Its a bird Its a plane Its biomechanics

It’s a bird! It’s a plane! It’s biomechanics!

Lesson Goals • Review the forces that act on an object in flight • Review the principles and mechanics of an airfoil • Understanding wing designs and wing relationships to mass • Compare how these flight principles apply to animals

What does it take to fly? FLYING SOLO • How does an object “defy” gravity and stay airborne? • What are some forces that act on an object in flight?

What about the wings? FLOCK TALK • How does the wing aid an object in flight? • Why don’t hot air balloons or rockets need wings?

Gravity • Gravity is the force that pulls objects with mass down to Earth • This is the opposing force for lift

Lift • Lift is the upward force that keeps an object off the ground • Usually provided by the wings of an aircraft or animal • Lift force must be greater than the object’s weight to keep it in the air

Thrust • This is the force a flying object produces to propel it forward • The engines on an aircraft or the wings on a bird provide thrust More thrust increases the speed, which creates more lift!

Drag • Drag is the hindering force on an object • The air in flight strikes the moving object and slows it down • This is the opposing force for thrust

Airfoil • Newton’s third law: For every action there is an equal and opposite reaction. • A moving airfoil accelerates still oncoming air over the top of the wing downward • This downwards air movement “pushes” up on the airfoil generating lift The density of the air impacts the amount of lift a wing generates!

How does an animal fly? FLOCK TALK • Unlike aircraft, flying animals provide thrust in a different way, How? • What are the ways these organisms can speed up, slow down, gain altitude, or lower in altitude?

Bird Flight • The bird creates lift forces with both forward and backward strokes of its wing similar to an airplane • https: //www. youtube. com/watch? v=4 j. Kokx. PRtck THINK-PAIR-SHARE • Why does the bird fold its wing in the backstroke?

Bird Flight • If a bird kept its wings extended in an upstroke, drag would counteract the thrust created from the downstroke FLYING SOLO • Why do we recoil our arms on the upstroke when breaststroke swimming, and why do frogs also do this?

Zero lift (Parasitic) Drag • Drag caused by air striking the parts of an object that don’t generate lift • This force increases with speed • Any parts that protrude outward severely slow the object • Streamlining the object reduces this force by minimizing protruding parts

Streamlining THINK-PAIR-SHARE – which aircraft is more streamlined? Why?

Induced Drag • Produced when High Pressure air under the wings spills over to the Low Pressure top of the wings at the wing tips • Produces trailing wing tip vortices • This spill over disrupts the ideal forward to rearward flow of air and creates a drag force • https: //www. youtube. com/watch? v=Vi. KYFs. N 3 p 24 • https: //www. youtube. com/watch? v=C-Wg. Hoo. Z 7 -Y

Air density impacts flight. CLICKER QUESTION A: True B: False

Wing inclination impacts flight. CLICKER QUESTION A: True B: False

Wing size and shape impacts flight. CLICKER QUESTION A: True B: False

Evolution time impacts flight. CLICKER QUESTION A: True B: False

Wing Loading • Total Mass/ Total Wing Area • High Wing Load • Small wing • Large Mass • Low Wing Load • Large wing • Small mass

Wing Loads CLICKER QUESTION Which wing load do birds of prey have? A: Low B: High

Wing Loads CLICKER QUESTION Which wing load do gliding birds have? A: Low B: High

Wing Loads CLICKER QUESTION Which wing load do animals that live in forests and crowded habitats have? A: Low B: High

Wing Loads CLICKER QUESTION Which wing load do diving birds have? A: Low B: High

Concept Questions FLYING SOLO • What other variables could affect an object’s flight performance? • Thermal Currents • Wind • Why do you think flocks of birds fly in a “V” formation skein? • To cancel induced drag vortices and improve efficiency.