Birds of Prey:Dynamics of FlightMichael P. Jones, DVM, Dipl. ABVP (Avian) Tennessee STEM Leadership Academy Oak Ridge Associated Universities June 27, 2012 raptorvet@bellsouth.net or mpjones@utk.edu
    • The History of Aviation and Aerodynamics• Man’s desire to fly and study of flight – Religion – Mythology – Art and History • Leonardo da Vinci – Codex on the Flight of Birds (1505) – Armed Forces (F22 Falcon) – My own experiences: • Flight • Falconry
    • Aerodynamics of Flight• Objectives: – Facilitate the understanding of principles of aerodynamics as they relate to flight in bird – Facilitate an appreciation of birds of prey
    • Aerodynamics of Flight• Major forces acting on a flying raptor: – Lift – Drag – Gravity Lift Drag Direction of flow Weight (Gravity)
    • Aerodynamic Forces and Flight• Any “fluid” passing over an object exerts a force – Lift—component of force that is perpendicular to the direction of air flow • Upward or downward (downforce) • Newton’s Laws of force • Bernoulli principle and pressure – Pressure above (decreased) and below the wing (increased) – Lift Coefficient (CL): capacity of airfoil to generate lift
    • Aerodynamic Forces and Flight • Lift – Airflow around the wingAny obstruction to airflowaround (especially above) Birds flying in formation takethe wing would interfere Advantage of vortices producedwith lift. by the wings
    • Aerodynamic Forces and Flight• Lift – Boundary layer—airflow close to the wing’s surface (can be laminar or turbulent) • Air viscosity affects flight • If airflow velocity is not strong enough to overcome viscosity then airflow “detaches” from the wing and becomes turbulent – Stalling
    • Aerodynamic Forces and Flight• Lift and Stalling – Stalling • Enhanced by: Birdsasart.com – Defects in the wing—increase drag and decrease lift • Prevented by: – Alula – Feathers that create an “eddy flap” on the dorsal aspect of the wing – Active and passive modification of the wing shape and airfoil
    • Aerodynamic Forces and Flight• Drag—component of force parallel to air flow – When a bird flies through the air it is affected by • Obstacle force (bird is an obstacle to airflow) • Friction between air and wing surface
    • Aerodynamic Forces and Flight• Drag—component of force parallel to air flow – Drag—Air or fluid resistance (3 components) • Profile drag—generated by friction • Induced drag—loss of kinetic energy • Parasite drag—of the body – Drag Coefficient—quantifies ability of an airfoil to generate drag • Form drag • Friction
    • The Dynamics of Flight• The Anatomy of Flight (Form and Function) – Avian flight is an extremely complex and energy demanding form of locomotion – Musculoskeletal System • Pectoral muscles, others • Humerus, radius and ulna – Integumentary System • Feathers and receptors – Nervous System – Special Senses—Eyes
    • The Dynamics of Flight• The Anatomy of Flight (Form and Function) – The Airfoil Lift Coefficient (CL): capacity of airfoil to generate lift
    • The Dynamics of Flight Beaufrère 2009
    • The Dynamics of Flight• Types of Flight • Raptors (birds) move forward under the influence of gravity, slowing sinking • Lift from airfoil of the wing • Climb rate vs. Sinking rate – Gliding and Soaring – Powered Flight – Hovering Flight
    • The Dynamics of Flight• Types of Flight – Gliding flight—”Traveling flight” • Continuously sinking in the air • Trading height for distance – Glide angle (ratio of height to distance traveled) – Weight—alters speed but not glide angle
    • The Dynamics of Flight• Types of Flight – Gliding flight—”Traveling flight” • Lift-to-drag ratio – Optimal ratio depends on bird’s hunting strategy/biology » Wing span, wing tip slots, and wing loading • Aspect Ratio = Span2/wing area – Trade speed for maneuverability (falcons) • Wing Loading = body weight/wing area – Higher speed with increased wing loading
    • The Dynamics of Flight• Types of Flight – Gliding flight • Lift-to-drag ratio – Hunting strategy • Aspect Ratio – Span2/wing area • Wing Loadiing – body weight/wing area
    • The Dynamics of Flight• Types of Flight – Soaring (a form of gliding) • Purpose(s): cooling, searching for prey, display • Surrounding air (thermals) rising faster than the birds is sinking • Air speed is sacrificed • Affected by wing loading, drag, and lift • Primary feather structure and slotting affects air turbulence
    • The Dynamics of Flight• Types of Flight – Powered Flight (Flapping Flight) • Aerodynamics of flapping flight is unsteady • Lift and Thrust generated by movement of the wing • Wing beat is a very complex elliptical movement – Downstroke—pronation, abduction and extension – Upstroke—flexion, supination and adduction
    • The Dynamics of Flight• Types of Flight – Powered Flight • Various speeds/gaits Fox 1995 – Slow speeds—upstroke is passive, there is no lift and no continuous vortex created » Creates a circular vortex with no lift » Energy /power consuming » All raptors; especially hawks and eagles
    • The Dynamics of Flight• Types of Flight – Powered Flight Fox 1995 • Various speeds/gaits – High speeds—upstroke is active, airspeed raises the wingtips and generates trailing vortices » Economical » Decreased wing-beat amplitude, wing- beat frequency, duration and angle of attack » Falcons and Accipiters
    • The Dynamics of Flight and Vision• Types of Flight – Powered Flight • Propulsion (Thrust) – Most birds generate propulsion on the downs stroke of the wing – Elliptical motion of wings when flapping – Accipiters (“sprinters”) produce propulsion on downstroke and upstroke Flickr.com Flickr.com
    • The Dynamics of Flight and Vision• Types of Flight – Powered Flight and Speeds • Golden eagle—29-32+ mph • Red-tailed hawk—20-40 mph • Merlin—30-45 • Gyrfalcon > 45 mph in level flight • Peregrine falcon—28-32 mph level flight – 175-250+ mph diving – Change body shape increase speed
    • The Dynamics of Flight and Vision• Types of Flight – Powered Flight • Maneuverability – Symmetry in forces between both wings through rolling motion of the body – Modification of wing shape » To produce more drag in one wing – Position of the legs and feet
    • The Dynamics of Flight• Aerodynamics of the tail – Functions: • Flight (lift, roll and stability) – Prevents upward pitch as wings flap downward and change center of pressure – Aerodynamic flap-redirect airflow from wings – Maneuvering • Display
    • The Dynamics of Flight and Vision• Avian Vision – Birds rely on their eyesight more than any other vertebrate • Exceptional visual acuity allows them to find and capture prey, navigate surroundings, identify conspecifics/mates, escape predation
    • The Dynamics of Flight and Vision• Avian Vision – Variable size and shape • Projects large image onto the retina • Little movement within the orbit – 12o in American kestrels (Falco sparverius) • Nictitating membrane • Cornea and sclera (ossicles) • Lens and accommodation
    • The Dynamics of Flight and Vision• Avian Vision – Retina—contains rods, cones and oil droplets • Color vision—birds are trichromatic to tetrachromatic – Also see in ultraviolet/near ultraviolet spectrum – Oil droplets act as filters for different wavelengths of light
    • The Dynamics of Flight and Vision• Avian Vision – Retina • Fovea—specialized regions in retina that allow greater visual acuity than surrounding retina • Humans (primates) only mammals with fovea • Birds—Bifoveate (central and temporal)
    • The Dynamics of Flight and Vision• Avian Vision – Retina • Fovea – Central fovea (deep) » Line of Sight (LOS) ~45o » Highest visual acuity – Raptors tend to look at distant objects/prey with central fovea – Near objects viewed with temporal fovea
    • The Dynamics of Flight and Vision• Avian Vision – Retina • Fovea 45o Tucker et al, 2000
    • The Dynamics of Flight• Avian Vision – “Conflict” between aerodynamics and vision • Need to keep heads and bodies aligned to minimize drag and reach maximum speed • Turn head towards LOS with one eye for maximum visual acuity ©2008 Richard Ettlinger
    • The Dynamics of Flight• Avian Vision – Curved flight path • Approach prey more quickly along curved flight path • Hunting from the sun • Misleading prey • G-Forces!!
    • The Dynamics of Flight• Conclusion: – Avian flight is a complex, biomechanical process that we don’t fully understand – Birds of prey are “cool”