The development of computationally efficient aerodynamic tools is essential for the preliminary analysis of lifting surfaces, propellers, and complex configurations. While high-fidelity computational fluid dynamics (CFD) methods provide detailed flow predictions, their computational cost often limits their use in parametric studies and early-stage design. This motivates the development of lower-fidelity solvers able to retain relevant physical modelling while remaining computationally affordable. This thesis presents the development and assessment of two such solvers, implemented from scratch within an in-house numerical library at the von Karman Institute for Fluid Dynamics (VKI). The first solver, VKI-BELL, is intended for steady propeller and rotor applications.