Bird Flight

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Bird Flight

• Summer Research 2002
• Jennifer Panik
• Advisor Ann Anderson

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Presentation Outline

• Discuss basic aerodynamic forces
• Discuss bird flight
• Present wind tunnel testing

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Basic Aerodynamic Forces

• Lift
• Defined as the component of aerodynamic force
  perpendicular to the relative wind
• Lift Coefficient (CL )
• Indicate capacity of an airfoil to generate lift
• Drag
• Defined as the component of the aerodynamic force
  parallel to the relative wind
• Drag Coefficient (CD )
• Indicate capacity of an airfoil to generate drag

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Stall

• High pressure on under surface and low pressure
  on upper surface
• Drag increases greatly and there is no lift
• Instead of smooth flow, air separates

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How Birds Maneuver

• Pitch
• Rotation about the transverse axis, running
  horizontally transversely through the center of
  gravity
• Related to control of speed
• Roll
• Rotation about the median axis running
  horizontally longitudinally
• Used to change direction, usually precedes a turn
• Yaw
• Rotation about the vertical axis
• Steering

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Flight Methods

• Active Flight
• Hovering Flight
• Migration
• Soaring
• Gliding Flight

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• Active Flight
• Basic requirements average lift balances weight
  average thrust balances drag
• Wings do not produce constant lift and thrust
  throughout the wing stroke
• Hovering Flight
• Production of a vertical force to balance the
  weight of the bird
• Symmetrical hovering
• Asymmetrical hovering

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• Migration
• Birds have well developed vision, a wide hearing
  range, can detect air pressure changes, and have
  a magnetic sense that aid in migration
• Line formations cluster formations
• A bird diagonally behind the leading bird
  exploits the upwash created by the flight of the
  leading bird

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• Soaring
• Static soaring
• Slope soaring
• Thermal soaring
• Dynamic soaring
• Gliding Flight
• Main component in soaring flight
• Muscles do no mechanical work
• Flap-gliding

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Features That Affect Flight

• Geometry of wing
• A.R. wing span / mean wing chord
• Wing loading weight / area
• Gliding speed proportional to wing loading
• Tail
• Feet
• Feathers
• Two physiological functions
• Alula

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Alula

• Basically a thumb
• Automatic action
• Prevents stall at low speed
• Spread wing tips

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Project Objective

• To test the wings to see if the alula prevents
  stall
• To generate pictures of the air flow over the
  wings

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Wind Tunnel Testing

• Wind tunnel set up
• Dynamometer
• Measures lift and drag

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• Mounting airfoil into machine
• Testing the NACA 4412 airfoil

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Mounting Mechanism
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Black Scoter Wing
Redhead Wing
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Wing Testing Results
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PIV Testing

• Instrumentation
• Wind tunnel
• Fog Machine
• Lasers
• Camera
• Image analysis software
• Coprocessor computer
• Data visualization program

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PIV Results for Redhead Wing
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Conclusions

• I attained lift and drag results for the wings
  with reasonable uncertainty
• I verified the basic theory of aerodynamics
• I did not see a large effect from the alula

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Future Work

• Confirm previous data
• Extensive PIV testing of the wings
• Multiple planes
• Multiple angles

Acknowledgements Professor Tobiessen Biology
Department Research funded by the National
Science Foundation