OICC Press Communications in Nonlinear Analysis 2371-7920 13 1 2025 06 30 A Novel Approach in Elastic Flight Simulation of a Slender Flexible Vehicle to Assess the Role of Thrust Deviations in ‎Stability 10.57647/cna.2025.hpsm-8n90 EN Hossein Faveadi Department of Mechanical and Aerospace Engineering, SR.C, Islamic Azad University, Tehran, Iran Ali R. Davari Department of Mechanical and Aerospace Engineering, SR.C, Islamic Azad University, Tehran, Iran https://orcid.org/0000-0003-0101-7069 Farshad Pazooki Department of Mechanical and Aerospace Engineering, SR.C, Islamic Azad University, Tehran, Iran Majid Pouladian https://orcid.org/0000-0001-6081-6376 Journal Article 2025 06 30 Because of the linearized and simplified models, many of the existing methods for stability analysis cannot accurately simulate the real flight behavior of the flexible vehicles, so non-linear models with minimum simplification should be employed instead. However, due to the need to simultaneously solve ‎coupled complex structural ‎and aerodynamic equations in each time step, such models require massive calculations, ‎greatly reducing the simulation speed and increasing the run ‎time. In this research, the volume of computations in each time step was reduced by appropriate lookup ‎tables made from some pre-performed calculations, and as a result, a higher execution speed ‎of the simulation was achieved. With this new strategy, the role of various design inputs, such as structure stiffness, which is usually represented by the natural frequency, exerted maneuvering acceleration, propulsion force function, and roll speed on trajectory, collision accuracy, and flight stability of a flexible projectile can be achieved. Only the role of thrust function and structure flexibility has been addressed in this research. The results show that the ‎‎inherent inaccuracies in the thrust force (inherent deviation and out-centering) and ‎reduction of the ‎natural frequencies increase the effect of aeroelasticity and the probability of the flight instability of the projectile in ‎open-loop flights. General (Classic) flight simulations often neglect elastic properties, which can sometimes result in significant errors. Taking the aeroelasticity into account would result in massive calculations and computational time costs, on the other hand. This paper makes the simulation velocity much faster (to somehow close to a rigid projectile simulation) by using some pre-prepared look-up tables from existing aeroelastic run-time computations. This method has not been employed in similar aeroelastic calculations reported in the literature.