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Bird Adaptations for Flight
Covering of the wings are light smooth feathers
1.Reduces the force of weight
2.Reduces the force of drag
Have beaks instead of boney jaws and teeth
1.Reduces the force of weight
All flying birds have an enlarged breastbone called a sternum for flight muscle attachment
1.Aids in the force of thrust
The bodies of birds are streamlined
1.Reduces the force of drag
Light bones. Filled with air sacs and thin, tiny crosspieces to make bones stronger
1.Reduces the force of weight
Rigid skeleton to provide firm attachments for powerful flight muscles.
1.Aids in the force of thrust
Planes have similar lightweight, streamlined, rigid structures for flight
Flight styles
Maneuverability - wren, stunt plane
Speed - falcon, fighter jet
Carrying loads - pelican, cargo plane
Soaring - condor, glider
Lift
SpeedShape of the wing
wing area bernoulli effect coanda effect
Angle of attack Newton’s third law of motion
Wing area
Increased speed along a larger wing area creates a longer path of air reducing air pressure creating more lift
Larger wings produce greater lift than smaller wings. To compensate, smaller wing birds/planes need to fly faster to maintain the same lift as larger wings going faster
Question – A light glider with large wings. Does it have to go fast or slow for lift?
Question – A heavier jet with small wings. Does it have to go fast or slow for lift?
How can you tell how fast a bird/plane must fly to maintain lift?
By WING LOADING. – divide the weight by the wing area
A smaller wing load number tells you the bird/plane can fly slower while still maintaining lift.
Do thinking lab page 737
A smaller wing load number tells you the bird/plane is more maneuverable.
Aspect ratioFound by dividing wingspan by average width.
Wings with high aspect ratios have greater lift and less drag. Low aspect ratio wings can turn more quickly and are more maneuverable.
Obtaining thrustGravityFlapping wings
1. Gliding 2. Fast forward flight 3. Slow forward flight 4. Combination of the three
Running
Gliding
Birds with high aspect ratio can glide or soar almost motionless. They generally nest high on trees or ledges. And begin their thrust by jumping from their ledge.
Gliding continued
Ex: going down a ramp – gravity gives the forward thrust
To stay up for a long time, the angle between flight path and horizontal ground must be small, which reduces thrust. So drag force must be small.
Hence, long skinny wings have high aspect ratio.
Fast Forward Slow Forward Flight FlightWings move up and downLarger birdsSlow moving wingsPage 746
Wings move from side to sideSmaller birdsFast moving wingsPage 747
Combination
Most birds go between gliding and fast forwardLarger birds – gliding, fast forwardSmaller birds – gliding, slow forwardTake off – slow forwardFlight – combinationLanding – gliding, slow forward
Obtaining height
Bernoulli, coanda, speed, angle of attackThermals – upward flowing wind by convectional currentsUpdrafts – land features pushes up wind