Bird+Feathers

=Feathers=

It is the shape of the wing that enables a bird to fly and the shape is formed by the feathers.
www.savalli.us/LSC294/Labs/12.BirdEvol.html || =Wing and Tail feathers=
 * [[image:bird21.jpg width="469" height="481"]]

Flight feathers are specialized contour feathers.
. =Wing Feather Technology:= . || friendsofblackwater.org || ====.==== =Notched feathers= naturebytom.blogspot.co.nz ||. =Tail feathers= =Streamlining with barbs, barbules and hooks= www.nurseminerva.co.uk/adapt/feathers.htm || =Feather Vanes= =Danger! Take-off and Landing=
 * ====an especially rigid shaft====
 * ====light, broad vanes====
 * ====overlapping to reduce friction and drag====
 * ====narrow, stiffer vane edge towards to wind for strength====
 * ====covered along the leading edge by smaller contour feathers called coverts which shape the airfoil====
 * ====shaped to twist and tilt in flight (remember why this is important? Click here)====
 * ====the twist is similar to a propeller which only turns half-circle====
 * ====Notched to make slots to prevent stalling (see below)====
 * ====Alula feathers which make a specialized slot====
 * ====Each wing flight feather has a notch on the leading edge of the vane.====
 * ====The notches leave spaces (slots) between the feathers when the wing is spread.====
 * ====Air speed is increased through the slots to increase lift.====
 * ====This helps even out airflow and prevent stalling.====
 * ====Feathers on the **alula** can spread to make an exta slot and increase **lift**.====
 * ====Raising the feathers on the leading edge of the wing also makes slots.==== ||
 * [[image:bird24.JPG width="480" height="311" align="center"]]
 * ====the tail acts as the rudder to balance and steer the bird.====
 * ====tail feathers have vanes of equal sizes====
 * ====can be tipped in different directions for stability====
 * ====can be spread in flight to increase the surface are to get more lift====
 * ====the whole tail can be twisted to change direction====
 * ====feathers turn downwards to make a brake when landing==== ||
 * [[image:bird17.jpg width="380" height="296"]]
 * ====Vanes are made up of hundreds of branches called barbs====
 * ====Barbs angle towards the tip of the feather====
 * ====Each barb has tiny branches of its own called barbules====
 * ====The vanes are smooth because of the barbs and barbules====
 * ====Barbules on the edes on the barbs facing the tip of the feather have microscopic hooks====
 * ====Barbules on the side facing the base of the feather have rounded ridges====
 * ====The hooks on the barbules of one barb catch the ridges of the next barbule====
 * ====The barbules are held together like a zip====
 * ====This zip gives a solid almost airtight surface====
 * ====As the feather tilts and twist during flight the hooks slide back and forth to keep the feather surface smooth and flexible.====
 * ====Birds zip up their feathers by preening.==== ||

Less speed is need for landing
. www.jrcompton.com || www.jrcompton.com || =How it works...=
 * Take-off: More air speed needed to create lift. || Landing: Less air speed needed to reduce lift. ||
 * [[image:bird26.jpg width="449" height="320"]]

Birds change air speed by:

 * ====changing their wing size. Why?====
 * ====altering the angle of their wing to the wind. Why?====
 * ====lowering vane flaps. Why?====
 * ====opening slots. Why?====
 * ====using existing wind. Why?====
 * ====increase the speed of their propellers by flapping their wingsfaster. Why?====

=Your Final Challenge:=

centre of gravity, streamlining, angle of attack, air resistance, stall, air speed, airfoil
www.jrcompton.com || www.jrcompton.com || Left: www.jrcompton.com Right: animalszooguru.blogspot.co.nz ||
 * [[image:bird27.jpg width="678" height="388"]]
 * [[image:bird28.jpg width="694" height="286"]]
 * [[image:bird_29.jpg width="437" height="387"]] [[image:bird30.jpg width="309" height="396"]]