1. (ICAO) English

2.  Stability
 Types
 Stable
 Unstable
 neutral
 Forms of stability
 Static stability
 Dynamic stability
 Planes of stability
 Longitudinal stability
 Lateral stability
 Directional stability
 Advantages

3. Have you ever thought that what actually is
stability and why do we need it ?

4. “ the property of a body that causes it, when
disturbed from a condition of equilibrium or
steady motion to develop forces that restore
the original condition”
 Now let’s learn more about the stability with
the help of few examples….

5. Every body tends to keep its stable state which
is the state of equilibrium.
 Darts is also an example of stability as its tail
keep its position stable or else it won’t be
able to hit the bull’s eye.

6. “The point in the body where the whole weight
of a body acts is called the center of gravity”
The body ahead of CG always tends to destabilize,
while the body behind the CG always tends to stabilize it

7. Stable:
“if a body achieve its position back after getting disturbed then
it is said to be stable”
Unstable:
“if a body doesn’t achieve its original position after getting
disturbed then it is known as an unstable body”
Neutral:
“if a body achieves a new position after getting disturbed then it is
said to be a neutral body”

8. There are two forms of stability
Static stability:
The initial reaction to get back to the original
position.
Dynamic stability:
The subsequent reaction of the initial reaction.

9. An object can be statically stable, unstable or
neutral. It all depends on the motion of the
object.
If the object will move towards the original
position then it is statically stable.
If it will attain a new position then it will be
statically neutral.
if it will goes out of range then we will regard it
as statically unstable.

10. In case of dynamic stability there are still the
same three cases that either an object can
be dynamically stable, unstable or neutral.

11.  There are three planes of stability.
 Longitudinal stability
 Lateral stability
 Directional stability

12. The stability along the lateral axis is called the
longitudinal stability. The control surfaces
used in longitudinal stability are elevators.
If the CP will be the leading force then the plane will pitch up and if the CP will
be behind the CG then the plane will pitch down.

13. The stability along the normal axis is known as
directional stability and its control surfaces
are known as rudder.
In this case the plane changes its direction due to the incoming air which made
an angle with the vertical stabilizer which in turn stabilize the plane by
producing a torque.
Hence we can increase the directional stability
either by increasing the area of vertical
stabilizer or by increasing the moment arm.

14. “The stability along the longitudinal axis is
called the lateral stability and the control
surfaces used in it are ailerons”
In lateral stability we discuss the side slip and
side skid.
The rolling affect is also known as banking.

16. 1. Noor-ul-ain
2. Moeez Amjad
3. Muhammad Uzair
4. Naqi Hamdani
5. Nawab Ali