Cessna 172SP

Overview

The Cessna 172SP project is a full-scale home cockpit build based on the world's most popular training aircraft. The defining feature of this build is a modular Main Instrument Panel (MIP): the entire instrument panel is designed as a self-contained, drop-in module that can be swapped between a classic six-pack steam-gauge layout and the Garmin G1000 glass cockpit variant — without modifying the cockpit frame, seat structure, or any permanent hardware.

This gives full flexibility to fly either the traditional analogue C172SP or its modern glass-panel counterpart, using the same physical cockpit shell.

Modular MIP Design

The MIP is the centrepiece of this build. Rather than committing permanently to one avionics variant, the panel is engineered as a bolt-in module:

• Standard Six-Pack MIP — six analogue flight instruments, a KAP 140 autopilot, a GNS 430W radio stack, and classic push-pull engine controls
• G1000 MIP — dual 10.4-inch displays (PFD + MFD), a GFC 700 autopilot glareshield, and a Garmin audio panel

Swapping panels means unbolting the current module, disconnecting a single wiring harness, and bolting in the other. All switches, circuit breakers, throttle quadrant, yoke, and rudder pedals remain in place — only the instrument panel face changes.

Design Goals

• Full-scale cockpit frame with accurate C172SP geometry
• Drop-in panel modules — both variants fit the same cutout and harness connector
• Yoke — Honeycomb Alpha or custom-built with aileron/elevator axis
• Throttle quadrant — real aircraft-style push-pull knobs for throttle, mixture, and carb heat
• Rudder pedals with toe brakes
• Full X-Plane 12 integration for both avionics variants

Six-Pack (Standard) Panel

The classic layout replicates the analogue C172SP instrument panel, with a traditional "T" arrangement of flight instruments.

Analogue instruments are driven by ESP32 controllers using servo motors or stepper-driven gauges, with all values sourced from X-Plane 12 datarefs.

G1000 Panel

The glass-panel layout replicates the G1000-equipped C172SP. Most flight data is rendered on-screen, reducing the number of physical instruments needed and making this variant faster to build and iterate.

Both PFD and MFD are driven by 10.4-inch monitors running X-Plane 12 with the Laminar G1000 plugin.

Current Status

The project is in the planning and research phase. Panel dimensions are being sourced from reference photographs and the Cessna 172SP Pilot's Operating Handbook. The MIP module system is being designed in Fusion 360, with a focus on making the swap mechanism clean and repeatable.

Planned Sub-Pages

Documentation for this project will grow to cover:

• MIP Module System — frame design, swap mechanism, wiring harness connector
• Six-Pack Panel — instrument layout, stepper/servo gauge integration, X-Plane dataref mapping
• G1000 Panel — display mounting, bezel fabrication, X-Plane plugin setup
• GFC 700 / KAP 140 Autopilot — physical encoder panels and software mapping
• Radio Stack — audio panel and transponder replica
• Yoke & Rudder Pedals — hardware selection and integration

Simulator Integration

Both panel variants integrate with X-Plane 12 via CockpitConnect. Below are the key datarefs and commands relevant to hardware integration across both avionics configurations.

Key Datarefs

# Autopilot (shared)
sim/cockpit2/autopilot/altitude_dial_ft
sim/cockpit2/autopilot/heading_dial_deg_mag_pilot
sim/cockpit2/autopilot/airspeed_dial_kts
sim/cockpit2/autopilot/vs_velocity_fpm
sim/cockpit2/autopilot/autopilot_state
sim/cockpit2/autopilot/approach_status
sim/cockpit2/autopilot/nav_status
sim/cockpit2/autopilot/altitude_hold_status
sim/cockpit2/autopilot/heading_status
sim/cockpit2/autopilot/vertical_mode

# Analogue flight instruments (six-pack)
sim/cockpit2/gauges/indicators/airspeed_kts_pilot
sim/cockpit2/gauges/indicators/altitude_ft_pilot
sim/cockpit2/gauges/indicators/vvi_fpm_pilot
sim/cockpit2/gauges/indicators/heading_electric_deg_mag_pilot
sim/cockpit2/gauges/indicators/pitch_deg_pilot
sim/cockpit2/gauges/indicators/roll_deg_pilot
sim/cockpit2/gauges/indicators/turn_rate_roll_deg_pilot

# Radios
sim/cockpit2/radios/actuators/com1_frequency_hz
sim/cockpit2/radios/actuators/com2_frequency_hz
sim/cockpit2/radios/actuators/nav1_frequency_hz
sim/cockpit2/radios/actuators/nav2_frequency_hz
sim/cockpit2/radios/actuators/transponder_code
sim/cockpit2/radios/actuators/transponder_mode
sim/cockpit2/radios/actuators/audio_selection

# G1000-specific (glass panel variant)
sim/cockpit2/g1000/pfd/...
sim/cockpit2/g1000/mfd/...
sim/cockpit2/g1000/buttons/...
sim/cockpit2/g1000/knobs/...

# Flight controls
sim/cockpit2/controls/yoke_pitch_deg
sim/cockpit2/controls/yoke_roll_deg
sim/cockpit2/controls/rudder_ratio
sim/cockpit2/controls/brake_ratio
sim/cockpit2/controls/flap_ratio
sim/cockpit2/engine/actuators/throttle_ratio_all
sim/cockpit2/engine/actuators/mixture_ratio_all

# Switches & Annunciators
sim/cockpit2/switches/...
sim/cockpit2/annunciators/...

# Electrical
sim/cockpit2/electrical/battery_on
sim/cockpit2/electrical/generator_on
sim/cockpit2/electrical/avionics_on
sim/cockpit2/electrical/bus_volts
sim/cockpit2/electrical/bus_amps

Key Commands

# Autopilot (shared)
sim/autopilot/altitude_hold
sim/autopilot/heading
sim/autopilot/vertical_speed
sim/autopilot/level_change
sim/autopilot/approach
sim/autopilot/nav
sim/autopilot/altitude_up
sim/autopilot/altitude_down
sim/autopilot/heading_up
sim/autopilot/heading_down
sim/autopilot/vertical_speed_up
sim/autopilot/vertical_speed_down

# Radios
sim/radios/com1_standy_flip
sim/radios/com2_standy_flip
sim/radios/nav1_standy_flip
sim/radios/nav2_standy_flip
sim/transponder/transponder_ident

# G1000 (glass panel variant)
sim/G1000n1/PFD_softkey1
sim/G1000n1/PFD_softkey2
sim/G1000n1/PFD_softkey3
sim/G1000n1/PFD_softkey4
sim/G1000n1/PFD_softkey5
sim/G1000n1/PFD_softkey6
sim/G1000n1/PFD_softkey7
sim/G1000n1/PFD_softkey8
sim/G1000n1/PFD_direct_to
sim/G1000n1/PFD_menu
sim/G1000n1/PFD_fpl
sim/G1000n1/PFD_proc
sim/G1000n1/PFD_clear
sim/G1000n1/PFD_enter
sim/G1000n1/PFD_range_up
sim/G1000n1/PFD_range_down
sim/G1000n1/PFD_cursor
sim/G1000n1/PFD_group_knob_up
sim/G1000n1/PFD_group_knob_down
sim/G1000n1/PFD_page_knob_up
sim/G1000n1/PFD_page_knob_down

# Flight controls
sim/flight_controls/flaps_up
sim/flight_controls/flaps_down
sim/flight_controls/pitch_trim_up
sim/flight_controls/pitch_trim_down
sim/flight_controls/yaw_trim_left
sim/flight_controls/yaw_trim_right

# Electrical
sim/electrical/battery_1_on
sim/electrical/battery_1_off
sim/electrical/generator_1_on
sim/electrical/generator_1_off
sim/electrical/avionics_on
sim/electrical/avionics_off

What's Next

See the Build Process page for a step-by-step construction log, or jump to Electronics for a deep dive into the ESP32 wiring.