Exploring Venus is difficult, so far, probes have managed to survive only few hours. However, Venus' atmosphere, composed of 96.5 % CO2 might provide an unique opportunity for a airbreathing vehicle. In this context, this paper intends to study the feasibility of a scramjet/ramjet engine for flying in Venus' atmosphere at an altitude of ~70 km. The first part of the work focuses on the choice of fuel. The most promising candidates to burn in CO2 are metals and their hydrides. In this context, the analysis of a wider range of these candidates including lithium (Li), beryllium (Be), magnesium (Mg), aluminum (Al), silicon (Si), beryllium hydride (BeH2), magnesium hydride (MgH2) and silane (SiH4) has been done. Once the fuel with better performance was chosen, weight and volume of a supersonic aircraft capable of carrying 200 kg of payload and operating range of 1000 km were estimated. The results showed that with a total weight of 995 kg it is possible to keep the size of the aircraft within the limits imposed by modern launchers, leaving enough room and mass weights for an orbital module to be attached to a future venus sound spacecraft. Nomenclature η = combustion efficiency Splan [m 2] = Wing area. Fuel V [m 3] = Volume of fuel. W fuel [kg] = weight of the fuel. W str [kg] = Weight of the structure vacuum, without payload and propellant. V tot [m 3] = Total volume