Non-stop seems to be such a blatant rip-off. **Universe ** and Common Sense was published in 1941, when Aldiss was 16. It’s not unlikely that he read Astounding, but then, I have no clue if he actually did.
What I want to know, if someone remembers or knows (because my research online didn’t turn up anything), was there ever a controversy about the similarities?
No “controversy” I can recall. It was just another author’s attempt at the standard “Generation Ship” story.
There are still only seven basic plots – the challenge is to see how well a given author tells the story.
I think it is 99.9% certain that Aldiss read the Heinlein books. I’m also pretty certain that Heinlein didn’t mind, since what you do with ideas is more important than reusing them. I don’t recall a comment on NonStop, but he wasn’t at all upset by Gerrold ripped off Martian Flatcats as tribbles.
There have been plenty of other books on generation ships, if not all having the forget where they are plotline. Poul Anderson had one from the '50s, and Panshin had Rite of Passage to name two off the top of my head.
I want to read a prequel to Orphans of the Sky: the story of the mutiny. Why did so many of the crew follow “Huff the accursed, the first to sin”? What was the legitimate captain doing to get everyone all riled up?
The “generation ship” concept dates back to J. D. Bernal’s The World, the Flesh and the Devil, anyway - a book of speculative essays which pre-dates Heinlein’s story by a number of years. (And I’m not even certain Bernal was the first to come up with it either.)