State-space representation of aerodynamic characteristics of an aircraft at high angles of attack

TLDR

Unsteady aerodynamic force and moment modeling is crucial for aircraft dynamics and stability at high angles of attack. The study proposes a state‑space representation of aerodynamic forces and moments for unsteady aircraft motion. The model uses internal state‑space variables—coordinates of separation points or vortex breakdown—governed by differential equations to capture separated flow around an airfoil and vortex breakdown on a slender delta wing. The model achieves good agreement with water‑ and wind‑tunnel data and shows that aerodynamic loads at high angles of attack depend strongly on motion time history.

Abstract

Mathematical modeling of unsteady aerodynamic forces and moments plays an important role in aircraft dynamics investigation and stability analysis at high angles of attack. In this article the state-space representation of aerodynamic forces and moments for unsteady aircraft motion is proposed. Consideration of separated flow about an airfoil and flow with vortex breakdown about a slender delta wing gives the base for mathematical modeling using internal variables describing the flow state. Coordinates of separation points or vortex breakdown can be taken, e.g., as internal state-space variables. These variables are governed by some differential equations. Within the framework of the proposed mathematical model it is possible to achieve good agreement with different experimental data obtained in water and wind tunnels. These high angle-of-attack experimental results demonstrate considerable dependence of aerodynamic loads on motion time history.