L3 Redfern - Wings Flashcards
How do symmetrical and asymmetrical feathers react in airflow?
symmetrical: edge-on to airflow are unstable individually, but when overlapping form a flight surface
Asymmetrical: edge-on to airflow are stable when on their own
Give 3 adaptations of the bones and joints of the pectoral girdle for flapping flight
- Large sternum or keel - to anchor the pectoral muscle, giving a lung pull and high mechanical advantage. Flight ability tends to correlate with the size of the keel
- Rigid thorax - fully ossified dorsal ad ventral ribs, strong connection between backbone and breastbone, reinforced ribcage
- Pectoral girdle - scapula, coracoid and fulcular (clavicle) forms and triangular system, this resists chest crushing pressures created by the wings during flight
Describe the outer wing skeleton of an avian wing
Fused hand and finger bones - carpals and metacarpals are fused to form a carpometacarpus
Most vertebrate wrists have 10 free carpals, birds only have 2.
Hand includes 3 digits - alula originates from digit 1 (thumb) and moved independently from the wing tip
Flight feathers are inserted over the hand and radius, ulna and humerus
What is the length of wing bones dependent on?
Species and Function
- Albatross = specialised dynamic glider - lift from secondaries is important - long radius and ulnar
- Hummingbird = a long hand is important for generating thrust - radius and ulnar are short and primaries longer
For wing bones, what are primaries, secondary’s and tertiaries?
primaries - digits
secondaries - ulnar and radius
tertiaries - humerus
What are the 2 muscles used for flight?
Pectoralis - in many species this represents 1% of total mass. Contraction pulls the wing down and generates thrust
- Supracoracoideus - important for the recovery stroke especially during take off
What happens if you cut the Supracoracoideus tendon?
The bird cannot take off but can fly at level fine
What are the 4 types of wing shape
- Elliptical wings
- High speed wings
- High aspect ration wings
- slotted high-lift wings
Describe these features about elliptical wings:
a) shape
b) speed/lift
c) example birds that have them
a) short low aspect ratio - short wing length and
b) high beat frequency, quick take off and quick acceleration, rapid turning
c) Birds of shrubbery - galliform birds, doves, woodpeckers, many passerines
Describe these features about high speed wings:
a) shape
b) speed/lift
c) example birds that have them
a) high aspect ratio - long and slender. taper to slender tips, no slots. low camber - flat profile
b) birds that feed in flight or long distance migrations
c) shore birds - swifts, hummingbirds, falcons, swallows
Describe these features about high aspect ratio wings:
a) shape
b) speed/lift
c) example birds that have them
a) extremely long and narrow, no slotting
b) high speed flight, dynamic soaring
c) albatrosses, frigate birds
Describe these features about slotted high-lift wings:
a) shape
b) speed/lift
c) example birds that have them
a) moderate aspect, deep camber, high slotting
b) high lift at slower speeds, narrower turning radius, most birds that soar a lot
c) Harks, owls, predators carrying heavy loads
What is the difference between soaring and gliding?
soaring - maintain or increase altitude without flapping
gliding - delay rate of decent by forwards movement
What are the 2 methods of soaring?
- static soaring
- uses rising air current - thermal currents, or currents from rising obstructions like cliffs - Dynamic soaring - using horizontal layering of air currents differing in velocity - e.g. wind at wave and water surface
What does static soaring require?
- longer tail and relatively short board wings
- urn in tight spirals the stay in rising currents
- slow speed needed to stay in thermal
- high camber, high slotting, increase lift at slow speeds
Describe how an albatross does dynamic soaring
-
What are the requirements of gliding and soaring?
- large size
- low wing loading/high manoeuvrability
- good turning ability
- soaring birds have relatively small breast muscles and shallow keels
Describe flapping flight
Variability throughout wing stroke cycle
- AOA
- Variable orientation of wing relative to body
- Extensive rotation and bending at the shoulder, elbow and wrist - requires a lot of flexibilities of the joints
Why is slotting of the primaries important in flapping flight?
because if you have a series of air foils one after the other, you get air flow over and between the slots: maintains laminar flow so they can gain lift at slower speeds
Where and how do primary feathers attach?
The hand - they attach to the Manus
They are responsible for providing forwards thrust and act like propellers
They do most of the flapping a they are at the end of the wing so they travel furthest through the air
Where do secondary feathers attach?
Attach to the forearm
Provide lift and act life airplane wings
Relatively stationary in sustained fliught
What 2 groups do birds i general comprise?
- Ratites
- flightless birds such as ostriches, emu etc.
- characterised by raft like sternum
- a palaeognathous palate - Carinates
- flying birds
- keeled sternum on which powerful flight muscles insert
- neognathous palate
What are the 4 sections of the avian skull?
- An upper jaw/braincase complex
- Pair of pterygoid bones
- Pair of quadrate bones
- Mandible
What are the 4 types of feather?
- down
- flight
- contour
- semiplumes
What are the 3 components of feathers?
keratin, melanin and carotenoid pigments
