(Short?) Story Identification: Generation ship, two species, air tank control, expected at destination

Question

I am looking for a (short?), possibly German, story. I read it around 1992, but it is certainly older.

It is a about a generation ship in which the human species has split into two; the ("lower") one being more savage-like, but still with intelligence, and controlling the parts of the ship with the air tanks. The human population is also still around, and there is a war between them.

There is no notion of memory loss (as in the movie Pandorum) and the aim of the mission is also still clear to the humans (unlike in Orphans of the Sky).

Humanity has since invented faster flight methods and the ship is indeed already expected at the destination...

Parts of the story are in the movie Pandorum, but then again lots is different.

Answer 1

What about Brian Aldis's non stop?

• There are two races
• It's reached a destination
• There is FTL travel

The novel's protagonist, Roy Complain, lives in a culturally-primordial tribe where curiosity is discouraged and life is solitary, poor, nasty, brutish and short. With a small group, he leaves his home and ventures into uncharted territory. The consequent discoveries will change his perception of the entire universe.

Complain's small tribe roam nomadically through corridors overrun by vegetation. After his wife is kidnapped, a tribal priest named Marapper encourages Complain to join a furtive expedition into the unexplored corridors. It is Marapper's belief that they are all living on board a moving space-craft, and that if they can reach the control room they will gain command of the entire, gargantuan vessel. _^wikipedia