ROTARY-WING HEAD AND CONTROLS
Lift is produced by a rotor system consisting of two
fully articulated rotors. Each rotor has three fiberglass
blades. The forward rotor is driven by the forward
transmission thru a rotor drive shaft. The aft rotor is
driven by the aft transmission thru a vertical drive shaft.
The rotor head consists of a hub connected to three
pitch-varying shafts by three horizontal hinge pins.
These pins permit blade flapping. Stops on the top and
the bottom of the hub limit the blade flapping motion.
The aft rotor head is equipped with centrifugal droop
stops, which provide increased blade flapping angle for
ground and flight operation. Covers are installed on
the centrifugal droop stops, which provide increased
blade flapping angle for ground and flight operation.
The covers prevent ice accumulation on the mechanism
and ensure proper droop stop operation following
flight in icing conditions. Mounted coaxially over the
pitch-varying shafts are pitch-varying housings to which
the blade leading and lagging. Each pitch-varying shaft
is connected to the pitch-varying housing by a laminated
tie-bar assembly. The high tensile strength and low
torsional stiffness of the tie-bar retains the blade against
centrifugal force and allows blade pitch changes about
the pitch axis. Blade pitch changes are accomplished by
three pitch-varying links connected from the rotating ring
of the swashplate to the pitch-varying housing on each
rotor blade. Cyclic pitch changes are accomplished
by tilting the swashplate. Collective pitch changes
are realized by vertical movement of the swashplate.
Collective and cyclic pitch changes result from combined
control inputs by the pilot. A direct action shock
absorber is attached to the blade and to pitch-varying
housing. When the inboard end of the shock absorber is
disconnected, the blade can be folded in either direction
about the vertical hinge pin.
The rotor hub contains splines that mate with splines on
the transmission rotor shaft. Pitch shafts are connected
to the hub through the three horizontal pins. These
pins ride in bearings supported by the hub lugs. Caps
retaining the pins and bearings are secured by locking
beams. The beams connect the leading cap of one pin
with the trailing cap of the next pin.
The pitch-varying housings are connected internally to
pitch-varying shafts by flexible, laminated steel tie-bars.
The laminated tie-bar allows the pitch housing to rotate
on the pitch shaft to change blade pitch. The tie-bar is
connected to the inboard end of the pitch shaft. The
pitch arm on each housing is connected by a pitch link
to a lug on the swashplate. The pitch link raises or
lowers the pitch arm to rotate the housing on two roller
bearings on the shaft. Outboard lugs on the housing
contain bearings for the vertical hinge pin.