vertical gyro displacement and rate signals are
PRINCIPLES OF OPERATION OF ASE
equal and opposite to the CG trim/position sensor
signal at the summing point. Therefore, there is
no command for flight control movement. If the
ASE stabilizes the helicopter at reference
pitch attitude changes without the cyclic stick
attitudes (pitch and roll), altitude (collective), and
heading (yaw) selected by the pilot. ASE may be
being moved, the vertical gyro senses the
movement. Signals from the vertical gyro then
engaged before takeoff and remain engaged
during an entire mission. Stability corrections are
cause the aircraft to return to its original pitch
introduced into the flight control system so the
attitude. If the pilot desires to change the pitch
pilot always has complete control of the helicopter
attitude, the cyclic stick is moved forward or aft.
This action produces an error signal at the
through normal use of the primary flight controls.
The flight control system consists of basic ASE
summing point. As the helicopter changes attitude
to correspond with the cyclic stick position, the
and coupler systems. Basic ASE has pitch, roll,
vertical gyro pitch displacement signal increases
collective, and yaw stabilization channels; and the
until the two signals are equal and opposite again.
coupler has related pitch, roll, and collective
This becomes the new pitch reference attitude.
stabilization channels. To stabilize the helicopter
During CPLR operation in the DOPP mode,
during basic ASE and coupler operation, signals
the system compares Doppler ground speed with
representing actual attitudes, altitude, and heading
the speed selected on the ASE control panel. Any
are continuously fed into the ASE amplifier.
difference between the actual ground speed and
These signals are compared with corresponding
signals representing reference attitudes, altitude,
the selected ground speed produces an error
and heading. The amplifier ties together all sensor
signal. The error signal causes the helicopter to
change speed until the two voltages balance. An
and control panel input signals to produce stability
correction output signals.
produces a rate signal to oppose any change in
ASE compensates for any combination of
speed. This signal prevents large rapid changes in
temporary or continuous aerodynamic dis-
pitch attitude. The hover trim control panel allows
turbances met by the helicopter. The attitude
the hoist operator to provide small attitude
indicating system uses signals from the ASE rate
changes in hovering flight.
gyro, the vertical gyros, and a dc rate gyro. These
signals provide the pilot and copilot with pitch
state error signal that may exist because of the
and roll attitude and rate-of-turn information.
difference between Doppler speed and selected
ASE has time delay, system interface, and
system interlock circuits. These circuits ensure the
speed (could be caused by head or tail winds). The
compatibility of modes and associated equipment
when these modes and equipment are selected for
correction is made until the Doppler speed equals
use with ASE.
In the cable angle mode, pitch attitude from
ASE has four basic channels of operation--
the vertical gyro is compared with the cable angle
pitch, roll, collective, and yaw. These channels
(in respect to the deck of the helicopter). This
are discussed in the following paragraphs.
allows the ASE to maintain the sonar cable
vertical to the earth's surface regardless of aircraft
attitude. The cable angle error signal is processed
in a similar manner as the Doppler error signal.
Automatic pitch attitude stabilization is
An inertial velocity system (IVS) circuit
maintained continuously after ASE engagement.
becomes operational in the cable angle mode when
The vertical gyro produces a signal proportionate
the IVS control relay energizes. The voltage to
to displacement of the helicopter fuselage from
energize the relay develops when the sonar
transducer submerges to a depth below 11 feet.
through a rate network to produce a signal
When the IVS circuit is operational, outputs from
equivalent to the rate of change of pitch attitude.
The direction of the displacement and rate signals
with the Doppler velocity signal. This combination
cause the rotor blades to produce lift, returning
produces a very accurate inertially derived signal.
the fuselage to the desired attitude.
The output of the coupler also goes to a stick
A combination of CG trim and cyclic stick
trim actuator circuit. When the coupler output
position serves to provide the reference attitude.
reaches a certain level, a solenoid of the pitch
In a balanced state, the following occurs: The