flight controls to be transmitted to the rotary-wing
blades. The sleeve and spindle and blade dampers allow
limited movement of the blades in relation to the hub.
These movements are known as lead, lag, and flap.
! Lead occurs during slowing of the drive
mechanism when the blades have a tendency to
remain in motion.
! Lag is the opposite of lead and occurs during
acceleration when the blade has been at rest
and tends to remain at rest.
! Flap is the tendency of the blade to rise with
high-lift demands as it tries to screw itself
upward into the air.
Antiflapping stops and droop stops restrict flapping
and conning motion of the rotary-wing head and blades
at low rotor rpm when slowing or stopping.
TAIL ROTOR GROUP
The directional control and antitorque action of the
helicopter is provided by the tail rotor group.
See
4-17
BLADE FOLD
ACTUATOR
FAIRING
BIFILAR
DAMPER
PITCH LOCK
ACTUATOR
ROTOR HUB
FOLD
HINGE
SPINDLE
ASSEMBLY
BLADE
LOCKPIN
PULLERS
ROTATING SCISSORS
LOWER PRESSURE PLATE
SWASHPLATE
PITCH CONTROL
ROD
PITCH CHANGE
HORN
ANf0119
ROTOR HEAD
BALANCE
WEIGHTS
Figure 4-19.—Main rotor head/hub assembly.
