Julián Simón obtained the degree in Aeronautical Engineering of the Polytechnical University of Madrid in 1966. For more than 40 years, until his retirement in 2007, he worked in the Spanish National Institute for Aerospace Technology (INTA). He passed through all the professional positions of the Institute. However, in those 40 years, his principal tasks were related to rockets, from sounding rockets until launcher vehicles. He worked in aerodynamics, flight dynamics, solid motors and project management. He also participated in several international committees as the Spanish representative.From the beginning of his professional life he was involved in the Spanish National Aeronautical Association, being elected member of the board several times.In 1986 he obtained the degree in Philosophy in the Spanish Open University (UNED) and in 1992 the doctorate. Even when his main job was always rather intense, he tried to combine it with the History of Science, especially theorigin of the fluid mechanics, given his knowledge of that subject. He has produced two books and several articles on this matter.