Numerical simulations of plume-induced flow separation around the Saturn V launch vehicle were carried out using ANSYS Fluent for a specific instant in its launch trajectory during the Apollo 11 mission. RANS simulations of the combination of internal flow through the five liquid-fueled Rocketdyne F-1 engines as well as external flow around the entire launch vehicle (Mach 4.4 at 45 km altitude) were conducted to evaluate the effect of turbulence model on plume-induced flow separation characteristics. The Spalart–Allmaras, RNG k-ϵ and the k-ω SST turbulence models were evaluated, of which the first two were seen to predict delayed flow separation on the launch vehicle by 16% and 23%, respectively, when compared to the observed separation location during the Apollo 11 launch. The k-ω SST, on the other hand, was found predict an early separation point, and it was the closest to the flight data, with a 14% difference.