Final Year Project2021–2022

Low-Order Model of a Rotary-Wing Aircraft

Real-time aerodynamic simulation using Blade Element Theory in Unity

C#UnityMATLABAerodynamicsSimulation

I built a real-time, interactive helicopter aerodynamics model in the Unity game engine using Blade Element Theory. It bridges the gap between slow engineering simulators and unrealistic video game physics. When benchmarked against MATLAB, it produced the exact same thrust and torque values, but executed in just 0.02 seconds (only 1.36% of MATLAB's compute time). Awarded 72/100 and published open-source under the MIT License.

The dissertation, 'Real-Time Low-Order Model of a Rotary-Wing Aircraft,' details the development of an interactive, physics-based helicopter simulation built entirely within the Unity game engine. The core objective was to bridge the gap between traditional engineering software (mathematically rigorous but computationally heavy and non-interactive) and commercial video game engines (real-time visuals but typically fake aerodynamic physics).

I utilised Blade Element Theory (BET) and C# scripting to compute dynamic aerodynamic forces on the fly, relying on Unity's native Nvidia PhysX engine. The project explored three distinct modeling approaches:

Method A (Aerodynamic Objects): A highly modular, object-oriented approach where independent plate elements are joined together manually. This allows for physical structural flex but naturally omits induced velocity effects.

Method B (Procedural Geometry): A script-driven implementation of Blade Element Momentum Theory (BEMT) that procedurally generates the rotor at runtime. This method successfully calculates induced velocity, capturing complex flight states.

Method C (Hybrid): An experimental paradigm attempting to combine Method A's structural modularity with Method B's real-time inflow calculations.

The testing phase strongly validated the model's accuracy and efficiency. When benchmarked against an industry-standard MATLAB BEMT solver, Unity's Method B produced the exact same thrust and torque values. Crucially, Unity completed these calculations in just 0.02 seconds. This open-source project proves that quantitatively accurate aerodynamics can be executed natively in real time, serving as a zero-cost, highly accessible tool for aerospace academics and game developers.

Awarded 72/100, University of Manchester FYP
Real-time simulation using BEMT in C#/Unity
Validated against MATLAB with identical results, 98.64% faster
MIT licensed, open-source on GitHub

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The Problem With Every Flight Simulator and Video Game Out There

You want to simulate a helicopter. The engineering world offers high-fidelity software like HeliDyn+ or MATLAB: mathematically rigorous, but computationally heavy and non-interactive. The gaming world offers commercial engines where helicopters use completely fake physics (a decorative visual mesh with an arbitrary upward vector for lift). Change the blade pitch or atmospheric density dynamically, and the physics engine has no idea how to respond.

This creates an uncomfortable gap. Academics and students are stuck with sterile, non-interactive numerical code, while game developers are stuck with arcade-like mechanics that violate basic physics. The Real-Time Low-Order Model was built to bridge this divide.

What It Is

An open-source, lightweight aerodynamic flight model built entirely within the Unity game engine using custom C# scripting. It computes real-time aerodynamic forces acting on rotary-wing aircraft at runtime using Blade Element Theory (BET). Users can actively modify control inputs (RPM, blade pitch) and see the immediate, physically plausible consequences on vehicle kinematics.

The Modeling Philosophy: Physical, Not Magically Baked

Most real-time virtual assets rely on pre-calculated lift-and-drag curves. This model doesn't. The engine strips the blade down to its core geometry, assigning explicit chord, thickness, and thickness-to-chord ratio. Instead of complex lifting-line theories that slow execution, the model uses thin-airfoil theory approximations, substituting standard lift and drag coefficients with explicit normal and axial force vectors. It trades away minor secondary effects (tip vortex shedding) for massive gains in computational speed, a calculated architectural trade-off.

Three Methods, Real-Time Physics

Method A (Aerodynamic Objects): A purely object-oriented approach where independent plate elements are manually bound together using configurable joints, allowing spring limits for structural blade flex, twist, and custom wing tapers.

Method B (Procedural Geometry): A script-driven model that procedurally generates the entire rotor at runtime from raw parameters (Radius, Chord, Element Count), integrating Disk Actuator Theory to live-calculate induced velocity effects and capture vortex ring states during descent.

Method C (Hybrid): An experimental paradigm attempting to link Method A's modular structural freedom with Method B's live induced-velocity calculations.

Results

When benchmarked against an industry-standard MATLAB BEMT solver with identical parameters, Unity's Method B produced the exact same thrust and torque values. Crucially, Unity completed these calculations in just 0.02 seconds: only 1.36% of the time MATLAB required. The project was awarded 72/100 from the University of Manchester and published open-source under the MIT License.

What It Demonstrates

Technically: that highly responsive, quantitatively accurate aerodynamic behaviors can run natively inside a real-time game engine at 60+ FPS without an expensive engineering backend. Philosophically: that a physics asset doesn't need to choose between being a dense, non-interactive mathematical black box or a fake visual illusion. By making calculated structural simplifications, you can create open-source tools that are accessible to engineering students and game developers alike.

Low-Order Model of a Rotary-Wing Aircraft

Key Highlights

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