Performance and Stability of a Winged Vehicle in Ground Effect

TL;DR

This paper develops an analytical model to evaluate the effects of vehicle attitude and sink rate on the performance and stability of winged vehicles operating close to the ground, highlighting factors often neglected in ground effect studies.

Contribution

It introduces a novel analytical formulation that accounts for vehicle attitude and sink rate in ground effect, enhancing understanding of stability and performance.

Findings

Aerodynamic coefficients vary significantly with vehicle attitude and sink rate.

Vehicle stability is highly sensitive to ground proximity and orientation.

Non-linear dynamics reveal complex stability behaviors near the ground.

Abstract

Present work deals with the dynamics of vehicles which intentionally operate in the ground proximity. The dynamics in ground effect is influenced by the vehicle orientation with respect to the ground, since the aerodynamic force and moment coefficients, which in turn depend on height and angle of attack, also vary with the Euler angles. This feature, usually neglected in the applications, can be responsible for sizable variations of the aircraft performance and stability. A further effect, caused by the sink rate, determines unsteadiness that modifies the aerodynamic coefficients. In this work, an analytical formulation is proposed for the force and moment calculation in the presence of the ground and taking the aircraft attitude and sink rate into account. The aerodynamic coefficients are firstly calculated for a representative vehicle and its characteristics in ground effect are investigated. Performance and stability characteristics are then discussed with reference to significant equilibrium conditions, while the non-linear dynamics is studied through the numerical integration of the equations of motion.