(2)
In the roll channel, the computer uses heading error signals and bank attitude signals to compute lateral steering commands. The heading error signal is supplied from the heading error control transformer in the flight director control panel and is proportional to the difference between the pilot's selected heading and the magnetic heading. The bank attitude signal is generated by the vertical gyro. In the computer, the HDG signal generated by the mode logic enables the heading error signal to pass thru the switch to the summing networks and then the bank limiter. After being limited, the error signal is summed with the bank attitude signal. The summed (difference) signal is the difference between the heading error and commanded bank (attitude) signals. The summed signal is amplified and converted to a dc signal to become the bank steering command output from the computer to the ADI.
(3)
In the pitch channel, the computer uses the pitch attitude signal and either a manual pitch or altitude error signal to compute vertical steering commands. The pitch attitude signal is supplied by the attitude reference system and is proportional to the airplane pitch angle. The manual pitch commands are supplied from the flight director control panel as selected on the pitch command knob. The air data system supplies altitude error signals during the altitude hold submode.
(4)
In the manual pitch submode; the manual pitch signals are proportional to the desired pitch attitude from horizontal as set on the pitch command knob. In the pitch channel, the pitch attitude signal is summed with the manual pitch command signal. The resultant is the difference between the actual attitude and commanded pitch. This signal is amplified and converted to a dc signal to become the pitch steering command to the ADI.
(5)
The altitude hold submode is enabled by placing the altitude hold switch on the flight director control panel to on. In the mode logic, this generates the ALT HOLD logic signal and turns the MAN PITCH logic signal off. At the summation point, the altitude error signal is summed with the pitch attitude signal from the low-pass filter (15 SEC delay network). The resultant signal is the pitch command signal that is required to maintain the desired altitude. The resultant signal is amplified and limited. It is then combined again with the pitch attitude signal. This produces a signal proportional to the difference between the commanded pitch and actual pitch. This signal is amplified and converted to a dc signal to become the pitch steering command to the ADI.
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Feb 15/79 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-26-0 Page 13
E. VOR/LOC Mode
(1)
In the VOR/LOC mode, the bank steering command signal provides steering command information to intercept and hold the selected VOR, or LOC course. The VOR/LOC position on the mode selector causes the computer pitch channel to operate in the manual pitch or altitude hold modes and the bank channel in either the VOR or LOC modes. When the navigation receiver is tuned to a localizer frequency, an ILS 28-volt dc signal is provided to the mode logic for selecting the localizer mode. In the absence of this signal, the computer will operate in the VOR mode. For VOR operation, the steering commands are limited to 25 degrees in roll and for LOC operation, the steering commands are limited to 30 degrees prior to and 15 degrees after the APPR signal has been generated. Pitch steering commands are limited to 12 degrees. The action is similar for either course, except that in LOC tighter coupling is provided. This is accomplished through logic circuits that alter the various gains and limits of the associated circuits.
(2)
In the roll channel, course error, VOR or LOC deviation rate, and roll attitude are used to generate lateral steering commands. The course error signals from the control panel are proportional to the difference between the selected course and the actual airplane heading. The radio deviation signal from the navigation receiver is proportional to the angular displacement of the airplane from the selected VOR or LOC course. The bank attitude signal is generated by the attitude reference system. These signals are applied to the complementary filter. The output of the filter is a radio damping signal which opposes the VOR or LOC deviation signal in order to prevent overshoot in following the command. The radio damping signal is combined with the direct radio deviation signal. In the LOC mode, it is again combined with the direct course error signal. The resultant is applied to the course cut limiter. The action of the limiter is to prevent intercept of the selected course at fixed heading angles greater than 30 degrees. The signal is then passed thru the bank limiter and summed with the bank attitude signal. The result is a signal that is proportional to the difference between commanded bank and actual bank attitude. The resultant signal is amplified and converted to dc signal to become the bank steering command to the ADI.
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