X-ProTurb — Professional Turbulence Engine
X-ProTurb is a FlyWithLua script that replaces the simplistic turbulence model of X-Plane 12 with a physics-based engine. Instead of a random "shake" driven by a 0–10 intensity slider, it computes turbulence from the same certification standards used to qualify full-motion Level-D airline simulators — and lets each airframe react to it individually.
Background
- Developer: sfkcyl (Safak Cayli, a Level-D simulator developer)
- Download: forums.x-plane.org
- Platforms: Windows, macOS, Linux (via FlyWithLua)
- Compatibility: X-Plane 12
- Dependency: FlyWithLua NG+
- License: Free for personal use
The Core Idea — Two Separate Systems
The engine cleanly separates "what is happening in the air?" from "how does my aircraft react to it?":
- The atmosphere carries its own physically modelled turbulence field.
- The aircraft responds according to its type — mass, wing, speed and structure are read automatically.
A light Cessna gets thrown around in the same gust that a wide-body barely notices — with no per-aircraft setup and no arbitrary intensity multiplier to guess at.
Standards
Turbulence is derived from recognised aviation norms rather than tuned curves:
- MIL-F-8785C — US military standard for flying qualities; the engine calibrates each aircraft's felt response to its certified target
- FAR 25.341 (Pratt) — FAA gust-load requirement transport aircraft are designed against
- ICAO 9625 Level-D — the highest fidelity tier for full-flight simulators used in airline pilot training
Features
- 6-DOF response: The aircraft moves in all six degrees of freedom — including true vertical heave (the sink-and-lift you feel in the seat) plus sway and surge
- Load factor Δn: Per-type variation of the g-loads via the FAR 25.341 Pratt formula, read automatically from each aircraft's geometry
- von Kármán / Dryden spectra: Two established gust models that distribute turbulence energy across realistic wavelengths instead of flat random noise
- CAT: Clear Air Turbulence using a Richardson-number model, a tropopause-locked CAT profile and Kelvin–Helmholtz billows — the insidious turbulence that strikes without visual warning
- Mountain-Wave suite: Queney lee waves, rotor zones, wave breaking, hydraulic jump (Boulder/Bora downslope windstorms) and the Scorer parameter for trapped vs. propagating waves
- CB / storm modelling: Cumulonimbus cores, hail and heavy-rain turbulence scaled to the official FAA severity bands (light → extreme)
- Fly-by-wire detection: On Airbus-style aircraft the engine recognises the electronic flight-control system and lets its control laws set the ride, the way the real aircraft would
Value in Flight Simulation
Default X-Plane turbulence is essentially a single random jitter with an intensity dial. X-ProTurb turns that into a true physics engine: the atmosphere is modelled on certification-grade standards, and every aircraft in your fleet reacts to it according to its own characteristics — no per-aircraft tuning required. A professional UI with five colour-coded tabs shows in real time what the engine is computing, including a live aircraft-recognition chip (type plus fly-by-wire or conventional) and honest readouts of every source driving the ride.
Installation
Download: forums.x-plane.org
Place the script files into Resources/plugins/FlyWithLua/Scripts/. The engine runs automatically across your whole fleet — from a glider to a heavy twin, default, freeware or study-level — with zero per-aircraft configuration.