Locomotion in Birds Flashcards
Flying is similar to swimming except that birds cannot generate _____ ____
passive lift (buoyancy)
How does an aerofoil work?
By creating differences in pressure.
(less pressure on top of the wing than underneath it)
(When an object is moving through a medium (air) if you tilt the object basicly the flow going under the wing has less of a distance to travel than the flow going over the top of the wing, so in going over the top of the wing theres more distance to travel therefore it has to travel faster to get from point A to B, velocity speeds up, when veloctiy speeds up you ge
ELABORATE
_______ movement of the wing pushes the body ______ generating thrust
Downward movement of the wing pushes the body forwards generating thrust
The shape wing aerofoil varies across the wing, why?
The shape of the wing aerofoil is _____ pronounced towards the tip because you dont want all of the lift out at the end of the wings as it will create alot of pressure/torque on keeping them in place, hence why the wider part of the foil is closer to the body so the chest muscles can control them better.
Less
Name A___ is located towards the ____ of the wing and the T___ W___S__ are located towards the ___
- Alula (leading edge wing flap)
- Terminal wing slots
CL =
&
CD =
Both increase the wing angle of attack
The Alula creates a slot at the leading edge of the wing that _______ the airflow over the upper surface of the wing and reduces risk of stalling
(Like the flaps that project on a aeroplane wing upon take off during the high angle take off)
Accelerates
Explain this
As airspeed increased
form drag increases
enduced drag decreases
What is going on here?
Wing tipped vortices
Development of wingtip vortices as a result of enduced drag where air is trying to move around the wing to equlaise the pressures. Varies with shape of the wing.
High aspect ratio wings like the shearwater give you less of what and more of what?
less induced drag but more profile drag snd greater bending stress.
(Low aspect ratio birds such as pheasents have low speed manouverability, high roll rate but greater induced drag)
Wing tip primary feathers _____ induced drag and create lots of ____ ____ rather than large ones
A. Dissapate
B. Small eddies
An engineering solution to reducing airflow at the end of the wing and reduce drag is…
Blended winglets. They are upturned wings on planes which significantly decreases the vortex size and amount of drag created by the plane. Creates a huge amount of turbulence which can cause a smaller plane to crash if it hits the ‘rough patch’ of air.
- You can alter the geometry of the wing for different amounts of lift
- Here you can see a plane coming into land
(Trailing edge flaps out for larger surface area for more lift as when the plane slows down it decreases the chance of a stall)
(When the plane is at cruising altitude, the plane retracts these flaps in order to reduce the over all surface of the wing in order to reduce drag)
Just cool to know
Why do birds fly in V formation?
- One leading bird
- Trailing birds positioned in V formation take advantage of vortex-induced upwash created by the leading bird which saves energy.
Feathers
Primary feathers provide a smooth surface but are
light and compliant
(the surface is not rigid)
-acts like whale blubber in the water = less turbulence
What is induced drag?
that part of the drag on an aerofoil which arises from the development of lift.
