Only the A-4E/F had APC (when modified). The A4G in RAN FAA service did not have APC. I looked in the F-8 NATOPS & online info for APC knowledge but nowt, so the description from the Skyhawk NATOPS will have to do for now.
A-4E/F & A4G Skyhawk NATOPS 1968
"
Approach Power Compensator
The approach power compensator (APC) system is installed in aircraft reworked per A-4 AFC 268-1-11-III. The APC controls the fuel control and is designed to maintain the optimum angle of attack of 17.5 units resulting in an optimum approach speed on the glide slope and during normal maneuvers in the landing pattern at any landing gross weight. Major APC components are the computer, amplifier, servo actuator, accelerometer, elevator potentiometer, angle-of-attack vane transducer, and the APC control panel.
The APC is designed to command throttle position between an approximate 70 percent rpm and an approximate military rated thrust (MTR) in response to angle of attack. The angle-of-attack signal is modified by normal acceleration and elevator control stick position. If the APC is engaged or operating when aircraft angles of attack are greater than or less than optimum, the APC will compensate by increasing or decreasing throttle position accordingly. At angles of attack greater than optimum, the APC will command an increasing throttle position until MRT (approximate) is attained or the angle of attack returns to optimum. Conversely, at angles of attack less than optimum, the APC will command a decreasing throttle position until 70 percent (approximate) rpm is attained or the angle of attack returns to optimum." [URL below is for a direct FREE - no subscription required - download to PDF described]
OneDrive:
_A4G_NATOPS_Text_Searchable+BookMarks.PDF (139Mb)
https://1drv.ms/b/s!AuYHBzTWY83LikE-...4XQ5k?e=NWQNM8