Test Stand for Measurements on Lateral Stability of Rotorcraft in Ground Effect

Abstract

The unique capability of helicopters to hover close to the ground offers significant operational advantages. However, hover flight in ground effect (IGE) involves complex aerodynamic phenomena that decrease power demands while simultaneously introducing stability challenges. These effects arise from interactions among blade tip vortices, detachment vortices, and wandering stagnation point flows with recirculating regions beneath the rotorcraft. Given the proximity to the ground, even minor instabilities can cause uncomfortable motions and, in extreme cases, safety risks. Despite its importance, the transient flow topology and stability characteristics of rotorcraft operating IGE remain insufficiently understood, particularly regarding root cutout, fuselage design, trimming, and crosswind conditions. Consequently, high-quality experimental data are required to better understand the flow mechanisms and improve helicopter safety and performance during IGE operations.