This is the Viking 5C engine. Four Viking 5C liquid-propellant rocket engines were used to propel the first stage of the Ariane 4 expendable launch vehicle used by the European Space Agency from 1990 to 2003.
A consortium of six countries, France, Germany, Spain, Belgium, Sweden, and Italy, designed and manufactured this engine. It uses a form of transpiration or "sweat cooling." In sweat cooling, a coolant (the fuel) is injected uniformly and continuously over the internal wall of the nozzle by using a porous wall material. The developer of this technique for the Viking was Heinz Bringer, who had worked on a similar system during the development of the German V-2 rocket of World War II. This object was donated to the Smithsonian in 2006 by SAFRAN.
Gift of SAFRAN.