The Viking engine is a gas generator storable propellant engine that powers the Ariane 4 first and second stages as well as the liquid strap-on boosters.  The Viking development program began in 1973 as part of Europe's effort to develop an indigenous launch capability.   Final qualification of the Viking 4A and 5A engines occurred in 1979 and the engines went on to power the first and second stages of the Ariane 1.  SEP continued to perfect and upgrade the engine and the Viking 4B and 5B engines powered the first and second stages of the Ariane 3.   For the Ariane 4 launch vehicle, SEP developed the upgraded Viking 5C to power the first (core) stage and the Viking 6 to power the liquid strap-on boosters.  By June 1st, 1995, SEP had produced 710 Viking engines accumulating 114,400 seconds (31.8 hours) of total run time (71,200 seconds in flight).