Q17-12. What term describes the effect that occurs
The single-rotor configuration requires the use of a
when a helicopter experiences an
vertical tail rotor to counteract torque and provide
uncontrollable loss of altitude because of a
d i r e c t i o n a l c o n t r o l . T h e a d va n t a g e s o f t h i s
combination of heavy gross weight, poor
configuration are simplicity in design and effective
density conditions, and low forward speed?
directional control. In the tandem rotor design, one
rotor is forward of the other. Sometimes the rotor
blades are in the same plane. They may or may not
TYPES OF HELICOPTERS
intermesh. The design offers good longitudinal
stability since lift occurs at two points, fore and aft.
LEARNING OBJECTIVE: Identify the two
The tandem rotor has little torque to overcome because
basic types of helicopters. Recognize the
these rotors rotate in opposite directions.
advantages of each type.
Q17-13. What is the most common type of helicopter?
Two basic types of helicopters are the single-rotor
and multirotor types. The single main rotor with a
Q17-14. The CH-46 multirotor helicopter has what
vertical or near vertical tail rotor is the most common
type of rotor design?
type of helicopter. The SH-60 and SH-2, shown in
Q17-15. What feature provides the single rotor
figure 17-5, are examples of single-rotor helicopters.
configuration with excellent directional
Multirotor helicopters fall into different groups
control?
according to their rotor configuration. The CH-46,
Q17-16. In what direction does a tandem rotor operate
shown in figure 17-5, is a multirotor helicopter of the
that results in little torque?
tandem rotor design.
Figure 17-5.--Representative types of naval helicopters.
17-5
