Computational Prediction of Nose-Down Control for the Pre-Production F/A-18E at High Angles of Attack

Abstract

Computational fluid dynamics was used to predict the longitudinal stability and control characteristi cs of the pre -production F/A -18E Super Hornet configuration with neutral and full nose -down control at high -angle -of -attack, subsonic condition s. Such data contribute to an analysis of the ability of the pilot to recover from extreme angles of attack. The calculations were made for Mach 0.082 at a Reynolds number of 1.15 million based on mean aerodynamic chord at angles of attack between 0° and 60 °. The F/A -18E was modeled with 34° leading -edge flaps, 4° trailing -edge flaps, 0° aileron deflection, a rudde r deflection of 30°, a spoiler d eflection of 60° and horizontal -tail deflections of 0° and 20°. The flow conditions and configuration corresponded to those used in tests of a 15% -scale F/A -18E wind -tunnel model tested at the 30 - by 60 -ft Full -Scale Wind T unnel at the NASA Langley Research Center in Hampton, VA. The flow solver used during this project was USM3D , which was developed by the NASA Langley Research Center. The forces and moments predicted by USM3D compared well to the wind -tunnel data for ang les of attack between 0° and 40°. For angles of attack from 40° to 60 °, however, the results from USM3D differed from the wind tunnel data . These differences are attributed to the unsteady nature of the flow and turbulence effects not adequately captured by the computations .