CHAPTER 7
HELICOPTERS AND TURBOSHAFT
POWER PLANTS
CHAPTER OBJECTIVES
After completing this chapter, you will be able to:
Identify helicopter flight characteristics.
Identify maintenance procedures for
helicopter transmission and rotor systems.
Recognize the purpose and major engine
c o m p o n e n t s of turboshaft engines and
helicopter transmission and rotor systems.
The lift generated by a rotating wing enables
The helicopter has become a vital part of naval
the helicopter to accomplish its unique missions
aviation. Helicopters have many uses. Some of
involving hovering and operating in confined
these uses are antisubmarine warfare (ASW),
areas. It also creates some unusual operating and
search and rescue, minesweeping, amphibious
control problems. Since rotor aerodynamics are
warfare, and the transferring of supplies and
the main difference between helicopters and fixed-
personnel between ships. Transferring of supplies
wing aircraft, let's first examine the rotor in detail.
and personnel is made through internal loading
We will then look at helicopter controls, types of
or vertical replenishment (VERTREP). The
helicopters, engines, and finally, transmission and
advantage the helicopter has over conventional
rotor systems.
aircraft is that lift and control are relatively
independent of forward speed. A helicopter can
fly forward, backward, or sideways, or it can
HELICOPTER FLIGHT
remain in stationary flight above the ground
CHARACTERISTICS
(hover). Helicopters do not require runways for
takeoffs or landings. The decks of small ships or
The rotor is subject to the same physical laws
open fields provide an adequate landing area.
of aerodynamics and motion that govern fixed-
wing aircraft flight. However, the manner in
The main difference between a helicopter and
which the rotor is subjected to these laws is much
an airplane is the source of lift. The airplane gets
more complex. Fixed-wing flight characteristics
lift from a fixed airfoil surface (wing) while the
depend upon the forward aircraft speed and
helicopter gets lift from a rotating airfoil (rotor).
control surface movements. In a helicopter, the
The word helicopter comes from the Greek words
rotational speed and pitch variations of the rotor
meaning relating wings. You may find it easier
blades determine the flight characteristics. Since
to understand how a helicopter operates by
flight is independent of forward speed, a
imagining the following: Remove the wings from
helicopter is able to move in any direction at a
a conventional aircraft and install them above the
controlled low speed.
airplane. Rotating the wings causes a low-pressure
area to form on the wings' upper surfaces and
HELICOPTER THEORY OF LIFT
provides lift. This low-pressure area and resulting
Rotor lift is explained by either of two
lift is, the same as that formed by fixed wings on
theories. The first theory uses Newton's law of
an aircraft.
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