(b)
During heading synchronization, an interlock signal is applied to the heading computer motor clamp circuit, which allows a power amplifier circuit to drive the heading computer. The heading computer will be driven in the direction which causes it to be synchronized with the airplane heading as sensed by the heading compass (directional gyro) system. The output of the heading computer control transformer (heading CT) is applied to summing point 4, amplified by the motor amplifier, and drives the heading servo in a direction to reduce the output of the heading CT to a null. This action produces heading synchronization because the heading CT stator is coupled to a heading synchro in the directional gyro. At this time energized switch RS-6 prevents heading CT output from being applied elsewhere in the roll control channel.
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H59402
570 Roll Channel Simplified Block Diagram
Feb 15/78 Figure 5 22-11-0
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(c) During roll attitude synchronization, airplane bank angle information from the vertical gyro is stored in the roll computer. The stored information is used to provide a reference for the roll attitude hold function in the synchronization mode. An interlock signal applied to the motor clamp circuit allows the power amplifier circuit to drive the roll computer. When the roll computer is driven to the point where the roll computer control transformer (roll CT) output is at a null, then the existing bank angle is stored in the roll CT and the roll computer resolver. The roll CT output is maintained at a null during synchronization as follows: 1) The roll CT will produce an output signal if the rotor position fails to correspond to the airplane bank angle sensed by the vertical gyro. This output signal is developed as a result of the roll CT being coupled back-to-back with the roll synchro in the vertical gyro. 2) The roll CT output signal is fed to the motor amplifier past de-energized switch RS-1 and to summing point 8. The motor amplifier and the power amplifier amplify the signal so that it drives the roll computer motor-tachometer generator. 3) The motor-tachometer generator drives the roll CT in the direction which reduces the CT output. The roll computer will continue to drive until the roll CT output reaches a null.
4) Because the resolver (RS) is ganged to a common shaft with the roll CT, it stores bank angle information simultaneously with the roll CT. The resolver has two windings, the outputs from which are proportional to the sine and cosine of bank angle. The output from the cosine winding is applied to a lift compensation circuit which derives a signal proportional to the versine (1-cosine) of bank angle. This versine signal is routed to the pitch axis where it is used to compensate for decreased vertical lift in banked turns. During synchronization, the resolver (RS) signal is inhibited from reaching summing point 7 by solid-state switch RS-2 which is energized (closed). All other signals are removed from the input of the bank rate limiter during synchronization by action of other solid-state switches.
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5) The output from the tachometer portion of the motor-tachometer generator is fed to summing point 8 to provide damping for the roll computer servo loop. Part of this tachometer signal is shunted to ground during synchronization by switches RS-3 and RS-4. The resulting decrease in tachometer feedback allows the roll computer servo loop to follow up error signals more rapidly during synchronization.
(d) Valve amplifier synchronization consists of establishing a null at the output of the valve amplifier to eliminate roll axis engagement transients. Prior to roll axis engagement, a modulated output of the valve amplifier is fed to the electronic integrator. This amplifier output is applied to the electronic integrator through de-energized switch RS-9. During synchronization, the other integrator input is grounded by switch RS-10. Therefore, any output produced by the integrator during synchronization is a result of input signals from the valve amplifier. The integrator output will be of the phase required to cancel the inputs to summing points 9 and 10, which are causing valve amplifier output. The net result of the closed synchronization servo loop is to reduce the valve amplifier output to a null.
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