Throttle Quadrant
Cessna 172SP throttle quadrant — throttle, mixture, and carb heat push-pull controls with Hall-effect axis sensing.
Overview
The Cessna 172SP throttle quadrant consists of two push-pull controls mounted in the lower centre of the instrument panel:
- Throttle (black knob) — engine power
- Mixture (red knob) — fuel/air mixture
The 172SP's Lycoming IO-360 is fuel-injected, so unlike the carburetted 172 models it has no carb heat control.
Unlike the 737 MAX throttle quadrant, there are no levers — the C172 uses friction-held push-pull cables with distinctive knob colours.
Design
The quadrant housing is laser-cut from 3mm MDF or aluminium sheet and mounts flush into the sub-panel. Each control uses a 10kΩ linear potentiometer (or Hall-effect sensor) attached to a sliding shaft inside a tube.
The knob caps are 3D-printed in PLA and painted/finished to match the real aircraft:
- Throttle: black knurled knob
- Mixture: red knurled knob
Axis Mapping
| Control | X-Plane Dataref |
|---|---|
| Throttle | sim/cockpit2/engine/actuators/throttle_ratio[0] |
| Mixture | sim/cockpit2/engine/actuators/mixture_ratio[0] |
Each sensor connects to an Analog Input on an ADC1 pin of the ESP32 (GPIO 32 and 33 in the Blueprints). The controller calibrates the travel and reports a 0–1 position, which the Bridge writes to X-Plane.
Friction Mechanism
The real push-pull controls use cable friction. The replica uses an O-ring or felt pad friction fit on the sliding shaft to give a realistic resistance that holds position without snapping back.
Status
Planning — dimensional drawings in progress.