This thesis is part of a project from UPM, universidad politecnica de Madrid, of designing and building an autonomous electrically powered full scale ekranoplane, a kind of vehicle that was firstly developed in the 1970s and didn't have much of a history after that. Starting from scratch a simulator for an ekranoplan with 6-dof is built for the purpose of providing a benchmarking tool for the design of advanced contollers and trajectory planners that are gonna be later developed during the course of the project. The first part addresses the issue of the aerodynamic forces, evaluating many different sources and previous works.