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 |
Even when the engine is operated at a fairly low speed,
the four-stroke cycle takes place several hundred times
each minute. [Figure 6-5] In a four-cylinder engine, each
cylinder operates on a different stroke. Continuous rotation
of a crankshaft is maintained by the precise timing of the
power strokes in each cylinder. Continuous operation of the
engine depends on the simultaneous function of auxiliary
systems, including the induction, ignition, fuel, oil, cooling,
and exhaust systems.
Figure 6-5. The arrows in this illustration indicate the direction of
motion of the crankshaft and piston during the four-stroke cycle.
The latest advance in aircraft reciprocating engines was
pioneered in the mid-1960s by Frank Thielert, who looked
to the automotive industry for answers on how to integrate
diesel technology into an aircraft engine. The advantage
of a diesel-fueled reciprocating engine lies in the physical
similarity of diesel and kerosene. Aircraft equipped with a
diesel piston engine runs on standard aviation fuel kerosene
which provides more independence, higher reliability, lower
consumption, and operational cost saving. |
In 1999, Thielert formed Thielert Aircraft Engines (TAE)
to design, develop, certify, and manufacture a brand-new
Jet-A-burning diesel cycle engine (also known as jet-fueled
piston engine) for the GA industry. By March 2001, the first
prototype engine became the first certified diesel engine
since World War II. TAE continues to design and develop
diesel cycle engines and other engine manufacturers such as
Société de Motorisations Aéronautiques (SMA) now offer
jet-fueled piston engines as well. TAE engines can be found
on the Diamond DA40 single and the DA42 Twin Star, the
first diesel engine to be part of the type certificate of a new
original equipment manufacturer (OEM) aircraft.
These engines have also gained a toehold in the retrofit
market with a supplemental type certificate (STC) to reengine
the Cessna 172 models and the Piper PA-28 family.
The jet-fueled piston engines technology has continued to
progress and a full authority digital engine control (FADEC,
discussed more fully later in the chapter) is standard on such
equipped aircraft which minimizes complication of engine
control. By 2007, various jet-fueled piston aircraft had logged
well over 600,000 hours of service.
Propeller
The propeller is a rotating airfoil, subject to induced drag,
stalls, and other aerodynamic principles that apply to any
airfoil. It provides the necessary thrust to pull, or in some
cases push, the aircraft through the air. The engine power is
used to rotate the propeller, which in turn generates thrust
very similar to the manner in which a wing produces lift.
The amount of thrust produced depends on the shape of the
airfoil, the angle of attack of the propeller blade, and the
revolutions per minute (rpm) of the engine. The propeller
itself is twisted so the blade angle changes from hub to tip.
The greatest angle of incidence, or the highest pitch, is at the
hub while the smallest angle of incidence or smallest pitch
is at the tip. [Figure 6-6]
The reason for the twist is to produce uniform lift from the
hub to the tip. As the blade rotates, there is a difference in
the actual speed of the various portions of the blade. The tip
of the blade travels faster than the part near the hub, because
the tip travels a greater distance than the hub in the same
length of time. [Figure 6-7] Changing the angle of incidence
(pitch) from the hub to the tip to correspond with the speed
produces uniform lift throughout the length of the blade. A
propeller blade designed with the same angle of incidence
throughout its entire length would be inefficient because as
airspeed increases in flight, the portion near the hub would
have a negative angle of attack while the blade tip would
be stalled. |
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