A LIGHTWEIGHT 6-DOF FLIGHT DYNAMICS MODEL WITH STABILITY-AUGMENTED EULER INTEGRATION FOR REAL-TIME DESKTOP TRAINING SIMULATORS

Abstract

Desktop flight simulators need physics that is cheap to run, simple to integrate, and numerically well-behaved under frame-rate-driven time steps. Certified-grade 6-DOF tools meet the last requirement by relying on aerodynamic datasets that hobbyist and student projects rarely have. This paper presents a lightweight 6-DOF flight dynamics engine for the .NET 8/WPF Flight Simulator Suite that computes forces and moments from only 14 coefficients. Its central idea is a stability-augmented semi-implicit Euler integrator: an attitude-proportional restoring moment and angular-rate damping together form a proportional-derivative (PD) attitude augmentation that keeps rotational motion bounded at variable time steps. We analyse the augmentation in closed form (natural frequency ≈ 0.9 rad/s, damping ratio ≈ 0.11) and validate the real implementation with 20 automated tests and five experiments: closed-form comparison, step response, perturbation recovery, a 2,000-run randomised robustness study, and timing. Steady states match theory to two decimals, all 1,000 disturbed zero-control runs return to level flight, no run produces a non-finite state at time steps up to 0.099 s, and one physics step costs 0.18 µs. The analysis also exposes a weakness: the shipped gains are lightly damped (70% overshoot), so we recommend retuning. The result is a low-cost, headless-testable model that complements, rather than replaces, certified-grade tools.

Index Terms—Flight dynamics, 6-DOF simulation, real-time systems, stability augmentation, Euler integration, desktop training simulators.