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Pilot's Handbook of Aeronautical Knowledge
Aerodynamics of Flight
Aircraft Design Characteristics

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Pilot's Handbook of Aeronautical Knowledge

Preface

Acknowledgements

Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making

Appendix

Glossary

Index

Static Stability
Static stability refers to the initial tendency, or direction of
movement, back to equilibrium. In aviation, it refers to the
aircraft's initial response when disturbed from a given AOA,
slip, or bank.
• Positive static stability—the initial tendency of the
aircraft to return to the original state of equilibrium
after being disturbed [Figure 4-18]
• Neutral static stability—the initial tendency of
the aircraft to remain in a new condition after its
equilibrium has been disturbed [Figure 4-18]
• Negative static stability—the initial tendency of the
aircraft to continue away from the original state of
equilibrium after being disturbed [Figure 4-18]

Dynamic Stability
Static stability has been defined as the initial tendency to
return to equilibrium that the aircraft displays after being
disturbed from its trimmed condition. Occasionally, the
initial tendency is different or opposite from the overall
tendency, so a distinction must be made between the two.

Dynamic stability refers to the aircraft response over time
when disturbed from a given AOA, slip, or bank. This type
of stability also has three subtypes: [Figure 4-19]

• Positive dynamic stability—over time, the motion
of the displaced object decreases in amplitude and,
because it is positive, the object displaced returns
toward the equilibrium state.
• Neutral dynamic stability—once displaced, the
displaced object neither decreases nor increases in
amplitude. A worn automobile shock absorber exhibits
this tendency.
• Negative dynamic stability—over time, the motion
of the displaced object increases and becomes more
divergent.
Stability in an aircraft affects two areas significantly:
• Maneuverability—the quality of an aircraft that
permits it to be maneuvered easily and to withstand
the stresses imposed by maneuvers. It is governed by
the aircraft's weight, inertia, size and location of flight
controls, structural strength, and powerplant. It too is
an aircraft design characteristic.
• Controllability—the capability of an aircraft to
respond to the pilot's control, especially with regard to
flightpath and attitude. It is the quality of the aircraft's
response to the pilot's control application when
maneuvering the aircraft, regardless of its stability
characteristics.

Types of static stability.
Figure 4-18. Types of static stability.
 

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