KAP 140 Autopilot
Physical Bendix/King KAP 140 autopilot control unit for the Six-Pack glareshield — 3D-printed bezel, illuminated buttons, encoder knobs, and X-Plane mapping.
Overview
The Bendix/King KAP 140 is the two-axis autopilot fitted to the Six-Pack variant of the 172SP. It sits on the glareshield and provides autopilot engage, heading, navigation, approach, altitude hold, and vertical speed modes, plus an altitude alerter.
This page covers the physical build of the KAP 140 control panel — the bezel, button layout, encoder knobs, and integration with X-Plane.
Panel Layout
| Control | Type | Function |
|---|---|---|
| AP | Illuminated pushbutton | Autopilot engage/disengage |
| HDG | Illuminated pushbutton | Heading mode |
| NAV | Illuminated pushbutton | NAV/GPS track |
| APR | Illuminated pushbutton | Approach mode |
| REV | Illuminated pushbutton | Reverse/backcourse mode |
| ALT | Illuminated pushbutton | Altitude hold |
| VS/ARM | Illuminated pushbutton | Vertical speed mode |
| BARO | Pushbutton | Baro-corrected altitude alerter |
| UP / DN | Pushbuttons | Vertical speed pitch wheel |
| HDG knob | Rotary encoder | Heading bug (shared with HI) |
| ALT knob | Rotary encoder | Altitude alerter / VS target |
Construction
The bezel is 3D-printed in PLA and painted to match the glareshield. Illuminated pushbuttons use 12mm momentary switches with integrated LEDs, driven by ESP32 digital outputs. The encoder knobs are 3D-printed caps over 24-pulse rotary encoders.
X-Plane Integration
# Datarefs (shared autopilot)
sim/cockpit2/autopilot/autopilot_state
sim/cockpit2/autopilot/heading_status
sim/cockpit2/autopilot/altitude_hold_status
sim/cockpit2/autopilot/vertical_mode
sim/cockpit2/autopilot/heading_dial_deg_mag_pilot
sim/cockpit2/autopilot/altitude_dial_ft
# Commands
sim/autopilot/servos_on
sim/autopilot/heading
sim/autopilot/NAV
sim/autopilot/approach
sim/autopilot/altitude_hold
sim/autopilot/vertical_speed
sim/autopilot/heading_up
sim/autopilot/heading_down
sim/autopilot/altitude_up
sim/autopilot/altitude_down
Status
Planning — bezel design not yet started.