This was Foss's concept for the opening scene of Jodorovsky's 'Dune' film project, showing pirate craft attacking a spice tanker.
Never made, but there is a brilliant documentary about it all. The studios were scared of Jodorovsky and would not fund it on account of him being borderline mental. He loved 'Dune' despite having never read the book and wrote his own plot based loosely on the general idea. He had lined up Orson Wells, David Carradine and Mick Jagger to star in it, Chris Foss to design spacecraft and costumes, H.R. Giger to design the Harkonnen palace, and Dan O'Bannon (Alien) to write the script.
He cast his own teenage son to play Paul, and the poor kid spent several years in high-intensity martial arts training in readiness for the role before it got canned.
I had the 1979 annual for Disney's 'The Black Hole' as a larva, and I always loved the 'Cygnus' although it clearly absorbed most of the special fx budget. There apparently wasn't much left over to design or build the other ship, the 'Palomino'.
Compare and contrast the steampunk gothic of the one, and the Blue Peter build quality of the other, which wouldn't even get on 'Fireball XL5'.
Actually seeing the film was a massive let-down, take away the visual effects and John Barry's soundtrack, and it's chad.