Airspeed Indicator
Physical Airspeed Indicator (ASI) for the Cessna 172SP Six-Pack panel — bezel, dial, needle mechanism, and X-Plane dataref mapping.
Overview
The Airspeed Indicator (ASI) sits top-left in the classic six-pack "T" arrangement, showing indicated airspeed in knots via a sweep needle against a graduated dial with colour-coded speed arcs (white flap range, green normal range, yellow caution range, and a red line at VNE).
Construction
Like the other six-pack instruments, this gauge is built as a self-contained module:
- Bezel / Face Plate — 3D-printed bezel with a laser-cut, printed dial face showing the ASI scale and colour arcs
- Dial / Needle — single sweep needle over the printed dial face
- Internal Mechanics — stepper motor driving the needle, geared or direct-drive
- Back Housing — 3D-printed enclosure mounting to the MIP frame's instrument cutout
- PCB & Controller — ESP32 driving the stepper from the X-Plane airspeed dataref
- Lighting — edge-lit or backlit dial for night/IFR panel illumination
X-Plane Integration
sim/cockpit2/gauges/indicators/airspeed_kts_pilot
The needle follows the Skyhawk's own dial, which isn't linear: 40 kt at 30°, 100 kt at 162°, 160 kt at 268° from the zero stop. An X27.168 gauge stepper sweeps 315°, so the needle stops at about 196 kt, well past VNE (163 kt). In the Cessna 172 (six-pack) Blueprint the stepper's coils are on GPIO 13, 14, 16 and 17.
Status
Planning — design not yet started.