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Instrument Flying Handbook
Aerodynamic Factors
Load Factor and Icing

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Instrument Flying


Table of Contents

Chapter 1. Human Factors
Chapter 2. Aerodynamic Factors
Chapter 3. Flight Instruments
Chapter 4. Section I
Airplane Attitude Instrument
Using Analog Instrumentation
Chapter 4. Section II
Airplane Attitude Instrument
Using an Electronic Flight

Chapter 5. Section I
Airplane Basic
Flight Maneuvers
Using Analog Instrumentation
Chapter 5. Section II
Airplane Basic
Flight Maneuvers
Using an Electronic Flight

Chapter 6. Helicopter
Attitude Instrument Flying

Chapter 7. Navigation Systems
Chapter 8. The National
Airspace System

Chapter 9. The Air Traffic
Control System

Chapter 10. IFR Flight
Chapter 11. Emergency

Adverse Yaw.
Figure 2-15. Adverse Yaw.

Load Factor
Any force applied to an aircraft 1.0 deflect its flight from a
straight line produces a stress on its structure; the amount of
this force is termed load factor. A load factor is the ratio of
the aerodynamic force on the aircraft to the gross weight of
the aircraft (e.g., lift/weight). For example, a load factor of 3
means the total load on an aircraft's! structure is three times
its gross weight. When designing an aircraft, it is necessary
to determine the highest load factors that can he expected in
normal operation under various operational situations. These
"highest" load factors are called "limit load factors."

Aircraft arc placed in various categories, i.e., normal, utility,
and acrobatic, depending upon the load factors they are
designed to take. For reasons of safety, the aircraft must he
designed to withstand certain maximum load factors without
any structural damage.

The specified load may be expected in terms of aerodynamic
forces, as in turns, in level flight in undisturbed air, the
wings are supporting not only the weight of the aircraft, but
centrifugal force as well. As the bank steepens, the horizontal
lift component increases, centrifugal force increases, and the
load factor increases. If the load factor becomes so great that

an increase in angle of attack cannot provide enough lift to
support the load, the wing stalls. Since the stalling speed
increases directly with the square root of the load factor, the
pilot should be aware of the flight conditions during which the
load factor can become critical. Steep turns at slow airspeed,
structural ice accumulation, and vertical gusts in turbulent
air can increase the load factor to a critical level.

One of the greatest hazards to flight is aircraft icing. The
instrument pilot must be aware of the conditions conducive to
aircraft icing. These conditions include the types of icing, the
effects of icing on aircraft control and performance, effects
of icing on aircraft systems, and the use and limitations of
aircraft deice and anti-ice equipment. Coping with the hazards
of icing begins with preflight planning to determine where
icing may occur during a flight and ensuring the aircraft is
free of ice and frost prior to takeoff. This attention to detail
extends to managing deice and anti-ice systems properly
during the night, because weather conditions may change
rapidly, and the pilot must be able to recognize when a change
of flight plan is required.