This work presents an enhanced version of a simple model of surface fire spread, already reported in [1]. The simplicity of the original model was preserved and the 'faster than real time' simulation speed were retained. The empirical relations were replaced by physical equations using flame geometry considerations, and it now uses only two model parameters. This model was tested and validated using a large set of lab and field scale experiments, carried out across fuel beds under different slope and wind conditions. Finally, this model was implemented as the physical core of a wild fire simulation tool for field scale fires and the case of a large wild fire was successfully treated as a first code evaluation.