Attitude Indicator

Physical Attitude Indicator (artificial horizon) for the Cessna 172SP Six-Pack panel — bezel, horizon mechanism, and X-Plane dataref mapping.

4 min read Updated 2026-10
Cessna 172SP

Overview

The Attitude Indicator (AI), also known as the artificial horizon, sits top-centre in the six-pack "T" arrangement. It shows aircraft pitch and roll against a moving horizon ball/disk, with a fixed miniature aircraft symbol for reference.

Construction

Like the other six-pack instruments, this gauge is built as a self-contained module:

  • Bezel / Face Plate — 3D-printed bezel with a printed roll-angle scale around the rim
  • Dial / Needle — the "dial" here is the horizon ball/disk itself rather than a needle
  • Internal Mechanics — two axes of motion (pitch and roll) are required; built as a 2-axis servo-driven horizon ball (a small round display rendering the horizon is an alternative the Blueprint doesn't cover)
  • Back Housing — 3D-printed enclosure mounting to the MIP frame's instrument cutout
  • PCB & Controller — ESP32 driving the pitch/roll mechanism (or display) from X-Plane attitude data
  • Lighting — backlighting for night/IFR panel illumination

X-Plane Integration

sim/cockpit2/gauges/indicators/roll_vacuum_deg_pilot
sim/cockpit2/gauges/indicators/pitch_vacuum_deg_pilot
sim/instruments/ah_ref_up / ah_ref_down     miniature aircraft adjust knob

The steam Skyhawk's attitude indicator is vacuum-driven, so it reads the vacuum datarefs and tumbles with a failed vacuum pump, as the real one does. Its pitch scale isn't linear: the pitch servo follows the horizon card's own travel, 0° to 90° for −90° to +90° of pitch, with level flight at 45°. In the Cessna 172 (six-pack) Blueprint roll is a servo on GPIO 13 (180° sweep), pitch a servo on GPIO 14 (90° sweep), and the adjust knob an encoder on GPIO 25 and 26.

Status

Planning — design not yet started.

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