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Force exerted on a body as it moves through air or gas
The aerodynamic force is the resultant
vector
from adding the lift vector, perpendicular to the flow direction, and the drag vector, parallel to the flow direction.
Forces on an
aerofoil
.
In
fluid mechanics
, an
aerodynamic force
is a
force
exerted on a body by the
air
(or other
gas
) in which the body is immersed, and is due to the
relative motion
between the body and the gas.
Force
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There are two causes of
aerodynamic
force:
[1]
: §4.10
[2]
[3]
: 29
Pressure acts normal to the surface, and shear force acts parallel to the surface. Both forces act locally. The net aerodynamic force on the body is equal to the pressure and shear forces
integrated
over the body's total exposed area.
[4]
When an
airfoil
moves relative to the air, it generates an aerodynamic force determined by the velocity of relative motion, and the
angle of attack
. This aerodynamic force is commonly resolved into two
components
, both acting through the
center of pressure
:
[3]
: 14
[1]
: § 5.3
- drag
is the force component parallel to the direction of relative motion,
- lift
is the force component perpendicular to the direction of relative motion.
In addition to these two forces, the body may experience an aerodynamic
moment
.
The force created by
propellers
and
jet engines
is called
thrust
, and is also an aerodynamic force (since it acts on the surrounding air). The aerodynamic force on a powered airplane is commonly represented by three
vectors
: thrust, lift and drag.
[3]
: 151
[1]
: § 14.2
The other force acting on an aircraft during flight is its
weight
, which is a
body force
and not an aerodynamic force.
See also
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References
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