Louis Renault himself conceived the new tank's overall design and set its basic specifications. He imposed a realistic limit to the FT's projected weight, which could not exceed 7 tons. Louis Renault was unconvinced that a sufficient power-to-weight ratio could be achieved with the production engines available at the time to give sufficient mobility to the heavy tank types requested by the military. Renault's most talented industrial designer, Rodolphe Ernst-Metzmaier, generated the FT's detailed execution plans. Charles-Edmond Serre, a long time associate of Louis Renault, organized and supervised the new tank's mass production. The FT's tracks were kept automatically under tension to prevent derailments, while a rounded tail piece facilitated the crossing of trenches. Because the engine had been designed to function normally under any slant, very steep slopes could be negotiated by the Renault FT without loss of power. Effective internal ventilation was provided by the engine's radiator fan, which drew its air through the front crew compartment of the tank and forced it out through the rear engine's compartment.