| An unsteady, wing-following, wake-shedding vortex-lattice scheme has been developed to predict the aerodynamic forces and moments experienced by single and multi-wing configurations during coning motion. A computer code, based on the vortex-lattice scheme, has been developed and used to model the lifting-surface configuration of the F-15 fighter aircraft, consisting of the main wing, the tailplane and the two fins, in coning motion. Results have been obtained for incidences up to 35°, and coning rates up to 0.7. Comparisons made between these and experimental results of the F-15 aircraft, including the body, reveal reasonable agreement between the magnitudes and trends of the computed and experimental force and moment coefficients up to 20° incidence. However, further increase in incidence shows considerable deterioration in the accuracy of the computed results, which is attributed to wing stall and increased body influence. Neither of these effects are not taken into account in the calculation of the results. Additionally, the vortex-lattice scheme has been used to investigate the interaction between various surfaces of the F-15 configuration in coning motion. The importance of wake rollup modelling in coning motion has also been studied. A calculational procedure, based on Total Incidence Plane Aerodynamics, has also been developed in order to synthesise the aerodynamic characteristics of a circular cross-sectioned ogive cylinder in coning motion. The procedure uses nonrotary experimental data to synthesise the rotary force and moment coefficients. Comparisons made between the synthesised results and those obtained from experiment indicate that the proposed calculational procedure can be successfully implemented to determine the trends in the force and moment variations with coning rate of an ogive cylinder. The procedure has also been used to investigate the effect of coning rate and coning point location on the local and overall forces and moments of an ogive cylinder. Finally, the proposed calculational procedure has been implemented to synthesise the lateral aerodynamic coefficients of the forebody section of the F-15 and the High Incidence Research Model (HIRMII) in coning motion. The reasonably good agreement found between the synthesised coefficients and the experimental coefficients of the entire vehicle indicates that, in coning motion at high angles of attack, the long and slender forebody section of a modern fighter aircraft, or a missile, plays a major role in determining the overall lateral aerodynamic characteristics of the vehicle. |
