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Pilot's Handbook of Aeronautical Knowledge
Aircraft Systems
Powerplant

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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

Changes in propeller blade angle from hub to tip.
Figure 6-6. Changes in propeller blade angle from hub to tip.

Relationship of travel distance and speed of various portions of propeller blade.
Figure 6-7. Relationship of travel distance and speed of various
portions of propeller blade.

Small aircraft are equipped with either one of two types
of propellers. One is the fixed pitch, and the other is the
adjustable pitch.

Fixed-Pitch Propeller
A propeller with fixed blade angles is a fixed-pitch propeller.
The pitch of this propeller is set by the manufacturer and
cannot be changed. Since a fixed-pitch propeller achieves
the best efficiency only at a given combination of airspeed
and rpm, the pitch setting is ideal for neither cruise nor
climb. Thus, the aircraft suffers a bit in each performance
category. The fixed-pitch propeller is used when low weight,
simplicity, and low cost are needed.

There are two types of fixed-pitch propellers: climb and
cruise. Whether the airplane has a climb or cruise propeller
installed depends upon its intended use. The climb propeller
has a lower pitch, therefore less drag. Less drag results in
higher rpm and more horsepower capability, which increases
performance during takeoffs and climbs, but decreases
performance during cruising flight.

The cruise propeller has a higher pitch, therefore more
drag. More drag results in lower rpm and less horsepower
capability, which decreases performance during takeoffs and
climbs, but increases efficiency during cruising flight.

The propeller is usually mounted on a shaft, which may be
an extension of the engine crankshaft. In this case, the rpm
of the propeller would be the same as the crankshaft rpm. On
some engines, the propeller is mounted on a shaft geared to
the engine crankshaft. In this type, the rpm of the propeller
is different than that of the engine.

In a fixed-pitch propeller, the tachometer is the indicator of
engine power. [Figure 6-8] A tachometer is calibrated in
hundreds of rpm and gives a direct indication of the engine
and propeller rpm. The instrument is color coded, with a green
arc denoting the maximum continuous operating rpm. Some
tachometers have additional markings to reflect engine and/or
propeller limitations. The manufacturer's recommendations
should be used as a reference to clarify any misunderstanding
of tachometer markings.

Engine rpm is indicated on the tachometer.
Figure 6-8. Engine rpm is indicated on the tachometer.

The rpm is regulated by the throttle, which controls the
fuel/airflow to the engine. At a given altitude, the higher
the tachometer reading, the higher the power output of the
engine.

 

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