1) Bird flight is enabled by Bernoulli's principle and aerodynamic properties of wings. Bernoulli's principle states that air pressure decreases where the air velocity increases over the curved upper wing surface, creating lift. 2) When air flows around a bird's wings, it bifurcates with some flowing over and some below the wing. This displacement of air causes lift. The convex upper wing surface displaces more air, creating lower pressure and higher velocity to generate lift. 3) For a bird to fly, the lift force must be greater than or equal to gravitational force, and the thrust force from wing flaps must be greater than the drag force resisting flight. The balance of these positive and negative aerodynamic forces enables

1. BIRD FLIGHT
MECHANISM
Name :
Soumyadeep chakraborty
Reg no : 211420101610009
Roll no: 14201621013
Institution : Meghnad Saha
Institute of Technology

2. MECHANISM OF FLIGHT IN BIRD
Sir George Cayley
Mechanism of flight is based on two
main point-
Bernoulli’s principle Aerodynamics Properties

3. This principle was first worked out
by Swiss mathematician DANIEL
BERNOULLI in 1738.

4. Bernoulli’s principle can be defined mathematically
V ∞ 1/P [where, V= velocity, P=Pressure.
Velocity is inversely proportional to pressure. When the pressure is least where velocity is
greatest and vice versa.
Bernoulli’s principle apply for the adult fluid flow. But in case of bird there is no fluid flow but
there is air that interact with wing. Wing act as a solid and the air act as a fluid flow.

5. When the air flow just comes towards the bird the
air bifurcate in two ways-
o Over the wing &
o Below the wing.
There is a displacement of air towards the wing that
cause the lifting of the bird.

6. • It is says that the upper surface of the wing
is convex and the lower surface of the
wing is concave.
• The concave side of the wing has the lower
surface area, so there will be less
displacement.
• Whereas, the convex side of the wing has more
surface area, so there will be more
displacement i.e., there will be less pressure and
more velocity and vice versa.

7. DUE TOTHIS PRESSURE DIFFERENCE ABOVE OR
BENEATH THE WING-
o It lift the wing up.
o The drag force is less there.

8. o There is a
forward movement
of the bird.
o lifting of the bird.
• This all causes the bird
to fly.

9. Sir George Cayley
The Aerodynamics property was first discovered by SIR GEORGE CAYLEY
IN 1809.
He called both as “THE FATHER OF AEROPLANE” and also “THE FATHER
OF AERODYNAMICS”.
 He was born in 27th Dec 1773.

10. Aerodynamics is a branch of science which deals with the interaction of
air with solid object and how air moves around this solid object.
The air exhibit different types of force on the wing and this force can be
resolved into-
 Vertical lift component perpendicular to the air.
 Backward drag component parallel to the air sting.
 We see the force due to gravitation that universally denoted by Fmg.
Lift force denote by = FL
Thrust force denoted by = FT
Drag force denoted by = FD
Gravitational force = FG

11.  Condition for the bird to fly :-
First Condition
Force of the lift must begreater or equal togravitational
force.
FT > FD 2nd Condition.
Force of thrust must be greater than drag force otherwise
bird cannot fly.

12. More+
More
Less
Less
The lift and thrust
force that are the two
+ve force due to
which the bird fly and
weight and drag are
two –ve force due to
which the bird cannot
fly because they resist
the flight of the bird.