The paper presents the effect of fluctuating yaw angle and wind speed on the performance of a horizontal axis airborne wind turbine of three different shell shapes for the high altitude operational conditions. For this purpose, a numerical analysis has been performed by considering the ranges of yaw angle and wind speed of 0 degrees-20 degrees and 10m/s-25m/s, respectively. The turbine shell shapes are based on the three aerofoil profiles of NACA-5415, NACA-9415 and NACA-5425 to investigates the influence of the aerofoil camber and thickness. The turbine has been modelled using a NREL Phase IV rotor with the fixed rotor radius of 2m for all shell configurations. A 3-D numerical analysis has been conducted by implementing k-omega SST turbulence model to solve the Reynolds-averaged Navier-Stokes equations. Numerical results demonstrated that the increment in both the tip speed ratio and yaw angle augmented the rotor thrust coefficient. At the high yaw angles, the buoyant shell is prone to encounter instability due to unbalancing of the aerodynamic forces subjected to the shell body. Among all the studied shell configurations, the NACA-9415 aerofoil based shell displayed the relatively higher turbine power coefficient as well as the stable operation. (C) 2018 Elsevier Ltd. All rights reserved.